If asked tomorrow, could you evidence Part L compliance across your project?
Updated in 2022 as part of the UK’s drive towards net zero, Part L sets mandatory energy efficiency standards for new and existing buildings in England. While all builds must adhere to the regulation, it can be a disjointed process in capturing and demonstrating compliance clearly, quickly and consistently.
This blog explores what Part L demands, and where homebuilders experience the most risk in Part L reporting.
What are the key milestones of Part L reporting?
Part L governs the conservation of fuel and power in new and refurbished dwellings. The introduction of Part L in 2022 raised the bar on energy performance, carbon reduction, and proof of delivery.
Key milestones homebuilders need to demonstrate include:
- Design intent and energy modelling: Energy models must align with the approved designs, build-ups, and specified systems, with any design changes formally reviewed and updated.
- Specified materials and systems installed on site: Products and systems installed must match approved specifications, with any substitutions clearly documented, justified, and linked to their energy performance impact.
- Photographic and documentary evidence during construction: Evidence must be captured at the point of installation, in a consistent, traceable manner, showing that energy-critical elements were installed as designed before being concealed.
- Final as-built submissions used for certification and handover: As-built submissions must be compiled from verified project data, reflecting the final constructed state, and supported by auditable evidence.
If those elements do not line up, compliance is quickly put at risk.
Why is Part L a risk issue?
Part L risk rarely occurs due to poor design or workmanship. Risk emerges in the ability to demonstrate compliance with confidence.
Homebuilders are caught out in three main areas:
- Sign-off delays caused by evidence gaps
Inaccurate, incomplete, or late Part L submissions (SAP calculations, BRUKL reports, as-built evidence) can result in Building Control refusing completion certificates.
What begins as a compliance issue, also quickly becomes a commercial one. Delays at completion affect handover dates and erode margins.
- Design-as-built performance gap
Design changes and product substitutions are often reasonable and approved in isolation. However, unless these changes are consistently reflected in energy models and supporting documentation, a gap opens between what was designed and what is reported.
Reconciling differences becomes complex and time-consuming, particularly if decisions were not clearly documented or assessed for their energy impact at the time.
- Weak information management and audit trails
Part L compliance depends on traceability across multiple data sources. When information is dispersed across platforms, teams, and devices, establishing a clear audit trail becomes difficult. Questions arise around which version is correct, whether approvals were granted at the right stage, and how changes were governed.
This lack of clarity places pressure on individuals to explain decisions after the fact. It also makes organizations vulnerable during audits or regulatory review, where confidence in information management is just as important as the information itself.
How technology is supporting Part L
When used effectively, digital systems help maintain alignment between approved designs, site installation, and final energy submissions.
When procuring technology to support Part L, here are 3 features you should look for:
Automated forms and workflows: Teams can use automated forms and workflows to standardize the capture and approval of Part L evidence across site. Configurable forms ensure the correct information is collected for each plot or building element, while embedded validation checks reduce errors and omissions. Automated workflows route submissions to the appropriate reviewers, creating a clear audit trail and ensuring evidence is reviewed, approved, and stored in line with Part L compliance requirements.
Apps to connect site-to-office: Part L photographic evidence requires site-based images that are clearly labeled and demonstrate what has been installed, including insulation, airtightness measures, and windows. Select a field tool that integrates with your existing Information Management System or Common Data Environment. Features such as automated geotagging and time stamping significantly reduce the need for manual photo tagging and improve compliance efficiency.
Robust information management: A Common Data Environment provides a single, controlled source of truth for all Part L evidence and compliance information. By centralizing photographic evidence, forms, and approvals in one system, teams can ensure data is consistently stored, and auditable to Building Control.
Part L compliance depends on information being captured in a consistent manner, governed by standard processes, and reported from trusted project data. Where evidence relies on manual effort or individual knowledge, compliance becomes fragile. Where systems standardize how information, approvals, and changes are connected, compliance becomes more robust.
The cost of getting it wrong
Getting Part L wrong is costly. It leads to delayed completions, deferred revenue, and unplanned rework as teams are held up resolving compliance evidence late in the program. Where compliance cannot be clearly demonstrated, organisations also face reputational damage, enforcement action, and financial penalties.
Part L compliance, out of the box
Asite supports Part L compliance through out-of-the-box compliant reporting. Alternatively, teams can work with Asite to deliver custom Part L reports aligned to your existing forms.
In our guide, Demonstrating Quality and Compliance for Homebuilders in 2026 , learn how Tilia Homes streamlined Part L reporting alongside snagging and quality assurance.
