Subject: Passive Solar home to be built in RI?

From: [email-masked] (NOMAD29)
Date: 9 Jun 1996 22:31:59 -0400

I've just taken a job in RI and have decided to have a passive solar home
built.  I'm  Looking for a competent architect/solar engineer and builder
for the project.  any ideas??

Also I'm seriously concidering a large massonary heater system for the
house.  Any feelings pro or con??

The settleing NOMAD

---

From: [email-masked] (Nick Pine)
Date: 11 Jun 1996 07:08:35 -0400

William R Stewart  <[email-masked]> wrote:
>NOMAD29 wrote:

It's a good idea to find an engineer to help.

>> house.  Any feelings pro or con??

Did you say you wanted a "solar" house? :-)

>I've selected a modular home built by Avis America, who participated with 
>DOE and Fully Independent Residential Solar Technology (FIRST) to design and
>build energy efficient homes that incorporate passive solar heating and
>photovoltaics.

Sounds good...

>See Solar Today Sept/Oct 1995.

That sort of house (house 1 below, essentially a Trombe wall house) is fairly
expensive and low-performance, as solar houses go, and needs a separate solar
water heating system. It gets off the mark in a house race, but quickly tires
in the backstretch, in partly cloudy climates, vs houses built with exactly
the same materials, or less expensive materials, in a different configuration.

>A builder in your area is EnerPro Engineering, Inc at 508.677.3533.
>The energy designer is Lyle Rawlings at 609.466.4495.

You might ask Lyle for the isolated gain, isolated store model :-)
 
Nick

They're off!

               Direct        Isolated      Isolated      Isolated
               gain,         gain,         gain and      store
Day            wall store    wall store    store         temp
 
 0             36 F          36 F          36 F          36 F
 1             51.625        51.625        51.625        51.625  
 2             62.06671      63.92594      64.2358       64.2358 
 3             69.04458      70            70            74.41387 
 4             70            70            70            83.32878 
 5             70            70            70            91.93831 
 6             70            70            70            100.2529 
 7             70            70            70            108.2827 
 8             70            70            70            116.0375 
 9             70            70            70            123.5266 
 10            70            70            70            130.7591 
 11            70            70            70            137.7439 
 12            70            70            70            144.4895 
 13            70            70            70            151.004 
 14            70            70            70            157.2953 
turn off the sun...
 15            58.72116      64.11539      70            150.1516 
 16            51.18385      59.24927      70            143.111 
 17            46.1469       55.22536      70            136.1719 
 18            42.78086      51.89789      70            129.3329 
 19            40.53144      49.14633      70            122.5925 
 20            39.02822      46.87101      70            115.9493 
 21            38.02367      44.98949      70            109.402 
 22            37.35235      43.43362      70            102.9491 
 23            36.90374      42.14703      70            96.58922 
 24            36.60394      41.08312      70            90.32111 
 25            36.4036       40.20335      70            84.14339 
 26            36.26971      39.47585      70            78.05479 
 27            36.18024      38.87426      70            72.054 
 28            36.12045      38.37679      66.13976      66.13976 
 29            36.08049      37.96542      60.92326      60.92326 
 30            36.05379      37.62525      56.60962      56.60962 

10 'a house race, among three 8' cube contenders, each having
20 '  R13 walls, one 8'x8' R2 window, and 4096 Btu/F of thermal mass.
30 '  House 1: a direct gain house with thermal mass in the walls.
40 '  House 2: an isolated gain house with thermal mass in the walls.
50 '  House 3: an isolated gain house with isolated thermal mass store.
60 OPEN "HROUT" FOR OUTPUT AS #1
70 PRINT#1,"They're off!"
80 PRINT#,
90 PRINT#1,"               Direct        Isolated      Isolated"
100 PRINT#1,"               gain, wall    gain, wall    gain and     store"
110 PRINT#1,"Day            store         store         store        temp"
120 PRINT#1,
130 'warmup over a long string of average Phila December days
140 RWIND=2'US R-value of window
150 RWALL=13'US R-value of walls
160 C=4096'thermal mass (Btu/F)
170 TA=36'average outdoor December temp in Phila (F)
180 SUNIN = 8*8*1000'average daily solar input (Btu)
190 TM1=36:TM2=36:TM3=36'initialize thermal mass temperatures
195 TLIM=36'initialize limiting temp
200 FOR DAY=1 TO 14'warmup over two weeks of average December days
205 FOR I=1 TO 10000:NEXT'delay loop
210 E1=24*(TM1-36)*64/RWIND+24*(TM1-36)*5*64/RWALL
220 TM1=TM1+(SUNIN-E1)/C'new thermal store temp
230 IF TM1>70 THEN TM1=70'overheating limit in sunny weather
240 E2=6*(TM2-36)*64/RWIND+18*(TM2-36)*64/RWALL+24*(TM2-36)*5*64/RWALL
250 TM2=TM2+(SUNIN-E2)/C
260 IF TM2>70 THEN TM2=70
270 E3=6*(TM3-36)*32/RWIND+18*(TM3-36)*32/RWALL
275 E3=E3+24*(TLIM-36)*(32+5*64)/RWALL
280 TM3=TM3+(SUNIN-E3)/C
285 IF TM3<70 THEN TLIM=TM3 ELSE TLIM=70
290 IF TM3>212 THEN TM3=212'water boils
295 PRINT#1, DAY,TM1,TM2,TLIM,TM3
310 NEXT DAY
340 'coming into the backstretch, a string of cloudy days
345 SUNIN=0'turn off the sun
346 PRINT#1,"turn off the sun..."
350 FOR DAY=15 TO 30'simulate two weeks of cloudy days
360 E1=24*(TM1-36)*64/RWIND+24*(TM1-36)*5*64/RWALL
370 TM1=TM1+(SUNIN-E1)/C
380 IF TM1>70 THEN TM1=70
390 E2=0*(TM2-36)*64/RWIND+24*(TM2-36)*64/RWALL+24*(TM2-36)*5*64/RWALL
400 TM2=TM2+(SUNIN-E2)/C
410 IF TM2>70 THEN TM2=70
430 E3=0*(TM3-36)*32/RWIND+24*(TM3-36)*32/RWALL
440 E3=E3+24*(TLIM-36)*(32+5*64)/RWALL
450 TM3=TM3+(SUNIN-E3)/C
455 IF TM3<70 THEN TLIM=TM3 ELSE TLIM=70
460 IF TM3>212 THEN TM3=212
470 PRINT#1,DAY,TM1,TM2,TLIM,TM3
480 NEXT DAY
500 CLOSE

---

From: William R Stewart <[email-masked]>
Date: Mon, 10 Jun 1996 05:10:38 -0400

See Solar Today Sept/Oct 1995.  A builder in your area is EnerPro Engineering, 
Inc at 508.677.3533.  The energy designer is Lyle Rawlings at 609.466.4495.

Cheers,

Will Stewart

---

From: William R Stewart <[email-masked]>
Date: Tue, 11 Jun 1996 20:34:49 -0400

> Did you say you wanted a "solar" house? :-)

A home can be passive solar AND have a fireplace.

> That sort of house (house 1 below, essentially a Trombe wall house)

It is not a Trombe wall house.

> is fairly
> water heating system.

You'll have to pardon our local eccentric, Nick Pine.  His ideas are the only
ones worth considering.  If you don't believe that, just ask him...

Nick provides a simple (but spaggetti) code exercise that somehow support
his thesis statements.  Note below how many temperatures 'magically' end 
up at 70 F.  The answer is buried in the 'code'.

> Day            wall store    wall store    store         temp

R13 walls are far below the R24 walls that are in the Avis home walls.
The R2 windows ignore the window shade insulation that would be used.

> 230 IF TM1>70 THEN TM1=70'overheating limit in sunny weather^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I've never heard of this rule before; where did you come up with this,
Nick?  The thermal store can be far above the ambient temperature of the
room.  This explains why you don't understand the concept of a masonry heater
fireplance.  Do you think that the thermal store is simply going to stop accepting
heat input?

Have you no shame?

> 260 IF TM2>70 THEN TM2=70
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
More bogus rules.

> 380 IF TM1>70 THEN TM1=70
^^^^^^^^^^^^^^^^^^^^^^^^^^^

More bogus rules.
 
> 410 IF TM2>70 THEN TM2=70
^^^^^^^^^^^^^^^^^^^^^^^^^^^

More number cooking

> 470 PRINT#1,DAY,TM1,TM2,TLIM,TM3

Back to the drawing board yet again, Nick.

Cheers,

Will Stewart

---

From: [email-masked] (Nick Pine)
Date: 12 Jun 1996 01:39:12 -0400

>> It's a good idea to find an engineer to help.

Or a physicist...

>A home can be passive solar AND have a fireplace.

Right... A friend of mine has a beautiful, seaworthy deep keel 28' Cape Dory
sailboat, with a small inboard diesel engine, federally-registered with the
merchant marine as an "oil screw," to reduce taxes and let him clear customs
more easily :-) Would you hang an outboard motor on your America's Cup boat?
 
>> >DOE...

>> Sounds good...

Did you say DOE? :-)

>It is not a Trombe wall house.

It's essentially a Trombe wall house, from a thermal point of view.
Direct gain, storage at close to room temp, ritual night insulation...
This has been around since 1881, with variations. It's time to do it better.

>> is fairly expensive and low-performance, as solar houses go, and needs a
>> separate solar water heating system.
 
>ones worth considering.  If you don't believe that, just ask him...
 
Norman Saunders, PE, Howard Reichmuth, PE, William Shurcliff, PhD,
William Beckman, PhD, John Duffie, PhD, and Steve Baer make a lot of
sense to me. I've talked with them all. Norman and Steve are American
Solar Energy Society Passive Solar Pioneers, and I've spent a few days 
talking over solar closets with each of them in person. I had the good
fortune to drive Norman from Boston to Lewiston, Maine in February, for 
the Maine Solar Energy Association's Sustainable Building Conference,
where Norman was one of the speakers at the session I moderated on
passive heating and cooling techniques. Norman is amazing. He's 80 years
old now, and he got into solar heating in 1944. At the moment, he's
helping design solar houses in Pennsylvania, California, and the UK.
Of course, he's no Will Stewart :-)

>his thesis statements.

Your CS degree is showing... :-) How many 3rd graders can understand C?
How many CS graduates are willing to understand simple physics, involving
ASHRAE-type R-value calculations?

>Note below how many temperatures 'magically' end up at 70 F.

This is the magic of temperature control by ventilation in the winter...
In houses with thermal stores with  no  insulation between the heat store
and the living space, like yours, you have to live inside the heat store.
So, during sunny weather, if you want to store heat for more cloudy days,
you have to live in a warmer house. How warm a house can you tolerate?
These houses work better if you are willing to let their indoor temps rise
to a high value in sunny times, and walk around in T-shirts and shorts in 
December. I picked 70 F as the upper limit for this sunny day house temp
limit. Perhaps I should have picked 80 F. Are you willing to live in a
house that is 80 F in December? The results don't change much.

>The answer is buried in the 'code'.

>> Day            wall store    wall store    store         temp
...

                      ^             ^                          ^
These are simple exponential decays |         So is this ------       
      well-known in heatflow                  But who cares, until it
                                              cools to 70 F?

>R13 walls are far below the R24 walls that are in the Avis home walls.

I suppose your house will be larger than an 8' cube too. This was just
an example of how the same materials can be arranged well or not so well,
>from  a solar performance point of view.

>The R2 windows ignore the window shade insulation that would be used.

True. That's house 2 above, if you cripple it slightly more.

>> 70 PRINT#1,"They're off!"
...

>I've never heard of this rule before; where did you come up with this, Nick?

That's my guess at how warm a house somebody might tolerate in sunny
winter weather. What's your limit, Will? Another issue for direct gain
houses is privacy, as Kurt Smith of Avis mentions. Or lack thereof, and
the interaction with house temperatures. One can only take off so much
clothing, with all those windows, especially near Washington, DC.

