Climate change and energy: energy efficiency

How to calculate annual CO2 emissions from energy use in a new building

Current Building Regulations (Part L) requires that developments involving new and existing buildings (including extensions greater than 100m square and greater than 25% of existing floor area) calculate and assess the:

  • Dwelling Emission Rate - DER - estimated carbon dioxide emissions in kg per metre square, per annum, arising from energy use for heating, hot water and lighting for the actual dwelling, and the
  • Target Emission Rate - TER - the maximum emission rate permitted by building regulations

Different methodologies apply to different types of building and the most effective way of calculating these emissions is to hire a qualified professional to do the calculation using the relevant methodology.

Planning applicants are recommended to use the energy statement: format and guidance document which allows applicants to submit information on energy use and CO2 emissions.

This is available in 'Word' format which can be downloaded, completed and submitted as part of a planning application. This document contains guidance on how the statement should be completed. It is intended that applicants should consider how the development will reduce its CO2 emissions at the earliest possible stage of the project, in other words, the design stage.

This will enable the role of passive energy efficiency measures (improved building fabric) to be maximised before active measures (low or zero carbon (LZC) technologies) are considered. This approach of improving building fabric first, before adding on LZC technologies, reduces CO2 emissions to a minimum and lowers fuel bills.  

Small scale residential developments required to achieve level 3 of the Code for Sustainable Homes must have a DER 25% below the TER.

New build medium-scale, major and Greenfield developments are required to be zero carbon (reach code level 6 for Dwelling Emission Rate).

If zero carbon is not achieved any residual emissions can be off-set through off-site improvements to the environmental performance of existing homes in the vicinity of the site (see Sustainable Building Design Annex and the climate emergency design guide).

Zero carbon

Where zero net annual carbon emissions are not achieved on site, planning applicants are expected to compensate for CO2 emissions from the proposed development by reducing carbon emissions in buildings in the vicinity of the development. 

This action can be taken through 2 options:

Option 1: improvements carried out by planning applicants/developers

The planning applicant/developer may choose to carry out one or a set of the following energy efficiency retrofit measures to housing in the vicinity of the development, like:

  • loft insulation to 300 mm
  • cavity wall insulation
  • draught proofing
  • condensing boilers, including boiler itself
  • improved heating controls
  • solar water heating or other active measures

These improvements can be carried out to existing homes near the site. The planning applicant/developer will be expected to provide evidence of implementation of agreed measures prior to occupation.

Option 2: financial contribution

Alternatively, planning applicants/developers may choose to make a financial contribution to the city council’s Section 106 account. In this option the planning applicant/developer makes a financial contribution to offset any CO2 emissions predicted to be emitted from the proposed development.

The carbon contribution for these 2 options is explained in paragraphs 3.2.2 of SPD08 Annexe (Supplementary Planning Document on Sustainable Building Design). 

Option 2 will allow the council to take undertake improvements to existing homes through its portfolio of home energy efficiency and renewable grants/discount schemes.

In order to comply with Circular 05/2005 requirements, such grants/discount schemes will be available to all Brighton & Hove residents.

Find more information about home energy efficiency and renewable grants and discount schemes.