Subject: Re: mobile homes inside commercial plastic film greenhouses

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
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---

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: [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]
Date: Thu, 27 Jun 1996 21:39:03 GMT

>sure nobody could actually build any REALLY cheap housing?  <sigh>
...or contractor-dominated.  The late author/builder  Ken Kern, 
et.al. dealt with this issue in his 1978 book " The Owner-Builder and
The Code".   We are considered a nation of home-owners but how many
really OWN their home as opposed to "renting" it from the bank, 
hoping a rising market will net them some equity.  Soon - a nation 
of maids, janitors, and renters.

---

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 !!!!!

_________________________________________________________
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/

---

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