Put the quality into indoor air
Hern Yau discusses the importance of air quality for optimal occupant performance and safety.
With the average Brit spending 90% of their day indoors, it is not only a legal requirement that business owners ensure they provide employees with sufficient fresh air, there is also a business benefit to it as well.
According to the World Health Organisation, air pollution is a “public health emergency” with 90% of the global population exposed to toxic air. The negative health consequences are only continuing to mount up with a new review, The damaging effects of air pollution (published in the medical journal Chest) suggesting that air pollution harms every organ in the body.
As the summer arrives, and with many older buildings being ill equipped to provide fresh air to occupants via mechanical means, offices across the country fling open their windows, if they can, to get access to ‘fresh’ air. This, however, often exposes occupants to the harmful effects of outdoor air pollution, especially in a busy city or if the window opens onto a road. A largely unseen health concern for many.
And what about those buildings that can’t open their windows? It has been shown that poor air quality trapped in an office environment can reduce the wellbeing of employees as they suffer from headaches, sore eyes and loss of concentration owing to poor air circulation and ventilation within a building, ultimately impacting on their performance.
As well as outdoor air pollution, Volatile Organic Compounds (VOC) found inside buildings can cause health effects much worse than CO2. VOC’s come from aerosol sprays, cleaning and disinfectant products, air fresheners, and electrical equipment such as printers and photocopiers, and even dry-cleaned clothing. All these things are very common in an office environment, making the need to remove internal air and replace it with fresh air a significant priority.
Furthermore, even with the governments clean air strategy aimed at cleaning up the air outdoors making it easier for the population to access fresh air, the pollution generators indoors will always exist making the need for ventilation timeless.
Air conditioning plays an important role in helping to keep a building’s temperature comfortable and productive all year round, but without including adequate ventilation, the internal climate may actually be affecting the health of occupants. Many of the UK’s older commercial buildings were not built with air conditioning in mind and as such either don’t have a system in place or rely on old units that are ineffective.
Once air conditioning is installed, windows that were openable previously must now be shut for the space temperature to cool down effectively and efficiently. But thought is rarely given to the quality of the internal air that is being conditioned once this change takes place – worse than this, when indoor pollutant levels increase, occupants will continue to suffer from headaches, drowsiness, and lack of concentration etc., or they can resort to opening windows to bring in ‘fresh’ air. This wastes all the energy that has been used to cool the building down and reduces the effectiveness of the investment in creating a more productive environment.
The UK’s Health and Safety Executive (HSE) found that 30% to 50% of newly-constructed or renovated buildings showed at least some element of Sick Building Syndrome (SBS) – a condition where otherwise healthy individuals experience symptoms of physical distress in the workplace. Up to 85% of the occupants within these classified ‘sick’ buildings experienced symptoms of SBS.
How do we ensure that building occupants are provided with enough air at a comfortable temperature to be both productive and healthy, whilst using the least amount of energy possible?
This is where MVHR or mechanical ventilation with heat recovery systems, working in tandem with air conditioning can play such an effective role. MVHR’s are specifically designed to deliver fresh air to a building whilst simultaneously extracting stale air in the most energy efficient way. They do this using heat recovery technology. As stale air is extracted from a building, up to 80% of the temperature of the outgoing air is recovered and transferred to the incoming fresh air, keeping the building at a comfortable temperature and helping reduce overall energy costs.
If the indoor air is 21°C for example, but the outdoor air is 27°C, then any incoming air needs to be cooled down to 21°C, which means the air conditioning needs to work harder and consume more energy.
With MVHR though, the incoming air passes over the cooler, outgoing air, to reduce the 27oC temperature to around 22.3oC. By transferring heat to the outgoing cooler outgoing air. This incoming air therefore needs less energy to bring it down to the desired temperature of 21oC, saving energy.
MVHR systems deliver controlled ventilation into a building through slow but constant air movement. This has an advantage over natural ventilation which delivers uncontrolled and sometimes unreliable air flows. A steady stream of indoor air is extracted and replaced with fresh air, rather than in ebbs and flows. By delivering a controlled air flow path throughout a building, all occupants can benefit from the improved air quality, rather than those sitting by trickle vents or the open window.
When you consider the fact that 90% of business operating costs are staff related, small changes to the working environment can have a significant impact. We’ve already seen that there are various health implications associated with poor indoor air quality, ranging from respiratory problems, to discomfort and even time off work. The Green Building Council report Health, wellbeing and productivity in offices estimates that businesses can achieve an 11% increase in productivity thanks to the reduction of airborne pollutants and the delivery of fresh air to workstations.
But, it’s not just about productivity. Businesses have a duty of care to look after their employees and ensure they are working in an environment that doesn’t adversely impact their health. Using the correct MVHR system means that latent heat (moisture and humidity) and sensible heat (temperature) are always kept in balance to deliver a comfortable internal environment that reduces the likelihood of employees suffering from airborne illnesses.
With many new buildings designed to be airtight to help improve energy efficiency, the idea of installing more technology that is constantly running can be seen as counterproductive. However, because MVHR units recover the heat or cooling that would normally be lost as part of the ventilation process, energy wastage is in fact reduced in airtight buildings and an estimated 30% can be saved on heating or cooling bills.
Couple this with MVHR systems that have a thermal efficiency of 95% and you can save an additional 30% on overall running costs, deliver excellent energy efficiency, and provide a healthy environment for your building occupants.
Hern Yau is Ventilation product manager from Mitsubishi Electric
