Mechanical ventilation with heat recovery helps buildings maintain good indoor air quality (IAQ) while reducing ventilation heat losses. By transferring heat from extract air to incoming fresh air, heat recovery systems can improve energy efficiency and comfort, particularly in well-insulated and airtight buildings. Different technologies, including plate heat exchangers, rotary heat exchangers, and run-around coils, each have specific benefits and design considerations. Independent certification helps ensure that declared performance data is reliable, comparable and verified.
As buildings become better insulated and more airtight, effective mechanical ventilation becomes essential. Fresh air is needed to help manage indoor air quality, moisture and pollutants, while stale air needs to be effectively extracted, especially from wet areas such as bathrooms and kitchens. However, ventilation can also lead to unnecessary heat loss when warmer air is extracted to the environment and cooler air introduced on the supply side. Heat recovery systems address this challenge by using the heat contained in outgoing extract air to pre-heat incoming outdoor air.
Heat recovery systems transfer thermal energy between extract and supply air streams. They are common in many types of ventilation systems from residential Mechanical Ventilation with Heat Recovery (MVHR) systems to Air Handling Units (AHUs) designed for residential, commercial and industrial applications. In winter, they recover heat from warm stale air before it leaves the building and use it to temper the incoming fresh air. In some systems, recovery can also support summer operation by limiting unwanted heat gains or enabling heat transfer away from the supply air, depending on the system design.
As effective as heat recovery systems can be, it should be noted that the performance of a ventilation system should never be assessed on heat recovery efficiency alone. Airflow rate, leakage, pressure drop, fan power, sound levels, controls, frost protection, filtration, installation quality and commissioning all influence real-life performance, comfort and running costs.
Plate heat exchangers, including crossflow and counterflow designs, are widely used in residential ventilation units. The supply and extract air streams pass through separate channels divided by thin plates, allowing heat to transfer without the two airflows intentionally mixing. This separation helps reduce the risk of cross-contamination.
Plate exchangers have no rotating recovery component, which can simplify maintenance. However, their efficiency must be considered alongside pressure drop and fan energy, as higher resistance can increase electrical consumption. Frost protection may also be required in cold climates to protect the heat exchanger and maintain airflow.
Rotary heat exchangers, also known as thermal wheels, use a rotating matrix to transfer heat between outgoing extract air and incoming supply air. As the wheel turns, it absorbs heat from one airstream and releases it into the other. Depending on the wheel type, some rotary exchangers can also transfer moisture, which may help manage indoor humidity in certain applications.
Rotary heat exchangers can deliver high heat recovery performance, but the energy used by the drive motor, the risk of carry-over and any internal leakage must be considered when assessing overall efficiency and suitability. In applications where air purity is critical, the potential for cross-contamination should be carefully evaluated.
Run-around coil systems, also known as twin coil heat exchangers or a heat recovery system with intermediary heat transfer medium, are used when supply and extract ducts are not located close enough for a compact heat exchanger. A coil is placed in each airstream and a heat transfer fluid circulates between them, carrying heat from the extract air to the supply air.
This approach keeps the air streams physically separate, which can be useful where hygiene, layout or contamination risks are key design factors. However, pump energy, fluid-side losses, freeze protection, control strategy and heat transfer efficiency must all be included in the performance assessment.
For specifiers, installers, developers and homeowners, choosing the right heat recovery system is not only a question of selecting a technology. It requires verified data, correct sizing, good installation practice and proper commissioning. A heat recovery method that is poorly specified or installed may fail to deliver the expected indoor air quality, comfort or energy performance, even if the product itself is efficient.
This is where Eurovent Certified Performance can make a meaningful difference. Certification gives decision makers access to independently verified, comparable and up-to-date product performance data. It supports fair comparison between products and helps ensure that declared performance, such as airflow, heat recovery efficiency, electrical consumption, sound power and leakage, is based on recognised testing and certification processes.
The best option depends on the building, available space, required airflow, climate, hygiene requirements, comfort expectations and energy strategy. Plate heat exchangers are common in residential MVHR units, rotary heat exchangers can offer high recovery performance, and run-around coils are useful when ducts are separated. The most suitable choice should be based on the full system design, not one performance figure alone.
Certified performance helps reduce uncertainty. It gives specifiers and buyers confidence that declared product data has been independently checked and can be compared on a consistent basis. This is particularly important for ventilation systems, where airflow, heat recovery efficiency, electrical consumption, leakage and sound levels all affect comfort, compliance and running costs.
Eurovent certified heat recovery systems provide independently verified performance data, helping professionals compare products fairly and design systems using reliable information rather than manufacturer claims alone. Choosing products certified under Eurovent Certified Performance supports transparency, confidence and energy-efficient building design.
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