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Insulated Floors In Greenhouses: It Makes Sense!
As energy costs continue to rise many greenhouse owners are seeking
ways to reduce their energy usage. The following is a discussion
that should help guide you down the road towards reduced energy
consumption.
Even if you have a conventionally heated greenhouse, you can still
reduce your energy demands and reduce your heating bills by understanding
some of these basics that relate to higher energy efficiency. To
better understand the energy savings related to different kinds
of building, but especially in greenhouses, one must know how energy
is lost. We can think about a building as a fortress. The more unprotected
(uninsulated) gaps we leave the less secure the stronghold is. The
floor is certainly one of these gaps that needs to be protected.
People very often neglect floor insulation because they do not
judge floor insulation as necessary. This oversight seems to be
caused by the belief that floor insulation does not play an important
role in building heat losses. This idea stems from a common misconception
that heat rises. Heat does not rise; hot air rises because of relative
densities. Heat energy generally moves from hotter to colder; or
more simply, heat follows cold.
As one of the most important things for plants is to grow them
in warm soil, the soil temperature is a more important factor in
a greenhouse than air temperature. Floor insulation can stop heat
loss and can also work to store heat. Uninsulated concrete floors
gain heat from heating systems and then transfer that heat to the
ground below. Insulation reduces heat movement into the ground and
keeps heat in the soil.
For greenhouses floor-heating systems seem to be more efficient
than other methods but it is only truly efficient if the heated
floor is well insulated. A great deal of research has shown that
insulating a heated floor saves up to 50% of energy use compared
to uninsulated floors. If the floor, and thus the soil, is warm
plants can often tolerate a colder air temperature. Therefore, below
floor heating can be very efficient even with cooler greenhouse
temperatures.
A widely accepted advantage of pipe heating systems is warm floor
heating. Heat is provided through a hot water or steam pipe system
below the soil or concrete floor. The main advantage is homogenous
heat delivery throughout the greenhouse from the large surface area
of the floor. Heating from the bottom of the greenhouse allows warm
air to rise through the plants, providing better circulation of
the heat. In addition, heating the roots increases plant health
and growth. Keeping the temperature of the leaves above the dew
point is an excellent way to prevent condensation and thus fight
common greenhouse diseases. Also, new approaches to disease and
pest management require careful attention to the microclimate of
crops, using heating and humidity as tools to treat diseases and
even affect insect behavior.
The solution is to insulate your floor and the outside perimeter
foundation with INSTA-PANELS®. INSTA-PANELS® are 1¾”
thick polyurethane foam covered on both sides with steel sheets
and they have R-value equal 12.0 [BTU/hr ft2 F]. These panels can
be used to insulate all kinds of floor and foundations. In comparison
to other common used insulation materials, polyurethane panels provide
longer lasting thermal protection in a wide range of temperatures
and humidity levels. Foundation insulation should be placed vertically
and extend down to an absolute minimum of 1 foot in most temperate
areas. If you live in a colder zone, consider even deeper foundation
insulation (3-5 feet) (refer to diagram below). The payback period
for well-done insulation is very quick, usually between 6 and 12
months.
The floor and foundation of your greenhouse should not be a heat
sink, drawing heat from the air and transferring it to the ground
below. Setting the Insta Panel insulation under the floor and against
the outside of the foundation will make your greenhouse much more
energy efficient and let you keep more money in your pocket.
Insufficiently Insulated
Perfectly Insulated
Learn More about INSTA-PANELS®
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