>The thermal store can be far above the ambient temperature of the room. 

A few degrees above, for a few minutes... Recall the half-hour time constant
for these water walls. We have discussed that before, but you didn't seem
to be listening. You are in a difficult psychological posture. Try this:
T(t) = 70 + (80-70)exp(-t/30), where t is in minutes.

>This explains why you don't understand the concept of a masonry heater
>fireplance.

I understand such fireplances, but what do they have to do with solar heating?

>Do you think that the thermal store is simply going to stop accepting
>heat input?

Is this a metaphysical or a physical question? The heat goes in one side
of those (opaque, window blocking?) water walls and out both sides, almost
immediately, heating the room air. This is similar to a person for whom 
ideas go in one ear and out the other. Mark Twain said perhaps such a person
should take out his brain and dance on it, to soften it up.
 
>Have you no shame?

I tell the truth, as I see it.

Cheers,

Nick

---

From: [email-masked] (Nick Pine)
Date: 12 Jun 1996 04:16:28 -0400

>R13 walls are far below the R24 walls that are in the Avis home walls.

OK. Let's change them all to R24.

>The R2 windows ignore the window shade insulation that would be used.

True. That's house 2, if you cripple it slightly more.

>What's your limit, Will?

Let's use 80 F as a house upper temp limit, disguised below as:

205 TU=80'upper temp limit for wall store houses (F)

John D. Muccigrosso <[email-masked]> wrote:
>[email-masked] wrote:

>| Nick provides a simple (but spaggetti) code exercise that somehow support
>| his thesis statements.  Note below how many temperatures 'magically' end 
>| up at 70 F.  The answer is buried in the 'code'.
>| 
>| >                Direct        Isolated      Isolated      Isolated
>| >                gain,         gain,         gain and      store
>| > Day            wall store    wall store    store         temp
>
>Hmmm, seems to me that the first 3 columns of temps are air temp, or at
>least living quarters temp including walls and stuff. The 70 degree limit
>would then be regulated by the homeowner who opens a window or closes a
>vent (or has some automatic (magic?) mechanism do this) so that the temp
>doesn't exceed 70.

Right. Or 80 F now, as below. BTW, a nice way to do winter ventilation
for a house might be to move open a hinged piece of foil-faced foamboard
with a $50 Honeywell damper actuator that uses 2 Watts when it is moving,
and 0 Watts when in a fixed position, connected to a cooling thermostat.
A less accurate and leakier way might be to use an automatic foundation vent
with some aluminum louvers that move with a bimetallic spring, such as
Leslie-Locke's FV-1B, which Home Depot sells for $11.83. Drill a hole in
the aluminum bracket covering the spiral spring and adjust the spring mount
with a screwdriver so the vent is open at 80 F, and mount it inside-out,
so the spring is exposed to house air.

>If the house gets above 70, that would be nice for those who like it hot,
>I guess, and would make the house cool down to an unacceptable temp more
>slowly, but probably wouldn't be desirable for most people.

Agreed. Here's the race again, with some NREL numbers for Providence, RI...

They're off!

               Direct        Isolated      Isolated     Isolated
               gain, wall    gain, wall    gain and     store
Day            store         store         store        temp
 
 0             33.8 F        33.8 F        33.8 F        33.8 F
 1             44.7025       44.7025       44.7025       44.7025 
 2   House 1   53.4434       54.97771      55.51239      55.51239 
 3   is a      59.8625       63.8481       65.32996      65.32996 
 4             64.57653      71.50574      70            74.24631 
 5   s         68.03838      78.11644      70 House 3    82.60956 
 6   l         70.58069      80            70 is always  90.72779 
 7   o         72.4477       80 The        70 the same.  98.60819 
 8   w         73.81877      80 ritual     70 A good     106.2577 
 9             74.82566      80 thermal    70 house for  113.6831 
 10  starter.  75.5651       80 curtains   70 reptiles?  120.891 
 11            76.10812      80 help       70            127.8877 
 12            76.5069       80 house      70            134.6794 
 13            76.79975      80 2.         70            141.2722 
 14            77.01482      80            70            147.6718 

House 1 one never quite makes it to 80 F, in 2 weeks of average December
weather. I would say house 2 is too hot, but chacun a son chaleur...
BTW, these are max temps for houses 1 and 2. They will be cooler at night,
vs house 3, which could be cooler at night, if it had a setback thermostat.

House 2 now has a fairly respectable RC time constant of 256 hours, and its
performance is not bad... House 1 is much poorer, with about 45 hours.
Will's Avis house might be about 53 hours, including the water walls,
with all the curtains drawn 24 hour a day, IF they work perfectly. 
How much do they cost, Will? And how do air leaks affect them?

Now let's turn off the sun again...

 15            65.27026      75.575        70            143.5775 
 16            56.64535<--   71.56485      70            139.5151 
 17  Houses    50.31143      67.93063      70   Look     135.4845 
 18  1 and 2   45.65995 too  64.63714      70   how      131.4854 
 19  get cold  42.24403 cold 61.65241      70   nicely   127.5176 
 20  very      39.73546      58.94749      70   house 3  123.5807 
 21  quickly   37.89323  --> 56.49616      70   rides    119.6746 
 22  since     36.54034      54.27465      70   out      115.799 
 23  their     35.54681      52.2614       70   almost   111.9537 
 24  thermal   34.81719      50.4369       70   3 weeks  108.1385 
 25  mass      34.28137      48.78343      70   of       104.353 
 26  was       33.88788      47.28499      70   cloudy   100.5971 
 27  never     33.59892      45.92702      70   weather  96.87059 
 28  very      33.3867       44.69636      70   tra la   93.17316 
 29  warm...   33.23086      43.58108      70   tra la   89.50462 
 30  And       33.11641      42.57035      70   ...      85.86474 
 31  house 1   33.03237      41.65438      70   :-)      82.25331 
 32  has that  32.97064      40.82428      70            78.67008 
 33  B I G     32.92532      40.072        70            75.11484 
 34  bare      32.89203      39.39025      70            71.58738 
 35  window.   32.86759      38.77242      68.08748      68.08748 

Looks like house 3 finishes 19 days ahead of the nearest contender,
if you call 68 F and 80 F comfortable interior temperatures.

10 'a house race, among three 8' cube contenders, each having
20 '  R24 walls, one 8'x8' R2 window, and 4096 Btu/F of thermal mass.
30 '  House 1: a direct gain house with thermal mass in the walls.
40 '  House 2: an isolated gain house with thermal mass in the walls.
50 '  House 3: an isolated gain house with isolated thermal mass store.
60 OPEN "HROUT" FOR OUTPUT AS #1
70 PRINT#1,
80 PRINT#1,"They're off!"
100 PRINT#1,"               Direct        Isolated      Isolated     Isolated"
110 PRINT#1,"               gain, wall    gain, wall    gain and     store"
120 PRINT#1,"Day            store         store         store        temp"
130 PRINT#1,
140 'warmup over a long string of average December days
150 RWIND=2'US R-value of window
160 RWALL=24'US R-value of walls
170 C=4096'thermal mass (Btu/F)
180 TA=32.8'average outdoor December temp in Providence, RI (F)
190 SUNIN=8*8*900*.92*.92'average daily solar input (Btu)
200 TM1=TA:TM2=TA:TM3=TA'initialize thermal mass temperatures
205 TU=80'upper temp limit for wall store houses (F)
210 TLIM=TA'initialize limiting temp for isolated store house
220 FOR DAY=1 TO 14'warmup over two weeks of average December days
240 E1=24*(TM1-TA)*64/RWIND+24*(TM1-TA)*5*64/RWALL
250 TM1=TM1+(SUNIN-E1)/C'calculate new thermal mass temp
260 IF TM1>TU THEN TM1=TU'ventilate house to limit indoor temp
270 E2=6*(TM2-TA)*64/RWIND+18*(TM2-TA)*64/RWALL+24*(TM2-TA)*5*64/RWALL
280 TM2=TM2+(SUNIN-E2)/C
290 IF TM2>TU THEN TM2=TU
300 E3=6*(TM3-TLIM)*32/RWIND+18*(TM3-TA)*32/RWALL'south wall loss
310 E3=E3+24*(TLIM-TA)*(32+5*64)/RWALL
320 TM3=TM3+(SUNIN-E3)/C
330 IF TM3<70 THEN TLIM=TM3 ELSE TLIM=70
340 IF TM3>212 THEN TM3=212'water boils
350 PRINT#1, DAY,TM1,TM2,TLIM,TM3
370 NEXT DAY
380 'coming into the backstretch, a string of cloudy days
390 SUNIN=0'turn off the sun
400 PRINT#1,"turn off the sun..."
410 FOR DAY=15 TO 35'simulate three weeks of cloudy days
430 E1=24*(TM1-TA)*64/RWIND+24*(TM1-TA)*5*64/RWALL
440 TM1=TM1+(SUNIN-E1)/C
450 E2=0*(TM2-TA)*64/RWIND+24*(TM2-TA)*64/RWALL+24*(TM2-TA)*5*64/RWALL
460 TM2=TM2+(SUNIN-E2)/C
470 E3=0*(TM3-TLIM)*32/RWIND+24*(TM3-TA)*32/RWALL'south wall loss
480 E3=E3+24*(TLIM-TA)*(32+5*64)/RWALL
490 TM3=TM3+(SUNIN-E3)/C
500 IF TM3<70 THEN TLIM=TM3 ELSE TLIM=70
520 PRINT#1,DAY,TM1,TM2,TLIM,TM3
540 NEXT DAY
550 CLOSE
 
Nick

---

From: William R Stewart <[email-masked]>
Date: Wed, 12 Jun 1996 22:19:09 -0400

[Followups to alt.solar.thermal, for the umpteenth time.  Nick wanders away and
we have to gently lead back to his cell^h^h^h^h room]

 
> more easily :-) Would you hang an outboard motor on your America's Cup boat?

So sailboats with motors are no longer sailboats?  I have to admit, you continue
to amaze me...  Bought any 12 watt rabbits, lately?

> >> >I've selected a modular home built by Avis America, who participated with

Are you hard of hearing?
 
> >> >See Solar Today Sept/Oct 1995.

A publication of the American Solar Engineering Society.

> Direct gain, storage at close to room temp,

By what measure?  Feel free to invent things right off the top of your head.

> ritual night insulation...

Go do so.

> sense to me.

I'll let them speak for themselves.  And a PE or PhD doesn't make a person a 
god, merely respectable, so stop worshipping.

> I've talked with them all. 

That doesn't make you a god, either.

> Your CS degree is showing... :-) How many 3rd graders can understand C?

Earth to Nick...

> ASHRAE-type R-value calculations?

Those who also have electro-mechanical engineering degrees.

> house that is 80 F in December? The results don't change much.

Not that your code can be trusted anyway.
 
> >> 230 IF TM1>70 THEN TM1=70'overheating limit in sunny weather

You make this assertion but fail to support it.
 
> clothing, with all those windows, especially near Washington, DC.

I wasn't planning on going nude where neighbors could see me.  The lots I'm
looking at are all over 5 acres.

You fail to realize that the thermal store can be much warmer than the ambient
room temperature.  Since the water wall will be painted (or papered) a light
color, most of the heat transfer will be from convection.  Do you understand how
to calculate convection?
 
> to be listening. 

You failed to supply a reasonable calculation.  A little bit of knowledge is
a dangerous thing.  Perhaps you should start another quiz so that you can 
pick up a few more formulas>.

>You are in a difficult psychological posture.

Quack, heal thyself.

> Try this:

Thermal mass, silly.  Do you think they are right at room temperature?
How do you think they can continue warming a room for up to 24 hours?
Perhaps you should learn something from one of those people you worship.
 
> immediately, heating the room air.

