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Design Services

MVHR design service

The best MVHR system is one you don't know is there. We're nationally recognised for our expertise in designing, supplying and commissioning MVHR systems for Passivhaus and low energy projects.


Why good design matters

Good MVHR optimises the efficiency of the heat recovery, prevents noise, mechanical vibration and air turbulence problems and maximises energy efficiency of the MVHR unit.

Through our detailed design process, we can ensure that we've designed the quietest, most efficient system possible for your building. Any potential problems are solved at the design stage, avoiding costly and inconvenient alterations later on.

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 does our design service include?

Specialist knowledge

Our team has specialist knowledge of Passivhaus and low energy construction


We will provide all the advice you'll need for the right MVHR system for your specific needs and budget.

Noise minimalisation

We can reduce noise through careful positioning of attenuation.

Ducting modelling

We provide careful positioning of ducting modelling for pressure loss and sound attenuation.

Air flow calculations

Air flow calculations provided for building control.

2D & 3D models

We'll assist with 2D and 3D plans that are fully labelled products and parts lists, for ease of installation.


Technical support is a given, including telephone support to installers.

Optional commissioning service

There is an optional commissioning service available, where we set the system to run to designed flow rates and offering extra quality control.

We have been very happy both the products & service from 21°. I would have absolutely no hesitation in using them again. We have also had very positive feedback about MVHR systems from our clients. In fact, the only complaints we have had are that people are worried that they're not on, because the systems are so silent in operation!

Andrew Years, EcoArc Architects - Lancaster Cohousing Scheme

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 UBBINK, 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.

Take a step towards a more energy efficient home today

From triple-glazed and alu-clad windows and doors to exceptional solutions to MVHR, it all starts with finding our your exact requirements

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