Today’s building services industry faces a complicated balancing act between building design, energy efficiency and indoor air quality.
In recent years, the building services industry has focussed on energy efficiency; insulating our buildings and making them as airtight as possible. While this unquestionably has benefits in reducing energy usage, it has had unanticipated consequences for indoor air quality; essentially trapping pollution within.
The most effective way of improving indoor air quality is to reduce pollution at the source, however this is a challenge for building owners, managers and developers as there are so many sources ranging from cleaning products, office equipment such as printers and copiers, and even furniture and the building materials themselves. While it is possible to take steps and select less-polluting options, it is fundamentally impossible to eliminate all sources. In addition, a significant proportion of indoor air pollution is from outdoor sources, and it’s rarely possible to relocate a building! Unfortunately, there is no such thing as external “fresh air” anymore, so simply introducing outdoor air inside is not going to solve the issue of poor indoor air quality. Increasingly, the only real option is to remove pollution from the incoming air using filtration.
Setting the standard
Lately, the building services industry has seen the release of a whole raft of standards and regulations such as BS EN ISO 16890:2016 – Air filters for general ventilation, BS EN 16798:2017-2019 – Energy performance of buildings – Ventilation for buildings, ErP and Ecodesign directives, which add yet another level of consideration and complications to the design process. It should go without saying that filtration efficiency should not be lowered on behalf of the energy saving, but this creates a challenge for the design team in designing for the best energy efficiency possible, delivering good indoor air quality throughout, at the same time as taking into consideration the overall building design and the footprint requirements of the ventilation system. While these changes no doubt pose a serious headache for designers, the standards set do offer considerable benefit for building owners and managers as well as the building users themselves; and will potentially even help to reduce outdoor air pollution in the long run by reducing the energy usage of ventilation systems.
Understanding pollution levels
The introduction of BS EN ISO 16890, the global standard for classifying filters for general ventilation, made the decade-old EN 779 obsolete. With increasing knowledge around the impact of particulate matter upon health, filtration is no longer just to protect mechanical equipment or the ventilation system, it has a much higher purpose of maintaining or even improving indoor air quality. The new standard focusses on the filter’s capacity to remove different sizes of particulate matter and takes into account the air quality in the vicinity of the building’s location and the specific requirements of the building’s occupants. This may sound difficult, but localised outdoor air quality data is readily available from government and other reputable resources. Understanding the pollution levels at the building’s location should be the very first step designers take as, along with the planned usage and supply air requirements, this determines the design requisites of the ventilation system.
Considering the direct impact this has on the health of a building’s occupants, there is definite need for industry focus to be placed on meeting this standard, particularly as it requires a more measured and technical approach and has the potential to make a real impact. However, despite these new filter classes being in place since 2018, a worrying number of products are still sold based on old classifications, and a number of designers seem to be oblivious to the changes. In addition, for those in the industry who are aware of the new standards, there is understandable confusion around how to apply the new standards, particularly as there is no direct comparison or conversion from the old filter classes possible.
Journey to efficiency
The journey for energy efficiency and good indoor air quality must start at the very beginning of the building design process. Particularly with the latest standards, it is rarely possible to simply install a “one size fits all” ventilation system following building construction and easily meet regulations. Designers now need to balance filter selection against ODA categories, specific fans power levels, air handling unit footprint plus energy recovery efficiency, all while ensuring that the air supplied into the building is of good quality and according to the required SUP categories – it’s a fine balancing act between a myriad of variables.
Designers must adopt an innovative approach, utilising technology such as demand controlled and intelligent ventilation, real time monitoring and smart maintenance to ensure that there is a continuously healthy indoor air quality and thermally comfortable usable spaces for all building occupants through the systems’ entire lifetime. While we would hope that the health benefits of good indoor air quality are enough to encourage building services professionals to ensure that they are utilising the correct filter classes for their buildings, the well publicised productivity and performance benefits should help to further support the cause.
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