Another option that is in between a permanent floor and dirty is the use of pea gravel and a special
flooring designed for greenhouses, a durable fabric that goes on top of the gravel. The combination of
these materials will facilitate the water drainage and block the weeds from infiltrating the inside of the
greenhouse.
By sticking with a simpler and less permanent flooring it would also be easier to move the greenhouse
for other locations, if necessary, and reduce cost and work required to build it. Other advantages are the
prevention of decease and obviously a better work environment since there will be constant water
spillage on the floor.
2.3.1.5 Insulation
Thermal insulation is the reduction of heat transfer between objects. The principle of insulation is to
keep one side warmer than the other, which means that insulation not only keeps the ambient air inside
the greenhouse warm in the winter but it also keeps the ambient air cooler in the summer. This air
regulation can be achieved using engineered materials or by simply trapping air. According to Bartok,
“Insulation is basically trapped air and air is a good insulating material” (John W. Bartok J. , 2007).
Because air is a poor heat conductor, it will reduce the heat transfer.
Insulation efficiency is measured by the R-value. The higher the R-value the better the insulation of the
material. The R value can be found on the label of most insulation products found in distributor stores
around the country. It should not be confounded with the U-value, which is a measure of the heat loss
by the material. For the U-value the smaller the number, the less heat the material loses. The amount of
insulation needed depends on a series of factors, like the climate, air circulation, and the design of the
greenhouse.
All these factors considered, the main reason to insulate a greenhouse is the increase in energy
efficiency. Proper insulation of a greenhouse is the most efficient way of saving energy and reducing the
utility costs. Choosing the right material is not only important to conserve the temperature ambient
inside of the greenhouse, but it is also vital for the survival of the business.
According to the Department of Energy, “Heating and cooling account for 50 to 70% of the energy used
in the average American home. Inadequate insulation and air leakage are leading causes of energy
waste in most homes.” (Desjarlais, 2008). Taking in consideration that a greenhouse is generally less
prepared to withstand cold weather than a house, having the proper insulation is essential to save
energy in both winter and summer. Greenhouse heat loss can be calculated in a similar process to
homes, considering insulation, air circulation etc. In the long run after the installation costs have been
paid out, the cost of running the greenhouse will be drastically reduced if proper insulation is
maintained.
2.3.1.5.1 Thermal Blankets
In general, greenhouses are designed to take in as much light as possible and therefore it becomes
poorly insulated. During the day, the greenhouse is warmer due to the sun’s radiation, but at night heat
must be conserved in order to maintain a good thermal environment. The roof and the walls are the
areas that loose most heat during the night.
A very effective way to conserve the heat in the greenhouse is to use thermal blankets on the walls and
roof at night and remove it during the day. These movable blankets can save a substantial amount of