Solar Power Your Garden Dome
How to harness the power of
the sun - Use the suns radiant solar energy to heat your dome
As with all greenhouses, dome greenhouses make
excellent solar collectors. One reason why a dome can make more
efficient use of solar energy is due to the round shape; one or more
dome triangles is always on a nearly straight direct path to the sun
overhead. There is a more consistent, even warming effect through out
the day. Inside the dome air circulates
more freely bottom to top for more ventilation and healthy plant life.
best ventilation use a cupola top with windows and exhaust fans or one
more fans attached to the dome frame. Use thermostat controlled fans,
heaters and cooling system. A computer with special software can
regulate the temperature and operate and monitor irrigation, humidity
and other factors. Thermal actuators such as the Uni-vent can
automatically operate windows.
Passive Solar Collectors
I use 55 gallon drums filled with water for my solar
collectors. The are flat black plastic, previously used for detergent
for car washes. The flat black absorbs more of the suns light energy,
don't use a shiny black as it reflects the light. I have 9 of them in
my 15 ft. Garden Dome 2 with the Base Option, and more would do well in
climates further north. The top of the drum gets the hottest. When the
temperature warms up I put plants and
shelves on the tops of the drums. Also the water can be easily poured
siphoned out, and the drums taken out too. I live in north Texas so the
aren't that regular, and I need only a small electric heater with
control to keep the dome temperature around 55-60 degrees F when it is
32 outside. Any dark colored jugs filled with water will absorb heat
sunny days and dissipate heat at night inside the dome.
Another solar collector is rock. I've noticed
my dome get hot on sunny days. If they are dark colored they will get
hotter. This method of passive solar collection is a valid option to
containers. One way to do this is to make a cage of fence material to
your rocks in, located in a position to receive maximum sunlight. A fan
the rocks will circulate the heat given off at night.
Rigid foam insulation inserted into the north
triangular faces of the dome will help retain heat during winter. The
type will reflect light back into the dome. Press to fit panels are
installed and removed. For cutting them out, try making a triangle
with large cardbourd or plastic film, and marking the outline on the
I have a ceiling fan to circulate air and blow
down as the dome height is about 10 feet. The fan is attached on a
pentagon shaped piece of 1/2" plywood, that is screwed onto the five
top struts of the dome. For greatest floor area and least height, the
Garden Dome 3 is best.
Winter observations from my own Garden Dome 2
that I use as a workable demonstration dome.Inside the dome there's no
circulation must be created when the windows are closed. I use the
fan and an excersize bike that has a fan incorporated. I have only
plants of many types, but the carbon dioxide I put out is important to
It can be very windy outside but calm inside the dome. There's no wind
chill factor. If it is 30 and windy outside and snow on the ground,
it's 50 inside the dome on a cloudy morning and that's without using
the small electric heater.
I'm not using the foam insulation, only super poly and my dome is 98%
from outside air flow. We had a "mild" winter.
Summer observations. The dome was getting too
hot inside (110+ degrees F) so we added some misters, window, shade
cloth and an extra fan. Some of the plants were baking while others
(succulents) have adapted quite well to the heat. I constructed a
hinged triangle frame window/vent and placed it on a top triangle. Then
spray atomizer misters ( Misty Mate brand) were
attached to upper dome struts, and a Y connector for a water hose in
the dome (misters are plugged right into a garden hose). Next a square
piece of shade cloth was stapled inside the dome to reduce afternoon
heat on the herb growing area; an an extra fan to supplement the
ceiling fan. We've had a period of unusually record breaking hot days
and little to no cloud cover or rain for 3 weeks. June '98
Some pre-engineering of you dome foundation can bring
more passive solar heat by using the ground as the solar collector.
some ideas of how to do this:
1. Where your dome floor will be dig down about 2
feet. Here you will insulate from the ground up. Put in hard foam board
insulation right on the dirt.
