What is a Mechanical Ventilation With Heat Recovery System (MVHR)?

Put simply, MVHR (Mechanical Ventilation with Heat Recovery) provides fresh filtered air into a building whilst retaining most of the energy that has already been used in heating the air and building. This is different to most natural ventilation scenarios where stale hot air (from kitchens and bathrooms) is simply exhausted outside along with the heat and cold fresh air comes in.

If you’re thinking about building a modern, energy efficient building, an MVHR system is a really important consideration. There are several factors which make it very suitable, and almost a requirement for these buildings. It’s important to consider a building as a whole package and so you need to consider ventilation, heating, cooling, moisture, and energy efficiency.

Here’s what it’s important to consider:

Controlled Ventilation:

In energy-efficient buildings, maintaining proper ventilation is essential for ensuring good indoor air quality while minimising energy loss. Very efficient buildings, such as the new Consolidated Fisheries offices we are working on, are designed to be very airtight to prevent unwanted air leakage and associated heat loss. MVHR systems provide controlled ventilation by continuously circulating fresh air into the building and expelling stale air. This helps to remove pollutants, excess moisture, and odours, creating a healthier and more comfortable indoor environment for occupants.

Older buildings often have inadequate insulation and many air leaks. So in older buildings, it is not as necessary to open windows as often as there is passive and continuous air leakage through the fabric. To make a very energy efficient building we need to remove these leaks, but then provide adequate ventilation.

We regularly fit MVHR units to new buildings in the UK. It’s becoming the norm, especially when a client wants an energy-efficient building.

Heat Recovery:
A key feature of MVHR systems is their capability to recover heat from the outgoing air before it’s expelled from the building. This is achieved through a heat exchanger that transfers heat from the warm exhaust air to the incoming fresh air. By pre-heating or pre-cooling the incoming air with the recovered heat, MVHR systems significantly reduce the energy required for heating or cooling the building, contributing to energy savings and lower utility bills.

Energy Efficiency:

Energy-efficient buildings are designed to minimise energy consumption and reduce environmental impact. MVHR systems help achieve this by optimising the ventilation and heat recovery processes, thereby reducing the building’s overall energy demand. This not only lowers operational costs for occupants but also reduces greenhouse gas emissions associated with heating and cooling systems.

Comfort and Health:

Proper ventilation and indoor air quality are vital for occupant comfort and health. MVHR systems ensure a constant supply of fresh, filtered air throughout the building, eliminating the need to rely on natural ventilation, which can be unpredictable and inconsistent. By maintaining optimal indoor air quality, MVHR systems help create a healthier and more enjoyable living or working environment.

While the initial investment in an MVHR system may be higher than traditional ventilation methods, the long-term cost savings in energy bills helps offset the upfront costs. Additionally, the improved indoor air quality and comfort provided by MVHR systems can lead to increased user satisfaction.

It is possible not to have an MVHR system, but you would then need to incorporate trickle vents to windows and simple extracts from kitchen and bathroom areas into the design. This will work, but it will reduce the energy efficiency of the building as the air is simply exhausted, and any air coming in through vents will be at the external air temperature. In winter this would be very cold. MVHR systems ensure continuous air movement by extracting from bathrooms and kitchens and inputting pre-warmed fresh air.

If you’d like to know more about MVHR for your project, do get in contact.

Scroll to Top