MVHR Explained – What It Is, How It Works, and Why It Matters

ByRenewable Heating

Mechanical Ventilation with Heat Recovery, more commonly known as MVHR, is a whole-home ventilation system designed to deliver fresh, filtered air while retaining heat that would otherwise be lost. It is becoming increasingly common in modern, energy-efficient homes and is often paired with technologies such as heat pumps and solar PV to create a low-carbon, high-comfort living environment.

This guide explains what MVHR is, how it works, and when it makes sense for your property.

What Is MVHR?

MVHR is a balanced ventilation system that continuously extracts stale, moist air from areas like kitchens, bathrooms, and utility rooms, while supplying fresh air to living spaces and bedrooms.

The key difference from traditional ventilation is heat recovery. Instead of simply expelling warm air outside, an MVHR unit transfers most of that heat to the incoming fresh air using a heat exchanger. The two air streams never mix, but heat is retained.

The result is a constant supply of fresh air without the heat loss associated with extractor fans, trickle vents, or opening windows.

How MVHR Works

An MVHR system consists of:

  • A central heat recovery unit
  • Ductwork distributing air throughout the home
  • Filters to remove dust, pollen, and pollutants

Air is extracted from wet rooms and passed through the heat exchanger. At the same time, fresh air is drawn in from outside and warmed by the outgoing air before being supplied to living spaces.

Most systems recover 85 to 95 percent of the heat from extracted air, significantly reducing ventilation heat losses.

Key Benefits of MVHR

Improved Indoor Air Quality

MVHR provides a constant supply of filtered air, helping to reduce dust, allergens, and outdoor pollutants. This is particularly beneficial for people with asthma or allergies.

Reduced Heat Loss

Because heat is recovered from extracted air, homes stay warmer for longer with less reliance on heating systems.

Condensation and Mould Control

By continuously removing moisture, MVHR helps prevent condensation, damp, and mould growth, which are common issues in well-sealed homes.

Quieter, More Comfortable Homes

With no need to open windows for ventilation, MVHR reduces external noise and eliminates draughts.

Lower Energy Bills

When combined with an efficient heating system, MVHR can contribute to lower overall energy consumption.

MVHR and Heat Pumps – A Natural Pairing

MVHR works particularly well alongside air source or ground source heat pumps. Heat pumps operate most efficiently in homes with low heat demand and stable indoor temperatures.

By reducing ventilation heat losses, MVHR helps heat pumps run more efficiently and consistently. This can improve comfort and reduce running costs.

In all-electric homes, MVHR plays a key role in maintaining warmth without excessive energy use.

Is MVHR Right for Your Home?

MVHR is best suited to:

  • New builds
  • Self-builds
  • Deep retrofits
  • Homes that are highly airtight

Airtightness is critical. MVHR relies on controlled ventilation, so it performs poorly in draughty properties. For existing homes, significant improvements such as airtight membranes, upgraded windows, and careful sealing may be required.

For this reason, MVHR is often designed into a project early, rather than added later as an afterthought.

Design and Installation Considerations

Proper design is essential for MVHR to perform well. This includes:

  • Correct sizing of the unit
  • Thoughtful duct routing to minimise noise and pressure loss
  • Easy access for filter changes and maintenance
  • Commissioning and balancing after installation

A poorly designed system can be noisy, inefficient, or ineffective. A well-designed system should be almost unnoticeable in day-to-day use.

Running Costs and Maintenance

MVHR systems are inexpensive to run, typically costing only a few pounds per month in electricity.

Maintenance is simple:

  • Filters are usually changed every 6 to 12 months
  • The unit should be checked periodically to ensure airflow remains balanced

Good maintenance ensures consistent air quality and long system life.

MVHR in Low-Energy and Passivhaus Homes

MVHR is a core component of homes built to the Passivhaus standard, where airtightness and energy efficiency are paramount.

In these homes, MVHR is not optional – it is essential for maintaining air quality while meeting strict energy targets.

MVHR is not just a ventilation upgrade. It is a fundamental part of creating a comfortable, healthy, and energy-efficient home.

When designed correctly and paired with modern heating systems, MVHR improves air quality, reduces heat loss, and supports the move towards low-carbon living.

MVHR stands for Mechanical Ventilation with Heat Recovery. It is a whole-house ventilation system that supplies fresh air while recovering heat from the air being extracted.

No. MVHR does not generate heat. It recovers heat that would otherwise be lost through ventilation and transfers it to incoming fresh air. Your main heating system still provides the heat.

For airtight, energy-efficient homes, yes. MVHR provides controlled, continuous ventilation without heat loss, draughts, or external noise. Opening windows is uncontrolled and significantly increases heat loss, especially in winter.

MVHR can work in older properties, but only if they are upgraded to be sufficiently airtight. Without good airtightness, performance drops and efficiency benefits are reduced. Many older homes are better suited to MVHR as part of a full retrofit rather than a standalone upgrade.

Ideally, a home should achieve good airtightness with minimal uncontrolled air leakage. New builds, self-builds, and deep retrofits are usually suitable. Airtightness testing is often recommended before specifying MVHR.

Get in touch with our team to discuss how we might be able to help you.