Mechanical ventilation with heat recovery draws stale, moist air out of a house and fresh air in through a single ducted system, passing the two air streams across a heat exchanger so most of the warmth in the outgoing air is transferred to the incoming air rather than lost. In a new build, fitting it before the plasterboard goes up typically costs £2,500–£5,000 for a standard system, or £6,000–£7,500 for a higher-specification, Passivhaus-grade unit. Retrofitting the same system into a house that's already finished is a different job entirely: £5,000–£8,000 where the loft or floor voids give the ductwork somewhere easy to run, rising to £8,000–£15,000 or beyond where they don't.
But it depends on more than which side of that line your project sits on. Property size, the number of wet rooms needing extract points, the specification of the unit itself, and whether a proper design service has actually calculated room-by-room airflow rates all move the number before a single duct is fitted.
I should be straight about where I sit on this one. I don't design or install MVHR systems — that's a specialist ventilation contractor's job, not a surveyor's. What I do, usually as part of a PAS 2035 retrofit assessment, is independently measure what a ventilation system is actually delivering once it's in: extract and supply airflow rates checked room by room with a calibrated anemometer, across MVHR, MEV, intermittent extract and passive-stack systems alike. That's a useful check on a system already specified or fitted; it isn't a reason to take my word on installation pricing over anyone else's. What follows is a straight market summary, not a pitch for a service I don't offer.
The short answer
Figures below were checked on 3 September 2026 against current UK MVHR supplier and installer pricing, cross-referenced across several sources, and should be read as a starting point rather than a quote. As with the rest of this series, jobs in London and the South East — my own patch included — tend to price above the England-wide average for a comparable specification.
| Scenario | Typical cost (2026) | What's included |
|---|---|---|
| New build, standard system (3–4 bed) | £2,500–£5,000 | Unit, ductwork run during first fix, basic design, commissioning |
| New build, Passivhaus/high-spec | £6,000–£7,500 | 90%+ heat recovery unit, summer bypass, fuller design service and enhanced commissioning |
| Retrofit, straightforward (loft/void access, single unit) | £5,000–£8,000 | Unit, ductwork boxed through accessible voids, commissioning |
| Retrofit, complex (solid floors/ceilings, poor access, larger house) | £8,000–£15,000 | Structural and joinery work to route ducts, extensive making good, sometimes two units |
The hardest retrofits — a large older house needing two units to keep duct runs short enough, with extensive boxing-in and redecoration — can run to £20,000, though that's the exception, not the rule. Running costs sit at roughly £50–£200 a year in electricity to drive the fans, plus £20–£120 a pair for filters every 6–12 months and an annual service from around £150–£300 — worth building into the decision, not just the install price.
What drives the price
New build or retrofit. This is the single biggest factor by far. In a new build, ducts are routed through open joists and studwork before anything is boarded over. In an existing house, the same ductwork has to be threaded through a finished building — behind wardrobes, along the tops of walls, through boxed bulkheads or old chimney voids — which is slower, needs more skill, and generates more making good.
Property size and layout. More bedrooms and wet rooms mean more extract and supply points, longer duct runs and a bigger unit, which is why pricing is almost always tiered by house size.
Duct routing and access. A bungalow with a loft above every room, or a house being stripped back to the joists for a deep retrofit anyway, is a straightforward job. Solid floors, vaulted ceilings, steel beams or a flat with no loft and no floor void at all push a job toward the top of its bracket or make it impractical without compromise.
Unit specification. Heat recovery efficiency, specific fan power (SFP), filtration grade and whether the unit has a summer bypass (to avoid pumping warm summer air through a heat exchanger that's meant for winter) all affect price. A cheap, high-power unit can undermine the running-cost case the whole system is sold on.
Design. A proper MVHR design calculates supply and extract rates room by room against the actual floor plan. A "supply and fit" job priced off a sketch, without that calculation, is cheaper up front and a common source of systems that never quite ventilate the rooms furthest from the unit properly.
Commissioning. This should be a distinct, costed stage — not something folded silently into the install price — and it's one of the most commonly skipped or shortcut steps I come across.
Do you actually need MVHR, or something simpler?
MVHR only earns its keep in a house that's reasonably airtight. It recovers heat from air being extracted in a controlled, ducted way — but if the fabric is still leaking air uncontrolled through gaps around old windows, loft hatches, suspended floors and service penetrations, the system is competing with holes it can't see, and a meaningful share of the benefit disappears into draughts the ductwork was never built to address. It comes into its own once a home has been through a genuine fabric-first retrofit, or is built to a tight specification from the start — not bolted onto a leaky older house as a standalone upgrade.
