SAP Calculations for Wales

All New Dwellings in Wales must have a SAP calculation before construction commences and comply with Part L of Building Regulations. 

What is a SAP calculation?

Standard Assessment Procedure (SAP) is the UK government's national calculation methodology used to demonstrate a building's compliance with Building Regulations. In Wales, new builds must comply with Part L of Building Regulations similar to properties in England. 

Two SAP Calculations need to be performed: Design Stage (before the building is constructed) and As-Built (after construction).

The building must meet 5 main criteria:

1. The calculated Dwelling CO₂ Emissions Rate (DER) must not exceed the Target CO₂ Emissions Rate (TER).
2. Heat gains and losses through the fabric of the dwelling should be limited.  
3. There should be reasonable provisions to limit overheating in new dwellings from solar and other heat gains during the summer months.
4. Dwellings must be constructed and equipped so that the performance is consistent with
   the Dwelling Emissions Rate (DER) as calculated at the completion of the building work.
5. The owner of the dwelling should be provided with sufficient information so that the building can be operated in such a manner as to use no more fuel and power than is reasonable in the circumstances.

Does my building need a SAP Calculation?

All new dwellings, extensions and conversions which result in a material change of use of a property, must have a SAP calculation in order to demonstrate compliance with Building Regulations. However, there are a few notable exceptions. 

The following buildings do not require a SAP calcultion:

• Listed buildings
• Those in a Conservation Area
• Scheduled Ancient Monuments

Conservatories are exempt if they are under 30m² with walls, windows and doors retained from the original property that separate it from the main house. If the original ones are removed and replaced by others that meet the energy efficiency requirement, and providing the heating system of the main house does not extend into the the conservatory, it is exempt. The same rule applies for porches.