On leaving the EU the CE Mark will change to the UKCA mark. For a limited time manufacturers will be able to use either the CE Mark or the UKCA mark. The CE Mark can be used until 1st January 2023.
The UK government is keen to have a Mutual Recognition Agreement with the EU but most commentators feel this is unlikely. If the EU are not going to accept type test evidence from UK notified bodies, then it will probably mean that the UK will not accept type test evidence from EU notified bodies.
The transition phase has now been changed to 31st Dec. 2022 so it is possible that an agreement will be reached by that time..
More information can be found at: https://www.legislation.gov.uk/uksi/2019/465/made
Most UPVC profile suppliers have already supplied all the relevant information to calculate a thermal performance for plastic windows, the timber industry has been a little slow to get their figures on to various calculators. However, this is now changing and joiners should contact The British Woodworking Federation where they will find all the support they need to calculate a thermal performance and use the CE Mark on their product.