Home Blog The Ultimate Guide to Heat Recovery Ventilation (MVHR)

The Ultimate Guide to Heat Recovery Ventilation (MVHR)

16th January 2025

Indoor Air Quality
New Build
Self Build
MVHR

Contents

    Why is ventilation in homes needed?

    Homes in Ireland and the UK have changed a lot in construction and energy efficiency over the past few decades. The 1970s saw the introduction of stricter insulation standards, triggered by the oil crisis. This led to a transformation in home construction. Modern houses are now much more airtight. They lose less heat and use less energy than houses built before the 1970s. However, this shift came with unintended consequences.

    typical victorian terrace homes vs modern new builds in the uk

    In older homes, ventilation often occurred unintentionally. Draughty windows, doors, and chimneys let air flow freely, although this came at the cost of energy efficiency. With the introduction of double glazing, cavity wall insulation, and high-performance building fabrics, these natural air pathways were sealed off, resulting in reduced ventilation. As homes became more airtight, issues like condensation, mould, and poor indoor air quality (IAQ) began to surface. 

    Mould in a UK home due to poor ventilation
    Example of mould occurring in a home due to poor ventilation

    Research published in the International Journal of Environmental Research and Public Health reveals alarming findings, with many homes failing to meet CO₂ standards, even if window trickle vents were present.  

    This shortfall in fresh air circulation posed significant health risks. Occupants with respiratory issues like asthma or allergies faced particular challenges. The study showed a pressing need for better home ventilation systems to protect residents' well-being.

    To address this, building regulations began to mandate ventilation standards. This led to modern solutions like Mechanical Ventilation with Heat Recovery (MVHR) systems.


    What is Mechanical Ventilation with Heat Recovery (MVHR)?

    MVHR stands for Mechanical Ventilation with Heat Recovery. It is also referred to as Heat Recovery Ventilation.

    Schematic drawing showing how Heat Recovery Ventilation (MVHR) works

    MVHR is a whole home ventilation system that extracts stale air from the home and brings in fresh, filtered air. A key feature of the MVHR system is that it retains up to 92% of heat that's normally lost through open windows, trickle vents and extractor fans, allowing you to make valuable energy savings.

    The system includes a unit which is usually installed in the roof space, and a network of ducting which is installed within the walls of your home, much like your electric cables and plumbing.

    Why Modern Homes Need Mechanical Ventilation

    A study commissioned by the UK government evaluated ventilation and IAQ in new homes built to modern energy efficiency standards. The findings indicated that many homes relying solely on natural ventilation, such as trickle vents in windows, failed to meet recommended IAQ levels. This inadequacy was linked to elevated concentrations of indoor pollutants, including carbon dioxide and volatile organic compounds, which can adversely affect health.

    Given that individuals spend approximately 80-90% of their time indoors, prolonged exposure to poor IAQ can have significant health implications, including respiratory issues and exacerbation of allergies.


    Benefits of MVHR

    An MVHR system is vital for modern, energy-efficient living. It combines fresh air with heat recovery. This enhances your home's comfort, health, and efficiency. Here's how it can transform your space:

    • Save energy with up to 92% heat recovery.
    • Reduce asthma and allergy symptoms with filtered air.
    • Prevent condensation and mould for a healthier home.

    Our daughter had been diagnosed with asthma and in our previous house she would have coughed all night. We heard a Heat Recovery Ventilation System could help with this as the air coming into the house is filtered. After lots of research and recommendations from family and friends, we went with BEAM because they are a high-quality company.”

    Photo of Katherine McCorry

    Katherine McCorry
    @orchardhouseni

    Discover The Ideal MVHR System For Your Home

    Explore our range of MVHR solutions tailored to meet the unique needs of your home. From energy efficiency to improved air quality, find the perfect system for your lifestyle.

    How Does MVHR Work?

    Mechanical Ventilation with Heat Recovery (MVHR) enhances indoor air quality and energy efficiency. It removes stale air and brings in fresh, filtered air, with minimal heat loss. Let's explore how MVHR works, including its components and technical details.

