Campus Center for Appropriate Technology- Greenhouse


    The Campus Center for Appropriate Technology is a student operated research site for sustainable technology.  The CCAT greenhouse is located on the south side of the demonstration home.  The greenhouse is used by students for gardening and demonstration purposes.

The Greenhouse at CCAT on a warm November day

    The Campus Center for Appropriate Technology's greenhouse provides passive solar heating for both the garden and the CCAT house.  The greenhouse utilizes the heat stored during the day in the rock wall, brick floor and water tube.  The temperature in the greenhouse is elevated because of trapped solar energy that has been able to enter the greenhouse but not leave.

Brick Floor 

Planting bed

Why use solar greenhouses?

    Solar energy from the sun is an excellent form of energy.  Often however much of the Sun's energy is lost back into the atmosphere.  Using a greenhouse will help to retain some of the heat energy.  In a greenhouse the temperature is able to be raised and held somewhat constant, allowing more success and opportunity for a variety in your garden.

How a greenhouse works

    The Campus Center for Appropriate Technology's greenhouse works by passive solar heating.  As the suns rays pass through a transparent medium such as glass or plastic into a greenhouse, some of the energy becomes trapped and is not allowed to escape to the outside.  This has the effect of intensifying the heat in  the enclosed space.  This trapped heat is the basis for how a greenhouse works.

    Brick and concrete are used as the floors in the greenhouse because these materials retain heat well. A planter box is constructed from rocks to further add to the heat retention.

Stone Wall aids heat retention

Nice and toasty on a winter day


    It is essential that greenhouses get proper ventilation.  Temperature in a greenhouse can elevate rapidly compared to the outside air. Plants in a greenhouse will suffer if the temperature becomes too hot.  Proper ventilation will allow the air to circulate providing the plants with CO2 and keeping the temperature from becoming too hot. Another important factor to maintain is humidity.  If plants in a greenhouse become too saturated with water it can have detrimental effects on them.   Disease and insects can also wreak havoc on a greenhouse garden because of the confined space and hospitable environment.  The CCAT greenhouse has windows on the north side that provide adequate ventilation and also help to heat the demonstration home main building.

Further information on Greenhouses

    Backyard Gardener - Greenhouse Gardening Tips

    ACF Greenhouses

    EnviroCept Greenhouse Garden Products

    Charley's Greenhouse 

    Alaska Science Forum - How do Greenhouses Work?  


This page made by Joshua Kuhnel who can be contacted at for more information.

Photos by Ron Kuhnel.