Wood is a natural insulator. The energy efficiency of modern high performance wooden windows often exceed those required in the Building Regulations.
The type of glazing used in any window will impact the energy efficiency. BWF Members manufacture windows with double or triple-glazed units (with the exception of specialist period windows). Due to the strength of wooden window frames, they are particularly suited to triple-glazing. Depending on the window design, triple-glazed units are generally fitted in wooden window frames without the need for additional thick sections, helping to preserve the aesthetic integrity.
Future Homes Standard
The UK Government hosted a public consultation that ran from October 2019 until February 2020 which looked at proposed changes to the Building Regulations. This consultation set out plans for the Future Homes Standard which aims to ensure that new homes built from 2025 will produce 75-80% less carbon emissions than homes built under the current Building Regulations.
In 2021, as part of the Government’s commitment to bring all greenhouse gas emissions to net zero by 2050, a draft amendment to Approved Document L (conservation of fuel and power) for both new and existing dwellings was proposed. The Department for Levelling Up, Housing and Communities (DLUHC) published amendments to approved documents L and F (ventilation) and these came into effect on 15th of June 2022 with a ‘grace period’ lasting until 15th June 2023.
What does this mean for timber products?
The updates made to approved documents F and L have imposed significant changes on the performance of external doorsets and windows to be used in England.
Approved Document L covers the recommendations to conserve fuel and power with volume 1 applying to building work on both new build and existing dwellings e.g. houses and flats.
For work on existing dwellings the U-values for both external doorsets and windows that must be achieved to comply with the building regulations have been lowered meaning these products are required to permit less energy to transfer through them from the warm, heated environment inside the property to the colder environment outside.
There are two measurements that are used to show the energy efficiency of external doorsets and windows,
a) A U-value is used to measure how well or badly a component, such as a window or doorset, transmits heat from the inside of a building to the outside of a building. A lower U-value shows that less heat will be transferred from a warm environment to a cooler environment. U-values are also an essential characteristic for conformity marking (e.g. CE and UKCA marking) and must be published on the manufacturers declaration of performance.
b) Energy Ratings, which not only take into consideration the U-value of the product but also allow for the energy required to heat cold air that may enter the warmer environment through the product and the heating effect of sunlight passing through the glazing. Energy Ratings apply to both Windows (WER) and doorsets (DSER).
July 2023 BWF Blog: Clarification of the new requirements for U-Values in new build and existing dwellings CLICK HERE
December 2022 BWF Blog: U-Values explained CLICK HERE