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Re: A zero-fossil-fuel studio?



Mike Youso  <arctech@yknet.yk.ca> wrote:

>A major concern with any thermal storage system is the moisture from 
>condensation on the surface of the thermal storage modules if a remote 
>storage bank is used.

I agree this is a good thing to avoid. I don't see a problem with moisture
condensing on these containers of water while the containers are heating
the house on a cloudy day, do you? Would moisture condense on the containers
of water as they are being heated by sun-warmed air? Perhaps, if the air is
moist. But the air should be fairly dry in the winter, if the house is
reasonably-well ventilated and the sun heats it up. Do you think condensation
will occur in this system, or are you just saying it's a concern? If so,
I wonder under what conditions might it occur, and how might we avoid it?

>If the storage bank gets much above 60% rh some rather nasty organisms
>will be growing in the air supply system with possibly serious considerations
>for IAQ. 

I wonder how the humidity would increase to 60%? It seems that, say, 32 F air
at 100% relative humidity will have a much lower RH at 68 F, and on an average
day in December, this solar closet should be about 130 F inside.

>The most succesful thermal storage uses direct-gain solar mass walls
>rather than ducting warm moist air to a storage bank.

Again, where does the moist air come from? During charging, the air in a
solar closet is completely self-contained. There is no mixing with house air...

And when you mention "successful" direct gain solar mass walls do you mean
Trombe walls? 

A few years ago, I spent some time explaining to a local architect, a more
technical person than most, who had taken a few engineering courses on the
way to architecting, that a "Trombe wall" with some dark-colored insulation
on the outside and an air gap between the insulation and glazing and some
to the inside of the house that opened up during the day was a lot more
efficient at collecting and keeping solar heat in the house than a plain old
"traditional" Trombe wall, with masonry right behind the glass, with no
insulation. Here's what I said:

  A modified "Trombe wall" with insulation on the outside, and 1 ft^2 of south-
  facing single-glazed area and an R-value of 20, will receive about 1000
  Btu/day of heat on an average 32F December day, where I live. If the room
  behind it has a constant temp of 70F, and the sun shines 6 hours a day,
  on the average, the energy that leaks out of the glass will be about 6 hours
  x (70F-32F) x 1 ft^2/R1 = 228 Btu during the day, and 18 hours x (70-32) x
  1 ft^2/R20 = 34 Btu at night, a net gain of 1000 -228 -34 = 738 Btu/day.
  Simple, no? (~750 Btu, net, with double glazing, which passes less sun.)

  A standard unvented Trombe wall (Table IV-14b of Mazria's book says vented
  ones don't work much better) with a very large uninsulated thermal mass
  right behind the glass and an R-value of, say 2 (roughly 1' of masonry),
  would have an average temperature at the outside wall surface of about
  32F + R1 x (70F-32F)/(R2+R1) = 45F, if there were no sun. If you add a
  heatflow of 1000 Btu/day of sun to that model, falling on the outside
  of the wall, the outside wall surface will have an average temperature
  of about 45F + 1000/24 x (R=2/3) = 72.4F, which contributes 24 hours x
  (72.4F- 70F) x 1 ft^2/R2 = 29 Btu/day to the room behind the wall.

  So the "improved Trombe wall" above, (actually an air heater with the
  thermal storage inside the house) is _more than 25 times as efficient_
  (738/29) at collecting and keeping heat in the room behind it, than
  the usual Trombe wall. This is a bit oversimplified...

Trombe walls are also thermal disasters during long strings of cloudy days.
When the sun goes in for a week or two, they lose their stored heat in less
than a day, and then leak house heat badly, dramatically raising backup
heat or other solar thermal storage requirements.

>Two or three layers of drywall is a good compromise since only the first
>1.5" to 2" is diurnally active.

Seems to me that a few "accent drums" full of water sprinkled around
the house might be cheaper...
 
>a zero fossil fuel studio is quite feasible almost anywhere south of the 
>arctic circle.

