Aerator
A device installed on sink faucets to reduce their water use and the energy
needed to heat water. Faucet aerators, coupled with low-flow shower heads, can
reduce your home's water use by 50%. If an aerator is already installed on your
faucet, it will have its rated flow imprinted on the side. This should read
2.75 gpm (gallons per minute) or lower.
Air Barrier
Building
assembly
components/products that work as a system to restrict air flow through the
building. An air barrier may or may not act as a vapor barrier. The air barrier
can be on the exterior and/or the interior.
Air Handler
A fan that a furnace, central air-conditioner, or heat pump uses to distribute
heated or cooled air throughout the house.
Air-Source Heat Pump
Heat pump that relies on outside air as the heat source and heat sink; not as
effective in cold climates as ground-source heat pumps.
Airtight Drywall
Use of drywall with carefully sealed edges and joints that serves as an
interior air barrier in building assemblies.
Albedo
Percentage of light reflected off a surface; a material with high albedo is
highly reflective.
Ammonium Sulfate
Flame retardant commonly used in cellulose insulation. Borates are also used.
Asbestos
Mineral fiber once commonly used in building materials, including insulation,
fireproof siding, and resilient flooring; a known human carcinogen causing lung
cancer, asbestos is no longer used in the United States.
Backdrafting
A potentially dangerous indoor air quality problem in which combustion gases
escape into the house instead of going up the chimney.
Balanced Ventilation
Ventilation system in which fans exhaust stale indoor air and bring in fresh
outdoor air in equal amounts; often includes heat recovery or heat and moisture
recovery
Batch Solar Water Heater
Solar water heater in which potable water is heated where it is stored. Also
referred to as an integral collector storage (ICS) solar water heater.
Binder
Glue used in manufacturing wood products, such as medium-density fiberboard
(MDF), particleboard, and engineered lumber. Most binders are made with
formaldehyde. Two types of binders include urea-formaldehyde binder and methyl
diisocyanate (MDI) binder.
Bio-Based Material
Material made from living matter, like agricultural crops. Bio-based materials
are usually biodegradable.
Biophilia
Theory developed by biologist Edward O. Wilson
suggesting that humans have an innate affinity for nature.
Biomass
Plant material such as trees, grasses and crops that can be converted to heat
energy to produce electricity.
Blackwater
Wastewater generated from toilets and kitchen sinks that contains high levels
of bacterial pollutant.See also, greywater.
Blower Door Test
Test used to determine a home’s airtightness. A powerful fan is mounted in an
exterior door opening and used to pressurize or depressurize the house. By
measuring the force needed to maintain a certain pressure difference, a measure
of the home’s airtightness can be determined. Operating the blower also
exaggerates air leakage and permits a specialized contractor to find and seal
the leakage areas.
Blowing Agent
Compound used in producing foam insulation. Mixed as a liquid with the foam
ingredients under pressure, the blowing agent evaporates, creating gas bubbles
that provide the insulation. Until recently, most blowing agents (HCFCs and
CFCs) depleted Earth’s protective ozone later; except for extruded polystyrene,
the industry has now switched to ozonesafe blowing agents.
Boiler
System used to heat water for hydronic heating. Most boilers are gas-fired or
oil-fired, although some are electric or wood-fired; a boiler can also heat
water for domestic uses through a tankless coil or an indirect water heater.
Built Environment
The man-made creation of or alterations to a specific area, including its
natural resources. On a home site, this includes everything that has been
construction.
Buildable Land
The portion of the site where construction can occur. When used in density
calculations, the calculation for buildable land excludes public streets and
other public rights of way, land occupied by non-residential structures, public
parks, and land excluded from residential development by law.
Building Envelope
Exterior components of a house that provide protection from colder (and warmer)
outdoor temperatures and precipitation. The envelope includes the house
foundation, framed exterior walls, roof or ceiling, and insulation and
air-sealing materials.
Capillary Forces
Forces that lift or pull water through porous materials, such as concrete.
Carbon Footprint
A measure of an individual's, family's, community's, company's, industry's,
product's or service's overall contribution of carbon dioxide and other
greenhouse gases into the atmosphere. It takes into account energy use,
transportation methods and other means of emitting carbon. A number of carbon
calculators have been created to estimate carbon footprints, including one from
the U.S. Environmental Protection Agency.
Carbon Neutral
Achieving an overall neutral (zero) total carbon release, brought about by
balancing the amount of carbon released with the amount sequestered. It is
typically achieved by reducing energy use and obtaining energy from renewable
sources combined with offsetting remaining emissions through such means as
carbon offsets.
Carbon-Neutral House
House that, on an annual basis, does not result in a net release of carbon
dioxide, which is a greenhouse gas that contributes to global warming, into the
atmosphere.
