Monitoring and evaluation — referred to throughout PAS2035 as M&E — is a mandatory requirement for all domestic retrofit projects receiving public funding in the UK. It is also one of the least well-understood elements of the standard, frequently treated as a post-completion exercise rather than an integral part of project planning and delivery.

Understanding what M&E requires, why it matters for residents and programmes, and how to build it properly into the project plan from the outset is essential for every Retrofit Coordinator.

Why M&E Is Required

The fundamental purpose of monitoring and evaluation in retrofit is to verify that the measures installed are performing as intended — that residents are achieving the energy savings, carbon reductions and comfort improvements that the retrofit was designed to deliver. Without M&E, there is no systematic way to identify underperforming installations, address resident issues early, or build the evidence base that improves future programme design.

PAS2035 requires M&E because the retrofit sector has historically had limited visibility of actual post-installation performance. Measures installed to the correct specification do not always perform as modelled — because of building fabric interactions, occupant behaviour, installation defects or equipment failure. M&E creates the feedback loop that identifies these gaps.

The Three Levels of PAS2035 M&E

PAS2035 specifies three levels of monitoring and evaluation, each with different requirements and purposes:

Basic M&E

The minimum requirement for all projects. Basic M&E does not require access to the property and should be delivered between three and six months after project completion. It involves a review of the retrofit documentation — comparing the measures installed against the design specification, checking that all documentation is in order and identifying any outstanding issues. Basic M&E is primarily a documentation quality check.

Intermediate M&E

Intermediate M&E builds on basic M&E by adding a physical inspection of the property to verify that the measures are in place and functioning. It checks all the requirements from basic M&E and additionally involves resident contact to identify any concerns, a review of energy bills where available, and an inspection of installed measures to confirm they are operating correctly. Access to the property and resident agreement are required.

Advanced M&E

Advanced M&E involves detailed performance monitoring using sensors, smart meters and data logging to track actual energy consumption, indoor temperature, humidity and air quality over time. It is typically required for more complex installations — heat pumps, MVHR systems, district heating connections — where performance verification requires ongoing measurement rather than a single inspection visit.

Planning M&E from the Outset

The most common mistake in retrofit M&E is treating it as an end-of-project task. By the time installation is complete, the window for cost-effectively installing monitoring equipment has passed, resident engagement for M&E access has not been established, and the baseline data that M&E results should be compared against has not been collected.

M&E planning should begin at Stage 1, when the pre-retrofit assessment is being conducted. The assessment visit is the opportunity to collect baseline data on the property's condition, energy consumption and indoor environment that M&E results will later be compared against. Agreeing M&E arrangements with residents at this early stage — before they are asked to agree to works — establishes the expectation and reduces the access issues that arise when M&E requests arrive unexpectedly after installation.

M&E and the Retrofit Evaluator Role

PAS2035 specifies that M&E activities are carried out by a Retrofit Evaluator — a role with defined competency requirements set out in Annex A of the standard. In many projects, the Retrofit Coordinator also acts as the Retrofit Evaluator, but this must be explicitly defined and documented. Where a separate Evaluator is appointed, the relationship between the two roles and the handover of responsibility at the M&E stage must be clearly established in the project documentation.

Using M&E Data to Improve Programmes

The value of M&E extends beyond individual projects. Systematic collection and analysis of M&E data across a programme provides the evidence base for improving future designs, identifying underperforming measure types or suppliers, and demonstrating the outcomes achieved to funders and stakeholders.

Housing associations running large retrofit programmes should establish a programme-level M&E framework that aggregates data from individual projects into portfolio-level reporting. This is increasingly expected by funding bodies and will be required to demonstrate the outcomes of Warm Homes Plan investment over the programme period.

Thermographic Surveys

Thermal imaging — surveying properties using specialist camera equipment that reveals heat loss patterns — is a particularly useful advanced M&E tool for verifying the effectiveness of insulation installations. Thermographic surveys are most effective in cold weather, when the temperature difference between inside and outside is greatest. They can identify insulation defects, thermal bridges and areas of unexpected heat loss that would not be apparent through standard inspection. Where thermographic surveys are specified as part of M&E, specialist contractors should be engaged — the equipment and interpretation skills required are beyond the scope of a standard property inspection.