By what transfer mechanism, convection?  Please show me the calculation.  
You're in new and strange territory here, Nick.  Ohm's law only takes an 
EE so far in thermodynamics...

> This is similar to a person for whom

*THAT'S* what you've been up to; that explains everything....
 
> I tell the truth, as I see it.

The former is seldom, the latter, obvious.
 
Cheers,
 
Will Stewart

---

From: [email-masked] (John D. Muccigrosso)
Date: Wed, 12 Jun 1996 23:46:15 -0400

In article <[email-masked]>, [email-masked]
(Nick Pine) wrote:

| 180 TA=32.8'average outdoor December temp in Providence, RI (F)
| 190 SUNIN=8*8*900*.92*.92'average daily solar input (Btu)

| 380 'coming into the backstretch, a string of cloudy days

| 430 E1=24*(TM1-TA)*64/RWIND+24*(TM1-TA)*5*64/RWALL

Here's what I'm wondering. Shouldn't one really use not a string of avg
winter temp days, but a string of nasty, colder-than-usual, cloudy ones?
Say a week or two of a nasty arctic air mass stuck in your region.

-- 
John D. Muccigrosso                         Department of Classical Studies
[email-masked]                            University of Michigan

---

From: [email-masked] (Nick Pine)
Date: 13 Jun 1996 02:21:48 -0400

>| 190 SUNIN=8*8*900*.92*.92'average daily solar input (Btu)
                      ^-- these are for glazing transmission loss, BTW.

>| 430 E1=24*(TM1-TA)*64/RWIND+24*(TM1-TA)*5*64/RWALL
 
That's for a direct gain house. For an isolated gain house, eg one with
a low-thermal-mass sunspace, on a cloudy day we have lower loss:

>| 430 E1=24*(TM1-TA)*64/Rwall+24*(TM1-TA)*5*64/RWALL
                         ^^^^^--much higher

>Say a week or two of a nasty arctic air mass stuck in your region.

Sure. But this is a starting point. It seems to me that one can design a
good sunspace and solar closet house with just two numbers: the average
temp in the coldest month and the average amount of sun that falls on a
south wall. Successive refinements might be to look up the average daytime
high in that month, and use that number instead of the 24 hour average temp,
for the sunspace collection efficiency, to do a TMY2 simulation for the
house, using hourly NREL weather data for a typical meteorological year,
and to do a simulation using hourly weather data for the last 30 years,
>from  one of three $130 Sampson CD-ROMs available from [email-masked].
It seems to me that in many parts of the country, cold days are sunny...

Nick

---

From: [email-masked] (Nick Pine)
Date: 13 Jun 1996 03:33:14 -0400

William R Stewart  <[email-masked]> wrote:

>[Followups to alt.solar.thermal, for the umpteenth time...

Feeling uncomfortable, Will? :-)

>A publication of the American Solar Engineering Society.

My copy says "Published by The American Solar Energy Society."

>Those who also have electro-mechanical engineering degrees.

I have yet to see one... These calculations are just HVAC craftsmanship, not
"thermodynamics." (Is "electro-mechanical engineering" pinball machines? :-)

>color, most of the heat transfer will be from convection. Do you understand how

Sure. I just use an R-value of 2/3. I don't add anything for paint or paper.
Other people go on about Nusselt and Grashof numbers, but the results are
similar. R-values are actual physical measurements that include convection.

>> >The thermal store can be far above the ambient temperature of the room.

Not for long.

>>The heat goes in one side of those window-blocking water walls and out
>>both sides, almost immediately, heating the room air.

>By what transfer mechanism, convection?  Please show me the calculation.  

My NREL data book says about 1050 Btu/ft^2 would shine in your double-glazed
windows over a 6 hour winter day, of which they estimate 710 Btu/ft^2 would
get through the window, and shine on the water wall in your 70 F room, with
a still air film R-value of 2/3 for each side (see ASHRAE HOF, Fig 1, p 22.1),
heating it up to a temperature T, where 710 = 6(T-70)2/(2/3), so T = 109 F.
If the wall contains 4" of water, ie about 21 pounds per square foot of wall,
the RC time constant of the wall is about 2/3/2x21 = 7 hours. These walls
might keep your house warm for several hours, not just a half-hour...

If you close your curtains at 3 PM, and keep your solar house at 70 F all
night by burning wood, by 9 AM the next morning, the water walls might have
a temperature  

T(t) = 70 + (109-70)exp(-18/7) = 73 F.

If the next day is cloudy, and you leave your curtains closed, and keep
your solar house at 70 F by burning wood for the next 24 hours, the next
morning your water walls might have a temperature of 

T(t) = 70 + (109-70)exp(-42/7) = 70.1 F.
 
Suppose you didn't burn wood the first night. As I recall, your house had
an overall U value of about 150 Btu/hr-F. So over 18 night hours, at 30 F
outside, it would need about 18(70-36)150 = 92K Btu to stay warm. The 3300
lb of water walls and 1000 Btu/F (?) of house would need to cool 92K/4.3K 
= 21 degrees F to do that, so in the morning, your solar house and water
walls would have a temperature of about 70-21 = 49 F.

Over the next 24 hours, if it's 30 F outside, and you keep all of the thermal
curtains drawn all day, and they insulate as well as you say they will (who
makes these curtains, anyhow, and how much do they cost?) your house would
need less than 24(49-30)150 = 68K Btu to stay at 49 F, so after another day
your solar house and water walls would be at least 49 - 68K/4.3K = 33 F...

You could do these calculations in more detail, if you desired. 

The results wouldn't change much.

Nick

---

From: [email-masked] (John D. Muccigrosso)
Date: Thu, 13 Jun 1996 09:20:53 -0400

In article <[email-masked]>, [email-masked]
(Nick Pine) wrote:

| Successive refinements might be to look up the average daytime
| high in that month, and use that number instead of the 24 hour average temp,
| for the sunspace collection efficiency, to do a TMY2 simulation for the
| house, using hourly NREL weather data for a typical meteorological year,
| and to do a simulation using hourly weather data for the last 30 years,
| from one of three $130 Sampson CD-ROMs available from [email-masked].

Yeah, this is what I meant.

| It seems to me that in many parts of the country, cold days are sunny...

Right (having lived in MN where those cold Canadian air masses are often
cloudless), but you would build for a 30-yr (or 10-yr or some other
long-term) low, not for typical winter days, right? (Though avg days are
fine for a quick comparison of types.)

---

From: William R Stewart <[email-masked]>
Date: Thu, 13 Jun 1996 08:45:04 -0400

[followups to alt.solar.thermal for the umpteenth +1 time...]

> Feeling uncomfortable, Will? :-)

Trying to reduce the embarrassment you create for yourself...

> My copy says "Published by The American Solar Energy Society."

Do you have any problems with this organization, or are they all ignorant
and criminal, too?
 
> "thermodynamics." 

I wonder how many people in sci.engr.heat-vent-ac would consider you an
HVAC "craftsman"...  

Perhaps an understanding of thermodynamics should be your foundation for 
HVAC calculations, as is the normal in engineering schools.  Don't forget 
you are posting to sci.ENGR.heat-vent-ac.  You continue to strip away all 
of my followups to alt.solar.thermal, so you must suffer the consequent 
loss of face.  If you are trying to attract clients, this isn't a very good
approach.

> similar. R-values are actual physical measurements that include convection.

Convection equivalents are not so cut and dry.  Newton's law of cooling is;

qc = hc*A(Ts - Tf)

where 
  hc= average convection heat-transfer coefficient over the surface A
      in W/m2*K (Btu/hr*ft^2*F).  hc for air, free convection is 
      1-5 Btu/hr*ft^2*F 

  Ts= Surface temp
  Tf= Undisturbed fluid temperature

Because the thermal store wall will be resting on a perpendicular floor, and
will have a perpendicular table top extending 18 inches into the room, I will
assume an hc value of 1 for purposes of discussion.  The wall design is not 
completely set; one design I am looking at is 10'x2.5'x8", which is slightly 
different from 10'x4'x4".  This design would give a storage per wall at 
16.6 ft^3 X 7.48 gal/ft^3 X 8.33 lb/gal = 1041 Btu storage for each degree F 
delta T.  If they are exposed to 700 Btus/hr ft^2 solar insolation through
dual pane windows, then;

Each storage wall will receive 25 X 700 = 17500 Btus during the day.

With 4 walls, that translates to 17,500 x 4 = 70,000 Btus.

Of course each window group has an addition 50 ft^2 of window space that bypasses 
the thermal storage walls, so another 140,000 Btus will enter those windows.

Two more south window groups do not have thermal storage walls (will likely have
storage floors, such as slate or dark tile on concrete),
so 2 x 70 x 700 = 98,000 Btus additional input.

70K + 140K + 98K = ~310,000 Btus of solar insolation input on an average December day
(January and February are higher).

If we want to add in the thermal storage of other aspects of the house, such as
drywall and flooring, we will find that the thermal mass of the house is 
considerably more, though it is at, or close to, room ambient temperature. If the
room temperature is higher in the daytime, then this thermal mass will rise to
(almost) meet the ambient temperature high.  You calculated 4000 Btu/F for internal
secondary storage in an earlier post, so if the indoor daytime temperature is 75 F 
and the base winter room temperature is 65 F, then internal secondary storage is 
40,000 Btus.

If the Ts = 85 F and Tf = 75F (after a day of average sunlight in 
December), then;

qc = 1*50*(85-75) = 500 Btu/hr per storage wall

which, according to your calculation of my house design at 150 Btu/hr F 
(which you admit needs significant rework, I'll address this in another post),
would raise the room ambient temperature, conversely lowering the qc.

As the room and thermal storage walls starts to cool down to 
Ts = 73 and Ts =68 F, for example, then qc =  125 Btu/hr per storage wall

With 65 F being the base winter room temperature, the storage walls would 
still have 32000 Btus of energy left, not counting the wall, ceiling, and floor
thermal storage.

> might keep your house warm for several hours, not just a half-hour...

I'm glad to see that you admit you can be wrong.  Your understanding of 
convection still needs work, though, because we haven't even touched on Nusselt, 
Prandl, Reynolds, or Grashof.  You'll find fluid dynamics plays a large role 
in convection, free or forced.  Thermal conductivity physics only takes 
you so far in the real world.

Cheers,

Will Stewart

---

From: Raymond Bahm <[email-masked]>
Date: Tue, 11 Jun 1996 17:41:46 -0600

> Inc at 508.677.3533.  The energy designer is Lyle Rawlings at 609.466.4495.

You can always look in the back pages of SOLAR TODAY for the Ads.
If you haven't got the Passive Solar Industries Council Guidelines for passive
solar design in your area, you are missing the most authoritative and best
resource for design information taylored to your local climate.  Well worth
the money spent.

-- 
Ray Bahm  --  [email-masked]

---

From: [email-masked] (paul milligan)
Date: 13 Jun 1996 21:18:50 GMT

In article <[email-masked]>,
   [email-masked] (John D. Muccigrosso) wrote:

~~>| from one of three $130 Sampson CD-ROMs available from [email-masked].

	Or http://www.ncdc.noaa.gov , their web site.

_________________________________________________________
No Disclaimer needed - This is my own PPP account, and my
employer doesn't care what I think anyway !  :-)
_________________________________________________________

The SEHVAC FAQ is at: http://www.elitesoft.com/sci.hvac/
My humble personal pages are at: http://www.webbuild.com/~pjm/index.html

---

From: [email-masked] (Nick Pine)
Date: 13 Jun 1996 18:30:04 -0400

>Do you have any problems with this organization, or are they all ignorant

They are good guys with their hearts in the right places, like yours, however,
we haven't seen many 100% solar houses like those of Norman Saunders, PE,
described in their pages lately. Bill Yanda and Steve Baer figure nicely
in their publications. Their technical journal is somewhat clogged with
academics, IMO.

>HVAC calculations, as is the normal in engineering schools.

