Heat-island effect — As cities replace natural landscaping with streets, buildings and other infrastructure, the average ambient temperatures within these areas begin to rise, as much as 10 degrees F higher than in less developed rural areas. This increases the need for cooling energy; can exacerbate pollution problems; and may contribute to the problem of global warming. Heat islands can be effectively reduced by shading streets with trees and improving the urban forest overall. Ironically, heat islands can be beneficial in cold climates in the winter by reducing heating demands; however, the overall effect is much more on the negative side.
HVAC — The acronym for heating, ventilation and air conditioning.
Hydronic radiant heating — A system of heating a building by using a central boiler or hot water heater to distribute heat through a system of tubes just under the flooring surface. A single heater may be zoned to provide independent heat to different parts of a building as needed. The heating system is efficient and provides a comfortable conditioned room.
IAQ — Indoor air quality. As buildings become tighter, indoor air quality suffers unless specific measures are taken to improve the exchange of fresh air without sacrificing heating/cooling economy.
Infiltration — The entrance of exterior unconditioned air through various means into a building. Under the older codes, a dwelling generally had the equivalent of a 4-foot-diameter hole in infiltration leakage. While newer buildings greatly improve this leakage, other problems such as poor indoor air quality and transpiration of moisture to internal stud bays now occurs and must be remedied with such items as air-to-air exchangers and specialized waterproofing techniques.
Insulated concrete form (ICF) — Expanded polystyrene foam (EPS), high-density polyethylene (HDPE), polyvinyl chloride (PVC) or polycarbonate (PC) is cast or injection-molded in various panel shapes and become the permanent forming method for reinforced concrete walls. These highly insulated forms have various thermal resistance values (R-values) ranging from about R-22 up to about R-40. In hot or cold climates, these forms can significantly reduce heating and cooling loads. The panels are usually pre-engineered and produce a fire resistive barrier up to 4-hour rated.
LEED — Leadership in Energy and Environmental Design. The LEED program was developed by the U.S. Green Building Council as a system for rating new and existing commercial, institutional and residential buildings. It evaluates the overall environmental performance during the lifecycle of a building and provides a tangible methodology for analyzing the standards of a green building.
Light pollution — Light pollution comes from many sources, but generally from unshielded lighting that allows light on a site to escape. Shielding cannot effectively reduce some lighting, such as parking-lot or street lights that reflect off structures and bounce light away from the site. However, simple hooding of the "naked" light source directing the light to the ground or limiting its outward influence can significantly reduce light pollution.
Manufactured locally — Refers to products that are manufactured within a relatively short distance from the job site. Depending on who is making the definition, this can be within 100 to 1,000 miles. The main intent is to be cognizant of long-distance shipping and the energy expended and pollution created to move a product from greater
distances.
MDF — medium density fiberboard. An engineered panel product that can be used for such things as cabinets and wall panels, while other MDF products can be shaped into moldings, ceiling tiles, flooring, interior doors and a variety of other uses. Exterior grades of MDF can be made into garage doors, sheds and other outdoor applications. A middle grade called "moisture resistant MDF" can be used externally but must be protected from water intrusion by sheltering.
