Glossary of Terms



CFC (Chlorofluorocarbon):

A chlorofluorocarbon (CFC) is an organic compound containing carbon, chlorine, and fluorine produced as a volatile derivative of methane and ethane. A CFC which also contains hydrogen is known as an HCFC. They are commonly known by the brand name Freon. CFCs are used as refrigerants, propellants, and solvents.

The manufacture of CFCs is being phased out by the Montreal Protocol because they contribute significantly to ozone depletion. Ozone is an upper-atmospheric gas which filters potentially damaging electromagnetic radiation (UV rays) from the Sun.

Ozone is destroyed in the atmosphere by atomic chlorine and bromine. The main source of these compounds are CFC compounds, which drift into the stratosphere after being emitted at the surface. The reduction of atmosphere ozone allows an increasing amount of ultraviolet light to reach the Earth's surface, resulting in a host of consequences increasing skin cancer, cataracts, damage to plants, and reduction of plankton populations in the oceans.

The Montreal Protocol was adopted in 1989 to ban the production of CFCs in an attempt to slow down, and eventually eliminate and reverse, ozone depletion. Though the use of CFCs and HCFCs is being phased out, they may still be used in some products. Most CFC and HCFC-free products are clearly labeled as such, and should be always be sought out and used in any green home design and construction.

G- M


A heating and cooling system that uses the constant temperature of the earth. Compared to traditional HVAC systems, geothermal heating and cooling uses approximately 40% to 70% less energy.

LED (Light Emitting Diode):

A newer, more efficient lighting alternative to incandescent or fluorescent lights. LED lights last over two decades, and consume 75% less energy than incadescent light.

Low-E Glass:

A low-emissive coating on window glass reflects damaging UV rays away from the home's interior, reducing fading of drapes, carpets, and furniture. The thin metallic coating of low-E glass is invisible, and also keeps radiant heat from entering the interior, reducing cooling costs.

Passive Solar:

A design concept that allows a structure to collect, circulate, and store energy from the sun in place of conventional heating sources.


The R-Value is a measure of an insulation material's resistance to heat flow. It is also known as thermal resistance. The higher the R-value of an insulation material, the greater its' insulating effectiveness. The R-value of any insulation is given in terms of thermal resistance per inch of insulation. For example, heat will have more difficulty passing through R-18 insulation than R-11 insulation.

Increasing the installed thickness of any insulation material will increase the thermal resistance, resulting in a greater R-value.

It is important to remember that the structural supports in a home (wall studs) typically have a much lower R-value than the insulation that surrounds them. Wood insulates to only about R-1 per inch, and steel studs have an even lower R-value. A 'whole-wall R-value' takes into account the relative area of framing materials and insulation and the R-values of both.

For any insulation material to live up to its expected R-value and thermal resistance, it is imperative that it be properly installed. If insulation does not fill wall or ceiling cavities completely or is compressed too much to fit into spaces, the energy performance of the space being insulated will be greatly reduced.


Net-Zero Energy:

Net-zero describes a home or other structure that creates as much energy on-site as it consumes.