In December 2021, the Government announced changes to three Building Regulations, all of which are designed to help the UK achieve its net zero targets.

Due to come into effect in England on 15 June 2022, the updates include a requirement for new homes to produce around 30% less CO2 than current standards, with a 27% reduction of emissions required from other new buildings. The devolved administrations in Scotland and Wales are consulting on changes to their versions of the documents.

The updates are paving the way for the Future Homes and Buildings Standard in 2025, which will aim for all future homes to be net zero ready. With heating and powering buildings currently making up 40% of the UK’s total energy use, all new residential buildings must also now be designed to reduce overheating, making sure they are fit for the future. Improvements to ventilation are also being introduced to support the safety of residents in newly built homes and to prevent the spread of airborne viruses in new non-residential buildings.

Three documents are affected by the updates: Approved Documents L (Conservation of Fuel and Power) F (Ventilation) and O (Overheating). However, it is the updated Document L that will have the greatest impact on aluminium window and door manufacturers, fabricators and installers, with the changes applying to both residential and commercial projects, whether new build or refurbishment.

New thermal regulations for windows and doors

Document L has two Volumes. Volume 1 applies to dwellings and Volume 2 applies to commercial buildings, with new limiting U-values laid out for both.

For example, the limiting U-value in the 2010 regulations for doors and windows in new homes was 2.0, whereas the update sets the value at 1.6.

For windows being refurbished in existing homes, the change is less pronounced, but the limiting U-vale is still reduced, from 1.6 to 1.4 (or Band C to Band B using the Energy Rating system).

Glazed doors are compliant with a C Rating. In new build commercial projects, the change is even more marked, the new limiting U-value being 1.6 compared to the 2010 value of 2.2.

Target Emission Rates

As well as introducing new limiting values, the updated Building Regulations state that 'where a building is erected, it shall not exceed the target emission rate for the particular building…'.

Target Emissions are calculated though the Standard Assessment Procedure (SAP) for domestic properties, or Simplified Building Energy Model (SBEM) calculation for commercial.

Both establish the target as a minimum allowable for the energy performance of a building based on a “notional building”. Where the “notional building” is a building of the same type, size and shape to the proposed building with the CO2 based on default or “notional values” for the different building elements.

After notional values have established the Target Emissions Rate, there is the ability when calculating the actual building performance to offset up to the “Limiting Values” (maximum possible U-values for each element). As long as the overall building meets or exceeds the notional Target Emission rate.

What is Smart doing?

Since the changes were announced, we have been assessing the updated U-values against our current products and developing new products, to comply with the new requirements.

As a UK manufacturer, we have made sure that our full window and door product portfolio have thermal simulations and energy rating to demonstrate compliance. We have also developed new systems including our Alitherm 400 windows and doors, Visofold 1000 Slim slide/fold door system and Visotherm to comply with the updates.

What do fabricators and installers need to do?

Most importantly, the whole industry needs to become familiar with the new requirments, so that we are all prepared for their implantation. It should be noted though that for new build projects the date applicable is from date of building application, so it does not apply to work subject to a building notice, full plans application or initial notice submitted before the 15 June 2022, provided the work for each building is started before 15 June 2023.

Full details of the limiting U-values and Target Emission Rates, as well as the updates to Approved Documents F and O, can be found on the Government’s website - www.gov.uk.

For technical support or for more information on the updates to the Building Regulations please visit https://www.smartsystems.co.uk/understanding-document-l, or call Smart Technical Support on 01934 876 100 or email support@smartsystems.co.uk.