Been there, done that. ASHRAE calcs are more useful and straightforward here.

>>>You fail to realize that the thermal store can be much warmer than the
>>>ambient room temperature. Since the water wall will be painted (or papered)
>>>a light color, most of the heat transfer will be from convection. 

BTW, I think the light color is irrelevant here, unless you are talking about
a shiny metallic surface. Dark colors are good for solar absorption, but IR
emission at eg 80 F is pretty much independent of color. Perhaps you believe
in painting radiators dark colors... I don't think that matters.

 
>qc = hc*A(Ts - Tf)

Right. Ohm's law for heatflow :-)

>      in W/m2*K (Btu/hr*ft^2*F).  hc for air, free convection is 

That's a U (=1/R) value, and it's hard to get below 1.5 in still air. It
increases if the air is moving to about U = 1.5 + V/5 for smooth surfaces,
U = 2 + V/2 for rougher ones like stucco, where V is in mph. See ASHRAE HOF
Fig 1, p 22.1. You might be able to get U < 1 if you make the water wall faces
shiny metal (U ~ 0.5 for upward heatflow, ~ 0.25 for sideways heatflow), but
that won't work for the side facing the sun, which will impose a lower limit
on the overall U-value of at least 1.5, unless it's a selective surface.
 
>  Tf= Undisturbed fluid temperature

Natch.

>assume an hc value of 1 for purposes of discussion.

1.5 is probably closer to the truth, especially since the floor and table top
will act as conductive fins. Gluing foil-faced foamboard to the non-south
surfaces would help...

>The wall design is not completely set; one design I am looking at is
>10'x2.5'x8", which is slightly different from 10'x4'x4".

OK.

>This design would give a storage per wall at 16.6 ft^3 X 7.48 gal/ft^3 X
>8.33 lb/gal = 1041 Btu storage for each degree F delta T.

OK.

>If they are exposed to 700 Btus/hr ft^2 solar insolation

That was 700 Btu/day-ft^2. Full sun is 311 Btu/hr-ft^2, max, on earth.
                 ^^^
>through dual pane windows, then;

>Each storage wall will receive 25 X 700 = 17500 Btus during the day.

Agreed, for a 25 ft^2 water wall face...

>With 4 walls, that translates to 17,500 x 4 = 70,000 Btus.
 
OK.

>Of course each window group has an addition 50 ft^2 of window space that
>bypasses the thermal storage walls, so another 140,000 Btus will enter
>those windows.

OK. But irrelevant.

>Two more south window groups do not have thermal storage walls (will
>likely have storage floors, such as slate or dark tile on concrete),

OK. But irrelevant.

>70K + 140K + 98K = ~310,000 Btus of solar insolation input on an average
>December day (January and February are higher).

OK. But irrelevant.

>considerably more, though it is at, or close to, room ambient temperature. 

That's what we will find, huh? :-) How much? Numbers please.

>If the room temperature is higher in the daytime, then this thermal mass
>will rise to (almost) meet the ambient temperature high.

Sure. Or higher, if it's in the sun, eg the floor.

>You calculated 4000 Btu/F for internal secondary storage in an earlier post,

That was a guess. Your house might have 4,000 ft^2 of 1/2" drywall with a
thermal mass of 0.5 Btu/F, ie 2,000 Btu/F. How much will your solar fireplace
weigh? That would add about 0.16 Btu/lb...

>so if the indoor daytime temperature is 75 F and the base winter room
>temperature is 65 F, then internal secondary storage is 40,000 Btus.

OK, go ahead, double that number, but that's still a drop in the bucket
compared to a typical day's energy need of 24(70-40)150 = 108K.

>If the Ts = 85 F and Tf = 75F (after a day of average sunlight in December),

Is Ts the water wall temp, and Tf the room and wall temp?

>qc = 1*50*(85-75) = 500 Btu/hr per storage wall

Let's see, you said above,

>qc = hc*A(Ts - Tf)

and you said you wanted to use hc = 1, altho 1.5 is a more reasonable min...
So where did the 50 come from? Oh, 2 sides to each water wall, each 25 ft^2.
I guess you'd want to add the perimeter area of 8"/12" x 25' = 17 ft^2, and
something for the floor and table fins? So I'd make this 1.5x67x(85-75) =
1,000 Btu/hr/wall, altho you seem to have pulled the 85 F out of a hat.
Perhaps you'd like to recalculate that 109 F with these new shapes.

>(which you admit needs significant rework, I'll address this in another post),

Perhaps you would like to recalculate that. It's your house.

>would raise the room ambient temperature, conversely lowering the qc.

Right. Until you are parading naked :-)
 
>Ts = 73 and Ts =68 F, for example, then qc =  125 Btu/hr per storage wall

What difference does that make? You might rework that too.

>still have 32000 Btus of energy left, not counting the wall, ceiling, and floor

OK. I get 33,312 Btu, using your numbers above.
But what's the point of this calculation, Will?

 
 
>I'm glad to see that you admit you can be wrong.

Sure. I miscalculated before. You are building a whole house wrong :-)

>Your understanding of convection still needs work, though, because we haven't
>even touched on Nusselt, Prandl, Reynolds, or Grashof. You'll find fluid
>dynamics plays a large role in convection, free or forced. Thermal
>conductivity physics only takes you so far in the real world.

R-values are sufficient here.

So let's see. Your new water walls have a thermal resistance of 2/3/67 ft^2
and a thermal mass of 1041 Btu/F, so their RC time constant is 10.35 hours,
and your house with the 4,000 Btu/F of inherent thermal mass and 150 Btu/F-hr
with all the curtains drawn has a time constant of 26.6 hours, so if I'm doing
this right, we might figure the RC time constant of your entire house with 
all those ritual curtains drawn as the RMS value sqrt(26.6^2+10.35^2)=28.5 hr.

Suppose we say the average temp of the thermal mass in your house is 80 F
to start with. Then when it's 30 F outside, with all the thermal curtains
drawn in the dark, 24 hours a day, the indoor house temp will be:

T(t) = 30 + (80-30) exp(-t/28.5)

80 F after 0 hours, 52 F after 24 hours, and 39 F after 48 hours.  
 
Still not a solar house by a long shot, I'd say. Altho it could be
dramatically improved by rearranging the same materials... 
 
Nick

---

From: [email-masked] (Nick Pine)
Date: 13 Jun 1996 21:15:37 -0400

I wrote:

>we might figure the RC time constant of your entire house with all those
>ritual curtains drawn as the RMS value sqrt(26.6^2+10.35^2)=28.5 hr.

On second thought, it's probably more accurate to calculate the steady-state
water wall temp and model the house as having a fixed hold time of a few hours
followed by an exponential cooling with a time constant of 8000/150 = 53 hours.

Still piss-poor solar performance...

Nick

---

From: [email-masked] (John D. Muccigrosso)
Date: Wed, 12 Jun 1996 00:59:37 -0400

In article <[email-masked]>, [email-masked] wrote:

Hmmm, seems to me that the first 3 columns of temps are air temp, or at
least living quarters temp including walls and stuff. The 70 degree limit
would then be regulated by the homeowner who opens a window or closes a
vent (or has some automatic (magic?) mechanism do this) so that the temp
doesn't exceed 70. If the house gets above 70, that would be nice for
those who like it hot, I guess, and would make the house cool down to an
unacceptable temp more slowly, but probably wouldn't be desirable for most
people.

(BTW, it's "spagHetti" and while I've heard of spaghetti westerns, I'm not
familiar with spaghetti code, though maybe I'm just ignorant. :-) )

---

From: [email-masked] (Nick Pine)
Date: 11 Jun 1996 07:08:35 -0400

Sounds good...

 
Nick

They're off!

 0             36 F          36 F          36 F          36 F

---

From: William R Stewart <[email-masked]>
Date: Mon, 10 Jun 1996 05:10:38 -0400

Cheers,

Will Stewart

---

From: William R Stewart <[email-masked]>
Date: Tue, 11 Jun 1996 20:34:49 -0400

Have you no shame?

More bogus rules.

More number cooking

Cheers,

Will Stewart

---

From: [email-masked] (Nick Pine)
Date: 12 Jun 1996 01:39:12 -0400

Or a physicist...

 

Did you say DOE? :-)

 

...

                      ^             ^                          ^

...

 

Cheers,

Nick

---

From: [email-masked] (Nick Pine)
Date: 12 Jun 1996 04:16:28 -0400

They're off!

 
Nick

---

From: William R Stewart <[email-masked]>
Date: Wed, 12 Jun 1996 22:19:09 -0400

Are you hard of hearing?

Go do so.

Earth to Nick...

 

 

 

Quack, heal thyself.

 

 

Cheers,
 
Will Stewart

---

From: [email-masked] (John D. Muccigrosso)
Date: Wed, 12 Jun 1996 23:46:15 -0400

---

From: [email-masked] (Nick Pine)
Date: 13 Jun 1996 02:21:48 -0400

^^^^^--much higher

Nick

---

From: [email-masked] (Nick Pine)
Date: 13 Jun 1996 03:33:14 -0400

Not for long.

 

Nick

---

From: [email-masked] (John D. Muccigrosso)
Date: Thu, 13 Jun 1996 09:20:53 -0400

---

From: William R Stewart <[email-masked]>
Date: Thu, 13 Jun 1996 08:45:04 -0400

qc = hc*A(Ts - Tf)

where 

  Ts= Surface temp

Cheers,

Will Stewart

---

From: Raymond Bahm <[email-masked]>
Date: Tue, 11 Jun 1996 17:41:46 -0600

---

From: [email-masked] (paul milligan)
Date: 13 Jun 1996 21:18:50 GMT

---

From: [email-masked] (Nick Pine)
Date: 13 Jun 1996 18:30:04 -0400

Natch.

OK.

OK.

 
OK.

OK. But irrelevant.

OK. But irrelevant.

OK. But irrelevant.

 

 

 
 
Nick

---

From: [email-masked] (Nick Pine)
Date: 13 Jun 1996 21:15:37 -0400

Nick

---

From: [email-masked] (John D. Muccigrosso)
Date: Wed, 12 Jun 1996 00:59:37 -0400

---

From: [email-masked] (Nick Pine)
Date: 13 Jun 1996 13:46:11 -0400

>Yeah, this is what I meant.

OK...

>long-term) low, not for typical winter days, right?

Right, but... 

>(Though avg days are fine for a quick comparison of types.)

Yes, and for the more complete simulations I've run, I've noticed that
a house design based on daily averages works fine. It usually turns out
to be overkill. Simple simulations allow one to tweak the design a little,
to reduce the size of the required sunspace or thermal store, or decrease
the R-value of the walls or windows, or increase the allowable air
infiltration rate, vs. an average-day design. 

Nick

---

From: [email-masked] (John D. Muccigrosso)
Date: Thu, 13 Jun 1996 01:56:05 -0400

In article <[email-masked]>, [email-masked] wrote:

| John D. Muccigrosso wrote:
<snip>
| > Hmmm, seems to me that the first 3 columns of temps are air temp, or at
| > least living quarters temp including walls and stuff. 
| 
| No, his comments identify them as thermal mass temperatures
| 
| > 190 TM1=36:TM2=36:TM3=36'initialize thermal mass temperatures
| 
| TMx variables are for Thermal Mass.
| 
| > 195 TLIM=36'initialize limiting temp
| > 200 FOR DAY=1 TO 14'warmup over two weeks of average December days
| > 205 FOR I=1 TO 10000:NEXT'delay loop
| > 210 E1=24*(TM1-36)*64/RWIND+24*(TM1-36)*5*64/RWALL
| > 220 TM1=TM1+(SUNIN-E1)/C'new thermal store temp
| > 230 IF TM1>70 THEN TM1=70'overheating limit in sunny weather
| 
| Notice that he imposes an artificial limit on the storage wall temperature
| here (and other places, see my last post).
<snip>

OK, let me try this again.

