Retrofitting MVHR in Older Homes – What You Need to Know Before You Start

Why Older Homes Are Looking to Modern Ventilation Solutions

Many UK homes built before 2000 were not designed with airtightness or indoor air quality in mind. As a result, traditional ventilation methods—such as open windows, chimney draughts, and extractor fans—have been relied on to remove stale air and moisture. But as more homeowners seek to improve insulation, reduce heating bills, and create a healthier living environment, these passive systems fall short.

This shift in mindset has created a growing demand for Mechanical Ventilation with Heat Recovery (MVHR) in older homes. Retrofitting MVHR offers a way to bring modern ventilation technology into existing properties—without the disruption of a full rebuild.

In this blog, we explore whether MVHR can be added to your home, what it involves, what challenges to consider, and how to make it work effectively without compromising comfort, aesthetics, or air quality.

To speak with a ventilation expert about retrofitting MVHR in your home, visit https://www.climateworks.co.uk.

Why Retrofitting MVHR Is Gaining Popularity

More households are insulating lofts, upgrading to double or triple glazing, and improving airtightness as part of energy-saving renovations. But these measures also reduce natural airflow.

Without a proper ventilation system in place, this can lead to:

• Condensation and window moisture
• Mould growth in cold corners
• Poor air quality
• CO₂ build-up in bedrooms overnight
• Trapped pollutants from cleaning products, furniture, or cooking

An MVHR system provides fresh, filtered air and extracts stale, moist air—while recovering heat that would otherwise be lost. It's the only solution that balances air quality, thermal comfort, and energy savings in one system.

Can MVHR Be Installed in Older Homes?

Yes, MVHR can be retrofitted into most properties, but careful planning is needed. The suitability often depends on:

• The existing layout of the property
• Availability of loft space, ceiling voids, or service risers
• The airtightness level after renovation
• Willingness to accommodate ductwork routes or boxing-in

Older homes with high ceilings, unused lofts, or cellar areas often provide flexibility for installing ductwork discreetly. In more compact layouts, semi-rigid duct systems and strategic grille placements can reduce disruption.

What Type of Homes Benefit Most from MVHR Retrofitting?

• Homes that have undergone recent insulation upgrades
• Properties with sealed chimneys and new glazing
• Flats or maisonettes with persistent condensation or mould
• Townhouses where window ventilation is impractical
• Buildings near busy roads or polluted urban environments

Even homes without a full renovation can benefit from MVHR if internal airflow, heat retention, or air quality are significant concerns.

Case Study: 1930s Semi in Berkshire

In 2023, a family in Wokingham contacted ClimateWorks due to increasing condensation and recurring mould in upstairs bedrooms after upgrading their insulation and windows.

Their goals were:

• Eliminate indoor humidity issues
• Improve sleep by reducing CO₂ build-up overnight
• Maintain heating efficiency without losing warm air through window ventilation

After an initial survey, ClimateWorks designed a central MVHR system:

• The main unit was placed in the loft
• Ducts were routed through ceiling voids and boxed-in where needed
• Supply air was introduced into living areas and bedrooms
• Extract air was taken from the kitchen, bathroom, and en-suite

Results after 3 months:

• Humidity dropped from 70% to 48% indoors
• No condensation or damp on windows
• Bedrooms stayed fresher, with improved sleep
• Heating costs reduced by 12% due to heat recovery

Installation Process: What to Expect

Installing MVHR in an existing home involves a few key stages:

1. Home Survey and Feasibility Check

• Assess current air quality and insulation
• Identify ducting routes (lofts, risers, boxed-in areas)
• Evaluate access for unit installation and grille placement

2. System Design

• Tailored to your home’s size, layout, and occupancy
• Selection of low-profile ducting and grille locations
• Consideration of soundproofing and unit location

3. First Fix Installation

• Ductwork fitted through agreed routes
• Ceiling or wall grilles installed
• Boxing-in carried out where needed for aesthetics

4. Unit Commissioning

• MVHR unit mounted in loft, cupboard, or plant area
• System balanced and airflow measured per room
• Filters fitted and usage instructions provided

Most retrofits are completed in stages over 2–4 days depending on property size.

Common Challenges When Retrofitting MVHR

• Limited ceiling voids in older homes can restrict ducting
• Aesthetic concerns may arise from visible grilles or boxing
• Floor-by-floor duct routing can be more complex in multi-storey homes
• Noise control needs to be addressed with proper unit placement and duct silencers
• Insufficient airtightness in some properties may reduce heat recovery performance

At ClimateWorks, we work with homeowners to design discreet, effective systems with minimal disruption. We also advise whether additional insulation or air sealing is needed before MVHR can be fully effective.

‍