We seem to agree on that :-)

Nick




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SEI
 Pine.Associates.Ltd.
 Passive.Solar.Industries.CouncilFrom markh@ORA.COM Sat May 14 09:45:21 1994
Date: Fri, 13 May 1994 22:51:10 -0700
From: Mark Harrington <markh@ORA.COM>
To: Multiple recipients of list INDKNOW <INDKNOW@UWAVM.BITNET>
Subject: Solar oven design

On May 9,  9:39am, Eng-Leong Foo mtc wrote:
} Subject: ET-012: The Solar Oven A Tool Of Sustenance
>The Solar Oven A Tool Of Sustenance
>
>Mark Harrington <markh@ora.com>
>phone: (H) 707-526-0867
>       (W) 707-576-2434
>
>===================================================================
>
>        Our greatest example of sustainability is nature herself. By
>emulating her we have the possibility of designing and creating tools
>of sustenance. The Solar oven is an elegant example of sustainable
>design.  The intention of this paper is to provide design ideas,
>practical information, rules of thumb, and support for the
>dissemination and implementation of this elemental ecotechnology.
>
>        Passive Solar Ovens are a very simple, inexpensive, yet
>effective tool which can be used for cooking a wide array of
>foodstuffs, sanitizing medical instruments and bandages, and water
>pasteurization (1).   These devices work effectively in Northern and
>Southern latitudes during spring to fall seasons and in equatorial
>zones they have the potential to function very efficiently throughout
>the year.  Solar Ovens generally require relatively clear days for
>operation although they can utilize some diffuse light. I have heard
>of complicated, high tech parabolic cookers which store high
>temperature oil and can even operate at night.  Parabolic cookers are
>well suited to high temperature cooking such as stir frying which
>can't be accomplished in an oven.  Although, overall they are less
>versatile then the oven.  Parabolic designs will not be evaluated in
>this conference.
>
>        Solar energy has been bestowed in a compensatory fashion.
>Often the areas with the greatest poverty, deforestation, and
>shortages of costly cooking fuel are the equatorial zone, the area
>with the greatest solar resource.  Besides providing an economically
>advantageous alternative to other renewable or non renewable cooking
>fuels, many of the worlds poor, women in particular, die prematurely
>due to respiratory diseases from exposure to smoke from burning dung,
>wood, coal and other fuels.  Significantly increasing time and energy
>are needed to forage for fire wood.  This is especially a burden for
>pregnant and nursing mothers.  Deforestation continues unabated,
>especially in developing countries, with an ever increasing loss of
>agricultural potential.  In the hot season residences may also be
>rendered more comfortable when foods can be cooked outside with solar
>energy. Where air conditioning is utilized energy can also be
>conserved by reducing waste heat from within the dwelling.
>
>        In affluent countries cooking fuel is taken for granted. In
>developing countries heirloom furniture and clothing has been used as
>cooking fuel!  In desperation, mature, bearing fruit trees have been
>cut down to provide fire wood! The optimal operational temperature
>range of a solar oven is from 2500  to  4000 F (1210-2500 C) A wide
>variety of foods can be prepared in the solar oven: legumes, grains,
>pasta, meat, fish, tea, coffee, vegetables, breads etc. "Solar cooking
>can best be described as a combination of mild broiling and oven
>baking" (2).  Higher temperatures are not necessarily desirable,
>unless time is essential. Irregardless, solar cooking requires advance
>planning, yet less effort.  You don't need to stir the pot.
>
>sustainable design it is important to use locally available, and
>preferrably renewable materials whenever possible.   Use of synthetic
>construction materials may result in the emission of chemical vapors,
>or gases, used in their manufacture, for example formaldehyde resins
>in wood products, or materials such as styrofoam or plastics may emit
>hazardous decomposition by-products at elevated temperatures such as
>cyanide. These emissions may result in the contamination of food-
>stuffs cooked in the oven.  My preferred construction materials are:
>glass, soil, bamboo, grass, solid-wood, metal, etc. These materials do
>not typically present off-gassing problems at design temperatures.
>
>        I strive for a minimalists design, this is my bias.  I ask the
>question how can a design be simplified and sustained, so that it can
>be replicated by nomads in the Niger, Quechua indians in the Peruvian
>Andes, or suburban North American earthquake survivors.  With "space-
>age" materials you may be able to squeeze more performance out of an
>oven, but you can quite capably do the job with very basic materials.
>
>        The body, or outer shell of a Solar oven can be constructed of
>cardboard, wood or wood products, adobe bricks, rammed earth, wattle
>and daub, wicker, thatch, reed, sheetmetal, fiberglass, composites
>etc.  Optimally, the body of the oven should be non conductive and
>resistant to ultra-violet light and water.  If the body is a good
>conductive material, such as galvanized steel, design for additional
>insulation as there will likely be greater heat loss.
>
>        Some designs will have an inner liner made of sheet metal, or
>other conductive or non-conductive materials, with insulating material
>filling the void between the inner and outer shells. If an inner shell
>is used optimum performance will come from a good conductor that is
>light weight, such as thin, blackened sheet metal.  The inner surfaces
>of the oven should be of low thermal mass (light-weight) construction.