House 1          House 2       House 3      Not a house, but part of H2 & 3
-----------      ----------    --------     -------------------------------
Direct           Isolated      Isolated     Isolated
gain,            gain,         gain and     store
wall store       wall store    store        temp

H1 is a house that heats up inside due to insolation through windows into
the living space and that stores the heat thus gained in its own walls and
furniture and masonry floors and other things.

H2 is a house with the same kind of heat storage, but is heated up
indirectly by insolation of an isolated space (a sunspace).

H3 has the same kind of heating mechanism as H2, but relies on heat stored
in an isolated space that contains lots o' thermal mass (a solar closet)
while the thermal mass of the inside of the house is negligible.

So the thermal store for H1 and H2 is the stuff in the house (walls and
furniture and masonry floors and other things).  Nick assumes that TM _is_
room temp for H1 and H2 by considering the air to be in thermal
equilibrium with the thermal mass, but you're allowing the heat transfer
>from  thermal mass to air to be slow so that the air can keep grabbing heat
>from  the thermal mass through the night. Kind of like the streets and
sidewalk at night in the city during the summer (childhood memories
flooding back...). Hence,

| Don't forget, the thermal store can be considerably higher than the ambient 
| temperature.

So the nice masonry floor (or "store") will heat up during the day as the
sun shines on it. The heat loss to the air is slow relative to the heat
gain from the sun, so that the store's T increases at a faster rate than
the air's, resulting in a nice hot store and cooler air. The air loses
heat all the time to the outside via the walls, but the store is slowly
replenishing that heat as it cools and is not itself directly losing an
appreciable amount of heat. During the day, lost heat from the store is
replenished by the sun, but at night, the store just cools down. Reminds
me of reaction kinetics actually:

               k1
  sunlight + A -> B         k1 is the rate of A -> B

               k2
         B + C -> D + A     k2 is the rate of B + C -> D + A

Here, A is cold store, B is hot store, C is cold air and D is hot air
(ooh, opening myself up on that one). k1 is much faster than k2 and C is
small relative to B, so B builds up during the day. Then at night or on a
cloudy day, [sunlight] = 0 so k1 doesn't matter, and it's just k2 that is
working, cooling off the store. (Of course, I'm simplifying here and one
would probably work with thermal masses and stuff, but anyway...). It's
the old "kinetics vs. thermodynamics" thing.

In effect, the air acts as an insulator between the store and the walls of
the house, making the effective R-value that the store sees much larger
than the R-value of the walls. The store therefore loses heat relatively
slowly to the outside while the insulator (the air) stays warm
transferring heat between the two. For the program below, the TmassH1/2 is
allowed to go much higher than 70 (or 80) while the Tair is completely
unaccounted for.

Lots of critical variables in there, I guess. This doesn't change the
utility of Nick's high-T isolated store, though, unless the store can
conserve enough heat to last through those cold days.

------

I tried to relabel some variables in Nick's code (love that search and
replace) so that it is less spaghetti like and have given it below.

I suspect that I may not understand the layout of our cube houses, but the
only difference between H1 and H2 seems to be that H2 covers up the window
at night and on cloudy days, while H1 doesn't (hence isolated gain since
the store effectively transmits all of its heat to the house when it is
gaining it and doesn't act as a drain when it is not). H3 also closes up
the window and gets to store heat in an isolated thermal mass which takes
up the equivalent of half of one wall. (Sorry if I lost the original
sketches on this.)

While I realize that this is a grossly simplified setup, interesting to me are: 

1. H2 and H3 have window coverings that are equal in R-value to the walls
(i.e., R24), which seems to large.
2. H2 and H3 keep their window entirely covered (i.e., with an R-value of
24) when the sun is not out or it's night, which doesn't sound too
pleasant or realistic to me during those 21 cold and cloudy days. Perhaps
one should given them an R-value half that of the walls during part of
these times?

"The Code III"
10  '  a house race, among three 8' cube contenders, each having
20  '  R24 walls, one 8'x8' R2 window, and 4096 Btu/F of thermal mass.
30  '  House 1: a direct gain house with thermal mass in the walls.
40  '  House 2: an isolated gain house with thermal mass in the walls.
50  '  House 3: an isolated gain house with isolated thermal mass store.
60  OPEN "HROUT" FOR OUTPUT AS #1
70  PRINT#1,
80  PRINT#1,"They're off!"
100 PRINT#1,"               Direct        Isolated      Isolated     Isolated"
110 PRINT#1,"               gain, wall    gain, wall    gain and     store"
120 PRINT#1,"Day            store         store         store        temp"
130 PRINT#1,
135 '
140 ' Initialize some variables
150 RWIND=2                            'US R-value of window
160 RWALL=24                           'US R-value of walls
170 C=4096                             'thermal mass (Btu/F)
180 Tout=32.8                          'avg outdoor Dec T in Providence, RI (F)
185 SunIn=8*8*900*.92*.92              'average daily solar input (Btu)
190 Tupper=80                          'upper T limit for wall store houses (F)
195 TmassH1=Tout:TmassH2=Tout:TmassH3=Tout  'thermal mass T's
200 TinH3=Tout                         'inside T for isolated-store house
205 '
210 'warmup over a long string of average December days
220 FOR DAY=1 TO 14                         'warmup over 2 weeks of avg Dec days
230 ' Do house 1
240 Elost1=24*(TmassH1-Tout)*64/RWIND+24*(TmassH1-Tout)*5*64/RWALL
250 TmassH1=TmassH1+(SunIn-Elost1)/C        'calculate new thermal mass temp
260 IF TmassH1>Tupper THEN TmassH1=Tupper   'ventilate house to limit indoor T
240 ' Do house 2
270
Elost2=6*(TmassH2-Tout)*64/RWIND+18*(TmassH2-Tout)*64/RWALL+24*(TmassH2-Tout)*5*64/RWALL
280 TmassH2=TmassH2+(SunIn-Elost2)/C
290 IF TmassH2>Tupper THEN TmassH2=Tupper
295 ' Do house 3
300 Elost3=6*(TmassH3-TinH3)*32/RWIND+18*(TmassH3-Tout)*32/RWALL  'S wall loss
310 Elost3=Elost3+24*(TinH3-Tout)*(32+5*64)/RWALL  ' rest-of-house loss
320 TmassH3=TmassH3+(SunIn-Elost3)/C
330 IF TmassH3<70 THEN TinH3=TmassH3 ELSE TinH3=70 ' keep house at store T
335                                                ' unless store too hot
340 IF TmassH3>212 THEN TmassH3=212'               ' physical limit on store T
350 PRINT#1, DAY,TmassH1,TmassH2,TinH3,TmassH3
370 NEXT DAY
375 '
380 'coming into the backstretch, a string of cloudy days
390 SunIn=0'turn off the sun
400 PRINT#1,"turn off the sun..."
410 FOR DAY=15 TO 35                      'simulate three weeks of cloudy days
420 'DO House 1
430 Elost1=24*(TmassH1-Tout)*64/RWIND+24*(TmassH1-Tout)*5*64/RWALL
440 TmassH1=TmassH1+(SunIn-Elost1)/C
445 ' Do house 2
450
Elost2=0*(TmassH2-Tout)*64/RWIND+24*(TmassH2-Tout)*64/RWALL+24*(TmassH2-Tout)*5*64/RWALL
460 TmassH2=TmassH2+(SunIn-Elost2)/C
465 ' Do house 3
470 Elost3=0*(TmassH3-TinH3)*32/RWIND+24*(TmassH3-Tout)*32/RWALL'south wall loss
480 Elost3=Elost3+24*(TinH3-Tout)*(32+5*64)/RWALL
490 TmassH3=TmassH3+(SunIn-Elost3)/C
500 IF TmassH3<70 THEN TinH3=TmassH3 ELSE TinH3=70
520 PRINT#1,DAY,TmassH1,TmassH2,TinH3,TmassH3
540 NEXT DAY
545 '
550 CLOSE

---

From: [email-masked] (John D. Muccigrosso)
Date: Thu, 13 Jun 1996 09:26:54 -0400

In article <[email-masked]>,
[email-masked] (John D. Muccigrosso) wrote:

| I suspect that I may not understand the layout of our cube houses, but the
| only difference between H1 and H2 seems to be that H2 covers up the window
| at night and on cloudy days, while H1 doesn't (hence isolated gain since
| the store effectively transmits all of its heat to the house when it is
| gaining it and doesn't act as a drain when it is not). H3 also closes up
| the window and gets to store heat in an isolated thermal mass which takes
| up the equivalent of half of one wall. (Sorry if I lost the original
| sketches on this.)
| 
| While I realize that this is a grossly simplified setup, interesting to
me are: 
| 
| 1. H2 and H3 have window coverings that are equal in R-value to the walls
| (i.e., R24), which seems to large.
| 2. H2 and H3 keep their window entirely covered (i.e., with an R-value of
| 24) when the sun is not out or it's night, which doesn't sound too
| pleasant or realistic to me during those 21 cold and cloudy days. Perhaps
| one should given them an R-value half that of the walls during part of
| these times?

Ah, I think I see better now. H2 has no windows except for the one in the
isolated gain area and that's isolated form the rest of the house by the
same insulation as the walls have.

---

From: William R Stewart <[email-masked]>
Date: Thu, 13 Jun 1996 09:40:03 -0400

> fine for a quick comparison of types.)

One can provide 100% percent coverage of their heating needs over a span of 
dozens of years, but this is not normally the case in HVAC calculations, as
a very large system would be installed that would run inefficiently at moderate
temperatures.  

In some formulas, factors such as 97.5% or 99% percent coverage are 
considered,  where the temperature might dip below the design minimum a 
small percentage of the time.

If you are considering solar heat, you might want to consider a back-up, 
whether it is a gas furnace, an efficient fireplace, ground-source heat pump, 
or kerosene heater.  Passive alone cannot guarantee complete coverage, and 
active solar runs the risk of a component failure. Warm clothing can help 
ease the chill on the coldest of days.

Cheers,

Will Stewart

---

From: William R Stewart <[email-masked]>
Date: Wed, 12 Jun 1996 17:40:22 -0400

John D. Muccigrosso wrote:
> least living quarters temp including walls and stuff. 

No, his comments identify them as thermal mass temperatures

> 190 TM1=36:TM2=36:TM3=36'initialize thermal mass temperatures

TMx variables are for Thermal Mass.

> 230 IF TM1>70 THEN TM1=70'overheating limit in sunny weather

Notice that he imposes an artificial limit on the storage wall temperature
here (and other places, see my last post).

> The 70 degree limit

With a passive solar house, that would likely be lowering window shades.
The thermal mass helps to even out the temperature swings.  In a discussion
today with Lyle Rawlings, he mentioned that his house once hit 84 degrees
in midwinter, but his family enjoyed the warmth, being able to stroll around
barefoot in summer clothes, so he didn't draw any curtains.

Don't forget, the thermal store can be considerably higher than the ambient 
temperature.

> familiar with spaghetti code, though maybe I'm just ignorant. :-) )

Thanks for the spell check.  Spaghetti code is code that is difficult to follow,
whether due to cryptic variable names, 'goto's, sparse commenting, or buried rules.

I try to avoid calling people ignorant, even if I think I'm right.

Cheers,

Will Stewart

---

From: "Gerard T. Curd" <[email-masked]>
Date: Thu, 13 Jun 1996 19:51:52 -0700

> you so far in the real world.

Get a Room!!!!

---

From: William R Stewart <[email-masked]>
Date: Sat, 15 Jun 1996 05:49:28 -0400

Nick Pine wrote:
> >Direct           Isolated      Isolated     Isolated    [just H3 ----^]
> That was the idea. And this "direct loss" house loses lots of heat
> at night and on a cloudy day through the big uninsulated window.

You might redo you calculations to show the effects of insulating shades. 
Otherwise, what is the purpose of this exercise?

