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Glossary of Building Rating Terms

Click a term to see its definition.

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Is the measure of the rate of heat loss through a material. Thus in all aspects of home design one should strive for the lowest U-Values possible because the lower the U-value – the less heat that is needlessly escaping. The calculation of U-values can be rather complex - it is measured as the amount of heat lost through a one square meter of the material for every degree difference in temperature either side of the material. It is indicated in units of Watts per meter Squared per Degree Kelvin (W/m2K) [Source: Irish Energy Centre]

Ultra Low Energy Building

An ultra low energy house is better known as a Passive House. See Passive House definition.

United Nations

The United Nations is an international organization founded in 1945 after the Second World War by 51 countries committed to maintaining international peace and security, developing friendly relations among nations and promoting social progress, better living standards and human rights. [Source: UN Website]

United Nations Development Programme

UNDP partners with people at all levels of society to help build nations that can withstand crisis, and drive and sustain the kind of growth that improves the quality of life for everyone. It does this by helping developing countries to attract and use aid effectively. [Source: UNDP Website]

United Nations Environment Programme

UNEP seeks to provide leadership and encourage partnership in caring for the environment by inspiring, informing, and enabling nations and peoples to improve their quality of life without compromising that of future generations. [Source: UNEP]

Useful Energy

The portion of final energy which is actually available after final conversion to the consumer for the respective use. In final conversion, electricity becomes for instance light, mechanical energy or heat. [Source: European Nuclear Society]

Useful Floor Area

The floor area of dwellings measured inside the outer walls, excluding cellars, non-habitable attics and, in multi-dwelling houses, common areas. [Source: OECD Glossary of Statistical Terms]

Useful Heat

Useful heat means heat produced in a cogeneration process to satisfy economically justifiable demand for heating or cooling; [Source: Energy Efficiency Directive 2012/27/EU]

Useful Heat Gains

Proportion of internal and solar heat gains that contribute to reducing the energy need for heating. [Source: International ISO Standard 13790- Energy performance of buildings- Calculation of energy use for space heating and cooling (2008).]

Users of Residential Buildings

The users of residential buildings are considered only as occupiers, either as owners or as tenants. [Source: IEA Annex 31 Glossary]

Users of Service Providing Buildings

The users of service-providing buildings are only considered as occupiers. [Source: IEA Annex 31 Glossary]