>Excessive mass will not allow the oven to achieve design temperatures.
>Insulating materials can vary widely: fiberglass, synthetic foams,
>perlite, cardboard, rice hulls, straw, sawdust, wood chips, dry dung,
>hair, paper, corrugated plastic (3), etc.   Dead air spaces and aluminum
>foil (4) (shiny side facing in) are other strategies which may be used
>either by themselves or in partnership with other insulating
>materials.  Typical wall insulation thicknesses range from 20 to 150
>mm.
>
>        Some form of caulk or weather seal is desirable and can make
>an immense difference in the performance of an oven.  It should
>ideally be non conductive, soft and resilient, resistant to
>degradation by ultra-violet light, non toxic, and able to withstand
>peak design temperatures. This is especially critical for the mating
>surfaces of the solar aperature (glazing) with the body.  And also the
>access port, which is often the glazing. If this is the case it is
>important that the caulk does not harden, or adhere to the glazing.
>Some possibilities for the caulk are: rubber, latex, tar, silicone
>glue, felt, plastiline, leather,grease, pitch, gum resins etc.
>
>          The solar ovens I am describing here can be grouped into two
>categories, Portable and Monolithic ovens. The portable oven is
>versatile due to it's relative light weight, mobility and enhanced
>performance potential due to it's tracking capacities.  The most
>common configuration for a portable oven is a rectangular, or wedge
>shaped box with insulated sides and bottom.  The rectangular box form
>is easier to construct and  the angle of the glazing makes this design
>well suited for the tropics. In more extreme lattitudes the wedge
>shape design will be more efficient.  The optimal glazing angle will
>be perpendicular to incoming solar radiation. In practice this usually
>means manually moving the oven in increments along a horizontal plane,
>tracking the sun to optimize solar gains.  Some designs also have
>provisions for simultaneously pivoting the oven along a vertical axis,
>in order to optimize efficiency.  The latter design element, in my
>opinion, is usually superfluous, unless the oven is used in extreme
>lattitudes.  This design element requires a more complex oven design,
>with an inner suspension, so that the contents of the cooking
>vessel(s) do not spill. Portable ovens have the potential for much
>greater efficiency than their monolithic counterparts, although they
>are often more fragile, and a durable design is usually more expensive
>and complicated to build.  Portable ovens are more versatile.  They
>can be moved and transported and you can typically prepare two meals a
>day in a single oven, with an effective working range of 6-8 hrs. per
>day.
>
>         Monolithic ovens are usually fixed in position.  When earth
>is used as the structural body of the oven we create the alchemical
>marriage of the elements of earth, fire and water (food). They can be
>dug into a hillside, mound, or pit, where the earth itself, becomes
>the crucible, or they can be built above ground from adobe bricks,
>rammed earth etc.  The beauty of this design is that it is the most
>elegant, materially accessible, inexpensive and potentially one of the
>most enduring.forms.    The dug-in designs are well suited to desert
>areas, or dry season use.  The above ground designs should have a
>thatch or other protection from the erosive affects of rain.  A fixed
>oven's working range may only be 2-4 hrs. per day, usually one meal
>per day. It is feasible to have several fixed ovens, with different
>solar orientations, which share a common glazing and reflector.  In
>this manner we can compensate for the monoliths lack of tracking
>ability.
>
>        Single or multiple layers of glass or synthetic glazing
>material enclose the top and comprise the solar aperature.  Multiple
>glazings will have an air gap of 3 to 40 mm. between layers. Dead air
>spaces increase the insulative properties of the aperature.  However,
>consider that increasing layers of glazing will also reduce the amount
>of transmitted solar energy.  In most cases a single layer of standard
>window glass is quite adequate.  As a rule of thumb the thinner the
>glass the greater the transmittance of ultra-violet radiation, our
>workhorse.
>
>         A supplemental reflector, to increase the effective solar
>aperature, is usually required.  In equatorial regions the reflector
>may be optional if the oven is tight, well insulated, and oriented for
>maximum solar gain. Reflectors are strategically oriented and usually
>consist of glass mirrors, polished sheet metal, aluminum foil, or
>aluminized mylar (a type of plastic film).  Cardboard or plywood
>sheets painted white, or taut-stretched white fabric may also be
>effective, though less efficient.
>
>        You are welcome to join this conference with your questions
>and ideas.  Feel free to disseminate this paper.  In Sustenance...
>
>References:
>1. The Construction, Theory, and Use of the PAX Solar Water
>   Pasteurizer with Flat Heat Recuperator (Dale Andreatta, P.E. and
>   Derek Yegian)  Note: I understand that Derek will be presenting
>   this as a seperate paper for Ecotechnology Conference '94
>2. SBCI, Solar Box Cooker International Newsletter Spring. 1993
>3. The Solar Cookbook by Stella Andrassy
>4. SunWorld, Volume 14, Number 1, 1990
>
>
>************************************************************************
>              Please remember to refer to paper "ET-012"
>               in the "Subject" title of your message.
>Pls e-mail your questions, comments and answers to ET-LOKE@SEARN.SUNET.SE
>************************************************************************
}-- End of excerpt from Eng-Leong Foo mtc


