The building fabric elements of a dwelling are considered when calculating heat loss and energy use in DEAP.
Support for BER assessors
This section provides BER assessors with additional support, tools and guidance about building fabric in DEAP assessments.
You'll find the core information for building fabric in these documents:
Building fabric inputs in DEAP take account of elements including:
- Fabric insulation
- Thermal bridging
- Building envelope air permeability
Guidance and tools
Elements adjacent to unheated spaces
The procedure for treatment of U-values of elements adjacent to unheated space (also called semi-exposed elements) is described in:
- IS EN ISO 6946
- IS EN ISO 13789
- BR443 Appendix A
The Ru for typical unheated structures is given in Building Regulations 2019 TGD L Appendix A. Ru can also be calculated using this calculator, which is based on BRE443.
The heat loss due to thermal bridging at junctions between building elements is accounted for by inputting a thermal bridging factor in DEAP.
You'll find the options for deriving the thermal bridging factor for DEAP in:
Thermal bridging factor calculator
BER assessors can use this thermal bridging calculator to calculate a non-default thermal bridging factor for use in DEAP.
- Thermal Bridging Application Instructions (version 1.0) last updated on February 2012
- Thermal Bridging Application (version 1.0) last updated on February 2012
The thermal bridging factor calculator contains the psi-values associated with the Acceptable Construction Details, published by the Department of Housing, Local Government and Heritage. You can also input certified psi-values when using this calculator to calculate the thermal bridging factor of a dwelling.
Acceptable construction details
The Department of Housing, Local Government and Heritage has published guidance on acceptable construction details.
- Part 1 of the guidance covers the general theory of insulation continuity and airtightness in construction.
- Part 2 provides indicative detail drawings of thermal insulation and airtightness provisions for specific construction interfaces.
To learn more visit the website of the Department of Housing, Local Government and Heritage.
For further information read:
8th December 2021
This webinar explains thermal bridging, the information required for a default thermal bridging factor of 0.08, a non-default thermal bridging factor with default psi values from Part L and certified psi values as an acceptable form of evidence to use in a DEAP assessment.Thermal bridging webinar