ASHP Survey Requirements 2026: What Installers Need for BUS Compliance

For installers, the useful question is simple: can the ASHP survey file support the quote, design, BUS checks and installation without another round of chasing? This page covers the survey evidence that matters in 2026, including measured heat loss inputs, photos, assumptions, existing-heating notes and the records that need to survive review.

What Is an ASHP Survey, and Why It Matters in 2026

An ASHP survey checks the property before the installer commits to specification and installation. It should give the designer more than room sizes. The useful file shows room-by-room heat loss inputs, fabric assumptions, existing heating, outdoor-unit context, electrical evidence and the photos that support those decisions.

BUS work depends on the installation being properly designed and evidenced. Weak survey records can lead to follow-up questions, conditions or delays, especially where heat loss, EPC position, retained heating or eligibility is unclear.

To understand what a survey report should contain, see our full breakdown at the deliverables page.

Core ASHP Survey Requirements for UK Installers

For BUS work in 2026, the survey file usually needs to cover these areas:

1. Accurate Heat Loss Calculation

The heat loss calculation needs to be easy to review. It should be:

• Room-by-room
• Based on measured building dimensions
• Adjusted for construction type, insulation, glazing, and orientation
• Documented clearly in a way that a SAP or MCS assessor could verify

If the heat loss inputs are weak, the design can drift quickly: wrong heat pump size, awkward emitter choices, comfort issues or avoidable BUS questions.

Get pricing for compliant heat loss surveys via our pricing page.

2. Property Fabric Assessment

The survey also needs enough fabric detail for the designer to understand what the building is likely to lose:

• U-values of walls, floors, roof and windows
• Insulation type and depth
• Draughts and thermal bridging risks
• Existing heating system layout

That evidence feeds emitter sizing and ASHP capacity. If the fabric notes are vague, the designer is left guessing.

Documentation Every BUS Submission Should Include

For BUS work, the ASHP survey report should make the evidence easy to find:

• Site survey report with photographs — Clear images supporting measurements and existing conditions. These should be dated and tied to specific property areas.
• Heat loss calculation outputs — Presented in a format that correlates with the emitters selected and system sizing.
• ASHP specification sheet — Make, model, SCOP/SEER data, and installation considerations captured accurately.
• Emitter schedule — Shows radiators, underfloor heating layouts, and flow/return temperatures used in design.

More about typical survey deliverables is available at deliverables.

Good site habits for ASHP surveys

These are the habits that reduce follow-up questions later:

• Take precise measurements — Use laser measures rather than tapes where possible. Record all heights, widths and depths of rooms. Measure windows and doors separately.
• Photograph the decision points — Show the outdoor-unit area, boundaries, access, cylinder, consumer unit, emitters, controls and any awkward constraints.
• Separate measured facts from assumptions — If insulation levels or fabric details are assumed, say so clearly.
• Use the same structure each time — Consistent labels and sections make the report faster for office, design and install teams to review.

How outsourced surveys can help

Some installer teams keep this work in-house. Others use a survey partner when they need more coverage, faster diary movement or a cleaner handover into design.

Vertex provides ASHP survey support for UK installers, including:

• Room-by-room heat loss calculations
• Fabric assessments
• Survey reports built for quote, design and BUS evidence checks

For the commercial route, use the ASHP survey page or the guide price builder.

What to do next

If the job is going through BUS, treat the survey report as part of the evidence file rather than a set of informal site notes.

Before quoting, check that the file includes:

• Base designs on accurate, measured heat loss data
• Include documented evidence and photos
• Use clear reporting

For ASHP survey support, check pricing or send the job through the installer pricing route.

This article is for informational purposes only. Grant and compliance requirements are subject to change. Always verify current criteria with gov.uk and official sources.