Carbon Offset
The act of mitigating one's carbon emissions, often purchased through a carbon
offset provider that uses the money for carbon-sequestering activities
including tree planting, renewable energy, energy conservation and methane
capture.
Catchment Area
The surface area on a roof that captures rainwater for direction into a
rainwater harvesting system.
Cavity-Fill Insulation
Insulation installed in the space created by wall, ceiling, roof, or floor
framing, most commonly fiberglass-batt, spray-applied or dense-pack cellulose,
or spray polyurethane.
Cistern
Vessel for storing water, such as that collected with a rainwater-harvesting
system.
Cladding
Materials used to enclose a house, providing protection against weather.
Climate Change
The variation of the average temperatures, rainfall and other measures of
global or regional climate over time, whether caused by natural processes,
humanity's influence or a combination of both.
Closed-Loop Solar Water Heater
Solar water heater in which an electric pump circulates a freeze-protected
heat-transfer fluid through the collector and heat exchanger within a storage
tank.
Combustion Efficiency
Efficiency at which a fuel is burned in a combustion appliance when operating
at its rated output; the combustion efficiency is always higher than the annual
fuel utilization efficiency (AFUE).
Commissioning
Process of testing a home after a construction or renovation project to ensure
that all of the home’s systems are operating correctly and at maximum
efficiency.
Composite Lumber
Lumber made from plastic (often high-density polyethylene) and wood fiber or
other agricultural byproducts. Composite lumber often contains recycled
content.
Composting System
Outdoor bins for converting vegetable scraps, garden trimmings, and other plant
matter into a rich, high-organic-content soil amendment. An alternative for
indoor use is a worm bin.
Composite Wood
A product consisting of wood or plant particles or fibers bonded together by a
synthetic resin or binder. Examples include plywood, particle-board, OSB, MDF,
composite door cores.
Concrete Masonry Unit (CMU)
Block made of concrete used for wall construction. The hollow cores can be
filled with concrete to reinforce walls.
Conduction
Movement of heat through a material as kinetic energy is transferred from
molecule to molecule. The handle of an iron skillet on the stove gets hot due
to heat conduction. R-value is a measure of resistance to conductive heat flow.
Convection
Movement of heat from one place to another by physically transferring heated
fluid molecules, usually air or water. Natural convection is the natural
movement of that heat; forced convection relies on fans or pumps.
Cool Pavements
Materials and construction methods used in roads, driveways, parking lots,
sidewalks, and other hard surfaces, which perform to reduce the absorption,
retention and emittance of solar heat, thus minimizing urban heat island
effect. Techniques to achieve cool pavements include the use of coloration,
materials, porosity and other processes that promote solar reflectivity and
cooling through augmented air filtration and evaporation.
Cradle to Grave
Term used to describe the environmental impact a product has from it’s creation
to destruction.
Cripple Studs
Studs in a wall system that support headers above (and below) windows or doors;
indiscriminately placed, these additional studs can result in extra heat loss
because they do not insulate as well as the insulation in the wall cavity.
Cross-Linked Polyethylene (PEX)
Specialized type of polyethylene plastic that is strengthened by crosslinking
(chemical bonds formed in addition to the usual bonds in the polymerization
process). PEX is used primarily as tubing for hot and cold water distribution
and radiant-floor heating.
Current Loop
In electrical wiring, a situation in which separation of hot and neutral leads
results in higher than-normal electromagnetic fields (EMFs).
Daylighting
Use of sunlight for daytime lighting needs.
Degree Day
Measure of heating or cooling requirements based on the average outdoor
temperature. To calculate the number of heating degree days of a given day,
find the average of the maximum and minimum outdoor temperatures and subtract
that from 65°F.
The annual number of heating degree days is a measure of the severity of the
climate and is used to determine expected fuel use for heating. Cooling degree
days, which measure air-conditioning requirements, are calculated by
subtracting the average outdoor temperature from an indoor base temperature,
usually 75°F.
Demand Water Heater
Water heater that heats water only as needed; there is no storage tank and thus
no standby heat loss. This is also known as a tankless water heater.
Double Wall
Construction system in which two layers of studs are used to provide a
thicker-than-normal wall system to accommodate extra insulation. The two walls
are often separated by several inches to reduce thermal bridging through the
studs and to provide additional space for insulation.
Drain Back Solar Water Heater
Solar water heater in which water or another heat-transfer fluid is pumped
through the collector and drains back to a tank in the house when the pump
turns off.
Drip Irrigation System
An irrigation system that slowly applies water to the root system of plants to
maximize transpiration while minimizing wasted water and topsoil runoff. Drip
irrigation usually involves a network of pipes and valves that rest on the soil
or underground at the root zone.
