PAS 2035, and when you need an assessment
If the work is funded, it has to follow PAS 2035, and that starts with an assessment of the whole house rather than a quote for one measure. Here is what that involves and why the order is not optional.
PAS 2035 is the standard that governs domestic retrofit in the UK. Its central idea is that a house is one system: change the walls without thinking about the ventilation and you can create a damp problem that did not exist before. So it requires the house to be understood before any measure is specified.
When it applies
Any work delivered under a government-backed funding scheme has to follow it. That covers ECO4 and Warm Homes: Local Grant, which are the routes most insulation is funded through. Privately paid work is not legally required to follow PAS 2035, but the reasoning behind it does not change just because you are paying yourself.
Assessment or survey — they are not the same thing
These two get confused constantly, including by people selling them. They answer different questions and they happen at different points.
| Retrofit assessment | Retrofit survey | |
|---|---|---|
| What it answers | What does this whole house need, and in what order | What exactly is there, measured, for the design |
| When | First, before anything is specified | After the plan, before the work |
| Scope | The whole dwelling and how the measures interact | The detail a designer needs to specify the work correctly |
| Required by PAS 2035 | Yes, for funded work | Yes, where the measures need it |
In short: the assessment decides what and the survey establishes exactly how. One does not replace the other.
What an assessment actually involves
- A visit to the property, measuring the fabric, the heating and the ventilation as they actually are.
- An occupancy assessment — how the house is used, by how many people, and how it is heated now.
- A condition report covering damp, ventilation and anything that has to be fixed before insulation goes anywhere near it.
- A recommended sequence of measures, in the order that does not undo itself.
Why the order matters more than the measure
Insulating before dealing with a moisture problem traps the moisture. Making a house airtight without improving the ventilation moves condensation somewhere less convenient. Sizing a heat pump before the fabric work means buying a larger unit than the finished house needs and paying to run it for its whole life. None of these are hypothetical — they are why the standard exists.
Who has to be involved
PAS 2035 defines roles: a retrofit assessor, a retrofit coordinator who owns the project against the standard, a designer and the installer. On a funded job the coordinator is the person accountable for it hanging together, and the work is registered with TrustMark.
EcoGlow is certified to PAS 2035 and PAS 2030 and registered with TrustMark under licence 3288118. The assessment, the survey and the installation are the same company, so nothing is lost in a handover between them.
If you are paying privately
Privately paid work does not have to follow it. But the failure modes above cost more than an assessment does, and the order of work is the part people get wrong. It is worth having the sequence written down even when nobody is requiring it of you.
Sources. PAS 2035/2030 role and scope descriptions follow the published standard and TrustMark's requirements for registered retrofit work. ECO4 runs to 31 December 2026 per Ofgem. EcoGlow's certification numbers are listed in the footer of every page on this site.