Much of what gets reported to me as "the house feels damp" turns out to be condensation from inadequate ventilation rather than anything wrong with the walls. MVHR is one legitimate answer to that. It usually isn't the cheapest one. A continuous mechanical extract (MEV) system — a single central unit quietly extracting from wet rooms with fresh air entering through trickle vents, no heat recovery, no supply ductwork — solves the same moisture problem for a fraction of the retrofit cost, and is often the more proportionate answer where a full airtightness upgrade isn't otherwise part of the project. MVHR's real advantage over MEV is the heat it recovers rather than throws away with the extracted air, which only matters once you've stopped losing far more heat elsewhere through the fabric.
On grants: there isn't a dedicated one for MVHR, unlike the Boiler Upgrade Scheme for heat pumps. ECO4 has run to remediation only since early 2026, with no new delivery targets for suppliers to meet, and the Great British Insulation Scheme closed to new applications on 31 March 2026. The Warm Homes: Local Grant, delivered through local councils rather than energy suppliers, is now the main funded route for qualifying low-income households and can occasionally bundle a ventilation upgrade into a wider retrofit package where a survey identifies the need — but it isn't something to plan a standalone MVHR budget around.
What I'd watch for in a quote
- Ask for the design calculation, not just a unit spec and a price — room-by-room supply and extract rates, not a guess scaled from floor area.
- Check the unit's specific fan power and heat recovery efficiency are stated, not just "energy efficient" as marketing copy.
- Confirm commissioning is a separate, costed line, and ask to see the airflow-rate test results and commissioning notice once the job is done — Building Control needs this, and I've seen jobs where it's skipped or fudged.
- Ask how ductwork in cold voids (lofts, unheated spaces) will be insulated — uninsulated ducting in a cold loft risks condensation forming inside the ductwork itself.
- Get the ongoing filter and service cost in writing, not just the install price — it's a genuine running cost, not a footnote.
- For a retrofit, insist on an on-site survey of the actual duct route before pricing, not a quote worked up from a floor plan alone — this is where retrofit quotes most often go wrong.
Questions I get asked
How much does it cost to retrofit MVHR into an existing house? Typically £5,000–£8,000 for a straightforward retrofit into a house with reasonable loft or floor-void access for the ductwork, rising to £8,000–£15,000 where floors and ceilings are solid, access is tight, or a larger property needs two units to keep duct runs manageable. The hardest jobs — a large older house needing two units and extensive making good — can run to £20,000, though that's the exception rather than the rule.
Do I need Building Control approval for MVHR? Yes. MVHR is a controlled mechanical ventilation system under Part F of the Building Regulations, and since 15 June 2022 the airflow rates it delivers must be tested and a commissioning notice provided to Building Control before a project can be signed off. This applies whether the system goes into a new dwelling, an extension, or a retrofit that changes the ventilation strategy.
Is MVHR worth installing if my house isn't airtight? Generally no, or at least not yet. MVHR recovers heat from air being extracted in a controlled, ducted way — but if the building fabric is still leaking air uncontrolled through gaps, cracks and old vents, the system is competing with holes it can't see, and much of the benefit is lost. It earns its keep once a home has been made reasonably airtight, typically as part of a wider fabric-first retrofit or a new build built to a tighter specification. In a leaky older house, a simpler continuous mechanical extract (MEV) system usually solves a damp or condensation problem for a fraction of the cost.
Are there grants available for MVHR? Not a dedicated one. Unlike heat pumps or insulation, there is no standalone grant for MVHR. ECO4 has run to remediation only since early 2026 with no new delivery targets, and the Great British Insulation Scheme closed to new applications on 31 March 2026. The Warm Homes: Local Grant, delivered through local councils, is now the main funded route for qualifying low-income households and can occasionally bundle ventilation improvements into a wider retrofit package, but it isn't something to plan a standalone MVHR budget around.
I don't install MVHR systems, but if you're planning a retrofit and want a straight read on whether MVHR is actually the right measure for your house before you commit — or an independent airflow check once a system's gone in — that's where a PAS 2035 retrofit assessment or a ventilation testing visit can help; the testing isn't a substitute for your installer's own Part F commissioning paperwork, but it's a useful second opinion on what a system is actually delivering. If what's prompting this is damp or condensation rather than a planned retrofit, a proper diagnosis first is often the cheaper and more useful step. Call 07946 618203 or get in touch and I'll come back the same day.
Small print. This guide is general information, not advice on a specific property, and it doesn't replace a written quote from a qualified MVHR designer or installer for your own drawings. I don't design or install these systems myself, as noted above; the pricing here is checked against the wider market. Prices were researched and correct to the best of my knowledge on 3 September 2026; costs and regulations move, and quotes vary by region, property and specification. Always get at least three written quotes and confirm what's included at each stage — design, supply, ductwork and commissioning.