MVHR
MVHR is a fabric decision, not a gadget decision.
Fitted in the right house it is transparent; you never notice it and the air is always fresh. Fitted in the wrong house it is expensive noise. Everything in this page is about telling those two houses apart, before the ducts go in.
The question
Is whole-house Mechanical Ventilation with Heat Recovery the right ventilation answer for your home?
The short verdict
For a new build or a deep retrofit that has already reached near-Passivhaus airtightness, MVHR is transformative and the right specification from day one; for a typical existing UK home with sash windows, a loft hatch and skirting-board gaps, whole-house MVHR is the wrong shape of tool and the money is better spent on fabric, single-room heat-recovery units, or continuous extract.
10 min read
The house feels stuffy, or condensation and damp keep coming back.
Kitchen and bathroom extractors, actually run for long enough, remove the majority of everyday moisture. Worth confirming they work and are being used before adding a whole-house system.
A modern continuous-run extractor in the wettest rooms is a fraction of the cost of MVHR and solves most condensation cases in existing UK houses.
If you've considered these and MVHR is still the right answer for your home, here's how to choose well.
In an airtight home, or a full renovation where the ducting can be run cleanly, MVHR delivers filtered, warmed fresh air to every room and recovers most of the heat you would otherwise throw away. In the right house it is transformative.
The decision, in six questions
Six questions decide whether whole-house MVHR is genuinely the right answer, worth serious consideration, or the wrong tool for your house.
Is this a new build, a self-build, or a full renovation stripped back to the brickwork?
Specify MVHR from day one; the ducts can be designed into the structure and the envelope can be built airtight around them.
Strong candidate
A whole-house retrofit is possible but hard; the case has to earn its keep on airtightness and duct-routing grounds.
Worth considering
Has the house been (or can it be) tested at or below 3 m³/h/m² at 50 Pa?
The envelope is tight enough for the heat exchanger to see the airstream it is designed for.
Strong candidate
Above 5 the recovery collapses in practice; either commit to airtightness work first or pick a smaller tool.
Probably not for your home
Can the duct runs be routed cleanly (service voids, dropped ceilings, or lifted floors that are already coming up)?
The install disruption is manageable and the system can be commissioned properly.
Strong candidate
Duct routing through occupied rooms tends to be where MVHR retrofits go wrong; either bring the fabric into scope or step down to single-room heat recovery.
Worth considering
Do you have (or can you engage) a specialist MVHR designer with commissioning kit, not a generalist plumber?
The single largest determinant of a successful MVHR install is here.
Strong candidate
MVHR fitted by a generalist trade almost always underperforms; the design software and the commissioning report are the job, not optional extras.
Probably not for your home
Is your problem essentially one damp room or bathroom, not the whole house?
A single-room heat-recovery unit or a humidistat extract fan is a proportionate answer; whole-house MVHR is overkill.
Probably not for your home
Whole-house ventilation is a plausible frame for the problem.
Strong candidate
Are you prepared to change filters every six to twelve months for the life of the system?
Maintenance discipline is what keeps MVHR working over a fifteen-year horizon.
Strong candidate
Neglected units clog, noise climbs, occupants switch them off; the capital investment stops paying back.
Worth considering
What usually changes the answer
Change one of these and our recommendation often changes with it.
The house has been (or is being) taken to Passivhaus or Enerphit standard.
What changes
The renovation is already opening ceilings and floors for other reasons (rewire, replumb, ground-floor insulation).
What changes
The main problem is one damp bedroom or bathroom, not the whole house.
What changes
There is a real respiratory or allergy need in the household.
What changes
The house is a listed building or in a conservation area where airtightness work is constrained.
What changes
The budget is fixed at £15,000 for the whole ventilation and comfort improvement.
What changes
If this were our house
For a 1930s semi already partway through a fabric-first retrofit
We would not fit whole-house MVHR into this house at its current airtightness. The heat-recovery benefit would collapse in practice, the duct runs would eat ceiling voids in every bedroom, and the £12,000 quote would buy real fabric work instead: airtightness membrane at floor and ceiling junctions, properly sealed loft hatch, better trickle vents and a humidistat extract fan in each bathroom.
We would fit a single-room heat-recovery unit in the coldest bedroom for around £900 fitted; that solves the specific problem the household actually feels every winter. And we would leave whole-house MVHR on the table for a future deep retrofit or extension, at which point the airtightness case can be made properly and the ducts can be designed in rather than fought into finished rooms.
When we'd say no
We would rather lose the sale than take you somewhere the numbers don't stand up.
You are being sold whole-house MVHR for an existing home that has not been (and will not be) taken below 5 m³/h/m² at 50 Pa. The recovery collapses; you are heating outdoor air at £10,000 to £18,000 of capital cost.
The installer is a general plumber or heating engineer taking on their first MVHR job. Design software, commissioning kit and specialist experience are the job, not optional extras; without them the system will underperform whatever unit you buy.
The duct routing requires cutting through finished bedrooms and living rooms. The mess is real and the acoustic penalty is real; either bring the fabric into scope so the routing is clean, or step down to single-room heat recovery.
