Retrofit Academy webinar presses case for performance testing under Warm Homes Plan

The Retrofit Academy has used its latest continuing professional development (CPD) webinar to argue that building performance testing is becoming essential to domestic retrofit, warning that it remains largely absent from current requirements as funding and delivery scale up.

The session, chaired by Jenny Pierpoint, Chief Operating Officer at The Retrofit Academy, brought together John Taylor, Publications Manager and Technical Specialist at BSRIA, and Richard Jack, Technical Director at Build Test Solutions. It examined the recently published BSRIA white paper, Retrofit Testing for Warm Homes.

According to The Retrofit Academy, the discussion asked how the sector should measure success when public money is flowing into retrofit but testing is not routinely required.

The performance gap

Taylor set out findings from the white paper on the gap between design intent and how homes actually perform once work is complete. The Retrofit Academy said a key contributor to that gap is the reliance on visual surveys and standardised assumptions during retrofit assessment.

Jack drew on building performance data that The Retrofit Academy described as covering more than 250,000 homes. He said about 85% of measured homes were more airtight than RdSAP assumptions suggest.

The Retrofit Academy said this means heat loss may often be lower than predicted, but ventilation requirements also need to be properly understood to reduce the risk of condensation, damp and poor indoor air quality.

Build Test Solutions' own published material supports the point. The company said RdSAP has historically relied on a conservative airtightness estimate, typically in the 10-15 m²/h.m² range, while its Pulse database shows a mean average of 8.3 m²/h.m².

The company said RdSAP 10 now allows in-situ airtightness measurements to be entered, which it expects to reflect actual building performance more accurately. It estimates a measured value would typically move an EPC rating by one to three points.

Testing tools

The webinar covered a range of techniques now available to retrofit professionals: airtightness testing, ventilation flow measurement, whole-house heat loss testing, U-value measurement, thermal imaging and ongoing monitoring of moisture and indoor air quality.

Speakers argued that performance testing should be treated as an investment rather than an added cost in PAS 2035 domestic retrofit projects, The Retrofit Academy said.

Build Test Solutions describes itself as a technology business focused on building performance measurement. The company said it licensed its Low Pressure Pulse air leakage measurement technology from the University of Nottingham.

Three priorities

The session set out three priorities for the sector, according to The Retrofit Academy:

• Embed performance testing throughout the retrofit process, from pre-retrofit assessment to post-installation verification.
• Strengthen client leadership so that testing is specified, commissioned and valued as part of every high-quality retrofit project.
• Invest in competence so that testing is delivered by suitably trained, quality-assured and insured professionals.

The policy backdrop

The government's Warm Homes Plan, published by the Department for Energy Security and Net Zero, commits £15bn of public investment to upgrade up to 5 million homes. The department said the plan aims to help up to one million households out of fuel poverty by 2030 and projects 180,000 additional jobs in energy efficiency and clean heating by the same date.

The Retrofit Academy said wider adoption of building performance testing could strengthen delivery of that programme by showing whether retrofitted homes deliver measurable improvements rather than simply recording that measures have been installed.