New Dwellings in Wales

New Dwellings in Wales

Pilkington Thermal Efficiency glass
Changes to Part L of the Building Regulations in Wales, including the supporting Approved Documents, are expected to have a significant impact on glass and glazing products in residential and non-residential buildings.  High performance, energy efficient glass and windows are expected to play a crucial role in delivering nearly zero energy buildings (nZEB) in the UK.

Through its current consultation ending on 12th March 2020, the Welsh Government has set out its proposed changes to Part L (conservation of fuel and power) and Part F (ventilation) of the Building Regulations for new dwellings.  The consultation also covers the future direction of building energy policy in 2025.

Consultation on proposed changes for existing dwellings and other buildings are anticipated in accordance with the following timeline:


Early 2020  Consultations on:
Overheating in new dwellings
Energy efficiency standards for work carried out in existing dwellings 
Energy efficiency standards for new buildings other than dwellings 
Energy efficiency standards for work to existing buildings other than dwellings
Early / mid 2020  Publication of new Part L, Part F and overheating regulations
Mid / late 2020  Part L, Part F and overheating regulations come into force

Major changes to the requirements have been proposed for Part L in 2020.  For new dwellings, the consultation sets out two options to uplift energy efficiency standards in 2020 and the requirements as follows:
Option Reduction in carbon emissions (compared with current standard)  Anticipated solution 
 1  37% High fabric standards (including windows), natural ventilation system, gas boiler, waste water heat recovery system and photovoltaic panels
 2  56% High fabric standards (including windows), mechanical ventilation with heat recovery, gas boiler, waste water heat recovery system and photovoltaic panels

The government has indicated its preference for option 1.

Proposed changes to the worst acceptable fabric performance values – sometimes referred to as 'backstop' values - include reducing (improving) the window U value from 1.6 to 1.4 W/m2K.  However, the expectation is that the U value will have to be lower than this to enable new dwellings to achieve the whole building minimum energy performance target.  This is highlighted in the impact assessment undertaken on the proposed changes for new homes, which has modelled building specifications based on a window U value of 1.3 W/m2K with a higher specification (i.e. triple glazing) envisaged for 2025.

Documents related to the consultation on proposed requirements for new dwellings can be found here.

If you have any questions on Part L 2020 in Wales and what the implications might be for glass, please fill in our online contact form.