Dual-Flush Toilet
Toilet that provides two flush levels: a full-volume flush for use with solid
wastes and a reduced-volume flush (often half the volume) when only liquid
waste and paper need to be flushed.
Duct Blaster
Calibrated air-flow measurement system developed to test the airtightness of
forced-air duct systems. All outlets for the duct system except for the one
being tested are sealed off and the system is either pressurized or
depressurized; the work needed by the fan to maintain a given pressure
difference provides a measure of duct leakage.
Electric-Resistance Heat
Heat provided by electricity in which high-resistance wires convert electric
current directly into heat. See heat pump.
Electromagnetic Field (EMF)
Field given off by electric current flow. Some health experts are concerned
that the magnetic field component of EMFs may be harmful or even cause cancer.
Magnetic fields are stronger near current in which there is separation between
the positive and neutral leads.
Embodied Energy
Energy that goes into making a product, including energy for transporting both
the raw materials and the finished product.
Emission
The output of greenhouse gases and other pollutants from mechanical,
industrial, transportation or other processes.
Endocrine Disruptor
Chemical that mimics natural hormones, such as estrogen, and may interfere with
reproductive development or alter. Endocrine disruptors include such commonly
used chemicals as phthalate plasticizers (used in PVC plastic), and bisphenol-A
(used in epoxies and polycarbonate plastic).
Energy Efficient
Maximizing, or at least increasing, the ratio between productive output and
energy use.
Energy Efficiency Rating (EER)
Operating efficiency of a room air-conditioner, measured in BTU’s of cooling
output, divided by the power consumption in watthours; the higher the number,
the greater the efficiency.
Energy Factor
Efficiency measure for rating the energy performance of dishwashers, clothes
washers, water heaters, and certain other appliances; the higher the number,
the greater the efficiency. A “modified energy factor” accounts for certain
adjustments according to accepted test procedures.
Energy Star
Labeling system sponsored by the U.S. Environmental Protection Agency and the
U.S. Department of Energy for labeling the most energy-efficient products on the
market. The ratings apply to a wide range of products, from computers and
office equipment to refrigerators and air-conditioners.
Energy-Efficient Mortgage (EEM)
Special type of mortgage in which the lending institution raises the allowable
mortgage amount for a given earnings level, since energy-saving features in the
house will reduce the monthly operating costs, thus leaving more money
available to pay the mortgage.
EnergyGuide
Label from the Federal Trade Commission that lists the expected energy consumption
of an appliance, heating system, or cooling system and compares consumption
with other products in that category, The energy performance is based on
specified operating conditions and average energy costs; actual performance may
vary.
Energy-Recovery Ventilator (ERV)
Type of heat-recovery ventilator (HRV) that captures water vapor as well as
heat from the outgoing airstream in a balanced ventilation system. In winter
months, this can reduce the drying that occurs when outdoor air is brought indoors
and warmed.
EPA
Environmental Protection Agency. A U.S. government agency that
oversees environmental laws and programs.
Evaporative cooler
Energy-efficient
cooling system in which a fine mist of water is evaporated, lowering the air
temperature. Evaporative coolers are most appropriate in dry climates, because
they add humidity to a house. Also known as a swamp cooler.
Exhaust-Only Ventilation
Mechanical ventilation system in which one or more fans are used to exhaust air
from a house, with make-up air supplied passively. See also balanced
ventilation.
Expanded Polystyrene (EPS)
Type of rigid foam insulation. Unlike extruded polystyrene (XPS), EPS does not
contain ozone-depleting HCFCs.
Extruded Polystyrene (XPS)
Type of rigid foam insulation that is widely used below grade, such as
underneath concrete floor slabs. In North America XPS is currently made with
ozone-depleting HCFC-142b.
Fan-Coil
Electric or hydronic heating or cooling element installed in a duct. In a
highly energy-efficient home, fan coils in ventilation ducting can be used for
heating or cooling the living space.
Fiber-Cement Siding
Siding material made from wood fiber and portland cement that is highly
durable, moisture resistant, and fire proof. Developed in New Zealand, the material is becoming common as
a siding material in North America.
Flashing
Material, usually sheet metal, rubber, or plastic, installed to keep rain from
entering a building. When properly installed in a wall or roof assembly,
flashing sheds rain to the exterior.
Forced-Air Heating
Heat distribution system in which heat is delivered by forcing warm air through
a network of ducts. A furnace or heat pump typically generates the warm air.
