Installing MVHR Systems in Renovated Homes: A Complete Guide for Homeowners

Renovating a home is the perfect time to think about modernising your ventilation system, especially if you are making improvements like adding insulation, replacing windows, or upgrading heating. Mechanical Ventilation with Heat Recovery (MVHR) is no longer just for new builds — it’s increasingly being installed in renovated and retrofitted homes across the UK.

As homes become more airtight due to better insulation and new windows, they trap moisture, CO₂, and pollutants that would have previously escaped. Without a controlled way to manage airflow, this leads to condensation, mould, and poor air quality.

In this guide, we’ll explain why MVHR is a smart investment during a renovation, how it works in existing homes, what to consider before installation, and how to ensure long-term performance.

To explore professional MVHR installations for renovations, visit our Heat Recovery page.

Why Renovated Homes Need MVHR Systems

Renovations Create Airtight Homes — and Ventilation Problems

When homeowners add cavity wall insulation, floor insulation, and double or triple glazing, they dramatically reduce the natural airflow that older properties used to rely on. While this is good for energy savings, it means there’s nowhere for humidity, stale air, and pollutants to go.

Common issues in renovated homes include:

• Condensation on new windows and walls.
• Mould growth in bathrooms, kitchens, and bedrooms.
• Poor air quality leading to asthma, allergies, and respiratory issues.

MVHR solves this problem by introducing controlled, filtered, and balanced airflow — all while retaining heat that would otherwise be lost.

Meeting Modern Ventilation Standards

Even in existing homes, when major renovations are carried out, Building Regulations Part F requires that ventilation be brought up to modern standards. This ensures:

• Adequate airflow for health.
• Controlled moisture removal.
• Prevention of air quality issues from trapped pollutants.

MVHR meets and exceeds these requirements while also supporting Part L energy efficiency targets.

How MVHR Systems Work in Renovated Homes

The MVHR Process

• Extract stale, humid air from bathrooms, kitchens, and other moisture-prone areas.
• Draw in fresh outdoor air, filtering it to remove dust, pollen, and pollutants.
• Use a heat exchanger to transfer warmth from the outgoing air to the incoming fresh air.
• Distribute filtered, pre-warmed air to living rooms, bedrooms, and other living spaces.

The result is a continuous flow of healthy, warm, fresh air, without having to open windows or compromise security.

Key Benefits of Installing MVHR During Renovation

1. Preventing Condensation, Damp, and Mould

✔ Renovations often seal a home tightly, which can lead to moisture problems.
✔ MVHR removes moist air before it can cause damage or health risks.

2. Lowering Heating Bills

✔ By recovering heat from extracted air, MVHR helps reduce the energy needed to heat incoming fresh air.
✔ Prevents the need to open windows for ventilation — keeping warmth inside.

3. Healthier Air Quality

✔ Constant airflow removes pollutants, allergens, and volatile organic compounds (VOCs).
✔ Filters external air — ideal for homes near busy roads or urban areas.
✔ Supports healthier breathing, especially for families with asthma and allergies.

4. Increased Property Value and Comfort

✔ Modern ventilation makes homes more desirable, especially for eco-conscious buyers.
✔ Creates stable, comfortable indoor environments, free from stale air and damp.

Who Should Consider MVHR During Renovation?

1. Homeowners Upgrading Insulation and Windows

✔ If you're making your home airtight, MVHR prevents moisture and stale air issues.

2. People Adding Extensions, Lofts, or Basements

✔ New living spaces require proper ventilation to prevent future condensation and mould.

3. Families with Health Concerns

✔ Allergy and asthma sufferers benefit from filtered, pollen-free air supplied by MVHR.

4. People Seeking Long-Term Energy Savings

✔ MVHR cuts energy use by recycling heat, lowering bills and reducing carbon footprint.

Key Components of an MVHR System for Renovated Homes

• MVHR Unit (Heat Recovery Core): Contains fans, filters, and heat exchanger.
• Ductwork: Routes fresh and extracted air — designed to fit within existing floors, ceilings, or walls.
• Supply and Extract Valves: Adjustable vents placed discreetly in each room.
• Filters: High-grade filters (usually G4 or F7) to trap dust, allergens, and pollution.

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