Glossary

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
Party wall

This is a wall shared between two properties. Coincidentally, in buildings with poor acoustic properties it can be the focus of much tension when neighbours throw parties

Passive House Planning Package

A software programme developed by the Passive House Institute that's used to design and test buildings aiming to meet the passive house standard. It's often used as a design tool for low energy buildings even if the architect or builder is not specifically aiming to meet the standard

PEFC certified wood

Like the FSC, the Programme for the Endorsement of Forest Certification certifies forests that are managed sustainably

Performance gap

The difference between how a building is designed to perform and how it subsequently does in reality once built. The term usually refers to energy consumption but can refer to other aspects of building performance too

photovoltaic

A technology that uses energy from the sun to produce electricity

PHPP
poroton

A type of masonry block with a lower embodied energy than traditional concrete, made from clay that is heated to about 1000C. Also known as teracotta block

Psi values

This is the 'linear thermal transmittance', the rate of heat flow per degree temperature difference per unit length of a thermal bridge. It is measured in W/mK, and is used to calculate the heat loss or gain through a thermal bridge. Under Irish and UK building regulations, the Psi-values for all non-repeating thermal bridges are multiplied by the measured length of each bridge before a Y-value for the building can be calculated, expressed in W/m2K.