Transcript Sustainable Low-Cost Heating for Season Extension Structures

Sustainable Low-Cost
Heating for Season
Extension Structures
Clinch Appalachian Farmers Enterprise (CAFÉ)
CAFÉ
 CAFÉ is a member-run organization of
20 farmers growing mainly for public
school and restaurant markets.
 In 2007-09, CAFÉ conducted trainings
and research in order to explore low-cost
sustainable heating alternatives for
greenhouses and hoophouses.
Composting
 CAFÉ found that composting added an
insignificant amount of heat to the interior
of the greenhouse.
Geothermal Energy
 Geothermal energy only differentiated the
temperature inside the hoophouse by
about 10 degrees; a well built, doublewalled greenhouse is already likely to be
eight degrees warmer than the outside
air, meaning a gain of only 2 degrees, at
considerable expense.
Heat Sink
 The area required for sufficient heat sink
material is so large that the growing area
in a normal sized greenhouse would be
greatly reduced. The temperature gains
would not be worth the loss of
production.
Insulating the North Side
of the Greenhouse
 CAFÉ members tried banking bales of
leaves against the north side and northwest corner of a greenhouse, but
temperatures inside the structure actually
dropped, though the plants growing there
were unaffected.
Low Tunnels in High
Tunnels
 CAFÉ members the temperature inside the
high tunnel was an average of 5.5 degrees
warmer than outside, and that the temperature
inside the low tunnel was an additional 4.9
degrees warmer, for a composite gain of 10.4
degrees for the low tunnel.
Co-generation Heating
 CAFÉ found that this method of heating a greenhouse
worked quite well, with temperatures ranging from 70
to 95 degrees (F), depending on fan-use and time of
day. This would be a sustainable way to heat a
hoophouse if the owner were already using wood fired
heat for his or her home.
Double-walled Greenhouse
 Usually an effective sustainable heating
strategy, CAFÉ’s experience with this
technique was marred by problems with
structural integrity. Double-walled
greenhouses usually produce an extra 8
to 10 degrees of interior warmth.