You have an EPC, an annual gas bill and perhaps a boiler with a large kW number on its front. Which one tells you the heat pump size you need? A proper heat pump survey brings those clues together, then checks the building room by room.
An EPC is useful background information, but it is not a substitute for a detailed heating design. The proposed heat pump and radiators need to meet the home’s heat loss under the chosen design conditions.
That distinction matters across Edinburgh and East Lothian, where homes can differ in construction, exposure, extensions and insulation even along the same street.
Want advice for your home? Call 0131 210 0405 or send an enquiry to Renew-Able Solutions.
What can an EPC tell you?
An Energy Performance Certificate can provide useful information about the building fabric, heating system and estimated energy demand. It can also highlight potential improvements.
However, parts of an assessment may rely on assumptions. Insulation added later, a converted room or a changed extension may not appear accurately in an older record.
Bring the EPC to the conversation, along with evidence of recent improvements. Treat it as a starting point for questions rather than an equipment shopping list.
What should a heat pump survey establish?
A room-by-room heat-loss calculation estimates the heat each space needs at agreed indoor and outdoor design temperatures. The designer then matches emitters and equipment to that requirement.
The Energy Saving Trust installer toolkit describes this approach and the value of a detailed site survey for existing properties. The result should be a design you can discuss, not just a total at the bottom of a form.
| Ask to see | What it helps you understand |
|---|---|
| Room heat losses | Which spaces need the most heat |
| Design temperatures | The conditions the system is intended to meet |
| Emitter schedule | Which radiators remain and which need changing |
| Proposed flow temperature | How the heating system is expected to operate |
| Equipment selection | Why the proposed model suits those conditions |
Why the existing boiler rating can mislead
A combi boiler may have a high output to provide hot water quickly. That number does not necessarily represent the heat needed to keep the house comfortable.
Similarly, a yearly fuel bill measures energy over time. It does not directly tell you the heating power required on a cold design day. Hot-water use, boiler efficiency and occupancy also affect that bill.
Use bills as a sense check and a source of context. Ask the designer to explain any large difference between calculated demand and observed consumption, rather than choosing a heat pump by copying the boiler badge.
What if two heat pump surveys give different answers?
Compare the assumptions before deciding that the larger unit is safer. The surveys may use different room temperatures, insulation values, ventilation assumptions or floor areas.
For example, one assessment might treat a wall as uninsulated while another uses documented insulation details. An exposed coastal home may also need different assumptions from a more sheltered property.
Ask each designer to identify the biggest uncertainties. Where practical, evidence about the building can narrow them. A bigger unit does not automatically solve a weak design, and unnecessary oversizing can create other operating problems.
Look beyond the outdoor unit
The survey should also consider the practical route to a working system. That includes available space, pipework, electrical supply, hot-water provision, controls and the proposed outdoor location.
If an older home is involved, read our guide to heat pumps in older Scottish homes. Age alone does not answer the suitability question.
A useful proposal should explain required building work and any assumptions about permissions or access. It should also make clear which items are included in the quoted scope.
How to prepare for your heat pump survey
- Your current heating and hot-water arrangement.
- Recent energy use, preferably covering a full year.
- Rooms that struggle to stay comfortable.
- Records of insulation, extensions or window changes.
- Planned renovations and any changes to occupancy.
Also explain your comfort priorities. A seldom-used spare room and a room occupied throughout the day may need different discussion, but the design should not rely on you accepting an uncomfortable home.
Heat pump survey results: questions about the proposal
Can I see why this model was selected?
Ask how its output at the proposed outdoor and water temperatures relates to the calculated demand. A brochure headline is not the whole performance picture.
Must I complete every insulation improvement first?
That depends on the design and planned work. Ask for a clear sequence. If insulation will change the heat demand, the final equipment choice should reflect it.
Where do costs and support fit in?
Use our Edinburgh heat-pump cost guide for context, then request a property-specific scope. Our Scottish funding guide links the support questions to check before committing.
Talk through your next step
Send your postcode, property type and current heating details. We can explain the next steps for a heat-pump assessment in your home.
Explore our heat-pump service, call 0131 210 0405 or submit an enquiry. Renew-Able Solutions serves Edinburgh, East Lothian and surrounding areas; tell us your postcode so we can confirm suitability and coverage.
Technical sources and examples checked on 3 October 2026. Illustrative figures are not quotations or guaranteed savings.
