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ADVICE CENTRE · OLDER PROPERTIES
Will a heat pump work in an old house? Yes — if someone respects the building
Solid stone walls, single-glazed sashes, floors that breathe and chimneys that certainly do: old houses get condemned by assumption more than any other property type. Here’s how a designer actually approaches pre-war, Victorian and stone-built homes — and why so many turn out better than their EPC suggests.
- 13 min read
- Updated July 2026
- By Phil · Heat Loss Hub
QUICK ANSWER
Yes — heat pumps can and do work in old houses, including solid-wall Victorian terraces, stone cottages and pre-war semis. The heat loss is higher than a modern home’s, so the system is larger and the design margins tighter, but the physics is identical. What old houses cannot tolerate is guesswork: assumed U-values, floor-area shortcuts and default air-change rates routinely overstate their losses by 30–50%, leading to oversized units, inflated quotes — and sometimes a wrongly issued “unsuitable”. Measure first; most old houses pass.
Why old houses get condemned unfairly
When an installer surveys a 1905 terrace in an afternoon window between two other jobs, they reach for defaults: solid brick, U-value 2.1; single glazing, U-value 4.8; air changes, pessimistic; verdict, enormous. The software dutifully multiplies the pessimism through forty surfaces and produces a heat loss high enough to justify either a huge heat pump or a polite refusal.
Each default is defensible in isolation. Compounded, they describe a building that often doesn’t exist. The real house has had its lofts topped up twice since 1980, gained double glazing in the 90s, had two chimneys swept and sealed, and hides render or rebuilt inner leaves that change the wall performance entirely. Age is not a construction specification — it’s a hint about where to look harder.
This is why the same old house can receive quotes whose calculated heat losses differ by a factor of two — the phenomenon we dissect in Why are heat pump quotes so different?. The building didn’t change between visits. The assumptions did.
What old fabric actually does
Solid walls are not all equal
A 225 mm Victorian brick wall genuinely does lose heat quickly — call it U ≈ 2.0. But a 500–600 mm Pennine stone wall, rubble-filled, plastered and rendered, can measure closer to U ≈ 1.2–1.4 — a third less loss than the standard “solid wall” default. Across sixty square metres of external wall, that single correction can remove two kilowatts from the calculation. Thickness, density and finishes matter, and they’re observable on survey: window reveals tell you wall depth in seconds.
Thermal mass changes how the house behaves
Heavy fabric charges up slowly and discharges slowly. That punishes the boiler habit of two hot blasts a day — the walls never finish warming — but suits the heat pump habit perfectly: gentle, continuous heat that keeps the mass topped up. Owners of stone homes routinely report the house feels more comfortable after conversion than before, because the fabric finally operates the way it likes.
Air leakage is the honest weakness
Where old houses genuinely bleed heat is uncontrolled ventilation: open chimneys (a swept, unsealed flue can leak heat equivalent to a permanently open window), suspended floor voids venting to outside, original sashes, and the gaps of a century of alterations. The good news: draught-sealing is the cheapest heat-loss intervention in existence, and every watt it saves is a watt of heat pump you don’t buy.
Surveying an old house properly
Our room-by-room heat loss survey treats an old building as evidence, not as an age band:
- LiDAR measurement of every room — irregular period rooms, sloping ceilings and thick reveals measured as they are, not as a rectangle approximation.
- Wall construction verified — depth at reveals, coring or borescope where justified, render and dry-lining noted per elevation. Different walls get different U-values in the same house.
- Every window recorded — original single sash, secondary glazing, 90s double glazing and last year’s A-rated units all coexist in old homes; each gets its own figure.
- Ventilation assessed room by room — chimney by chimney, floor void by floor void, rather than one building-wide guess.
- The heating archaeology — pipe runs, microbore, cylinder space, and what three generations of plumbers left behind.
DESIGNER'S INSIGHT
“Eighteen years of installation taught me that no two old houses are the same house — and the survey hours are where the truth lives. I’ve measured ‘identical’ stone terraces two doors apart whose heat losses differed by 30% because one had insulated under its floors and rebuilt a gable in the 70s. You cannot see that from a satellite photo, and neither can anyone else.”
