Retrofit compliance package
Retrofit compliance in the order decisions need evidence
Understand the existing home
Begin with a retrofit assessment and the records available for the building. Record construction, condition, occupancy and existing services before choosing measures. PAS 2035 sets out a framework for domestic energy retrofit; whether a particular project follows that framework depends on its agreed route and requirements. The package should be scoped around that route rather than described as proof that every associated role is included.
Establish the energy starting point
An EPC provides a defined energy-performance output. GOV.UK EPC guidance explains when a domestic certificate is needed. For improvement planning, identify whether an existing certificate reflects the present dwelling and what further assessment information is needed. The certificate alone cannot describe every defect concealed in a wall or explain the practical condition of a ventilation system.
Check proposed fabric changes
U-value calculations assess heat transfer through the proposed construction build-up. Where the work engages energy-efficiency requirements, use the applicable guidance in Approved Document L. Give the assessor layer thicknesses and material information, including uncertainties. A calculation for a generic wall is a poor basis for specifying insulation onto a wall with a different construction.
Consider moisture and airflow together
Condensation risk analysis considers the proposed construction and stated conditions. Approved Document C provides guidance on resistance to moisture, while Approved Document F addresses ventilation. These questions overlap in practice: changing insulation or reducing uncontrolled air leakage can alter how moisture behaves. Identify existing damp and its possible causes before presenting an insulation measure as the answer.
Verify the installed ventilation
Ventilation testing checks measured airflow in the installed system against the agreed design and relevant Approved Document F guidance. Plan the visit when terminals, fans and controls are ready. Retain the results with the final specification and operating information so later changes can be understood against what was actually measured.
Services connected by the retrofit compliance package
- Retrofit Assessments
A whole-house assessment of a home's condition and energy use, used to plan retrofit measures.
- EPC
Energy Performance Certificates for homes and commercial buildings that are built, sold or let.
- U-Value Calculations
Calculated U-values for walls, floors and roofs, set out in a document Building Control can check against the limits.
- Condensation Risk Analysis
Analysis of how moisture moves through a wall, roof or floor build-up, showing whether condensation risk is acceptable.
- Ventilation Testing
Airflow measurement of extract fans and ventilation systems, recorded for the Building Control completion file.
Retrofit compliance has a fabric track and an occupied-home track
The construction you intend to change
The fabric track follows walls, floors, roofs and their junctions. Ask how the proposed insulation meets adjacent construction, where continuity is uncertain and which existing layers will remain. Product literature can describe a material, but the assessor needs the proposed assembly. Include finishes, cavities and any areas that the installer cannot reach.
Investigations may reveal a gap between an assumed wall type and the real one. Treat that as a design question before installation proceeds. A revised build-up can affect the calculation and the moisture analysis together. Keep the survey observation, design response and final instruction linked so the installer receives one resolved detail.
The home people will continue using
The occupancy track follows heating patterns, moisture generation, room use and practical access. Ask residents about cold rooms, persistent condensation and how they currently use fans and windows. Their account helps form the brief, although it does not establish a technical cause by itself. Record observations distinctly from conclusions.
Plan how residents will use the completed measures. Controls that are hidden behind furniture or instructions that assume technical knowledge can leave a system poorly understood. Ask for operating information in language suited to the household, and keep the design intent with the handover records. A measured result is most useful when the installed arrangement remains identifiable.
Who the retrofit compliance package suits
This package suits homeowners, landlords and project teams considering connected energy improvements to an existing dwelling. It is useful when the preferred measures affect both the building fabric and ventilation, or where reliable information about the existing construction is missing. National Building Compliance provides a single project contact and arranges the accredited, qualified assessors needed for the agreed work.
A narrowly defined calculation may be enough if the construction is already established and another team holds the wider assessment brief. Conversely, a home with unresolved defects may need investigations or design work outside the listed package before measures can be specified. Tell us about that uncertainty. For intrusive work, discuss survey suitability using HSE asbestos survey guidance and the separate asbestos survey services.
The services belong together because they answer successive questions: what exists, how it performs, what may change and what the installed ventilation delivers. They do not all need to happen at the first visit. Agree the sequence against decisions and access, and avoid commissioning a final calculation while the wall build-up is still being selected.
Retrofit compliance guides for the next decision
Prepare the assessment brief
- What Happens During a Retrofit Assessment?
See what information to assemble and use the visit to distinguish observed conditions from assumptions that still need checking.
- What U-Values Do Building Regulations Require?
Understand the purpose of the calculation before comparing two insulation proposals or passing supplier information to the assessor.
- What Is a Part F Ventilation Certificate?
Read about ventilation evidence before arranging an installation visit, so the requested output matches the work being checked.
Retrofit compliance questions about scope and changes
Does this include the installation work?
The listed package covers assessments, calculations and testing. Confirm design roles, installation responsibilities and any further project requirements in the written instruction. If another organisation controls the improvement programme, share its specification and required outputs before arranging work.
What if the proposed insulation changes?
Send the revised material data and construction detail before proceeding. Ask which calculations and assumptions need review. Retaining both the original proposal and the replacement without explaining which was built makes the evidence difficult to interpret later.
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