How MVHR Supports Building Regulation Compliance in New Builds

Why Ventilation is Now Central to Building Compliance

As energy regulations in the UK tighten, modern new builds are expected to meet high standards of insulation, airtightness, and environmental performance. But as homes become more sealed, one crucial issue rises to the surface—ventilation. Without it, airtight homes can suffer from damp, mould, and dangerously poor indoor air quality.

Enter Mechanical Ventilation with Heat Recovery (MVHR) systems.

More architects, developers, and homeowners are incorporating MVHR into new-build designs to comply with Building Regulations Part F (Ventilation) and Part L (Conservation of Fuel and Power). MVHR doesn’t just help meet regulations—it contributes to energy efficiency, air quality, and long-term comfort.

This blog explains how MVHR fits into current compliance frameworks, how it meets legal requirements for airflow and sustainability, and why it’s becoming the preferred solution in the UK’s evolving construction landscape.

To explore MVHR options for your new build, visit https://www.climateworks.co.uk.

Why Building Regulations Have Changed

The UK Government updated Approved Document F and L in 2022 to reflect the need for better ventilation in modern homes. These changes are in preparation for the Future Homes Standard coming in 2025.

New requirements place more emphasis on:

• Minimum ventilation rates
• Airtightness targets
• Heat loss reduction
• Moisture management
• Indoor air quality for occupant health

Without planned mechanical ventilation, new homes risk non-compliance—which can delay sign-off, increase costs, or result in legal issues down the line.

The Role of MVHR in Building Regulations

MVHR systems support compliance in two primary areas:

1. Part F – Ventilation

Part F outlines ventilation rates required per room, as well as system types and commissioning requirements.

MVHR ticks all the boxes:

• Provides whole-house mechanical ventilation
• Supplies and extracts air continuously
• Meets required airflow rates (measured in litres/second)
• Includes filtration and humidity control
• Can be easily tested and commissioned for Building Control sign-off

2. Part L – Conservation of Fuel and Power

Part L focuses on reducing carbon emissions and energy loss in new buildings.

MVHR supports this by:

• Recovering up to 90% of heat from extracted air
• Reducing reliance on traditional heating systems
• Preventing heat loss through open windows or trickle vents
• Improving SAP scores (Standard Assessment Procedure) for compliance documentation

In many new builds, MVHR systems are the only way to meet required SAP ratings, especially in high-insulation or Passivhaus-standard projects.

Case Study: MVHR in a Compliant New Build in Oxfordshire

A self-builder in Oxfordshire was developing a four-bedroom detached home with solar PV, triple glazing, and underfloor heating. To meet SAP targets and ensure Part F compliance, they needed a reliable ventilation solution.

ClimateWorks installed a central MVHR system with ducting to all habitable rooms, ensuring:

• Air change rates exceeded Part F minimums
• CO₂ levels in bedrooms stayed below 1000ppm overnight
• Annual heating demand dropped due to heat recovery

The system passed commissioning on the first attempt, and the property received full sign-off for both Part F and L.

Key MVHR Features That Support Compliance

Automatic and Continuous Airflow

Regulations require continuous background ventilation. MVHR systems operate 24/7 without user intervention, ensuring fresh air at all times.

Measured Airflows and Balancing

Commissioning includes airflow testing at each grille. ClimateWorks provides full documentation, helping satisfy Building Control.

Whole-House Coverage

Unlike extractor fans, MVHR ventilates every room. This ensures uniform air quality and meets airflow rates for all areas, including:

• Bedrooms
• Bathrooms
• Kitchen
• Living areas
• Utility spaces

Filtered Supply Air

Part F now considers indoor air quality a compliance issue. MVHR systems use filters to trap fine particles, improving health outcomes and reducing airborne pollutants.

What Do the Regulations Say?

Approved Document F (2022)

• New builds must provide a minimum background ventilation rate of 0.3 litres per second per m² of floor area
• Bathrooms and kitchens must have dedicated extraction points
• Systems must be commissioned, and reports submitted to Building Control
• Natural ventilation alone is not considered sufficient for airtight homes

Approved Document L (2022)

• Homes must demonstrate energy efficiency via SAP calculations
• Ventilation losses and heating demand are included in the SAP model
• MVHR helps reduce air permeability and heat loss, improving SAP ratings

Installation Considerations for New Builds

The best time to install MVHR is during construction, when you can:

• Hide ducting in walls, ceilings, or floor voids
• Position the heat recovery unit in a loft, plant room, or utility area
• Coordinate with electricians and plumbers during first fix
• Plan grille locations for optimal air distribution

ClimateWorks works with builders, architects, and homeowners to integrate MVHR into new-build timelines—avoiding delays or costly rework.

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