Glossary

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Habitat
1. The natural home of an animal or plant.

2. The sum of the environmental conditions that determine the existence of a community in a specific place.

Habitat Fragmentation
Habitat disruption where natural habitat is broken into small, relatively isolated sections.

Halocarbons
Manmade chemicals that, when released into the atmosphere as greenhouse gases, can disrupt global climate patterns. Their most common use is in refrigeration and air conditioning technologies.

Halogen
A type of incandescent lamp with a higher energy-efficiency than standard ones.

Halons
Effective fire suppressants, which leave no residue and are of relatively low toxicity. Historically, they have been used in applications where conventional extinguishing agents (e.g., water) would be dangerous or result in significant peripheral damage - (e.g., electronics, electrical, and HVAC.) Note, Halons adversely affect stratospheric ozone and are being phased out.

Harvested Rainwater
Rainwater captured and used for indoor needs, irrigation, or both.

Hazard
A material or condition that may cause damage, injury, or other harm, frequently established through standardized assays performed on biological systems or organisms. The confluence of hazard and exposure create a risk.

Hazardous Waste
Wastes that are particularly dangerous or destructive; specifically characterized by one or more of the following properties: ignitable, corrosive, reactive, or toxic.

Heat Island Effect
The increase in ambient temperature that occurs over large paved areas compared to natural landscape. See also "Urban Heat Island."

Heat Pump
Similar to an air conditioner but can operate in reverse to heat as well as cool. Transfers heat (usually from the air) from one location to another.

Heat Recovery or Energy Recovery Ventilator (HRV/ERV)
A system that reclaims the heat from warm exhaust air exiting a building and uses it to pre-heat entering fresh air.

Heating Seasonal Performance Factor (HSPF)
Efficiency of a heat pump in the heating mode, taking cycling into account; the amount of heating provided per unit of electricity purchased. The higher the HSPF number, the more efficient the heat pump.

Heating Ventilation and Air Conditioning (HVAC)
A term generally used to describe a building's comfort system. In older buildings, heating (radiators), ventilation (windows), and air conditioning (window units) may be separate, but usually these services are integrated into a single system that conditions air that is distributed through ducts.

Heavy Metals
Elements such as lead, mercury, zinc, copper, cadmium, and so forth, that may be required in trace amounts by organisms, but can cause damage when ingested in larger quantities.

Herbicide
A chemical substance used to kill plants.

High Efficiency Particulate Air Filter (HEPA)
An air filter that captures a high percent of all particles, including very small particles not captured by other types of filters.

High Intensity Discharge
A generic term for mercury, vapor, metal halide, and high pressure sodium lamps and fixtures.

High Performance Building
A green or sustainable building often with an emphasis on the use of advanced technology, or "smart infrastructure," and its impact on tenant ability to control key building comfort measures such as temperature and light levels to increase performance.

High-quality Duct System
An alternative system in which all the ducts are sealed with fibrated latex material and fiberglass tape, and then run outside to avoid significant heating and cooling losses and potential health threats caused by de/pressurizing a house.

Historic Image Restoration
The renovation of a building or community that saves and restores the historic image of that place.

Holistic
A wide-reaching approach to a theory, a task, or a problem that encompasses all the elements of the system because of the interdependency of those elements.

Home Energy Rating System (HERS)
A collection of programs throughout the country that assign energy ratings based on predicted energy use of the house. Ratings are either on a scale of 1 to 100 points or 1 to 5-plus stars. Most houses built today without any special attention to energy efficiency typically earn an 80-point or three-star rating.

Horizontal Recycling
A recycling system that turns a majority of the original product back into a similar product as the original.

Hot Spot
An area of exceptionally high species richness, especially concentrations of localized rare species that occur nowhere else.

HVAC
See "Heating Ventilating and Air Conditioning."

HVAC&R (Heating Ventilating Air Conditioning and Refrigeration)
See "Heating, Ventilating and Air Conditioning."

Hydrocarbons (HC)
Chemical compounds that consist entirely of carbon and hydrogen.

Hydrochlorofluorocarbon (HCFC)
A fluorocarbon that is replacing chlorofluorocarbon as a refrigerant and propellant in aerosol cans; considered to be somewhat less destructive to the atmosphere.

Hydroelectric Power
The use of artificial or natural waterfalls to generate electricity.

Hydrological Cycle
The natural cycle of water from evaporation, transportation in the atmosphere, condensation (rain), and the flow back to the ocean.

Hydronic Heating
A radiant heat system that distributes hot water through pipes, either to radiators or through a thermal mass floor. The floor absorbs heat and evenly radiates it to the living space.

Hydrophilic
Having a strong affinity for water; attracting, dissolving in or absorbing water.

Hydrophobic
Having a strong aversion to water; repelling water.

Hydropower (hydroelectricity)
Clean energy technology that uses moving water to produce electricity. Water flows through a hydraulic turbine, which spins and then rotates generators and converts rotational energy into electricity.

Hypersensitivity
Exaggerated immune system response to an allergen.