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Design Air Permeability – The score you need to achieve to pass your air tightness test


How an air tightness score is expressed. Metres cubed of air leakage per hour, per square metre of building envelope


The Air Tightness Testing and Measurement Association. The governing body for all air tightness testing


ATTMA Testing Standard L1 – the standard that we test to for domestic/residential dwellings


ATTMA Testing Standard L2 – the standard that we test to for commercial dwellings


A method of creating pressure inside a building by blowing air into it, using an industrial sized fan


A method of creating a negative pressure inside a building by sucking air out of it, using an industrial sized fan

Building Envelope

This is the combined internal area of the floor, walls and ceiling of a dwelling or building

Air Permeability, Air Tightness, Air Infiltration

These all mean the same thing – they are all terms for what we are testing for – the amount of air (and therefore heating) escaping from a building



Standard Assessment Procedure (SAP) is the UK government’s recommended method system for measuring the energy rating of residential dwellings. The SAP rating is a scale from 1 to 100+, with dwellings that have a SAP over 100 being net exporters of regulated energy


The target CO2 emission rate (TER) sets a minimum allowable standard for the energy performance of a building. TER is expressed in kg CO2/m2/yr


The Dwelling emission rate (DER) is the actual CO2 emission rate of self-contained dwellings based on their actual specification. DER is expressed in kg CO2/m2/yr. The DER for the proposed building must not exceed the TER

Energy Performance of Buildings Directive (EPBD)

The European Union’s main legislative instrument aiming to promote the improvement of the energy performance of buildings within the Community

Predicted Energy Assessment (PEA)

These are for new build homes. Normally, when a home is designed, a “target energy rating” based on the design is produced to show a building inspector that the property will meet requirements under Part L of the Building Regulations

On Construction Energy Performance Certificate (OCEPC)

This is an Energy Performance Certificate, which gives information on the buildings energy efficiency, and is displayed similar to the A-G ratings found on electrical appliances


Accredited construction details (ACDs) are a set of standardised junction details that can be followed to ‘design out’ thermal bridges in compliance with the energy efficiency requirements (Part L) of the Building Regulations

PIR Board

PIR (polyisocyanurate) Board are the most popular type of rigid insulation boards currently available. PIR boards are usually laminated with aluminium foil facings. Celotex, Kingspan and Xtratherm are the most common brands


Dwelling Fabric Energy Efficiency (DFEE) is a measure of energy demand measured in kWh/m2/yr. The DFEE for the proposed building must not exceed the TFEE


Target Fabric Energy Efficiency (TFEE) is the target energy demand, measured in kWh/m2/yr, that a dwelling must achieve


U-values (W/m2K) are used to measure how effective elements of a buildings fabric are as insulators. The lower the U-value, the better the floors, walls and roofs are as heat insulators

Psi Values

The heat loss associated with the non-repeated thermal bridge is called linear thermal transmittance or psi-value or ψ-value (pronounced ‘si’). This is the rate of heat flow per degree per unit length of the thermal bridge that is not accounted for in the U-value of the plain elements



The name for sound that travels through the air, i.e. talking, TV, radio etc.


the name for sound the travels through a partition when an object is in contact with that partition, i.e. walking, washing machines, hammering etc.


The United Kingdom Accreditation Service – a governing body for sound insulation testing, amongst other things. RJ Acoustics are accredited by UKAS for Building Regulation Approved Document E sound testing


A unit for measuring sound


The speaker we use to create airborne noise

Decibel Meter

The machine we use to record the amount of noise (in decibels) coming through the wall or floor

Tapping Machine

The machine we use to create impact noise on the floor. A box with metal hammers that continually tap on the floor

Pre-Completion Testing

testing that is completed towards the end of a build, just before it is completed

White Noise

The type of noise created by our loudspeaker – it’s defined as noise containing many frequencies with equal intensities


Noise that bypasses the partition being tested. Eg, when testing walls, the noise would travel through the floor/ceiling void. When testing the floor/ceiling, the noise would travel through the walls


Flow Rate

The rate of air flowing through an extract fan or heat recovery vent


Litres per second. This is the rate that we measure flow at


British Plumbing Employees Council. Ventilation testing should be carried out by a BPEC qualified professional using UKAS calibrated equipment


a wind/flow speed meter. Used to measure the flow rate from and extract fan or heat recovery vent

Mechanical Extract Ventilation (MEV)

This can either be a whole house system or a localise system for specific rooms. Multiple ducts will run from a constantly running unit to wet rooms (kitchen, WC, bathroom) continuously extracting stale air. When these rooms are in use, the system will boost up to extract a larger volume of air

Mechanical Ventilation Heat Recovery (MVHR)

This is similar to Mechanical Extract Ventilation, except that it also supplies fresh air to all non-wet rooms (bedrooms, dining room, living room). The heat from the stale extracted air is kept in the central unit and used to heat the fresh air from outside before it is supplied to the house

Extract Fan

The fans found in most bathrooms and kitchen cooker hoods. Simply draws air out of a room to outside

Water Efficiency

Potable Water

Water that is suitable for drinking



A house, flat or other place of residence

Approved Document

A document that gives guidance for compliance with the Building Regulations for building work

Building Regulations

These are statutory instruments that seek to ensure that the policies set out in the relevant legislation are carried out. Building regulations approval is required for most building work in the UK

Building Control

The body that ensures that the building regulations are adhered to. They will have final sign off on your development