Why our buildings should be safe havens for good indoor air quality

Hern Yau
Hern Yau

It’s fair to say that indoor air quality has been a hidden issue for many years, but the COVID-19 pandemic has put it firmly at the top of the public agenda. Hern Yau of Mitsubishi Electric speaks out. 

As a result, public awareness of the correlation between health and the air we breathe has increased, and the role of ventilation in reducing the transmission of diseases is now under discussion at a government level. Both the UK’s chief scientific officer Sir Patrick Vallance and the British Medical Association (BMA) have called for higher standards for building ventilation and indoor air quality, in order to help the country, navigate a post-pandemic future.

This has created a window of opportunity to properly address concerns about indoor air quality for the first time, and to also set higher standards for the long-term. The need to improve indoor ventilation rates to reduce the risk of transmission of diseases – not just viruses – has considerably raised the stakes for mechanical ventilation and air filtration.

However, rather than purely focusing on preventing infection or disease, it’s important to consider a more positive approach towards air quality standards going forwards. This means prioritising the health and wellbeing of occupants, with our buildings acting as ‘safe havens’ from outdoor and indoor airborne dangers. This can allow occupants to have a more productive, more comfortable and healthier experience in buildings for years to come.

A major health issue

As many medical professionals have highlighted, the problems caused by poor indoor air quality have been with us for decades and will be with us long after COVID-19 has died down.

Air pollution is now one of the biggest health problems facing the UK today, causing between 28,000 and 36,000 deaths per year. These pollutants include nitrogen dioxide (NO2), which arises mainly from petrol and diesel engines, and sulphur dioxide (SO), released when coal is burned for fuel in power stations. However, some of the most harmful pollutants take the form of particulate matter (PM), tiny particles that are a mixture of solids and liquids present in the air. Sources of PM include friction from car brakes, dust from roads and construction work.

There are also numerous chemicals and substances in our homes, schools and offices that have a detrimental impact on health. These include carbon dioxide, caused by respiration built up in poorly ventilated spaces. There are also volatile organic compounds (VOCs) which cover various chemicals found indoors, such as cleaning products, scented candles, aerosol sprays, and photocopiers.

Homes can also experience excess humidity. This is often the result of poor heating and ventilation and can be caused by drying clothes in unventilated spaces. In addition to poor ventilation, damp conditions lead to mould, widely recognised as detrimental to lung health. Some dust, bacteria and viruses fall into the smallest category of particulate matter, PM1, which can penetrate deep into the human body and cause severe damage. After almost two years of COVID-19, tackling PM1 is becoming a growing concern for anyone managing the health and wellbeing of occupants in buildings.

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 from a group of 40 leading scientists and academics from around 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.

The colour of air

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-term while also safeguarding health, wellbeing and productivity.”

Good indoor air quality goes beyond simply keeping occupants safe from pollutants and viruses. It supports good physical and mental health, creating more productive environments in our offices, libraries and schools in the long term.

Hern Yau is Product Manager at Mitsubishi Electric 

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