Formaldehyde
Chemical found in many building products; most binders used for manufactured
wood products are formaldehyde compounds. Reclassified by the United Nations
International Agency for Research on Cancer (IARC) in 2004 as a known human
carcinogen. See also phenol-formaldehyde binder and urea-formaldehyde
binder.
Fuel Cell
Electrochemical device similar to a battery in which electricity is generated
by chemically reacting hydrogen with oxygen, producing electricity, water
vapor, and heat.
Glazing
Transparent or translucent layer of window or door that transmits light.
High-performance glazings may include multiple layers of glass or plastic, low
emissivity (low-e) coatings, and low-conductivity gas fill.
Global Warming Potential
Measure of how a given mass of greenhouse gas is estimated to contribute to
global warming compared against carbon dioxide, which is given a value of 1.0.
Gravity-Flush Toilet
Toilet whose flush is powered solely by the force of falling water. See also
pressure-assist toilet.
Graywater
Wastewater from a building that does not include flush-water from toilets or
(as most commonly defined) water from kitchen sinks or dishwashers. In some
places, graywater can be collected and used for subsurface irrigation.
Green Building
Design and construction of buildings that minimize impacts on the environment
while helping keep occupants healthy.
Green Electricity
Electricity generated from renewable energy sources, such as photovoltaics
(solar power), wind power, biomass, and small-scale hydropower. (Large,
conventional hydropower sources usually are not included in definitions of
green electricity.)
Geothermal
"Geothermal" literally means "earth heat." It is often used
to describe two different types of alternative energy source. "True"
geothermal energy is less commonly used. It draws on energy generated in the
earth's core, about 4,000
miles below the surface, via steam and hot water
produced inside the earth to heat buildings or generate electricity. More
common are geothermal heating and cooling systems that capitalize on the
relatively constant temperature of the ground to transfer heat. These systems
don't actually use the geothermal energy generated deep within the earth;
instead, they use a heat-transfer liquid to move heat from a few feet below
ground into a house during cold months, and from the house to the ground during
hot months.
Greenhouse Gas
A gas in the atmosphere that traps some of the sun's heat and preventing it
from escaping into space. Greenhouse gases are vital for making the Earth
habitable, but increasing greenhouse gases contribute to climate change.
Greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide,
and ozone.
Greywater
Wastewater generated from domestic processes such as washing dishes, laundry
and bathing. Greywater makes up 50-80% of residential wastewater. Greywater can
be used for irrigation, reducing water waste. See also, blackwater.
Grid-Connected Power System
Electricity generation system, usually relying on photovoltaics or wind power,
that is hooked up to the utility company’s electric grid through a net-metering
arrangement so that electricity can be obtained when the locally generated
power is not sufficient. See also stand-alone power system.
Ground-Source Heat Pump
Heat pump that relies on the relatively constant temperatures underground as
the heat source and heat sink. The energy performance of ground-source heat
pumps is usually better than that of air-source heat pumps.
Gut Rehab
Building
renovation in
which the walls are gutted (reduced to the wall framing and sometimes
sheathing), then insulated, sheathed, and finished.
Heat Exchanger
Device that allows for transfer of heat from one material to another. An
air-to-air heat exchanger, or heat-recovery ventilator, transfers heat from an
outgoing airstream to an incoming airstream. A copper-pipe heat exchanger in a
solar water heater tank transfers heat from the heat-transfer fluid circulating
through a solar collector into the potable water in the storage tank.
Heat Island Effect
Heat island effect The incidence of higher air and surface temperatures caused
by solar absorption and re-emission from roads, buildings and other structures.
See also, cool pavements.
Heat Pump
Heating and cooling system in which specialized refrigerant fluid in a sealed
system is alternately evaporated and condensed by altering its pressure; this
phase change allows heat to be transferred into or out of the house. See
air-source heat pump and ground-source heat pump.
Heat Distribution
System for delivering heat throughout a house. See forced-air heating and
hydronic heating.
Heat-Recovery Ventilator (HRV)
Balanced ventilation system in which most of the heat from outgoing exhaust air
is transferred to incoming fresh air via an air-to-air heat exchanger. See
also energy-recovery ventilator.
High-Efficiency Toilet (HET)
Toilet that provides at least 20% water savings over the federal standard of 1.6 gallons per flush
and still meets the most rigorous standards for flush performance.
Home Performance Audit
An energy audit that also includes inspections and testing assessing moisture
flow, combustion safety, thermal comfort, indoor air quality, and durability.
Home Run Plumbing System
Water distribution piping system in which individual plumbing lines extend from
a central manifold to each plumbing fixture or waterusing appliance. The piping
is typically cross-linked polyethylene (PEX). Because diameter of the tubing
can be matched to the flow of the fixture or appliance, hot water can be
delivered more quickly.
