As the UK pushes toward net-zero carbon targets, retrofitting existing buildings has become a crucial part of the journey. To ensure retrofit projects deliver measurable energy savings, maintain quality, and protect building integrity, the Publicly Available Specifications (PAS) framework provides a clear set of standards for compliance.
In 2023, updates to PAS2030 and PAS2035 refined these standards to improve quality assurance, accountability, and coordination across retrofit projects. Whether you’re a homeowner, contractor, or consultant, understanding and applying these standards correctly is essential for successful project delivery.
This guide will help you understand how to ensure your retrofit project meets PAS standards, from planning through completion.
What Are PAS Standards?
The PAS framework was developed by the British Standards Institution (BSI) in collaboration with government and industry experts. It defines best practices for domestic retrofit work — ensuring installations are safe, effective, and energy-efficient.
There are two key documents within this framework:
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PAS2035:2023 – The Retrofit Process: Covers the management, assessment, coordination, and design of retrofit projects.
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PAS2030:2023 – Installation Requirements: Specifies the technical and installation standards that installers must meet for each energy-efficiency measure.
Together, these standards form a whole-house, fabric-first approach that ensures retrofit projects are not just compliant, but deliver long-term performance improvements.
Why PAS Compliance Matters
Compliance isn’t just about ticking boxes — it ensures:
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Quality assurance: Each stage of the retrofit process is documented and verified.
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Eligibility for funding: PAS compliance is a requirement for many government-backed schemes such as ECO4 and the Great British Insulation Scheme.
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Reduced risk: Proper coordination prevents issues like damp, thermal bridging, or unintended energy losses.
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Improved building performance: The retrofit measures actually deliver measurable energy savings and comfort improvements.
1. Start With a Retrofit Assessment
Every PAS2035-compliant project begins with a Retrofit Assessment. This is a detailed evaluation of the property’s current condition, energy performance, and suitability for various measures.
A qualified Retrofit Assessor will:
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Collect data on the building’s construction, fabric, heating systems, and ventilation.
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Conduct occupancy assessments to understand how the property is used.
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Perform an Energy Performance Certificate (EPC) or equivalent analysis.
The resulting assessment report is then shared with the Retrofit Coordinator to inform design decisions and identify the most appropriate retrofit measures.
At Armstrong Eco Works, we provide PAS2035-compliant Retrofit Assessments that ensure your project starts with accurate data and a clear understanding of potential improvements.
2. Appoint a Qualified Retrofit Coordinator
The Retrofit Coordinator plays a central role in PAS2035 compliance. Acting as the project lead, they manage the process from start to finish — ensuring every stage aligns with the required standards.
Their responsibilities include:
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Reviewing assessment data and setting the retrofit pathway.
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Coordinating between designers, installers, and assessors.
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Ensuring designs meet PAS2035 and PAS2030 requirements.
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Verifying that installation work is compliant and risk-managed.
By engaging a qualified coordinator early, you’ll reduce costly errors and ensure that compliance is embedded from the outset.
3. Develop a PAS-Compliant Design
A PAS-compliant retrofit design goes beyond visual appeal — it’s a technical plan that ensures energy-saving measures work harmoniously.
A Retrofit Designer (often working alongside the Coordinator) will produce a detailed design that includes:
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Building performance calculations.
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Thermal bridging and condensation risk assessments.
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Specifications for materials, insulation, and ventilation systems.
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Heritage impact assessments, if applicable.
The design must follow the “fabric-first” principle — improving insulation and airtightness before upgrading systems like heating or renewables.
At Armstrong Eco Works, our consultancy team prepares PAS2035-compliant retrofit designs that integrate performance, sustainability, and compliance into every detail.
4. Select Accredited Installers (PAS2030:2023)
Even the best design will fail without proper installation. That’s where PAS2030:2023 comes in.
This standard applies to installers and ensures they follow strict quality and competency requirements for each type of measure — from wall insulation to heat pumps.
When selecting an installer, ensure they are:
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PAS2030:2023 accredited for the specific measure being installed.
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Affiliated with a TrustMark-approved scheme provider.
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Experienced in working within the PAS2035 process alongside a coordinator.
Always verify credentials and review past project outcomes before appointing a contractor.
5. Conduct Ongoing Site Visits and Quality Checks
PAS2035 places strong emphasis on ongoing quality assurance throughout installation.
The Retrofit Coordinator should schedule regular site visits to verify:
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Measures are installed according to design specifications.
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Materials and workmanship meet PAS2030 standards.
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Any deviations or issues are corrected immediately.
At Armstrong Eco Works, we provide PAS-compliant site inspections to ensure that each phase of installation maintains full compliance and performance integrity.
6. Keep Detailed Documentation
Every stage of a PAS-compliant retrofit project must be fully documented. This documentation acts as proof of compliance and provides a clear audit trail if required for funding or verification.
Key documents include:
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Retrofit Assessment Report
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Design and Risk Assessment Documents
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Installation Records
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Photographic Evidence of Works
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Post-installation Evaluation
Good documentation not only satisfies compliance but also demonstrates professionalism and accountability.
7. Post-Installation Evaluation and Handover
Once the work is complete, the Retrofit Coordinator performs a final evaluation to confirm that the project meets the design intent and PAS requirements.
This includes:
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Reviewing installation records and testing results.
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Updating the Energy Performance Certificate (EPC).
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Providing homeowners with a handover pack, detailing maintenance, ventilation, and energy-use guidance.
A proper post-installation review helps ensure that the retrofit delivers the predicted improvements and long-term comfort for occupants.
8. Stay Updated With PAS2030/2035 Changes
The PAS standards evolve to reflect advances in building science and industry feedback. The transition from PAS2030:2019 and PAS2035:2019 to the 2023 versions introduced new clarity around risk management, coordination, and installer responsibilities.
Regularly reviewing updates, training, and accreditation requirements ensures ongoing compliance. Working with consultants like Armstrong Eco Works helps keep your team aligned with the latest standards and best practices.
Conclusion: Setting the Standard for Retrofit Excellence
Meeting PAS2030 and PAS2035 standards is about more than achieving compliance — it’s about delivering quality, sustainable retrofit projects that stand the test of time.
By following a structured, PAS-aligned process — from assessment and design to coordination, installation, and verification — you protect both the building and the people who live in it.
At Armstrong Eco Works, we specialise in Retrofit Assessments, Coordination, and PAS-compliant Consultancy Services. Our expertise ensures your retrofit project not only meets PAS standards but exceeds expectations in energy performance, comfort, and sustainability.
Whether you’re an installer, developer, or homeowner embarking on an energy-efficiency journey, our team is here to help guide you every step of the way.
Get in touch with Armstrong Eco Works today to discuss how we can help you achieve full PAS2035:2023 and PAS2030:2023 compliance — and deliver retrofit projects that truly make a difference.