Also, you neglect to take into account the temperature of the thermal
wall storage, which will be at a higher temperature than the ambient 
room temperature.

> Yes. Or some transparent siding on the south side of the house, or a
> transparent steep south roof, with an insulated attic floor. These things
> actually cost LESS than normal construction, since they have no shingles,
> tarpaper or sheathing, and houses need roofs and siding anyway.

How many house designs can support 30 55 gallon drums filled with water?
The added costs associated with a *safe* design must be accounted for.

> This works better if the house has some inherent thermal mass, since that way
> the solar closet does not have to provide any heat for the house at night,
> on an average day, so it operates at a higher storage temperature, with no
> load on an average day. On the other hand, if the "house" is a school or
> office or church, that is only heated at certain times, having little thermal
> mass may be an energy advantage.
> 
> >room temp for H1 and H2 by considering the air to be in thermal equilibrium
> >with the thermal mass,

That's the assumption I take exception with, as shown by my calculations in an
earlier post.

> >but you're allowing the heat transfer from thermal mass to air to be slow
> >so that the air can keep grabbing heat from the thermal mass through the
> >night. Kind of like the streets and sidewalk at night in the city during
> >the summer (childhood memories flooding back...)
> 
> That works for a few hours, but in the long run, after a day or so,
> uninsulated thermal masses end up at about the same temp as the house air.

Agree with the 'day or so'.
 
> For instance, Will's newest water walls have a time constant of about
> 10 hours, meaning any temp difference between them and the house air
> decreases by a factor of 1/e every 10 hours, ie by a factor of about 3.
> So if they are initially 30 F warmer than the house air, after 10 hours,
> they are only about 10 F warmer, after 20 hours, 3 F warmer, etc. A 4"
> thick concrete floor with a thermal mass of 8.8 Btu/F and a thermal
> conductance of 1.5 Btu/hr has a time constant of 8.8/1.5 = 6 hours. A 6"
> solid concrete wall with a thermal mass of 12 Btu/F has a time constant
> of 12/1.5 = 8 hours, etc. But equally important is the fact that in these
> cases, you have to live inside the heat battery, so you can't charge it up
> to a high temp to make the heat last for more cloudy days. This is worse
> for concrete than water, since it has a higher thermal resistance, so
> the surface heats up more when the sun shines on it, vs water, and it
> transfers more heat to the air in the house than a water wall would.

Perhaps we should just acknowledge that I don't look to have long term storage
in my water walls.  You seem to think that prevents my house from being a solar
house, but the rest of the people in this newsgroup understand differently.

If you like your design, hey, more power to you.  But if you are an evangelist
for your design only, and a detractor for all others, you simply sound like just
another egomaniac.
 
> >The store therefore loses heat relatively slowly to the outside while
> >the insulator (the air) stays warm transferring heat between the two.

This shows an excellent grasp of the concept. Now if only Nick can realize
the same...

Cheers,

Will Stewart

---

From: [email-masked] (Harry H Conover)
Date: 14 Jun 1996 02:13:40 GMT

William R Stewart ([email-masked]) wrote:

: > Right... A friend of mine has a beautiful, seaworthy deep keel 28' Cape Dory
: > sailboat, with a small inboard diesel engine, federally-registered with the
: > merchant marine as an "oil screw," to reduce taxes and let him clear customs
: > more easily :-) Would you hang an outboard motor on your America's Cup boat?
: 
: So sailboats with motors are no longer sailboats?  I have to admit, 
: you continue
: to amaze me...  Bought any 12 watt rabbits, lately?

Better check your Chapmans.  Per Coast Guard and international
regulations, a sailboat with its motor running is ALWAYS considered a 
power boat, and is required to obey the navigational and lighting rules
for power boats.  If the motor is turned off, it employs the rules 
applicable to sailing vessels.  (The state of its sails does not
enter into this determination.)

I suppose that by the same logic you could conclude that a solar home
with an operating fireplace is simply a conventionally (albeit wood)
heated home, and that when the fire is extinguished it returns to its 
identity of a solar home.

Maybe you need a determination from the Coast Guard rather than the
FHA for this one!  :-)

                                              Harry C.

---

From: [email-masked] (Harry H Conover)
Date: 14 Jun 1996 02:41:09 GMT

: 
: Nick Pine wrote:
:  

"Federally-registered with the merchant marine as an oil screw?"

Huh?   :-)

You perhaps mean Coast Guard documented?  If so, how does this help
him reduce taxes and clear customs more easily, particlarly since he
has to moor the darn thing somehere, unless that somewhere is outside
U.S. waters?  (Does this effectively avoid state collection of sales
tax????) Still, since both mooring taxes and sales taxes are based on
selling price and or current valuation, how does the power plant enter
the tax equation?

I assume the tax benefit to him must be significant, since federal
documentation of a 28' boat is so pretentious as likely to get you laughed 
right out of your local boat or yacht club  -- but if there is a significant
tax advantage (which I am unaware of), I'll put up with a few chuckles
on my way to the bank.  

All things considered, nobody laughs at a Cape Dory.  They is one
fine piece o' sailboat!!! 

                                        Harry C.

---

From: William R Stewart <[email-masked]>
Date: Sat, 15 Jun 1996 06:01:23 -0400

> Say a week or two of a nasty arctic air mass stuck in your region.

One approach is to use data that represents the most common weather occurrences
(i.e., 97.5% or 99% of the time) for the region the shelter will reside in.  
That way one can avoid the great expense associated with building a system to 
meet the condition of the two or three worst days per year.  In the case
of a solar heated home, having backup heat (gas, efficient fireplace, etc) can
reduce the size and complexity of the overall solar heating system.  It is no
longer 100% solar, but we solar engineers don't lose any sleep over this.

Cheers,

Will Stewart

---

From: "Duane C. Johnson" <[email-masked]>
Date: Thu, 20 Jun 1996 10:56:37 -0700

John D. Muccigrosso wrote:
> 
> There seems to be some serious disagreement over how long it takes an
> unisolated heat store to cool down, so let me propose a very hypothetical
> situation and see how many different answers I get. :-)
> 
> I have this infinitely large room with no windows at a constant
> temperature of 70 F. Into it, Moses-like, I place a wall of water, 10'
> high, 10' wide and 1' thick. The top, bottom and short sides of this wall
> are insulated to an R value of infinity. I heat the water in this wall to
> a uniform temperature of 100 F.
> 
> How long before the temperature of the water in the wall is 70 F?
> 
> Show all work. If you use approximate methods, please introduce no more
> than 25% error.
> 
> --

Ok two of us have answered the question the same way. Why have you not 
responded to us.
-- 
CUL8ER

Duane C. Johnson
WA0VBE
Red Rock Energy
1825 Florence St.
White Bear Lake, MN, USA 55110-3364
[email-masked]
[email-masked]
http://www.geocities.com/SiliconValley/3027/
(612)426-4766 h  635-5065 d

---

From: [email-masked] (DAVID WILLIAMS)
Date: Mon, 17 Jun 96 15:37:00 -0500

-> There seems to be some serious disagreement over how long it takes an
-> unisolated heat store to cool down, so let me propose a very
-> hypothetical situation and see how many different answers I get. :-)
->
-> I have this infinitely large room with no windows at a constant
-> temperature of 70 F. Into it, Moses-like, I place a wall of water,
-> 10' high, 10' wide and 1' thick. The top, bottom and short sides of
-> this wall are insulated to an R value of infinity. I heat the water
-> in this wall to a uniform temperature of 100 F.
->
-> How long before the temperature of the water in the wall is 70 F?

Answer: Never. The temperature of the water will decline exponentially
towards the temperature of its surroundings - the 70 F room. It will
never *quite* get there.

                            dow

---

From: [email-masked] (Nick Pine)
Date: 23 Jun 1996 09:10:19 -0400

DAVID WILLIAMS <[email-masked]> quotes:

>-> unisolated heat store to cool down

Ignorant people have serious disagreements over surprisingly simple things.
One might resolve this with a teacup and a watch: start with boiling water,
put a lid over the cup to slow evaporation, and recall that things at 98 F
feel neither warm nor cool to the touch. 

>->...let me propose a very hypothetical situation...

>-> 10' high, 10' wide and 1' thick.

Sounds more like an anti-Moses :-) Doesn't he play antipodal trombone
with Bill Parker of the Red Sea Pedestrians? Let's ignore evaporation...

>-> The top, bottom and short sides of

>towards the temperature of its surroundings - the 70 F room. It will

Correct but stupid. A more interesting question is how long the water wall
will stay 15 F warmer than the room. The thermal resistance of a still air
film is about 2/3. The wall has two sides exposed to room air, and a cubic
foot of water weighs about 63 lb, so the RC time constant of the wall is
about 2/3/2ft^2x63 = 21 hours, over which time the initial wall-room temp
difference will decrease by a factor of 1/e, about 1/3. The wall temp at
time t will be T(t) = 70 + (100-70)exp(-t/21), so after time t in hours,
85=70+30exp(-t/21) ==> ln(15/30) = -t/21 or t = 14.6 hours, IF the room were
kept warm by other means. But why should that be important? We want to keep
the room warm with the wall, not vice-versa. 

If the water wall were half as thick, with about the same surface area and
volume as Will's water walls, it would have RC = 10.5 hours, so it would
cool to 85 F in -10.5 ln(1/2) = 7.3 hours, IF the room were kept at 70 F 
by other means ("Keep the Home Fires Burning" :-) 

If the room containing the wall needed 150 Btu/F-hr to stay warm, like Will's
house, in the dark, 24 hours a day, with the perfect ritual thermal curtains
so carefully drawn (who makes those, and how much do they cost?) and if it
were 40 F outside, what would the steady-state temp of the room be, if the
wall were 100 F? This has a simple electrical analog:

                       Troom
                       |       + 40 F -
100 F -------www-------|---------www----------40 F
             1/3/100             1/150

The total series resistance is 1/300 + 1/150 = 0.01, so the heat that flows
>from  left to right is (100-40)/0.01 = 6000 Btu/hr. This heat flowing through
1/150 "Ohm" makes a temperature difference of 6000/150 = 40 F, so the room
temperature would be 40 + 40 = 80 F. Warmish.

The RC time constant of the whole room, including the wall with 3200 lb of
water, might be about 0.01x3200 = 32 hours, so if there were no other source
of heat, the room temp T(t) after t hours might be

T(t) = 40 + (80-40)exp(-t/32) 

80                      0    
59                     24      
49                     48
...

How long would it take the room to reach 70 F? 70 = 40 + (80-40)exp(-t/32)
==> 30 = 40exp(-t/32) or t = -32ln(3/4) = 9.2 hours. If the room were 80 F at
3 PM on a mild winter day, what would the temp be at 9 AM the next morning?
T(18) = 40 + 40exp(-18/32) = 63 F.

How long could the wall keep the room at 70 F,  IF  its heat loss could be
controlled, vs uncontrolled natural cooling? The room needs (70-40)x150
= 4500 Btu/hr to stay 70 F, so the wall could keep the room at 70 F until
the wall temp reached Tmin = 70 + 4500/300 = 85 F. If the wall were 100 F to
start, and the room were 70 F, ie if the wall were somehow better insulated
to begin with, the wall could store (100-85)3200 = 48K Btu of usable heat,
and the wall could keep the room warm for about 48K/4500 = 10.7 hours.
A little better, but still not long.

If the same wall were inside an attic warmstore or solar closet, and started
out at 130 F, it might keep the house warm for (130-85)3200/4500 = 32 hours.
That's a higher-performance solar house. A solar closet might also dry food
or clothes, serve as a sauna, or make domestic hot water, which seems nice.
One might even build a solar oven into one's solar closet, and cook for a week
with no sun.

