Page 463 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

Definitions 423

Greenhouse Gases ‘Gases such as carbon dioxide, methane and CFCs that are relatively
transparent to the higher-energy sunlight, but trap lower-energy infrared radiation.’
Halons ‘Substances used in fire suppression systems and fire extinguishers in buildings.
These substances deplete the stratospheric ozone layer.’ Halons are haloalkanes as CFCs are,
but with bromine as well as chlorine or fluorine groups. Two common ones are bromo-
chlorodifluoromethane (halon 1211, CF BrCl) and bromotrifluoromethane (halon 1301, CF Br).
2 3
Heat Island Effect Effect that ‘occurs when warmer temperatures are experienced in urban
landscapes compared to adjacent rural areas as a result of solar energy retention on
constructed surfaces. Principal surfaces that contribute to the heat island effect include
streets, sidewalks, parking lots, and buildings.’

Horizontal View at 42 in ‘The approach used to confirm that the direct line of sight to
perimeter vision glazing remains available from seated position. It uses section drawings
that include the installed furniture to make the determination.’

HVAC Systems ‘Heating, ventilating, and air-conditioning systems used to provide thermal
comfort and ventilation for building interiors.’
Hybrid Vehicles ‘Vehicles that use a gasoline engine to drive an electric generator and use the
electric generator and/or storage batteries to power electric motors that drive the vehicle’s
wheels.’
Hydrochlorofluorocarbons (HCFCs) ‘Refrigerants used in building equipment that deplete the
stratospheric ozone layer, but to a lesser extent than CFCs.’ They are carbon-based organic
compounds (haloalkanes) that in addition to carbon include chlorine and fluorine atoms and
definitely hydrogen atoms. The hydrogen atoms are located in bonds that might have had
chlorine atoms if they were CFCs and therefore have less of a chance of releasing chlorine
atoms into the stratosphere. The chlorine atoms can cause chain reactions which destroy the
ozone molecule.

Hydrofluorocarbons (HFCs) ‘Refrigerants that do not deplete the stratospheric ozone layer.
However, some HFCs have high global warming potential and thus are not environmentally
benign.’ HFCs are haloalkanes as CFCs are, but with only hydrogen and fluorine groups
attached and no chlorine.
Illuminance Amount of light falling on a surface, measured in units of footcandles (fc) or
lux (lx) (as per LEED-NC 2.1).
Impervious Surfaces ‘Surfaces that promote runoff of precipitation volumes instead of
infiltration into the subsurface. The imperviousness or degree of runoff potential can be
estimated for different surface materials.’

Incident Light Light that strikes a surface. The angle between a ray of light and the
perpendicular to the surface is the angle of incidence. Wikipedia, accessed 10/10/06, http:/ /
en.wikipedia.org/wiki/Main_Page.
Individual Occupant Spaces ‘Typically private offices and open office plans with workstations.’

Indoor Adhesive, Sealant, and/or Sealant Primer Product ‘An adhesive or sealant product
applied on-site, inside of the building’s weatherproofing system.’
Indoor Air Quality ‘The nature of air inside the space that affects the health and well-being of
building occupants.’