2. Tubes below your dome floor will bring the heat
collected in the soil into the dome with a circulation fan. Array these
tubes strategically spaced on top of the foam insulation. Connected pvc
tubes will work well
and support the weight of the dirt on them. A blower will circulate the
warm air from the conducting tubes into the dome. Your insulated dirt
floor makes an excellent solar collector. And you can still grow plants
right in the soil
without interference. Plants will do well with a warmer ground
temperature. Your growing medium/soil can be replaced conveniently as
Below your dome frame base perimeter, a cinderblock
retainer wall can be placed in the ground when you are excavating for
placement of the foam insulation and tubes. This will also allow you to
insulate the below ground block wall with foam board insulation.
3. Fill the hole back up with the excavated soil.
This is your solar collector so you might plan on where no shadows are
Some more ideas about using your Garden
- Retain heat in winter with insulating techniques and solar
- Ventilate in summer with windows and fans.
- Use thermometer to regulate temperatures Shade
Thermometers, place away from direct sunlight for most accurate readings
- Store water for heat collectors in black containers; flat
black paint may be used
- Clear jugs may be used; add black paint to the water to
make it opaque.
- Situate water heat collectors next to north side foam board
insulation panels to avoid blocking light on plants
- Use weather stripping at doors and windows and rubber
sealant to minimize air infiltration
- Grow plants/vegetables suitable for the season and
- Wind, clouds, sun, growing zone and other factors determine
growing invironment-dome air and soil temperature
- In winter heat the water in the drums (or one that is
located) with a submersable heater 800 - 1000 watt; or space heater
- Use shade cloth during summer to reduce heat; it works best
installed on the outside
- Use windows with screens, for cross ventilation
- Use an exhaust fan
- Monitor temperatures more closely in Spring and Autumn when
temperature variations may be greater
- A thermal actuated automatic window opener works well
- Clean the covering once a year. Use biodegradable detergent
- Use double layers of film, and silver backed foam board for
- Make removeable triangle panels that are covered with the
film such as our Super Poly. These can be installed in winter for heat
and removed in summer. Or attach shade cloth to reduce heat in summer.
x 2" wood will make a good frame for the removeable triangles.
On the World Wide Web:
- Sunset- Garden
Patio Building Book (by Sunset Books and Magazine
1969). Old but usefull, lots of good illustrations.
- Growing Solar Food In Greenhouses
(by Delores Wolfe, Copyright 1981, Doubleday & Company, Inc., ISBN
0-385-17603-1) "A month-by-month guide to raising vegetables, fruits,
and herbs under glass" 1st Edition, 192 pages.
- How to Build and Use Greenhouses
(by Ortho Books, Copyright 1978, ISBN 0-917102-74-6) Lots of nice color
photos, charts and drawings; 95 pages.
- The Complete Greenhouse Book
Peter Clegg & Derry Watkins, Copyright 1978, Garden Way Publishing,
ISBN0-88266-142-6) "Building and Using Greenhouses from Coldframes to
Structures" More thorough and technical, 280 pages.
- The Big Book of Gardening Skills
(Copyright 1993, by the editors of Garden Way Publishing, Storey
Inc. ISBN 0-8826-796-3) Good book about gardeing in general with one
dedicated to greenhouses. 346 pages
- Add-On Greenhouses and Sunspaces
(by Andew M. Shapiro, Copyright 1985, Rodale Press, ISBN 0-87857-507-3)
"Planning, Design, Construction" Very thorough, 355 pages. Mostly
pertains to adding to an existing structure.
and Frames (by Peter McHoy,
1984 Blandford Press UK, ISBN 0-7137-1244-9) All aspects of flower and
greenhouse gardening 128 pages w/ color photos
- Building a Solar
Pit Greenhouse (by Greg Stone,
Way Publishing Bulletin A-37, Copyright 1980) 28 page booklet with
to build a partially sunken greenhouse that uses the earth and sun for
- Building and Using a Solar Heated
Greenhouse (John Fontanella and Alvis Heller, Garden Way
1979) Very informative but the dome building technique is
Links from Sierra
in Environmental Architecture (good article on solar greenhouse by
architect Raold Gunderson)
Web - Greenhouses and Structures Forum