    Step by Step Process of How MVHR Works

    1. Air Intake: Fresh air is drawn in and filtered, removing pollutants and allergens.
    2. Air Extraction: At the same time, stale, moist air is extracted from wet rooms like bathrooms and kitchens via the extract ducts.
    3. Heat Recovery: Both airflows pass through a heat exchanger, recovering up to 92% of heat.
    4. Air Distribution: This warmed, fresh, filtered air is then distributed to living areas within the home via discrete supply valves in the ceiling.
    5. Air Renewal Cycle: Depending on the system settings and fan speed, the MVHR system ensures a complete air change every 2-3 hours, maintaining optimal air quality.


    MVHR vs. Air Conditioning: What's the Difference?

    A common misconception is that MVHR systems and air conditioning perform the same function. While both improve comfort indoors, they serve entirely different purposes. MVHR focuses on ventilation and heat recovery, ensuring fresh air and energy efficiency, while air conditioning is designed primarily for temperature control. Here's how they differ:

    Comparison image of air conditioning and MVHR systems. Left: Air conditioning unit releasing cool air into an office space. Right: MVHR ceiling vent providing fresh air in a bathroom
    Air Conditioning vs. MVHR: A Visual Comparison of Indoor Air Systems


    MVHR:

    • It focuses on ventilation and heat recovery. It provides fresh air while retaining up to 92% of the heat from outgoing air. It does not cool or heat air beyond existing temperatures.
    • Features like Summer Bypass, available in all BEAM MVHR systems, prevent heat recovery in warmer months. But they do not cool air during heatwaves.
    • Highly energy-efficient, reducing heating demand and operating at low cost.

    Air Conditioning:

    • Cools or heats air through a refrigerant cycle.
    • Recycles indoor air, which may degrade air quality without a separate ventilation system.
    • This system is for temperature control only. It does not ventilate or recover energy.
    • Higher energy consumption, especially in summer, resulting in higher bills.


    Is MVHR the Right System for My Home?


    MVHR is the ideal solution for ventilating properties with high levels of air tightness. This whole home ventilation system is the most popular choice of mechanical ventilation for new build and self build homes.

    MVHR also meets building control regulations in Ireland and the UK. 

    For existing homes, it may be possible to have MVHR retrofitted. This would depend on key factors such as the style of the property and if there are building works being completed.

    Modern Irish new build home

    How to Install and Maintain MVHR Systems


    It is vital that an MVHR system is installed and commissioned correctly in accordance with the strict guidelines set by building regulations.

    Professional Installation with BEAM

    BEAM's skilled engineers and distributor partners are ready across Ireland to install your MVHR system. Our method guarantees:

    • Compliance with Building Regulations: Every installation complies with the rules outlined in Part K (Ventilation) (NI) and Part F (Ventilation) (ROI) of the Building Regulations.
    • Tailored Solutions: We provide bespoke system designs. They fit your property's unique layout and needs.
    • Quality Assurance: BEAM uses high-performance parts, including insulated ducting and energy-efficient fans. This ensures durability and efficiency.


    Can you install an MVHR system yourself?


    For those opting for a DIY approach, BEAM offers comprehensive support to ensure a successful setup:

    1. Custom Design Layout
      • We can create a detailed ducting layout tailored to your home, ensuring optimal air distribution and energy recovery.
    2. Material Supply
      • All required materials, including the MVHR unit, ducting, filters, and accessories, are provided with clear instructions.
    3. System Commissioning Service:
      • To meet building control requirements, BEAM offers professional MVHR commissioning. This includes airflow balancing, system testing, and certification to ensure your MVHR operates as intended.

    BEAM professional MVHR commissioning service


    FAQs: Your Questions About MVHR Answered

    Talk to an MVHR expert today!

    Ready to improve your home’s air quality? Talk to a Beam Expert today and discover the ideal MVHR system for your home.

    As our house was being built airtight, we knew we needed a mechanical ventilation system that would allow fresh air into our home. We knew BEAM were a reputable company and had been in the business for many years. We decided to have a look for ourselves at the Selfbuild Belfast show and were so pleased with the quality products after speaking with the team.”

    Photo of Roma

    Roma
    @fortloughview

    Talk to a Beam expert today!

    Our dedicated team of experts are available to answer any queries you may have.

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