Green Building Store is now 21°


The best MVHR system, is the one you didn't know was there. Our design service is qualitatively different to most other MVHR providers. As well as designing a system to physically fit in a building, we model the system in 3D software to check performance of the system in terms of noise, pressure, balance and airflow.

What is MVHR?

Breathing life into homes and enhancing health and happiness.

Mechanical Ventilation with Heat Recovery (MVHR) provides fresh, filtered air that promotes a healthy, comfortable environment for your home and family. It also recovers the heat from the stale, polluted air that is being extracted and uses this heat to pre warm the fresh air being brought into the home.

Well-designed and correctly installed heat recovery ventilation systems should be practically unnoticeable and virtually inaudible while ensuring good air quality throughout the building.

Come to the experts on MVHR for Passivhaus and low energy projects for quiet, efficient and robust heat recovery ventilation systems. Since 2008, we’ve worked on over 1,500 MVHR new build & retrofit projects with a nationwide reputation for quality and expertise.

Discover our MVHR Design Service

What is MVHR?

Learn more about heat recovery ventilation and MVHR and why it's essential for our health and wellbeing.

MVHR components

We stock a range of components for MVHR heat recovery ventilation systems including air valves, ducting, duct insulation and MVHR filters.

Zehnder units

A supplier partner, Zehnder deliver high-quality ventilation solutions for their customers worldwide and we stock their Passivhaus-certified MVHR units.


SALDA UAB are a supplier partner and their residential units have been awarded prestigious Passivhaus certification, reflecting its sustainability and energy efficiency commitment.

Book a MVHR design service and see how we maximise energy efficiency for you.

We’ll work alongside you and your project team to design, advise on the most suitable MVHR unit and ducting system for your needs and budget.

What makes our MVHR systems different?

  • MVHR ductwork is embedded into the fabric of the building and would be very disruptive to have to replace, so it is worth investing in a high quality system from the outset. We recommend galvanised steel spiral wound rigid ducting for our systems, designed to last the lifetime of the building.

  • We carefully calculate air flow rates of our systems to each room and look to select MVHR units that have constant volume flow fans. Ductwork airtightness is important to ensure that the designed air flow is delivered to the rooms. Air leakage is designed out through use of rigid steel round ducting systems with airtight joints. By minimising air leakage we reduce air speeds within the system, helping ensure lower energy consumption and noise levels.

  • By designing the ducting to minimise air resistance and to suit the air flow requirements in each part of the building, our designs deliver the appropriate amount of fresh air to each room in the house while minimising the energy required to move the air.

  • We offer a wide range of units from manufacturers including Zehnder and SALDA, to suit all projects and specifications. We help you choose a quality MVHR unit to suit the ventilation demands of the building and to achieve optimal heat recovery efficiency.

  • Condensation within an MVHR system could cause damage to ductwork, the unit or the building fabric. We design out potential problems by paying attention to the ductwork detailing and insulation requirements where temperature and humidity differences will cause condensation, either inside or outside the duct.

  • It is essential that MVHR systems run quietly, especially within already quieter well-insulated buildings. Unlike the majority of our competitors, we model the acoustics of our systems so that we choose the right size of sound silencer for each duct run. We specify primary attenuators (silencers) to reduce noise generated by the MVHR unit fans, and secondary ‘cross talk’ attenuators, to reduce voice transmission between rooms. The cross talk attenuators also offer further sound suppression for duct generated noise. Duct sizes in our designs are typically larger than those specified by other companies, helping to keep air speeds low, thus minimising duct generated noise. As a result, we design our MVHR systems to have noise levels of no more than 30 dB(A) at the extract valve and no more than 25 dB(A) at the supply valves.

  • As well as offering an Approved Installer scheme, we can also offer telephone support for installers and supply clearly labelled ducting drawings to facilitate step by step installation.

  • It is critical that the system is correctly commissioned in order to maximise comfort and energy efficiency. 21°s optional commissioning service also offers a valuable check on the installation process and functioning of the MVHR system.

  • 21° has a national reputation for designing high quality MVHR systems for Passivhaus and low energy builds, from one-off houses to large social housing schemes and community centres.

Shop for products you need on the 21° online store.

Browse our range of products for airtightness and specialist insulation and our MVHR filters.

MVHR support

Servicing and commissioning

Once you’re settled on your designed MVHR system, a specialist 21° commissioning engineer will visit the site to commission and balance the system to ensure it is performing as designed. A detailed handover of the system and its controls will be given to the end user and a certificate will be provided for Building Control.

You can choose to extend the life and ensure superior performance with our servicing options.

Download the MVHR brochure

Discover more detail about how MVHR works, the MVHR units and components, our MVHR design service and why MVHR will bring comfort - to you and your family.

Download now

The MVHR system delivers brilliant air quality into the house while operating noiselessly - so quietly, in fact, that we forget it is there!

Andrew & Linda, Woodlands Passivhaus

How can we help?

Visit the showrooms

Visit us at our showrooms in Huddersfield and Swindon or catch us at exhibitions around the UK to see our windows and doors.

Request a quote

Tell us about your project, and we'll make sure you get a no-obligation quote from us. Take a step towards a more energy-efficient home today.

Get in touch

We offer a friendly and responsive aftersales service for our windows and door ranges, with a dedicated office and on-the-road aftercare team.

Book an MVHR design service

We’ll work alongside you and your project team to design, advise and install the most suitable MVHR unit and ducting system for your needs and budget.

Find out more
Life changing homes