1. EDUCATIONAL SHEET
Thermal Regulations - England
Thermal Regulations in England
Part L (Conservation of fuel and power): The energy efficiency requirements of the
Building Regulations are set out in Part L of Schedule 1 to the Building Regulations and in a
number of specific building regulations.
Technical guidance is contained in four Part L Approved Documents and two building
services compliance guides.
The requirements for the conservation of fuel and power, which includes thermal insulation,
in buildings in England are detailed in Approved Documents (AD) L1A, L1B, L2A and L2B to
the Building Regulations 2013 which come into effect on 6th April 2014.
England 2013 Building Regulations Guides:
L1A New Build – Dwellings
L1B Existing - Dwellings
L2A New Build - Buildings other than Dwellings
L2B Existing - Buildings other than Dwellings
The regulations and guidance can be found at:
http://www.planningportal.gov.uk/buildingregulations/approveddocuments/partl
U- Values
The Building Regulations/Standards sets the levels of thermal insulation required when
carrying out building work, either for new build or refurbishment projects. These are
expressed as a U-value which needs to be achieved; the required U-value will depend on the
location of the project (England, Scotland, Wales), type of building (domestic, non-domestic)
and the application (floor, wall, roof). The table below shows current suggested U-Values:
Recommended U-Values in Domestic Buildings
England – April 2014
New Build Existing Buildings
Best starting point
(fabric only)
Extension Refurbishment
Wall 0.16 0.28 0.3
Floor 0.11 0.22 0.15
Pitched Roof –
ceiling level
0.11 0.16 0.16
Pitched Roof – rafter
level
0.11 0.18 0.18
Flat Roof 0.11 0.18 0.18
2. Recommended U-Values in Non-Domestic Buildings
England – April 2014
New Build Existing Buildings
Best starting point
(fabric only)
Extension Refurbishment
Wall 0.22 0.28 0.3
Floor 0.18 0.22 0.25
Pitched Roof –
ceiling level
0.19 0.16 0.16
Pitched Roof – rafter
level
0.13 0.18 0.18
Flat Roof 0.13 0.18 0.18
What is a U value?
A U value is a measure of heat loss in a building element such as a wall, floor or roof. It can
also be referred to as an ‘overall heat transfer co-efficient’ and measures how well parts of a
building transfer heat. This means that the higher the U value the worse the thermal
performance of the building envelope. A low U value usually indicates high levels of
insulation. They are useful as it is a way of predicting the composite behaviour of an entire
building element rather than relying on the properties of individual materials.
When to use U-values
U values are calculated at stages D onwards in the design process. A critical milestone in any
building project is obtaining building regulation approval. For this a SAP calculation for
housing or an SBEM procedure for non domestic work is obligatory. As part of this process,
the build up of any external construction element must be specified and from this its U
value can be derived.
SAP, SBEM and EPC
A Standard Assessment Procedure (SAP) Assessment is the Government’s method for
measuring the energy efficiency and carbon emission rates of residential dwellings.
The SAP calculation provides the cornerstone of the energy section of the Code for
Sustainable Homes.
SBEM is used for non domestic buildings. It helps to determine CO2 emission rates for new
buildings in compliance with Part L of the Building Regulations. It is also used to generate
Energy Performance Certificates for non-domestic buildings in construction, for sale or let.
