MVHR Installations and UK Building Regulations: What You Need to Know in 2025

Why MVHR Is No Longer Optional for New Homes

As energy standards for UK buildings become more stringent, proper ventilation is no longer just about comfort—it's about legal compliance. The rise of airtight homes and improved insulation has created a greater need for mechanical ventilation to manage indoor air quality and moisture levels. For homeowners, developers, and renovators, this means Mechanical Ventilation with Heat Recovery (MVHR) systems are quickly becoming the standard in both new builds and high-performance retrofits.

UK Building Regulations now place strict requirements on how air is extracted and supplied in residential settings. Poor ventilation can lead to health issues, excess humidity, mould growth, and heat loss. MVHR systems offer an all-in-one solution: they supply fresh, filtered air while recovering up to 90% of the heat that would otherwise be lost through extraction.

Understanding how MVHR fits into UK Building Regulations—and how to ensure your system is correctly installed and commissioned—is essential to meeting the legal standards for ventilation in 2024 and beyond.

The Growing Need for MVHR Systems in UK Housing

Across the UK, the drive to reduce carbon emissions and improve indoor health has accelerated the use of MVHR.

As more homes are designed to achieve low-energy or near-zero-carbon performance, natural ventilation is often no longer sufficient. This is especially true for properties with:

• Triple glazing
• Air permeability below 5 m³/h·m²
• High levels of insulation
• No trickle vents or window ventilation

These characteristics are found in most new homes, many major renovations, and virtually all Passivhaus or fabric-first builds. Without MVHR, indoor air becomes stale, humidity rises, and energy bills climb as windows are opened to compensate.

What the Regulations Say: Part F and Part L Explained

Approved Document F – Ventilation

Part F of the Building Regulations governs ventilation in new and existing buildings. It outlines:

• How much fresh air must be supplied per occupant
• Extraction rates for kitchens, bathrooms, and utility spaces
• The need for continuous or demand-controlled ventilation
• Ventilation performance targets for different building types

MVHR systems fall under System 4 in Part F, described as "mechanical supply and extract with heat recovery."

To comply, MVHR systems must:

• Be designed with appropriate flow rates (minimum 0.3 l/s per m² of internal floor area)
• Have low system resistance to avoid unnecessary fan power
• Be commissioned and balanced to match design performance
• Include controls that occupants can easily understand and use

Source: GOV.UK – Approved Document F

Approved Document L – Conservation of Fuel and Power

Part L deals with energy efficiency. MVHR helps reduce space heating demand by recovering up to 90% of the heat from outgoing air and transferring it to the incoming supply.

Part L encourages the use of heat recovery ventilation where airtightness is high. It also sets:

• Limits on specific fan power (SFP)
• Minimum heat recovery efficiency thresholds
• Requirements for continuous mechanical ventilation in airtight homes

Combining a compliant MVHR system with high building fabric standards can help meet SAP 10 targets and improve your EPC rating.

Source: GOV.UK – Approved Document L

Real-World Example: MVHR Installation in a New Basingstoke Development

A new residential development in Basingstoke required a solution that met both Part F and Part L while delivering modern levels of indoor comfort. The homes featured:

• Airtightness below 3 m³/h·m²
• High insulation (U-values below 0.15 W/m²·K)
• No openable windows in utility rooms

ClimateWorks designed and installed a whole-house MVHR system in each property. The systems included:

• Central heat recovery units
• Ducting routed in floor voids and ceiling spaces
• Low-SFP EC motors
• Summer bypass for passive cooling
• G4 and F7 filters to reduce pollen and particulates

The developer saw improved SAP scores, fewer compliance issues during inspection, and strong buyer interest due to the high-quality air system.

Common Pitfalls in MVHR Compliance – And How to Avoid Them

Installing an MVHR system is not enough on its own. To meet the regulations, the system must be correctly specified, installed, commissioned, and documented.

Issues we frequently encounter:

• Inadequate duct sizing leading to high system resistance
• Incorrect room placement of supply or extract valves
• Systems not commissioned or balanced
• Controls not labelled or explained to homeowners
• No access for filter replacement or maintenance

At ClimateWorks, we address these issues by:

• Designing each system based on SAP and airflow targets
• Using CAD drawings for duct layout
• Supplying clear user instructions and maintenance schedules
• Logging commissioning data for Building Control sign-off
• Offering aftercare packages to support long-term performance

How to Ensure Your MVHR System Is Fully Compliant

Whether you’re installing MVHR in a new build or retrofitting during a renovation, there are several steps to ensure the installation meets UK legal requirements.

Key compliance actions:

• Appoint an installer with BPEC or NICEIC MVHR certification
• Submit a ventilation design assessment to your Building Control Officer
• Ensure airflow is tested and recorded during commissioning
• Supply documentation to the homeowner or tenant on use and maintenance
• Provide future access for filter changes, coil cleaning, and motor servicing

Bullet Summary – How MVHR Helps Meet UK Regulations

• Complies with Part F by supplying continuous fresh air and extracting stale air
• Meets Part L by recovering heat and lowering energy use
• Improves SAP scores and EPC ratings
• Reduces the need for window ventilation, supporting airtight builds
• Supports compliance in new builds, renovations, and conversions

We Cover All Your MVHR Needs in the South East

We install and commission MVHR systems across:

• Basingstoke – Modern new builds in Hampshire requiring full mechanical ventilation
• Woking – High-spec family homes with tight insulation values
• Wokingham – Custom builds with open-plan layouts
• Newbury – Rural homes looking to improve air quality and reduce heating costs
• West London – Renovated townhouses balancing style with compliance

Our team ensures all installations meet the exact performance and documentation requirements of UK Building Control.

Get Compliant with MVHR Installation Experts

Looking for MVHR installation that meets every part of the UK’s ventilation and energy rules?

👉 Book a consultation with ClimateWorks to get started with a compliant, energy-saving installation.

Visit https://www.climateworks.co.uk to learn more about how we help you meet building standards the right way.

References

[1] GOV.UK – Ventilation: Approved Document F
https://www.gov.uk/government/publications/ventilation-approved-document-f
[2] GOV.UK – Conservation of fuel and power: Approved Document L
https://www.gov.uk/government/publications/conservation-of-fuel-and-power-approved-document-l
[3] NHBC Foundation – Mechanical ventilation with heat recovery in new homes
https://www.nhbcfoundation.org/publication/mechanical-ventilation-with-heat-recovery-in-new-homes/

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.

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