Adding a 36 Watt 560 cfm fan might lower the minimum usable space heating temp
to 75 F, extending the cloudy day heat storage time to (130-75)3200/4500 = 39
hours. Replacing the $2000 (?) window-blocking water walls with 220 recycled
5 gallon plastic paint pails, with lids, or 20 55 gallon drums in a 4' x 10'
x 6' tall solar closet would store (130-75)10,000 = 550K Btu of heat, for a
solar storage time of 550K/4500 = 122 hours or about 5 days, which would make
it a much nicer solar house, in my opinion.

Using a setback thermostat to make the house temp 60 F at night would lower
the average daily heating requirement to (8(60-40)+16(70-40))150 = 96K/day,
extending the solar storage time to 5.8 cloudy days. That can't be done with
exposed water walls. If the room were used as an office or workshop or school
or church, and it had little thermal mass, it might be 45 F at night and 70 F
for 8 hours a day, requiring only (16(45-40)+8(70-40))150 = 48K Btu/day, so a
well-insulated solar heat store would last for 11.5 days without sun. Better
still, but impossible using exposed water walls...

Nick

---

From: [email-masked] (Nick Pine)
Date: 24 Jun 1996 10:33:43 -0400

Suppose we put a 10' x 30' x 7' tall mobile home up on blocks, and put 75
55 gallon plastic drums full of water underneath to make a solar closet
3' tall x 30' long x 10' deep, with a single wall south polycarbonate glazing
area of 90 ft^2, and a glazing area/thermal mass area ratio of about 25x75/90
= 21:1 :-) We could cover the south wall with another layer of polyethylene
or single wall polycarbonate (about $1/ft^2 from Replex at (800) 726-5151)
that extended up to the roof of the mobile home, ie another 30' x 10' of
glazing to make a low-thermal-mass sunspace...

Or we might put it the mobile home inside a 30' wide x 70' long x 13' tall
commercial plastic film greenhouse to act as a sunspace. The usual covering
is 2 layers of 5 cent/ft^2 polyethylene film, with a 3 year guarantee,
statically-inflated with a 50 watt blower. A better cover for a residence
might be 1 layer of very clear Mylar, ie polyester film, which might cost
10 cents/ft^2 and last 10 years, with a layer of greenhouse shadecloth over
the outside in summertime. Wind fatigue might be prevented by making a partial
vacuum inside with an exhaust fan when the wind is blowing, using a wind
switch, or making some sort of venturi ridge vent. Putting the mobile home
inside this $1500 greenhouse would allow more daytime living space, storage
of not very valuable items, rainwater collection, food growing, sewage
treatment, methane production for cooking gas (?), and water recycling,
as well as a place to work during the day.

Where I live in PA, with an average 4"/month of rainfall, this 3000 ft^2
greenhouse roof would collect an average of 240 gallons of water a day.
A reliable water supply might require a cistern/pond volume of 10K gallons,
eg a pond 4' deep x 12' wide x 26' long, made from a single piece of 20' wide
EPDM rubber. Less volume would be needed if used water were recycled by
condensing it between the poly film greenhouse pillows. 

Using aluminum extrusion clamps (from E C Geiger at (800) 4GEIGER, geigerintl
@hortnet.com, http://www.hortnet.com.geigerintl/) 33-SL16 Unilock, $12.80/16',
also available from Stuppy at (800) 877-5025) for the poly film makes changing
and recycling it every 3 years not much more work than changing a bedsheet,
on a calm day.

Composting would help with food growing too. I wonder how much CO2 a ft^3 of
good compost makes each day. My NRAES 33 book (page 120) says plants need
about 0.003 ft^3 CO2/hr-ft^2 of greenhouse floor area, and give off CO2 
(how much?) at night, and a greenhouse might have about 0.5 ACH, and the
earth's atmosphere is about 0.03% CO2. The more CO2 the better, I guess.
Are high levels harmful to humans? Helpful to dinosaurs?

Putting the solar closet under the mobile home means we get some heat through
the floor, which would otherwise be wasted if the closet were adjacent, and
if we open a motorized damper under a floor return, we might easily get warm
air to flow up into the mobile home by natural convection. The drums need a
vapor barrier underneath. 

Suppose we run this "polytunnel" EW and capture all the sun that falls on
its south "wall," about 13' high and 70' long, ie about 1000 Btu/ft^2/day
x 13' x 64' x 0.92^2 (2 layers of poly film) = 704K Btu/day on an average
day in December in Philadelphia, when the average outdoor temp is 36 F.
The tunnel ridge might be raised to 15' with longer ground posts.

Adding a strip of white poly film on the ground or a white deck along the
south side of the mobile home, or adding a shallow frozen reflecting pool
along the south side of the greenhouse, outside, might increase the solar
input by about 1/3. The polytunnel would be a half cylinder with a roof
length along the curve of 47', so the roof area would be 47x70 = 3300 ft^2,
and the endwalls will make this 4000 ft^2 total. If this is all US R1.2, we
have 704K Btu/day going in over 6 hours, and 6(T-40)4000/1.2 = 20K(T-40)
leaving, so the average December daytime temp inside the greenhouse would be
36 + 704K/20K = 71 F. We would want a slow ceiling fan or two to bring down
some warm air from the peak. 

Recall the mobile home is 10 x 30 x 7' tall. Suppose the R-values of the
walls and roof are US R11, and the windows are US R2, double glazed, with
64 ft^2 of window area on the south and 64 ft^2 on the other sides. 

This makes a thermal conductance of about 2(10+30)7/11 + 10x30/11 + 128/2
= 50 + 27 + 64 = 141 Btu/hr-F, so keeping the mobile home warm for 24 hours
on a cloudy day might take 24x(68-36)141 = 108K Btu/day. Less on a day with
an average amount of sun, since the sunspace side or polytunnel will be
warmer during 6 hours. The sunspace, eg the glazed south side of the mobile
home might collect about 300x1000 = 300K Btu/day, and lose 1/4 of that to
the outside via the sunspace glazing, which seems fine on an average December
day, and the 75 drums full of water underneath would store (120-80)75x500
= 1500K Btu of usable space heat at 120 F (we might want some insulation on top
of the drums), enough for about 14 cloudy days in a row. Sounds like too many
drums. Will the steady-state December temp of the drums be at least 120 F?

Say the mobile home has an R11 floor, and the skirt around the drums is
insulated with R30 strawbales. Then we have about 90 ft^2 x 1.33 (with
a white surface in front) x 1000 Btu/ft^2/day x 0.92^2 = 101K Btu going
into the solar closet each day, and about 

   6 hours (T-71) 90 ft^2/R1        south wall, day
+ 18 hours (T-36) 90 ft^2/R30           "       night
+ 24 hours (T-68) 300 ft^2/R11      mobile home floor, 24 hours
+ 24 hours (T-36) 150 ft^2/R30          "       ENW skirt, 24 hours,
--------------------------------
= 540T - 38340
+  54T -  1944
+ 654T - 44509
+ 120T -  4320
---------------
= 1368T - 89113 = 104K,

so the steady-state December temperature of the drums would be 

(104K + 89K)/1368 = 141 F. Looks good... 

We might want a window fan or two turning on with a thermostat set to 130 F
in a small darkened glazed box exposed to the sun, to help move warm air
through the solar closet when the sun is shining... 3' is probably not enough
height to make plastic film backdraft dampers work well. 

And we'd want about 20' of fin-tube pipe under the floor, in a thermosyphon 
loop with the water heater in the mobile home, so the electric heating element
seldom turns on. That might require a bit more solar closet glazing, ie we
might put the mobile home 4' off the ground, so the solar closet glazing is
4' tall instead of 3', since Replex and Dynaglas plastics come in rolls and
sheets a bit over 49" wide.

Nick

---

From: [email-masked] (Gunslinger)
Date: Tue, 25 Jun 1996 11:05:48 GMT

On 24 Jun 1996 10:33:43 -0400, [email-masked] (Nick Pine)
wrote:

Yo, Nick! 
10 x 30 x 7 is more like a _camper_ than a mobile home (from one who
currently lives in a 14 x 70 x about 12 mobile home.)

=>Or we might put it the mobile home inside a 30' wide x 70' long x
13' tall
=>commercial plastic film greenhouse to act as a sunspace. The usual
covering
=>is 2 layers of 5 cent/ft^2 polyethylene film, with a 3 year
guarantee,
=>statically-inflated with a 50 watt blower. 
**snip**
 Putting the mobile home
=>inside this $1500 greenhouse would allow more daytime living space,
storage
=>of not very valuable items, rainwater collection, food growing,
sewage
=>treatment, methane production for cooking gas (?), and water
recycling,
=>as well as a place to work during the day.
**snip**

Seems to me it would get too hot to do much in the way of work, except
in the dead of winter.

=>Putting the solar closet under the mobile home means we get some
heat through
=>the floor, which would otherwise be wasted if the closet were
adjacent, and
=>if we open a motorized damper under a floor return, we might easily
get warm
=>air to flow up into the mobile home by natural convection. 

And you would lose the valuable storage space underneath the home,
thus requiring the construction of some sort of outbuilding.

Idea:
What about setting the mobile home against a hillside, framing awnings
over the outward facing windows and door(s), blowing shot-crete over
the whole thing (for strength), and then covering it all with dirt,
blending it in with the contour of the hillside. Might be the world's
first earth-sheltered mobile home.
   ______                        __   _                     
  / ____/ __  __  ____   _____  / /  (_)  ____   ____ _ ___   _____
 / / __  / / / / / __ \ / ___/ / /  / /  / __ \ / __ `// _ \ / ___/
/ /_/ / / /_/ / / / / /(__  ) / /  / /  / / / // /_/ //  __// /
\____/  \__,_/ /_/ /_//____/ /_/  /_/  /_/ /_/ \__, / \___//_/
                                              /____/

I've done so much with so little for so long, 
that now I can do anything with nothing at all.

---

From: [email-masked] (Nick Pine)
Date: 25 Jun 1996 10:25:42 -0400

Gunslinger <[email-masked]> wrote:

>[email-masked] (Nick Pine) wrote:
 
>Yo, Nick! 

Greetings, Gunslinger...

>currently lives in a 14 x 70 x about 12 mobile home.)

I used to know a couple who lived in a pickup truck... You have more space
than most sailors... I wonder why yours is 12' tall, 8'+ wheels? And how
do you haul that 14' wide thing on the road? Someone was telling me that
there are more mobile homes sold in this country than houses, these days.
I'd like to find a manufacturer who is interested in solar heating them.

>Seems to me it would get too hot to do much in the way of work, except

Putting some shadecloth over the south wall, rolling up the plastic film at
the edges, opening endwall doors and having a vent or two at the top might
take care of that, leaving this house in the shade cooler than most houses
sitting in sun. One might also cover the flat roof with a single layer of
EPDM rubber, with a 2" board under the edge, to make a shallow pond to keep
the roof at the wet-bulb temp. And divide the solar closet underneath into
two sections, one to stay hot for hot water, and one to stay cool by night
ventilation. The cool part might have another shallow EPDM rubber pond
underneath, and one might pump some of the cool water up into the house
through a fan coil unit.

Let's see. You have 2(14+70)x8' of R11 walls, and 200 ft^2 of R2 windows?
For an overall thermal conductance of 220 Btu/hr-F, which might gain
8 hr(95.5-75)222 = 36K Btu/day at 75 F inside in August in Austin TX, where
the average daytime high is 95.5 F and the average wet bulb temp is 69 F.
This might raise the temp of 60 drums full of water from 69 F to 69 F +
36K/30K Btu/F = 70.2 F every day, before the water cools down again at night.

The $139 all-copper 2' x 2' SHW 2347 duct heat exchanger made by Magicaire
might make a nice fan coil unit, if attached to the suction side of a $20
box fan. It moves 45K Btu/hour between 125 F water and 68 F air at 1400 cfm,
with a 0.1" H20 air pressure drop, so it might move 4K Btu/hr with a 5 F
delta T, ie 70 F water and 75 F air. You'd want a tiny submersible pump to
move about 4000/5/8/60 = 1.6 gpm through a head of about 4'. Hmmm. That's 
about 1 ft lb/sec, and 1 HP is 550 ft-lb/sec, or 746 Watts, so a perfect
pump might use 1.2 Watts for that job. Putting the duct heat exchanger up
near the ceiling would be a good idea, with a thermostat to turn on the fan,
and a gutter and drain under the heat exchanger. 