You are hoping MVHR will replace insulation. It will not; MVHR handles ventilation, not fabric losses. A leaky, poorly insulated house with MVHR is still a leaky, poorly insulated house.
The only problem is one damp bedroom or a persistently condensing bathroom. A £600 to £1,200 single-room heat-recovery unit is the proportionate answer.
You are not prepared to commit to filter changes every six to twelve months for fifteen years. Neglected units clog, noise climbs, occupants switch them off; the capital spend is wasted.
What most people get wrong
The trade at a glance
A five-step editorial scale, not a rating. Green weight is a gain; grey weight is a cost you carry.
Up-front cost
£6,000 to £18,000 fitted whole-house, depending on unit spec, duct complexity and airtightness works needed alongside.
Ventilation and air-quality effectiveness (airtight house)
Continuous filtered fresh air in every habitable room; real CO₂ and humidity control; no cold trickle vents.
Ventilation effectiveness (leaky house)
Field recovery falls below 40 per cent above 5 m³/h/m² at 50 Pa; the unit fights the leaks and mostly loses.
Running cost per year
The unit itself draws 30 to 80 watts continuously; £80 to £180 in electricity a year, offset by real heat-recovery savings in an airtight house.
Noise (well-designed)
Inaudible in bedrooms when silencers, duct sizing and terminal placement are correct. Noise complaints trace back to design shortcuts almost every time.
Install disruption
Ceilings, floors or service voids all likely disturbed in a retrofit; on a new build the ducts are designed in and disruption is minimal.
Maintenance burden
Filter changes every 6 to 12 months for the life of the system; occasional duct cleaning; commissioning airflow check every five years or so.
Lifespan
A well-installed unit runs for 15 to 20 years; heat exchangers and fans are the failure points and are usually replaceable.
What it costs
Vent-Axia, Vent-a-Cell, Aereco Aerex; solves one damp bedroom or bathroom without disturbing the rest of the house.
Low-wattage humidistat fans in every wet room; the honest fabric-agnostic answer for older UK homes.
Compact unit, short duct runs, straightforward commissioning.
The most quoted band; unit, ducts, silencers, commissioning, some builder's work.
Full duct routing designed into the structure, high-spec unit, extensive airtightness works bundled.
The line item that decides whether MVHR earns its keep; frequently omitted from quotes and always necessary.
30 to 80 watts continuous at 2026 UK tariffs; genuinely small, and offset by real heat-recovery savings in an airtight house.
The recurring cost most homeowners forget when comparing to intermittent extract.
Ranges are triangulated from BPCA and Passivhaus Trust guidance, independent installer quotes across the UK in 2025 to 2026, and building performance evaluation studies of retrofit MVHR installs. Airtightness thresholds and heat-recovery efficiency draw on the Passivhaus Institute's certified component data and Innovate UK's BPE programme. Refreshed each spring.
You've got the answer
On a new build or a deep retrofit reaching Passivhaus-grade airtightness, MVHR is the right specification and the money is well spent; specify a design-and-fit specialist, insist on room-by-room airflow commissioning, and put filter access somewhere you can reach standing up. Everywhere else, single-room heat recovery in the worst-affected room and continuous extract in the wet rooms do the useful work at a fraction of the cost and complexity.
You can stop here if you're still deciding. The rest of this page is for readers who have already committed and want to spend the money well.
If you're going ahead
This half of the page is written for the reader who has decided. It reads in the order the decisions come at you.
Which version
One unit in the loft, plant room or utility cupboard, ducted supply to bedrooms and living rooms, extract from kitchens and bathrooms, and a heat exchanger between the two airstreams. The system MVHR was designed as, and the right specification when the envelope supports it.
When we'd choose it
New builds, self-builds, Enerphit-grade retrofits, and deep renovations where airtightness is being taken below 3 m³/h/m² and ducts can be routed cleanly.
A compact through-wall unit that supplies and extracts on the same wall, with a small ceramic or metal heat exchanger in between. No ducting, no builder's work, no whole-house commissioning; solves one room at a time.
When we'd choose it
The right first step for most existing UK homes with one damp bedroom, bathroom or nursery. Also a good tool for extensions where whole-house MVHR would be disproportionate.
Low-wattage humidistat extract fans running continuously in wet rooms; supply air comes in passively through trickle vents and background leakage. No heat recovery, no filtered supply, but far more effective than intermittent extract.
When we'd choose it
Older homes that need better ventilation without full airtightness works, and rentals where a whole-house install is not on the table. Often the honest fabric-agnostic answer for pre-1980s stock.
A central fan pulls extract air from wet rooms through simple ducting; supply is passive. Simpler and cheaper than MVHR, no heat recovery, but a proper whole-house ventilation strategy.
When we'd choose it
Retrofit cases where the airtightness cannot be brought below 5 m³/h/m² but a coordinated extract strategy is wanted; often overtaken by dMEV on cost and simplicity.
A different system with a different job; supplies gently filtered air from the loft into the house and pushes moisture out through background leakage. Not MVHR and not a substitute for it in a tight house.
When we'd choose it
Older leaky homes with a damp problem; the honest primary answer where MVHR is not viable. See the PIV page.
