Your Home Climate
Scandinavian interior with white oak floors, plants, sage walls, and a discreet ceiling MVHR vent
Ventilation; Fresh air

A drier, healthier home; without opening a single window.

Modern British homes are airtight by design, and condensation, mould and stuffiness are the side effects. Mechanical ventilation quietly replaces stale air with filtered fresh air, recovering up to 90% of the heat on the way out.

MVHR is the gold standard for new builds and deep retrofits. PIV is the cheap, fast fix for older homes with damp problems. Neither is hard; both are routinely badly specified by installers who don't measure. Get the design right and you get a house that always feels fresh, without ever feeling cold.

How sure we are

Decision support, with the evidence shown.

Every recommendation below explains why it comes first, the evidence behind it, how confident we are, and when it would not apply.

Editorial confidence
High confidence. Multiple regulator, government or academic sources agree.
Evidence status
Reviewed this year · reviewed March 2026 · next review September 2026
Monitoring
We re-check Part F guidance and installed cost ranges every six months.
Evidence drawn fromBuilding standards: ADF, PAS 2035Professional bodies: ESTIndustry evidence: BSRIA

Typical heat-recovery efficiency

85 to 92 %

Source: Building Services Research and Information Association · BSRIA-tested figures; in-use efficiency depends on commissioning and filter condition.

Airtightness threshold for MVHR to pay back

≤ 3 m³/h·m² @ 50 Pa

Source: PAS 2035 / 2030 (Retrofit standard) · Below this air permeability, infiltration losses negate most of the heat recovery benefit.

Who this advice is for

Applies to

  • New builds or deep retrofits where airtightness is already a target
  • Properties where condensation, stale air or noise force windows shut
  • Homes where ducts can run within the insulated envelope

Not intended for

  • Leaky existing homes with no plan to airtighten; PIV or trickle ventilation is usually a better fit
  • Properties without a viable plant cupboard or ceiling void for ducts
01

Airtighten the envelope before you commission MVHR

Why this comes first

An MVHR unit in a leaky house is an expensive extract fan. The recovered heat goes straight back out through the unsealed envelope, and the unit ends up running on boost to compensate. The cheapest part of the project is the membrane and tape that makes the rest of it work.

Evidence

PAS 2035 makes airtightness a precondition for whole-house ventilation strategies; ADF Approved Document F and BSRIA testing confirm the efficiency cliff below 3 ACH.

PAS 2035 · ADF · BSRIA

Confidence

High confidence. Multiple independent sources agree on the direction and the order.

Exceptions
  • New-build Passivhaus where airtightness is part of the build
Next step
Try the MVHR readiness assessment
02

Pay for proper commissioning

Why this comes first

MVHR systems quoted at 92% efficiency routinely deliver 60% in the field because of unbalanced ducts, undersized terminals or skipped commissioning. The commissioning cost is a small fraction of the unit cost and is what makes the datasheet figure real.

Evidence

BSRIA in-use studies consistently show commissioning is the largest single factor in delivered MVHR efficiency.

BSRIA · ADF

Confidence

High confidence.

Exceptions

No common exceptions in UK homes.

Next step
Read the MVHR retrofit guide

Evidence behind this page

Every recommendation on this page is traceable to its source. Click a publication to read the original.

How we'd approach this

MVHR is an airtightness decision wearing a ventilation badge.

We would not specify MVHR until the envelope is sealed below 3 m³/h·m² at 50 Pa, because anything leakier wastes the recovered heat through gaps the unit cannot see. The membrane, the tape and an honest air-test are the cheapest line items in the project; without them the rest is theatre.

Commissioning is the second hidden decision. Units quoted at 92% efficiency routinely deliver 60% in the field because of unbalanced ducts or undersized terminals. We would insist on a commissioning certificate and a measured flow rate per room, not just a final invoice.

If the house is leaky and there is no plan to airtighten, MVHR is the wrong tool; PIV or improved trickle ventilation will give a better outcome for a fraction of the cost. We would only recommend MVHR where the airtightness target is realistic.

In this world

What we cover

MVHR cost guide

Real installed prices for 1-bed flats through to 4-bed detached homes.

Read

MVHR installation step-by-step

Survey, design, first fix, second fix, commissioning; how good installers work.

Read

Positive Input Ventilation (PIV)

The cheap, low-disruption fix for condensation in older UK homes.

Read
Coverage

Where we have vetted installers so far

We only match in places where we have personally vetted the installers. The list grows region by region. If your postcode is not yet on it, the form below puts you on the waitlist for when we are.

NottinghamDerbyLeicesterLincoln

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Get a properly designed ventilation system; not just a fan and a hope.

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