You might control humidity with a solar-dried dessicant system, eg a nice
triethylene glycol (which absorbs 11X its weight in water) or lithium chloride
pond on the roof, or a thin reinforced concrete floor with some insulation
underneath in the greenhouse, or some sort of vermiculite, charcoal, zeolite,
clay or calcium chloride sandbox, or even a pile of sheepskins somewhere
inside the greenhouse (a wool rug will absorb 23% of its weight in water from
moist air, according to the ASHRAE HOF), all exposed to the sun and vented
outside during the day, and washed with house air at night.  

>=>heat through the floor, which would otherwise be wasted if the closet were
>=>adjacent, and if we open a motorized damper under a floor return, we might
>=>easily get warm air to flow up into the mobile home by natural convection. 
 
>thus requiring the construction of some sort of outbuilding.

Like a 30' wide x 100' long x 15' tall commercial plastic film greenhouse
to enclose your mobile home, costing $2K, requiring 1 day for 3 people to
set up, from scratch? :-)

>first earth-sheltered mobile home.

I wouldn't call that very "mobile" :-) You might hump up the flat roof with
some soil first, to make it stronger. And put some sort of insulation over
the shotcrete, perhaps, and a layer of EPDM rubber over that. Putting some
large rocks on top of the soil might make for an interesting vaulted stone
ceiling inside your underground mobile home, if you removed the roof and soil
after the concrete set. You might want to consult an architect re aesthetics.

I like Monolithic Domes (800) 608-0001, which are made by inflating an
airform (like a tennis court cover), spraying the inside with 3" of urethane
foam, wiring up some rebar, and spraying the inside with 2" of shotcrete...
These can be wonderful passive solar structures, as well as fireproof,
tornadoproof, fast and cheap. They have been building these things up to 
260' hemispheres so far, for 20 years now, and they are working on plans for
1200' hemispheres. At last year's convention, someone asked whether he
could bury one under 60' of dirt. The answer was yes. Oddly enough,
nobody asked why.

Nick

It's a snap to save energy in this country. As soon as more people become
involved in the basic math of heat transfer and get a gut-level, as well as
intellectual, grasp on how a house works, solution after solution will appear.

					  Tom Smith

---

From: [email-masked] (david allen)
Date: Tue, 25 Jun 96 20:44:41 GMT

>first earth-sheltered mobile home.

not the first,  its common practice to use a mobile home as an 'insert' into a 
concrete lined cave or hole.  it greatly simplefies design considerations, 
but, it does constrain you to live in a mobile home floorplan (cheap or custom 
is allways a tradeoff).

da

Copyright, Dr. D.R. Allen, D.Chem., 1996. Microsoft Network is
prohibited from redistributing this work in any form, in whole or
in part. License to distribute this post is available to Microsoft
for $1,000. Appearance constitutes an agreement to these
terms. Please send notices of violation to [email-masked]
and [email-masked]

---

From: [email-masked] (Nick Pine)
Date: 25 Jun 1996 20:30:03 -0400

>From  this afternoon's email...

>Awhile ago (May 8, to be exact) you posted in alt.energy.renewable a 
>comparison of a high-mass sunspace to a very low-mass sunspace.  I like the
>idea of the low-mass alternative with a solar closet in a well insulated
>part of the house.

OK...

>In the post your calculations are based on maintaining the sunspace at 80F
>during the day.  You also mention that the water in the solar closet starts
>out at 130F and cools to 80F as its heat is needed to maintain the house
>temperature.  My question is, how does the water get up to 130F?  

The solar closet has an air heater on the south insulated side, so the sun
shines through the sunspace glazing, then through the solar closet air heater
glazing, and heats up the air inside the closet air heater to about 130 F. 

>I assume there is some kind of heat exchanger transferring the heat in the
>80F sunspace air to the water in the solar closet. 

No. There's no air exchange between the sunspace and solar closet, just sun, 
passing through the sunspace, then thru the solar closet glazing. A lot of
people seem to miss this. Perhaps it needs a better explanation. 

>As I understand it, the sunspace air must be allowed to get hotter than 130F
>at some time to get an efficient energy transfer.

No. Take a look at this two dimensional version:

           S1              S2               S3
32 F       |     T1        |       T2       |       70 F
outdoors   |               |                |       house
           |               |                |
1 ft^2 of  |    1 ft^2 of  |  1 ft^2 of R10 |
R1 glazing |    R1 glazing |         wall...|
           |               |                |
           |               |                |
1200 Btu   |    sunspace   |  solar closet  |
per ft^2   |               |                |
of sun over|               |                |
a 6 hour   |               |                |
day -->    |               |                |
           |               |                |
 
If surface S2 were dark-colored, with an infinite R-value, so there were no
other place for the solar energy to go, the average 200 Btu/hour of sun would
raise temperature T1 until all the heat that came into the S1 glazing went
back out through the glazing, so 200 = (T1-32)x1ft^2/R1, or T1 = 232 F. Right?

Now suppose S2 is perfectly transparent, with an R-value of 1, and S3 is dark,
with an R-value of 10. What will T2 be? Here's the electrical analog:

     ------------
 |  | 200 Btu/hr |
||--|   ----->   |-------     (The sun is a current source.)
 |  |            |       |
     ------------        |
                         |
32 F ---www--------www---------www--- 70 F
        R1    |    R1    |     R10
             80 F        T2

Say enough hot air is bled out of the sunspace into the house to keep the
sunspace at 80 F. Then we have 200 = (T2-80)1 ft^2/R1 + (T2-70)1ft^2/R10,
ie 200 = T2 - 80 + 0.1T2 - 7, ie 287 = 1.1T2, or T2 = 261 F, so you see the
solar closet can be a lot warmer than the sunspace, when there is no air
exchange between them, just sun passing through one space and into the other.

If each glazed surface were perfectly transparent, and there were N panes
of glass, each having an R-value of 1 (counting the still air film), and the
last surface were perfectly insulated, the temperature T in the last space
would be such that 200 = (T-32)/N, ie T = 32 + 200N. You can see something
like this if you put an oven thermometer on the lawn on a sunny day and cover
it with a few panes of glass, eg a few old storm windows. The thermometer
goes up to a few hundred degrees quickly, and the grass quickly turns brown.
The same thing happens inside a solar water heating panel on the roof, if
the pump fails, which is called "collector stagnation." 

Nick

---

From: Marc Popek <[email-masked]>
Date: Tue, 25 Jun 1996 22:57:51 -0700

> 100 F -------www-------|---------www----------40 F

What your point, Nick
Should we setback the temperature slightly when we come and go .. in and 
out of our homes?

Should lwe let the furnace roar in the winter to maintsin the wall 
temps??

Should we run the compressors too keep the walls cool?? or should we
add sensors to our thermostats that autmatically knew your coming and 
goings

The t-stat we know your " laws of colling and automajic setback the 
temperature sot hat thermal recovery was a set specified nkmber of 
minutes?????

---

From: [email-masked]
Date: Wed, 26 Jun 1996 16:52:51 GMT

Speaking of mobile homes - -   doesn't it seem as if every
realtor-dominated zoning board in America decided long ago to make
sure nobody could actually build any REALLY cheap housing?  <sigh>

---

From: Chad Berreau <[email-masked]>
Date: Wed, 26 Jun 1996 14:32:54 -0500

> sure nobody could actually build any REALLY cheap housing?  <sigh>
Have you ever been in a trailer home once the winds reach 50+mph.  It 
sounds like a tornado is right overhead.

Maybe what should be done is to design trailer homes to be more 
comfortable and not so easily moved in high winds.  

BTW I don't think that Mother Nature really likes trailer homes.  Just 
check the news the next time a tornado or straight line winds hits an 
area.

Modular homes though do seem a bit better constructed and secured than 
and trailer home I have ever seen.

---

From: [email-masked] (Nick Pine)
Date: 27 Jun 1996 03:53:15 -0400

>What your point, Nick

1. Uninsulated things cool fairly quickly in air.

2. Solar houses in partly cloudy climates work better if their thermal mass
   is insulated from the living space, and has an average temperature
   that is higher than the living space temperature. 

3. Given this higher temperature, you can also make hot water for showers, etc.

>Should we setback the temperature slightly when we come and go .. in and 

Makes sense to me, if we have low-thermal-mass houses. Turn down the
thermostat at night, or when we go to work...

>Should lwe let the furnace roar in the winter to maintsin the wall temps??

I think we should use the sun to heat houses.

>Should we run the compressors too keep the walls cool??

I'd say use more natural cooling, which can work in many locations.  

>or should we add sensors to our thermostats that autmatically knew
>your coming and goings
 
Interesting idea. Might work in a very low thermal mass house, with a
low-thermal-mass overhead radiant or forced air heating system. Like hallway 
lights that turn on ahead and turn off behind people, as they walk along? 
 
>temperature sot hat thermal recovery was a set specified nkmber of 

I'm not sure what to make of that...

Nick

---

From: Kathy Ging <[email-masked]>
Date: Sun, 30 Jun 1996 01:27:11 -0700

I recall reading last year that the average stick built home in
OR cost ca. $120k, average manufactured home $45k. So some
blame rests with the consumer who is not willing to pay
for environmental desisgns, who is not concerned with life cycle costing, 
minimum toxic concerns et al, but is more concerned with satellite
dishes.

I do not think Realtors so much as home builders can be blamed
for the lack of real affordable and well designed sun tempered
houses. Blame the ughitechts while you cast pebbles, the ones who
are paid on the price of the built environment (as Realtors are paid on
the price of the house). I am a Realtor and also secretary of
the Eugene chapter of the NW Eco-Building Guild and am a strong
promoter of alternative housing - organic pls.  (I am somewhat
of an anomaly in the profession - being an ole solar bozo and
a sixties activist.)

When Mother Earth News did a survey over a decade ago of 300
major homebldrs in the US, not one was paying attention to
simple solar principles when designing their subdivisions.
May they all freeze in the coming ice age!

Building trades are paid a lot of money - $28 hr + - this
does not promote alternative house construction.  If  builders
and other trades were willing to work for less, more people
could have fun, low profile houses  designed with climate.

A retired UO architect recently suggested that bldg codes should
be passed that required sustainability energy and other wise from
houses!          Kathy Ging M.A., GRI

---

From: [email-masked] (paul milligan)
Date: 1 Jul 1996 01:21:41 GMT

Damn, another spam thread  !!

cross posted to :

alt.architecture.alternative,alt.solar.thermal,sci.energy,
alt.energy.renewable,sci.engr.heat-vent-ac

STOP THIS THREAD NOW !!!!!

The SEHVAC FAQ is at: http://www.elitesoft.com/sci.hvac/
My humble personal pages are at: http://www.webbuild.com/~pjm/

---

From: [email-masked] (M J Epko)
Date: Tue, 02 Jul 1996 13:57:08 GMT

>STOP THIS THREAD NOW !!!!!

	I'm slightly (electronically) acquainted with Kathy Ging, the alleged
spammer, and am reasonably certain that she's not engaged in
self-promotion here. It didn't read like she was trying to sell
anything either. If you'll look at the (only FOUR, not forty)
cross-posted newsgroups, you'll note that they're all pertinent to her
post; I'm also reasonably certain that she's subscribed to all of them
& is looking for feedback & additional info. (Isn't that what this
newsgroup stuff is all about? An info vehicle?)
	Also, if you'd read the whole thing (maybe you did), you'd've noticed
that she was responding to a previous post.

	I'm with you all the way on your opinion of spammers, but I think in
this case the label's been mis-applied.

M J