Your house
The single most important variable. Below 3 m³/h/m² at 50 Pa the system is doing the job it was designed for; above 5 it is heating outdoor air. Test with a blower door before committing to MVHR; the result decides whether the £10,000 is well spent.
Retrofit airtightness work is a real programme in its own right: taped membrane at floor and ceiling junctions, sealed loft hatch, service penetrations detailed, existing trickle vents closed or replaced. Budget for it alongside the MVHR quote or the recovery will not materialise.
Whole-house MVHR needs supply and extract ducts to every habitable room, which means either service voids in ceilings (easy in new build, sometimes possible in bungalows), lifted floors above (during any renovation) or dropped ceilings and boxing (in retrofits).
The path the ducts take determines the acoustic performance almost as much as the unit does. Ducts run through a bedroom without silencers will be audible; the same ducts routed through a cupboard with proper silencers will not.
Filters need changing every six to twelve months for the life of the system. If the unit is in a loft accessible only by a step-ladder in an awkward corner, filter changes will be skipped; if it is in a utility cupboard at head height, they will not.
Specialists insist on filter access as part of the design; generalists put the unit where it fits and leave the owner to negotiate a hatch. Ask to see the filter-access plan before signing the quote.
Open trickle vents in an MVHR house short-circuit the supply and extract paths and collapse the recovery. Any MVHR install must close, block or replace every trickle vent; this is a specifier's job, not a homeowner's. Confirm the strategy on the drawings before the ducts go in.
In use
Extract air is drawn from kitchens and bathrooms, passed through a counter-flow or plate heat exchanger, and vented outside; supply air is drawn from outside through a filter, passed through the same exchanger, and delivered to bedrooms and living rooms. The two airstreams never mix; heat passes from one to the other through thin plates.
The exchanger's stated efficiency is measured in laboratory conditions with equal supply and extract flows and no leakage. In real houses, imbalanced flows, bypass leakage around the exchanger and duct heat loss all trim the field figure below the label.
MVHR runs continuously at low speed, with a boost for cooking and showering; it does not cycle. The steady rate is what keeps CO₂ down and humidity balanced, and it is why the unit's total energy draw stays modest despite running twenty-four hours a day.
A well-specified unit has a summer bypass that routes extract air around the heat exchanger when outside air is cooler than inside; the house then dumps its accumulated heat overnight without any heat recovery penalty. On a Passivhaus in July, this is a small but useful cooling assist.
MVHR is not air conditioning. It can shift a few degrees over the course of a summer night; it cannot lower a bedroom by five degrees on a heatwave afternoon. Where cooling is a real requirement, MVHR is not the tool.
Commissioning is where the design gets proven against the real house. The engineer measures the supply and extract airflow at every terminal, adjusts the balancing dampers until the design flows are hit, and issues a printed report. Without it the system is running on assumption; with it, the fifteen-year investment is anchored to a measured baseline.
Common mistakes
Whole-house MVHR fitted to a leaky envelope; the heat-recovery benefit collapses and the owner blames the unit.
Design done by a generalist trade without MVHR software; duct sizes are wrong, silencers are absent and the unit hums audibly into bedrooms.
Commissioning skipped or reduced to a single overall airflow reading; the room-by-room balance is never proven, some rooms are starved and others over-supplied.
Trickle vents left open after the unit is fitted; the supply and extract short-circuit and the recovery evaporates.
Filters never changed; airflow drops, noise climbs, extract effectiveness falls and the owner switches the unit off after two years.
Unit sited in an inaccessible loft corner; filter changes become an ordeal and get skipped.
Ducts run through unheated lofts without proper insulation; supply air arrives colder than designed and the exchanger works harder for less.
Owner runs the unit on high permanently to try to lower the temperature in summer; MVHR is not air conditioning and the higher speed just increases noise and running cost.
The installer
The gap between the best and worst installer on this list of trades is larger than the gap between products. Judge the person, not the brochure.
Maintenance
Change the supply and extract filters every six to twelve months depending on the local air quality; a rural site can stretch the interval, an urban main road cannot. Wipe the heat-exchanger cassette and check the condensate drain annually. Every three to five years, have a specialist re-measure the room-by-room airflows and rebalance any dampers that have drifted; the system stays honest only if it is checked. A well-installed unit runs for fifteen to twenty years with this discipline; a neglected one clogs within three.
Real questions
Whole-house MVHR is the right specification on a new build or Passivhaus-grade retrofit and rarely the right shape of tool anywhere else. The number that decides the buy is not printed on the unit; it is the air-permeability of the house. Below 3 m³/h/m² at 50 Pa the system is transformative; above 5 it is an expensive box in the loft. For most existing UK homes, single-room heat recovery in the worst-affected room and continuous extract in the wet rooms do the useful work at a fraction of the cost.
The honest alternative for older leaky homes where MVHR is not viable.
The proportionate answer for one damp bedroom or bathroom.
How MVHR fits alongside extract fans, PIV and passive ventilation.
Fabric performance is the other half of the MVHR case.
The short-term tool for damp while the ventilation strategy is worked out.