I have had numerous requests to post this, while it is long, I hope
you will find it useful.

--
Mark Harrington

email: markh@ora.com
phone: (H) 707-526-0867
       (W) 707-576-2434

.
'..
mobile-solar-unitFrom pgipe@igc.apc.orgThu Dec 21 13:47:48 1995
Date: Wed, 20 Dec 1995 07:59:26 -0800 (PST)
From: Paul Gipe <pgipe@igc.apc.org>
To: london@sunsite.unc.edu
Subject: New WWW Sites on Wind Energy

New WWW Sites
 
Here are some new www sites with information on wind energy. They are in no 
particular order. Some have already been announced.
 
http://www.igc.apc.org/hp/
 
Home Power magazine home page. Skillful use of colorful wiring diagrams and 
images of renewable power systems. Their wind energy page was linked to 
their pv pages when I viewed the site, but Home Power says they will add a 
wind section soon.
 
http://michell.maths.adelaide.edu.au/Applied/UA_DAM_FLUIDS/AERO/
WINDMILL/windmill.html 
 
Dept. of Applied Mathematics Fluids Group at the University of Adelaide 
(down under). Image of experimental straight-bladed vertical axis wind 
turbine and bibliography on VAWTs.
 
http://www.ecn.nl/unit_de/society/kennemer/
 
Home page for the Dutch wind turbine cooperative Windmolen Vereniging 
`Kennemerwind.' You don't have to know Dutch to get the gist of it. They 
use 8 Lagerwey 18/80s and plant to add two more in 1996. Evert Kuiken is 
one of the 500 members of this cooperative. The cooperative, the biggest in 
the Netherlands (een van de grootste?) has invested about $400,000. Wind 
Werkt!
 
http://www.ecn.nl/unit_de/society/eendragt/
 
Home page for Dutch wind turbine cooperative Windmolen Vereniging `De 
Eendragt.'
 
http://ourworld.compuserve.com/homepages/res_ltd/
 
Stewart Russell created this home page for British wind company Renewable 
Energy Systems Ltd. Several good photos of wind turbines in the United 
Kingdom. 
 
http://www.cadvision.com/arets/
 
Announcement of an Aeration Workshop of the Alberta Renewable Energy Test 
Site. More will be added later on wind pumps being tested at the test 
center near Pincher Creek, Alberta, Canada.
 
http://www.swbi.net/pfgolbeck_home.htm
 
Peter Goldbeck uses his home page to introduce www browsers to wind energy 
and specifically the Tacke 600 kW turbine at the Bruce Nuclear Power 
Development near Kincardine, Ontario, Canada. Peter is a technician at the 
nuclear plant and monitors the turbine for Ontario Hydro. He presents a 
table of production statistics from the turbine.
 
http://keynes.fb12.tu-berlin.de/luftraum/konst/stamps/
 
Klaus and I have added a whole series of postage stamps from different 
countries that depict windmills. The new images include four stamps from 
the U.S., two from France, one from Germany, and one from the Netherlands. 
We will add stamps from Denmark, Hungary and the Netherlands' Antilles 
early next year.
 
Paul Gipe
Paul Gipe & Assoc.; 208 S. Green St., #5; Tehachapi, CA 93561; 
ph: +805 822 9150; fax: +805 822 8452; pgipe@igc.apc.org/pgipe@mcimail.com 
Contributing editor to Independent Energy magazine and WindStats and author 
of Wind Power for Home & Business (Post Mills VT: Chelsea Green Publishing, 
June 1993), and Wind Energy Comes of Age (New York: John Wiley & Sons, May 
1995)--http://keynes.fb12.tu-berlin.de/luftraum/konst/gwindpower.html, and
http://keynes.fb12.tu-berlin.de/luftraum/konst/gwindenergy.html.


References: