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The Importance of Ventilation Design

Modern buildings prioritise airtightness for energy efficiency, adhering to building regulations and reducing carbon footprint. While this translates to lower running costs and a more comfortable environment, it also creates a need for effective mechanical ventilation.

These ventilation systems act as the lungs of your home. They constantly bring in fresh, filtered air, while removing stale air filled with pollutants, allergens, and odours. This ensures a healthy and comfortable living or working space, especially important with rising air pollution concerns. High-efficiency filters, commonly found in Passivhaus buildings, offer an extra layer of protection by removing even the tiniest airborne particles.

Boosting Efficiency with Heat Recovery

Mechanical ventilation systems with heat recovery (MVHR) take things a step further. These clever systems capture heat from outgoing exhaust air and transfer it to the incoming fresh air. Think of it as heat recycling – less energy is needed to regulate the temperature of incoming air, resulting in lower energy consumption and reduced carbon emissions. MVHR systems can typically recover a significant portion of the heat, typically between 73% and 95%.

Designing for Optimal Ventilation and Mitigating Overheating

Choosing the right ventilation system is crucial. Careful design and sizing ensure it delivers the perfect amount of fresh air for optimal comfort and indoor air quality. Factors like building size, occupancy, and ventilation rates all play a role in the design process. Undersized systems can compromise air quality, while oversized ones can lead to unnecessary energy consumption and higher costs.

When designing ventilation for airtight buildings, it's important to consider potential overheating, especially as our summers become warmer (albeit it does not feel like it in the UK so far this year) While MVHR helps retain heat in the winter, it can trap unwanted heat in the summer. Here are some strategies to address this:

  • Summer Bypass Function: Some MVHR systems have a summer bypass function. This feature automatically redirects incoming air around the heat exchanger during hot weather, bringing in cooler outdoor air directly.

  • Building Design: The most effective way to prevent overheating is through proper building design. This includes factors like building orientation, shading elements, and proper insulation. Optimising these aspects can significantly reduce the workload on the ventilation system.

Ensuring Long-Term Performance

Regular maintenance is vital for any machine, and ventilation systems are no exception. This includes filter changes, duct cleaning, and performance monitoring to maintain peak efficiency and identify potential issues early on. Commissioning, a thorough check by a professional installer, is a crucial step to ensure the system functions as intended.

The Future

Integrating ventilation systems in airtight buildings presents challenges, but the rewards are undeniable. Effective design tackles these challenges head-on, resulting in a trifecta of benefits: improved indoor air quality, energy efficiency, and a reduced carbon footprint. In short, mechanical ventilation systems are the key to creating healthy, comfortable, and sustainable homes and offices of the future.

We can help you with your ventilation system, from reviewing existing systems to designing new systems. We also carry out Part O and TM52 overheating assessments to ensure that the ventilation system design not only caters for air quality but helps to maintain a comfortable environment. Get in touch with us at or take a look at our Website for further information


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