What is PAS 2035?

26 March 2021 EcoTherm Insulation

Making energy efficiency improvements to an old property can be a big challenge. Wonky walls, hidden damp and dodgy pointing are just some of the issues that can crop up. Here in the UK, things are made tougher as our homes are generally much older than elsewhere in Europe. This means before fitting insulation or any other Energy Efficiency Measure (EEM), you need to get a clear idea about its current state, and what measures are right for the home. PAS 2035 has been created to help to get the best results on these projects.

PAS 2035: 2019 sets out the process for carrying out retrofit work on homes. This includes:
•    how to assess the condition of the property;
•    deciding how EEMs are selected and prioritised; and 
•    how the work is monitored and evaluated.

It works together with PAS 2030 which looks specifically at how installers should install and commission the EEMs.


When is PAS 2035 required?

From June 30th 2021, compliance with PAS 2030:2019 and PAS 2035:2019 will be a requirement for all installers carrying out work under the government TrustMark scheme. The only exceptions to this are for ongoing projects being completed under either the Green Homes Grant or Local Authority Delivery Phase 1 schemes. It will be possible to complete these under PAS 2030:2017 up until 30th October 2021.

Find out more about TrustMark. 

Even if you aren’t planning on joining this scheme, it is a good idea to learn about it and look to apply its framework on your projects.


Why has PAS 2035 been created? 

Both PAS 2030 and PAS 2035 have been created following the Each Homes Counts report. This report looked at some of the problems that had occurred during energy retrofits in the past, and how to stop these going forward. 

One of the key points it highlighted was that you can’t take a one-size-fits-all approach to these retrofits. Instead, the choice of EEMs needs to be based on a number of factors which are specific to the home. For this reason, PAS 2035 adopts what is known as a ‘whole house approach’.


What is a Whole House Approach?

A ‘whole house approach’ does what it says on the tin. Under PAS 2035, the project team carries out a Whole Dwelling Assessment, inspecting all aspects of a property including factors such as:
•    age;
•    construction;
•    condition; and
•    planning constrains. 

They then use this evaluation to develop a medium-term improvement plan (covering around 20 – 30 years) for the entire property. This not only sets out what package of EEMs will work well together but also the best order to install these to avoid unnecessary complications. 

The British Standards Institute (BSI) is currently implementing some limited amendments to PAS 2035:2019. These include providing additional clarity on what should be included within the medium-term improvement plan and placing more emphasis on ensuring all necessary pre-retrofit repairs are made and ensuring issues such as indoor air quality and overheating are considered.

The plan is stored in the TrustMark Data Warehouse. This is an online portal where you can add updated information about the property such as which EEMS are installed. All members of the project team can access this resource. There is also a separate portal for the homeowner to let them see key documents such as product guarantees. 


How does PAS 2035 work?

PAS 2035 creates a number of new roles– each with clear qualification requirements. Probably the most important is the Retrofit Coordinator who oversees the project from start to finish, coordinating with the owners and all of the other parties involved in the work. Multiple roles can be carried out by a single individual providing any conflicts of interest are addressed.

Projects should follow a clear step-by-step process:
1.    A Retrofit Advisor can offer some level of advice on potential different options for a home. (This role is likely to be removed as part of the expected amendments to the scheme and will be susbstituted with online or telephone advice services.

2.    If the owner/occupier is interested in getting work done, then the Retrofit Coordinator carries out a risk assessment of their home. This may include asking the owners about any issues they’re aware of, taking a look at the Energy Performance Certificate (EPC) and carrying out a survey of the home. They then rank the home from A (low risk) to C (high risk)

3.    A Retrofit Assessor then carries out the Whole House Dwelling Assessment. This is more extensive for higher risk homes.

4.    A Retrofit Designer uses this report to create the package of EEMs. This is developed into a 20-30 improvement plan by the Retrofit Coordinator who then gets it approved by the client.

5.    The Retrofit Coordinator briefs the Retrofit Installers for each EEM when it is ready to be installed. As the installer, it will be your responsibility to ensure the measures are installed and commissioned in line with PAS 2030.

6.    The Retrofit Coordinator then collects all the documentation, such as guarantees and briefs the owner on how to operate the EEM (if needed). 

7.    They will also recommend a new EPC is commissioned and carry this out where agreed.

8.    A Retrofit Evaluator undertakes a Basic Evaluation within three months of the EEM being installed. If they find any issues, they may carry out more extensive evaluations and make recommendations for remedial work which are circulated in the Data Warehouse. 

Still have questions?

If you have any other queries about how to carry out retrofit work then take a look at our  Educate section, where you can find everything from how to videos to FAQs.

EcoTherm Insulation Ltd

Harvey Road

Burnt Mills Industrial Estate



SS13 1QJ

01268 591155