Perplexed by all this talk of u-values and blower door tests? Our sustainable building glossary will help you get to grips with the key terminology.

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Term Definition
embodied energy

Energy required to extract, manufacture process, transport, and install a product

Energy Performance Coefficent

The Energy Performance Coefficent (EPC) and Carbon Performance Coefficient (CPC) measure the energy and carbon efficiency of buildings under the Irish building regulations. Here we compare the EPC and CPC for this dwelling to Ireland’s proposed nZEB standard and to the current (2011) and past versions of Part L of the Irish building regulations. The lower the fraction, the better the score - so for instance a house with an EPC of 0.4 is 60% better than the 2005 regs.

Synonyms: Carbon Performance Coefficient, EPC, CPC

This is the Passive House Institute's standard for retrofit projects. It demands airtightness of 1.0 air changes per hour and space heating demand of 25kWh/m2/yr (as opposed to 0.6 air changes per hour and 15 kWh/m2/yr for the original passive house standard).

Exhaust air heat pump

This type of heat pump extracts heat from waste air leaving a heating system and uses it to provide hot water or space heating, using electricity to boost the temperature if needed.

expanded polystyrene

A type of rigid foam used for insulation, typically for external insulation

External insulation

Insulation applied to the outside of a building