Glossary

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U-Value
Measurement of the thermal conductivity of a material, or inverse of R-Value. The lower the U-Value, the greater resistance to heat flow (lower U-Value = Higher R-Value.)

Unconditioned Space
Area within the outermost shell of a house that is not heated or cooled-the area outside of the thermal envelope. Such areas typically include crawlspaces, attics, and garages.

Underfloor Air Distribution
A system using an underfloor plenum (open space between the structural concrete slab and the underside of a raised floor system) to deliver conditioned air directly into the occupied zone of the building. Air is delivered through supply outlets typically located at floor level or integrated as part of the office furniture and partitions. Return grilles are located above the occupied zone. This upward convection of warm air is used to efficiently remove heat loads and contaminants from the space.

Upcycling
A term coined to describe the creation of a product with higher intrinsic value, manufactured from a material at the end of its service life, which had a lower initial end use value. It is important to note that the term as currently used, does not provide insight into environmental benefit (e.g. there may actually be less environmental benefit to upcycling if energy used to upcycle is more than recycling back to the same product).

Upstream Impacts
Environmental impacts that are caused by the extraction of raw materials, transportation, and the manufacturing process.

Urban Heat Island
The increase in ambient temperature that occurs in cities because paved areas and buildings absorb more heat from the sun than natural landscape and additional heat is generated by vehicles, lighting, and other equipment.

Urban Ore
The concept that wastes of today, such as materials disposed of in landfills, may serve as sources of valuable raw materials, such as metals, in the future.

Urethanes
A family of plastics (polyurethane's) used for varnish coatings, foamed insulations, highly durable paints, and rubber goods.

USGBC (U.S. Green Building Council)
The United States foremost coalition of leaders from across the building industry working to promote buildings that are environmentally responsible, profitable, and healthy places to live and work.