3 MINUTE READ
27th November 2024
Air Tightness Building Regulations Sustainability Technology
Buildings are increasingly being built or retrofitted to high standards of airtightness, which is crucial for energy efficiency and comfort. This level of performance, however, comes with its own set of challenges, primarily involving indoor air quality and ventilation. Mechanical Ventilation with Heat Recovery (MVHR) systems are at the forefront of addressing these challenges.
An MVHR system is a type of balanced ventilation system that extracts stale air and supplies fresh, filtered air throughout a building. It’s particularly notable for its ability to recover heat from the outgoing air, using it to pre-warm the incoming fresh air. This process reduces the need for additional heating – boosting energy efficiency. The heat exchanger at the core of an MVHR unit ensures minimal heat loss, contributing to the comfort and energy-saving potential of the building.
Not every building needs an MVHR system; its necessity depends on several factors, primarily the level of airtightness and the desired energy performance:
Airtightness Level: For buildings that achieve an airtightness rate below 3 air changes per hour (ACH) at 50 Pascals (Pa), MVHR systems become highly beneficial. At such levels, natural ventilation and simpler mechanical solutions like extract fans may no longer be effective in maintaining healthy air quality without significant heat loss.
Indoor Air Quality Concerns: As airtightness improves, a building’s natural ability to ‘breathe’ is reduced. Without controlled ventilation, pollutants, excess moisture, and carbon dioxide can accumulate, impacting occupant health and comfort. MVHR systems ensure a consistent supply of fresh air while preserving the thermal comfort of the space.
Energy Efficiency Goals: In low-energy homes such as those built to the Passivhaus standard, MVHR is often a requirement to meet stringent energy performance metrics. By retaining up to 90% of the heat that would otherwise be lost in traditional ventilation, MVHRs are integral to these projects’ success.
When working towards specific airtightness goals through advanced air sealing technologies such as AeroBarrier technology, MVHR systems typically become necessary when:
Airtightness falls below 1 ACH50: In ultra-low-energy buildings where airtightness is significantly optimised—often 0.6 ACH50 or lower to meet Passivhaus requirements—an MVHR system is critical. Here, passive or natural ventilation would not suffice due to the minimal leakage points.
Between 1 and 3 ACH50: For buildings in this range, MVHR systems are recommended but may not be strictly necessary. Depending on the size and occupancy of the building, alternative mechanical ventilation systems with heat recovery could be explored.
Airtightness is the cornerstone for an effective MVHR system. We specialise in creating airtight environments using our cutting-edge sealing technology, ensuring that buildings meet the necessary performance thresholds for MVHR integration. This process reduces unwanted air leakage, enabling MVHR systems to operate efficiently without compensating for excess air loss.
Our approach involves applying AeroBarrier sealant that evenly seals cracks and gaps in a building’s envelope, achieving precision in airtightness that would be challenging to replicate through traditional methods. This level of control ensures that when an MVHR system is installed, it works optimally, allowing the building to maintain its energy-saving potential and indoor air quality.
MVHR systems are becoming more commonplace as we build more energy-efficient buildings. They are essential as airtightness levels improve beyond what natural or simpler mechanical ventilation can handle. For any building striving to meet higher performance standards and provide healthier, more comfortable living conditions, considering an MVHR system is a step in the right direction.
Interested in enhancing your building’s airtightness or learning more about integrating MVHR systems? We can help guide you through your journey toward energy efficiency and optimal indoor air quality.
