Net Zero And Buildings

The UK’s Net Zero ambitions cover the whole of our economy, including transport, industry, energy production - and buildings.

The latest CCC report to Parliament in June 2023 stated that in 2002, buildings accounted for 17% of UK GHG emissions.

These are mainly the result of burning fossil fuels such as gas and oil for heating. Emissions from electricity use (known as indirect emissions) are caused primarily from using lighting and appliances. Homes account for 77% of building emissions; commercial buildings 14% and public buildings 9%.

The UK Green Building Council (UKGBC) also states that 25% of UK emissions are directly attributable to the built environment.

In 2023, there is no UK legislation that requires a building to be ‘net zero’ or to achieve net zero emissions in use. However, there is a growing interest from building developers and owners in this topic, particularly where they have corporate goals on sustainability and carbon reduction.

In addition, several local governments around the UK have introduced requirements for carbon considerations for major developments. The London Plan is one, but cities such as Manchester and Glasgow have Net Zero ambitions that impact building design and operation in their environs.

The construction industry is also developing some agreed terms and standards for what Net Zero buildings should look like. One example already in use is the RICS (Royal Institute of Chartered Surveyors) Whole Life Carbon Assessment.

In addition, the Chartered Institute of Building Services Engineers (CIBSE) is working with several groups including UKGBC and the Low Energy Transformation Initiative to establish standard definitions for terms such as Net Zero, Embodied Carbon and Operational Carbon for buildings.

There is a good chance that these will go some way to informing future legislation, and a significant group of associations, consultants, contractors and clients have set out a proposed Part Z of the Building Regulations which outlines requirements on the assessment of whole life carbon emissions (which is aligned with the RICS approach).

Important terms
It’s increasingly likely that BESA members will work on projects which are required by local planning regulations to undertake whole life carbon assessments. It may also be a voluntary process required by the project client. It’s therefore useful to understand some fundamental terms around carbon and buildings.

Embodied Carbon
Composed of carbon and other greenhouse gas emissions which result from the construction process and the manufacture of materials and equipment which go into a building. Embodied carbon therefore includes emissions created from the manufacture of concrete, steel, aluminium and any other metals and plastics in the building. But it also covers transportation of any materials (and personnel) to the building during its construction.

LETI one-pager on embodied carbon

Operational Carbon Emissions
Consists of carbon and other greenhouse gas emissions arising from energy consumed in the building over its lifetime. This is a particularly important concept as it links carbon emissions to energy efficiency in buildings – something that BESA members can help to optimise for their clients.

LETI defines a Net Zero Operational Carbon building as one where no fossil fuels are used, all energy use has been minimised and the building meets local energy use targets (see Energy Use Intensity below). Any residual emissions from energy generation and distribution should be offset.

Energy Use Intensity (EUI)
This is measured as kilowatts per hour per metre squared per year (kWh/m2/pa). It is becoming an increasingly important measure, particularly in building projects where carbon emissions reductions are targeted.

Many organisations in construction and property regard EUI as a more accurate measure (and target) for energy efficiency. In fact, the UK Green Building Council is campaigning for EUI to be adopted as the key measure of energy performance in the Building Regulations.

Whole Life Carbon Emissions
This is the total of embodied carbon plus operational carbon emissions.