Do I need MVHR if I insulate?

Not always — extractor fans may suffice, but MVHR is best for very airtight homes.

Does MVHR save energy?

It recovers heat that would otherwise be lost, lowering heating demand.

A well-installed MVHR is quiet; poor ducting is the usual cause of noise complaints.

Ventilation and MVHR

Airtight, insulated homes hold heat but also moisture. Without controlled ventilation you risk condensation, mould and poor air quality.

Last reviewed: August 2026Sources: PAS 2035 · Energy Saving Trust

Why insulation changes airflow

Older homes leaked air through gaps; sealing them saves heat but traps moisture from cooking, bathing and breathing.

Extractor fans and trickle vents

The simplest fix is decent extractor fans in kitchens and bathrooms plus trickle vents on windows. Cheap and effective for mild cases.

MVHR explained

Mechanical Ventilation with Heat Recovery quietly swaps stale air for fresh, recovering up to 90% of the heat. Best for highly insulated retrofits and new builds.

Plan it with the retrofit

Ventilation should be designed as part of a PAS 2035 whole-house plan, not bolted on afterwards.

FAQs

Do I need MVHR if I insulate?: Not always — extractor fans may suffice, but MVHR is best for very airtight homes.
Does MVHR save energy?: It recovers heat that would otherwise be lost, lowering heating demand.
Is it noisy?: A well-installed MVHR is quiet; poor ducting is the usual cause of noise complaints.