A
- Air permeability
- A measure of how much uncontrolled air leaks through a building’s envelope, expressed in m³/h·m² at 50 Pa. The lower the figure, the more airtight the building. → Air Pressure Testing
- Air tightness test
- A test (also called an air pressure or air permeability test) that pressurises a building with a fan to measure its air leakage rate against the Part L design target. → Air Pressure Testing
- Approved Documents
- The official guidance documents that explain how to meet the Building Regulations in England — including Part L (energy), Part F (ventilation), Part E (sound) and Part O (overheating).
- As-built SAP
- The SAP calculation produced after a dwelling is completed, incorporating the air test result and any changes made on site. It generates the final EPC. → SAP Calculations
- ATTMA
- The Air Tightness Testing & Measurement Association — the industry body whose registered testers carry out and lodge air tightness certificates accepted by Building Control. → Our Accreditations
B
- BREEAM
- The Building Research Establishment Environmental Assessment Method — a sustainability rating scheme for buildings, often required by planning conditions on larger or commercial schemes.
D
- DER / TER
- The Dwelling Emission Rate (DER) is the predicted CO₂ emissions of your design; the Target Emission Rate (TER) is the maximum allowed. To pass Part L, the DER must be at or below the TER.
- DFEE / TFEE
- The Dwelling Fabric Energy Efficiency (DFEE) is how efficient your building fabric is; the Target Fabric Energy Efficiency (TFEE) is the limit it must meet under Part L.
E
- EPC
- An Energy Performance Certificate — a rating from A to G showing a building’s energy efficiency. Required when a building is built, sold or let, and valid for ten years. → EPCs
H
- Home Energy Model (HEM)
- The UK government’s successor to SAP, being introduced with the Future Homes Standard. It uses half-hourly calculations, thermal zoning and live weather data for more realistic predictions. → Future Homes Standard
M
- MVHR
- Mechanical Ventilation with Heat Recovery — a whole-house system that supplies fresh air and extracts stale air while recovering heat. It must be commissioned and flow-tested under Part F. → MVHR Commissioning
P
- Part E
- The part of the Building Regulations covering resistance to the passage of sound. It sets the sound insulation standards proven by pre-completion sound testing. → Sound Insulation Testing
- Part F
- The part of the Building Regulations covering ventilation. New dwellings must have their ventilation systems commissioned and flow-tested to comply. → Ventilation Testing
- Part L
- The part of the Building Regulations covering the conservation of fuel and power — the energy efficiency rules that SAP, SBEM, air testing and EPCs demonstrate compliance with.
- Part O
- The part of the Building Regulations addressing overheating risk in new residential buildings, assessed by either the simplified method or dynamic thermal modelling. → Overheating Assessments
- Psi value (Ψ)
- A measure of heat loss at a junction in the building fabric — a thermal bridge. Calculating psi values instead of using defaults usually improves a SAP result. → Thermal Bridging Calculations
R
- Robust Details
- A set of pre-approved separating wall and floor constructions that, if registered and built correctly, can exempt a new build from pre-completion sound testing.
S
- SAP
- The Standard Assessment Procedure — the methodology used to show new dwellings meet Part L and to produce the EPC. → SAP Calculations
- SBEM
- The Simplified Building Energy Model — the non-domestic equivalent of SAP, used for offices, shops, warehouses and other commercial buildings. → SBEM Calculations
- Section 6
- The Scottish equivalent of Part L — the energy standards within the Scottish Building Regulations that SAP calculations in Scotland are assessed against.
T
- Thermal bridging
- Heat loss through junctions and gaps in insulation, such as around windows or at floor-to-wall junctions. Reducing it improves energy performance and helps avoid condensation. → Thermal Bridging Calculations
- TM59
- The CIBSE methodology for assessing overheating risk in homes using dynamic thermal modelling — one of the routes to demonstrating Part O compliance. → TM59 & TM52 Assessments
U
- U-value
- A measure of how much heat passes through a building element such as a wall, roof or window. The lower the U-value, the better the insulation. → What is a U-value?
V
- Ventilation test
- A measurement of the airflow rates of a dwelling’s extract and supply systems, checked against Part F. Required for all new dwellings. → Ventilation Testing
W
- Water efficiency calculation
- A Part G calculation that predicts a new dwelling’s water consumption per person per day, demonstrating it meets the regulatory limit. → Water Calculations
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