MVHR vs Extract-Only Systems: What’s Best for Your Home or Business?

Ventilation Isn’t One-Size-Fits-All

As more UK homes and commercial spaces are sealed for energy conservation, poor indoor air quality has become a growing concern. Whether you’re building a new home, retrofitting a flat, or upgrading a commercial unit, deciding on the right ventilation system is now a key part of the planning process.

Homeowners often search:

• MVHR vs extractor fans
• Best ventilation system for airtight homes
• Do I need mechanical ventilation in a new build?

With rising awareness of Building Regulation Part F and the importance of fresh air, many property owners are comparing MVHR (Mechanical Ventilation with Heat Recovery) systems with traditional extract-only systems.

In this guide, we’ll break down how both systems work, where they’re most suitable, what regulations say, and how to choose the right option based on your space, layout, and long-term goals.

For help with system selection and installation, visit https://www.climateworks.co.uk.

Understanding MVHR and Extract-Only Ventilation

What is MVHR?

MVHR stands for Mechanical Ventilation with Heat Recovery. It’s a whole-building system that both extracts stale air and supplies fresh air to your living or working spaces, all while transferring heat from the outgoing air to the incoming supply.

The system includes:

• A central heat recovery unit (often loft or wall mounted)
• Ducting that extracts air from ‘wet’ rooms (kitchen, bathrooms, utility)
• Ducting that delivers fresh air to ‘habitable’ rooms (bedrooms, lounge, offices)
• Filters to clean incoming air of pollen, dust, and pollution

What is an Extract-Only System?

An extract-only system, sometimes called MEV (Mechanical Extract Ventilation), removes air from wet rooms only. There is no fresh air supply. Instead, new air enters the building through background openings, such as trickle vents or air bricks.

This type of system is more common in:

• Older homes
• Flats or spaces where retrofitting ducting is difficult
• Buildings with limited airtightness

Where Each System Fits Best

MVHR Systems: Ideal For

• New-build homes with air permeability below 5m³/h·m²
• Full-house renovations with upgraded insulation
• Properties with existing ductwork or loft space
• Allergy-prone households or health-conscious occupants
• Workspaces needing clean, filtered air (studios, clinics, offices)

Extract-Only Systems: Better Suited To

• Existing homes where ducting is difficult or disruptive
• Small commercial properties with single-point extraction needs
• Lower-budget upgrades focused on humidity control only
• Spaces where outdoor air can still enter naturally

Real-World Installation: MVHR vs Extract in Action

Case 1: MVHR in a Detached Surrey Home

In 2023, a couple built a new four-bedroom home near Farnham. Due to high insulation, solar panels, and underfloor heating, they opted for MVHR. ClimateWorks designed a full system with air routes into all habitable rooms and extraction from kitchens and bathrooms.

Results:

• 80% heat recovery reduced heating bills
• Bedroom CO₂ levels stayed below 900ppm
• Stable humidity and zero condensation

Case 2: Extract-Only in a Renovated Flat

In a Victorian flat in South London, full MVHR wasn’t practical. The client had damp and odour issues in the bathroom and kitchen. We installed MEV units in both rooms with airflow routed via the roof.

Results:

• Humidity reduced by 60%
• Musty smells eliminated
• Quick, affordable install with no major building work

Key Differences Between MVHR and Extract-Only Systems

Airflow Type

• MVHR: Balanced airflow (both supply and extract)
• Extract-only: Negative pressure, relies on trickle vents for replacement air

Energy Use

• MVHR: Uses more energy but recovers up to 90% of heat
• Extract-only: Lower running cost, no heat recovery

Indoor Air Quality

• MVHR: Filters incoming air; ideal for allergy sufferers
• Extract-only: No filtration; outdoor air may contain pollutants

Regulatory Compliance

• MVHR: Complies easily with Part F and SAP ratings in new builds
• Extract-only: May struggle in airtight buildings without sufficient airflow inlets

Building Regulations and What They Require

Part F Ventilation Rules (2022 Update)

The UK’s Part F regulations require:

• Specified air changes per room per hour
• Proof of airflow and commissioning reports
• Mechanical ventilation for airtight properties (air permeability ≤ 5)

MVHR makes compliance straightforward. Extract-only systems may need extra proof that air replacement is effective, especially if windows are sealed or trickle vents are insufficient.

Installation Process: What to Expect

MVHR Installation

• Property survey and ducting layout
• Central unit fitted in loft, plant room, or utility
• Air inlets/extracts in ceilings or walls
• Commissioning, airflow testing, and filter checks

Installation time: 3–5 days depending on property size.

Extract-Only Installation

• Single fan units installed in bathrooms or kitchens
• Wall or ceiling mount with short duct runs
• Power connection and basic switch/boost control

Installation time: 1–2 days for most properties.

Which System Should You Choose?

If your property is new, airtight, or undergoing major renovation, MVHR is usually the best long-term solution. It provides cleaner air, reduced heating costs, and full compliance with energy and ventilation regulations.

If you're upgrading a smaller or older property, and the budget or layout makes full ducting impractical, a well-designed extract-only system can still be effective for moisture control and odour removal.

What About Combined Systems?

Some properties use hybrid ventilation:

• MVHR in the main living areas
• Extract-only or single-room units in extensions or hard-to-reach spaces

This setup maximises air quality without over-complicating the installation.

Need Help Deciding What’s Best for Your Space?

Choosing between MVHR and extract-only isn’t always obvious. ClimateWorks offers tailored assessments to help you select the most effective solution for your needs, layout, and long-term goals.

Our services include:

• Home and site surveys
• Design and airflow planning
• Full installation and commissioning
• Aftercare and maintenance packages

Learn more or request a quote at https://www.climateworks.co.uk.

Author Bio

Dr. Julian Carter is a highly experienced thermal systems expert with over 15 years in the field, holding a PhD in thermal systems. His career spans academic research, consulting, and teaching, focusing on air conditioning and refrigeration systems. Dr. Carter bridges the gap between theoretical advancements and practical applications, providing expert insights to organisations like ClimateWorks, where his guidance informs decision-making and industry best practices. Notably, he has worked on international projects with organisations such as Daikin Industries, the International Institute of Refrigeration (IIR), and the United Nations Environment Programme (UNEP). Currently a lecturer at Edinburgh University, Dr. Carter combines his expertise with a passion for educating the next generation of engineers and advancing climate control technologies.

References

[1] UK Government. (2022). Approved Document F – Ventilation. Retrieved from https://www.gov.uk/government/publications/ventilation-approved-document-f
[2] Building Services Research and Information Association (BSRIA). (2023). Mechanical Ventilation Best Practice. Retrieved from https://www.bsria.com
[3] Energy Saving Trust. (2024). Ventilation and Indoor Air Quality. Retrieved from https://energysavingtrust.org.uk

‍