Green Building Library

Green Building Glossary

Here's our compilation of some green building terms. We'll continue to build upon these basics, so check back frequently for new additions. We welcome your input.

Annual Fuel Utilitzation Efficiency (AFUE):

Measures the amount of heat produced compared to the amount of fuel used, expressed as a decimal number or a percentage. Furnaces or boilers with AFUE ratings above 90% are considered to be more efficient than a typical heating system. The measurement includes liquid fuel consumed for pilot lights and on-off cycles, but not electrical energy used for blowers, controls and other functions.

Appropriate Technology:

Technology that creates minimal environmental impact while serving basic human needs. Uses the simplest level of technology that can effectively achieve the intended purpose in a particular location.

Building Science:

Study of how all systems of a structure function together to optimize building performance and prevent building failure. This includes the detailed analysis of energy and moisture flows, building materials, building envelopes and mechanical systems.


Made from fibers found between the husk and the outer shell of a coconut, it is spun into yarn and woven into a variety of floor and wall coverings. Is durable, not damaged by moisture and resists insects, bacterial growth and rot. Is biodegradable and a renewable resource.

Cooling Degree-Day (CDD):

A way to keep track of the overall cooling demand of a particuluar locaton. CDDs are used to calculate the size of cooling equipment. The value is calculated by adding the average (mean) temperature of each day to a base value, generally 65°F. For example, if the mean temperature over a day was 88, then that day would have 23 cooling degree days. Values are available for hundreds of locations in the United States from the National Oceanic and Atmospheirc Administration's web page for Heating and Cooling Degree Data.

Embodied Energy:

The sum total of the energy necessary - from raw material extraction, transport, manufacturing, assembly, installation plus the capital, environmental and other costs - used to produce a service or product from its beginning through its disassembly, deconstruction and/or decompostion.

Green Building:

Construction that increases the efficiency with which buildings use resources — energy, water, and materials — while reducing building impacts on human health and the environment. May be accomplished by applying these requirements to siting, design, construction, operation, maintenance, and removal — encompassing the entire building life cycle.

Heating Degree-Day (HDD):

A way to keep track of the overall heating demand of a particuluar locaton. HDDs are used to calculate the size of heating equipment and estimate heating costs. The value is calculated by subtracting the average (mean) temperature of each day from a base value, generally 65°F. For example, if the mean temperature over a day was 48, then that day would have 17 heating degree days. The base was selected because it was assumed that homes would need supplemental heat when the temperature dipped below 65°F. Many energy-efficient homes do not need supplemental heat until temperature drops much lower. However, the standard definition is still used to calculate heating demand. HDD values are available for thousands of locations in the United States from the National Oceanic and Atmospheirc Administration's web page for Heating and Cooling Degree Data.

Indoor Air Quality:

Refers to the content of interior air that could affect health and comfort of building occupants. IAQ may be compromised by microbial contaminants (mold, bacteria), chemicals (outgassing from building materials and finishes, carbon monoxide, radon), allergens, or humidity levels that are too high or too low.


Similar in texture to wool. Because of its softness, it shouldn't be used in high traffic areas. Spun from soft, shiny vegetable fiber that can be spun into coarse, strong threads. Is biodegradable and a renewable resource.


Leadership in Energy and Environmental Design is a green building rating system developed by the U.S. Green Building Council that promotes a whole-building approach to sustainability. It recognizes performance in five key areas of human and environmental health: sustainable site development, water savings, energy efficiency, materials selection and indoor environmental quality.

Life Cycle Assessment (LCA):

Assesses the environmental performance of a product or building over its life cycle. This includes raw material extraction, manufacturing, transportaion, use, recycling and disposal. Green Seal is a well known non-profit organization that utilizes life-cycle analysis to evaluate and certify products and services that have a lesser impact on the environment and human health.

Natural Building:

Uses a range of techniques, building systems and materials that place major emphasis on sustainability. Focus is on durability and the use of locally available, minimally-processed, renewable, recycled or salvaged resources, as well as those which produce healthy living environments and maintain indoor air quality. Natural building tends to rely on human labor, more than technology.

Net metering:

An electricity policy for consumers who own small, renewable energy facilities, such as wind or solar power or use vehicle-to-grid systems. Net refers to what remains after deductions -- the deduction of any energy outflows from metered energy inflows. The customer receives retail credit for the excess electricity generated.

Net-Zero-Energy Homes:

Homes create at least as much energy as they use over the course of a typical year. Energy consumption is reduced to very low levels through the use of highly insulated walls, ceilings and floors along with very efficient windows. With space and water heating consumption at very low levels, it is possible to generate enough energy through on-site, renewable energy systems to balance the energy consumed with the energy produced. Currently, solar water heaters and photovoltaic systems are the most common methods of energy generation. This net-zero approach generally means that the building is connected to the electrical grid so that energy can be pulled from the power grid during the winter and pumped into the grid during summer when excess energy is available.


Refers to living in a self-sufficient manner without reliance on one or more public utilities. Usually involves a system of generating power that doesn't require connection to utility electricity grids.

Passive Solar:

Means of using sunlight for energy without active mechanical systems. Converts sunlight into usable heat (water, air, thermal mass), causes air-movement for ventilating, stores heat for future use without the assistance of other energy sources. Passive solar systems have little to no operating costs, often have low maintenance costs and emit no greenhouse gases in operation. Requires careful site planning, selection of building materials and building features. Energy conservation reduces the needed size of any renewable or conventional energy system, and greatly enhances the economics, so it must be performed first.


Design system and philosophy that uses land in a way that integrates human dwellings and activities with local natural ecologies. Loosely formed network of training in alternative cultural ideas and permaculture gardening.

Renewable Resources:

Natural resources qualify as renewable resources if they are replenished by natural processes at a rate comparable or faster than their rate of consumption by users (solar radiation, ocean tides, wind). Renewable resources may also include commodities such as wood, bamboo and crop waste.


Grow in marine, fully saline environments. Much softer than Coir or Sisal, Seagrass is also less durable and incompatible with moisture. Smooth in texture with a soft, neutral color. Is biodegradable and a renewable resource.

Sick Building Syndrome:

Often caused by flaws in heating, ventilation and air conditioning (HVAC) systems. Contaminants produced by outgassing of some types of building materials, volatile organic compounds, molds, improper exhausting of light industrial and cleaning chemicals have also been attributed to SBS.


Made from the central stalk of a type of Agave cactus. Produces a hard fiber that is mechanically spun into yarn and woven into rugs and wallcoverings. As durable as Coir, but with more sheen and a smoother texture. Is biodegradable and a renewable resource. Has no natural resistance to insects, bacteria and moisture. Should be used indoors only.

Sustainable Development:

Development that meets the needs of the present without compromising the ability to meet the needs of the future. Encompasses three parts: environmental sustainability, economic sustainability and social-political sustainability.


Superior durability with a natural resistance to soiling. Naturally flame resistant, sound absorbing, biodegradeable and a renewable resource.