Modern Building Services

26 MODERN BUILDING SERVICES FEBRUARY 2022 FEATURE INDOOR AIR QUALITY Prioritising ventilation The Building Engineering Services Association (BESA) previously raised awareness of indoor air quality back in 2019 when it called for buildings to be ‘safe havens’ to protect occupants from the worst impacts of air pollution. However, a recent report commissioned by Sir Patrick and published by the National Engineering Policy Centre (NEPC) has highlighted the importance of building ventilation in reducing the transmission of COVID-19 and other infections. It found that ventilation was often neglected prior to the pandemic, and that the COVID-19 crisis had revealed flaws in the design, management, and operation of buildings. An article for the journal Science froma group of 40 leading scientists and academics fromaround the world has also called for a “paradigm shift” in the way buildings are ventilated. Alongside advocating for the introduction of an air quality certification system for public buildings, they also estimated that the installation of ventilation and filtration systems able to remove airborne pathogens would add just 1% to the construction costs of a typical building. However, there is a growing indication that ventilation is being granted greater importance in building legislation. For example, both Part L and Part F of the Building Regulations contain new guidance on ventilation in non- domestic buildings and existing homes, stating that adequate ventilation needs to be provided in order to maintain good levels of indoor air quality. However, as the way we design, manage and operate our buildings changes according to new regulations and COVID-19 guidelines, ventilation must be given greater priority. Considering energy use While ventilation is key to achieving good indoor air quality, it must be set against other considerations such as building energy use and occupant comfort. It’s also essential to consider the energy required to heat or cool outdoor air before it enters a building, as introducing air that is too cold or too warm can adversely impact occupant wellbeing and performance. Mechanical ventilation with heat recovery (MVHR) is a valuable technology that balances energy efficiency with the provision of fresh air ventilation. MVHR systems can transfer around 80%-90% of the energy from outgoing stale air to heat incoming fresh air, meaning less energy is needed to heat the building compared to non-heat recovering ventilation systems. They can also deliver a slow but constant movement of air throughout a building, unlike natural ventilation, which delivers an uncontrolled supply. Selecting an appropriate level of filtration for these systems is also vital to achieving the best results. For example, class ePM1 filters can remove particulate matter down to PM1, making it an excellent choice for ventilation systems in buildings close to roads in city centres. Monitoring indoor air quality is another option to consider. While some indoor air quality tracking schemes and equipment can be costly, cheaper air quality monitors are available on the market. However, it’s important to check whether the monitors are calibrated instruments backed by support for interpreting results. In occupied spaces, CO2 is also useful for judging the effectiveness of fresh air systems and how well they are serving the space. CO2 monitors can be used to show the level of fresh air being delivered, so that it can be increased under high occupancy conditions and reduced once the room has less occupants. A new approach Adopting a health and wellbeing approach towards designing new buildings means considering how good indoor air quality can improve productivity and enjoyment of a space. This supports the principle that people should be able to inhabit ‘safe havens’ where the indoor air is better than the polluted outdoors, as advocated by BESA back in 2019. As Graeme Fox, head of technical at BESA has said: “Sustainability is not just about carbon and energy saving; it is also about ensuring that the facilities we build and refurbish can sustain human activity in the long-termwhile also safeguarding health, wellbeing and productivity.” Good indoor air quality goes beyond simply keeping occupants safe frompollutants and viruses. It supports good physical andmental health, creatingmore productive environments in our offices, libraries and schools in the long term.