Phil
Founder & Lead Designer, Heat Loss Hub
Fabric-first — but only where it earns its keep
“Insulate everything before considering a heat pump” is as lazy as “old houses can’t have heat pumps”. The design question is always £ per watt saved, and in old houses the league table is remarkably consistent:
TYPICAL FABRIC MEASURES IN OLDER HOMES — BEST VALUE FIRST
| Measure | Typical cost | Impact on heat loss | Old-house caveats |
|---|---|---|---|
| Loft insulation top-up to 300 mm | £ | High | Ventilate the cold roof properly |
| Draught-proofing & chimney control | £ | High for the money | Keep managed ventilation; never seal a damp house airtight |
| Suspended floor insulation | ££ | Moderate–high | Maintain void ventilation; do it when boards are up |
| Secondary glazing on originals | ££ | Moderate | Conservation-friendly; keeps the sashes |
| Internal wall insulation | £££ | High per wall | Moisture design is critical in solid walls — specialist territory |
| External wall insulation | ££££ | High | Planning, detailing, and often simply not right for the building |
Our designs price the heat pump for the house as surveyed, then show which fabric measures would change the numbers enough to matter — so you can sequence the work sensibly rather than being sold everything at once. Sometimes the answer is “top up the loft, seal three chimneys, and the 10 kW quote becomes an 8 kW design”. That’s a good afternoon’s reading.
Design strategies that work in old houses
- Honest flow temperatures. Old houses often design out at 48–55 °C rather than 45 °C. That’s fine — efficiency remains far beyond any boiler — and modern R290 units hold output at those temperatures. Pretending 40 °C to flatter a running-cost projection is how systems disappoint.
- Generous emitters where the period allows. Big rooms take big radiators gracefully; cast-iron columns often stay. See the radiator guide.
- Weather compensation, always. Heavy fabric plus compensated flow temperatures is a beautiful combination — the system whispers along at 35 °C most of the winter and only works hard on design days.
- Zoning with restraint. Heavy houses like steady state; aggressive setbacks fight the mass. Design the controls for the building you have.
- Respect the moisture. Old buildings manage damp by breathing. Every recommendation — insulation, sealing, emitter placement — is checked against that reality, because a warm damp house is not a success.
A stone terrace, measured
FROM THE DESIGN DESK
An 1898 stone end-terrace in the Colne Valley: 540 mm walls, cellar, attic bedroom, mixed glazing, two open chimneys. One national installer declined it; another quoted a 16 kW unit with full radiator replacement, “subject to survey”.
Measured room by room: 9.2 kW at −3.9 °C — with the two chimneys and the bare loft hatch responsible for almost 1.5 kW of it. After £600 of draught-work and a loft top-up the design settled at 8 kW, 50 °C flow, five radiator changes of thirteen. Two winters on, the owners’ words: “warmer than it’s ever been, including the coal years”.
Frequently asked questions
Frequently, yes. Listed building consent applies to the works, and conservation areas mainly constrain the outdoor unit’s placement and visibility. Sensitive siting, acoustic assessment and conservation-friendly fabric measures (secondary glazing rather than replacement, for instance) usually find a route. We design around these constraints regularly for architects.
Occasionally — modern R290 units delivering 65–70 °C can effectively drop-in replace a boiler. But running at boiler temperatures means boiler-adjacent bills. We treat high-temperature capability as design headroom and cold-snap insurance, not as a substitute for getting the emitters right.
They raise the losses in their rooms, and the calculation prices that honestly — but glazing is usually a smaller share of an old house’s total loss than walls and ventilation. Secondary glazing recovers most of the gap while keeping the originals; draught-sealed sashes are better than their reputation.
No — sequence it, don’t stall it. A good design tells you which fabric measures actually change the heat pump specification, so you do those first and design for the improved house. Waiting for a never-finished insulation project is how heating decisions drift for years.
Old houses qualify like any other — £7,500, or £9,000 for oil and LPG homes from July 2026, via your MCS installer. There’s no longer a requirement to complete loft or cavity insulation recommendations first, though we’ll usually recommend the cheap ones anyway because they shrink the system you’re buying.
CONTENTS
OLD HOUSE?
Pre-war and stone-built homes are our home ground in West Yorkshire. Tell us about yours and we’ll give you an honest first view, free.
OLD HOUSE, HONEST NUMBERS
Your house survived a century. It deserves better than a guess.
Tell us about your property — age, construction, what you’ve been told so far. We’ll reply by email with an honest view of the route that suits it best.