How to Commission a Retrofit Assessment

A retrofit assessment is the foundation of any successful energy efficiency improvement project. It provides the technical analysis needed to understand building performance, identify improvement measures, and plan the works ahead. Commissioning an assessment correctly ensures you have reliable data to make informed decisions and deliver value to your residents or clients.

Understanding What You're Commissioning

A retrofit assessment evaluates your building's current energy performance and recommends cost-effective improvements. The assessor will examine the fabric, heating systems, ventilation, water heating and other relevant components to identify where heat is lost and energy is wasted.

The output is typically a detailed report that prioritises improvements, estimates their costs and benefits, and helps you plan a delivery strategy. This might be a single intervention or a phased programme of works.

Preparation and Scoping

Define Your Objectives

Before approaching an assessor, clarify what you want to achieve:

• Are you targeting a specific energy performance standard?
• Do you have a fixed budget or timeline?
• Are you prioritising fuel poverty reduction, decarbonisation, or resident comfort?
• Will works be phased or completed in one project?

Clear objectives help the assessor focus their work and ensure the report addresses your priorities.

Gather Existing Information

Compile documentation before the assessment commences:

• Building plans and drawings (if available)
• Construction date and any previous renovation records
• Current Energy Performance Certificate (EPC)
• Utility bills for the past 2–3 years
• Details of any listed building status or conservation area designation
• Records of resident complaints (cold spots, condensation, draughts)
• Information about current heating system age and condition

Providing this information upfront saves time and improves assessment accuracy.

Determine Assessment Scope

Decide what the assessment should cover. Options include:

• Standard retrofit assessment: Full evaluation of building fabric and systems
• Fabric-focused assessment: Emphasis on insulation, air-tightness and thermal bridging
• Heating system assessment: Detailed analysis of current heating and options for replacement
• Whole-building deep-energy retrofit: Comprehensive analysis targeting near-zero emissions

Your objectives and budget will determine the appropriate scope.

Selecting an Assessor

Verify Qualifications and Experience

Ensure the assessor holds appropriate credentials:

• Understanding of PAS2035 standard (the key retrofit assessment framework in the UK)
• Relevant qualifications in building surveying, engineering or energy assessment
• Experience assessing buildings similar to yours (age, type, size)
• Knowledge of local building regulations and planning constraints
• Professional insurance and membership of recognised bodies

Request Proposals

When requesting proposals from potential assessors, specify:

• Building type, size and age
• Assessment scope and objectives
• Required timeline for completion
• Deliverables and report format
• Cost estimate and payment terms

Obtain at least two proposals to compare approach and value. The cheapest option isn't always the best—cheaper assessments may lack depth or miss important opportunities.

Key Deliverables to Expect

A comprehensive retrofit assessment should include:

1. Executive summary: Key findings and priority recommendations
2. Building description: Detailed analysis of construction, condition and characteristics
3. Energy modelling: Current performance and predicted impact of proposed measures
4. Improvement recommendations: Prioritised list with costs, payback periods and benefits
5. Technical drawings: Where needed to illustrate proposed changes
6. Implementation roadmap: Suggested phasing and delivery sequence
7. Risk register: Identification of potential complications or constraints

Managing the Assessment Process

Site Access and Surveys

Arrange timely access for the assessor to inspect the building thoroughly. This may require:

• Internal inspections of all rooms and roof spaces
• External façade examination
• Thermal imaging or other diagnostic testing
• Utility meter readings
• Interviews with occupants or building managers

Plan access in advance and brief residents if necessary.

Communication During Assessment

Maintain contact with the assessor throughout. Clarify any assumptions they're making and flag any building-specific issues that might affect the analysis, such as listed building constraints or planned future works.

Review and Sign-Off

Allow time to review the draft report before final completion. Verify that findings reflect your building accurately and that recommendations align with your objectives. Discuss any areas of uncertainty or divergence from expectations.

Next Steps After Assessment

Once the assessment is complete, use it to:

• Secure funding for retrofit works based on cost-benefit analysis
• Prioritise improvements and plan phasing
• Engage contractors and develop detailed specifications
• Communicate improvements and benefits to residents or stakeholders
• Establish baseline energy performance for measuring success post-completion

A well-commissioned retrofit assessment sets the technical foundation for successful, cost-effective building improvements. Time invested in proper scoping and assessor selection delivers better outcomes and informed decision-making throughout your retrofit project.