A safe indoor climate in a changing world

Source: Stedenbouw.nl

We spend more than 90% of our time inside buildings. Not only to work, live or learn, but also to play sports and recreate and sometimes to get better again.

In addition to good thermal comfort, the well-being of people in buildings is rightly increasingly being considered. Well-being is a feeling of well-being; it means that one is doing well physically, mentally and socially. 

All developments surrounding the current pandemic are putting pressure on both mental and social well-being. People are wondering whether it is still possible to work 'safely' in the office, whether 'interacting' with colleagues is still possible and what the risks are of possible infection.

What exactly is going on?

The COVID-19 virus is spreading and that is something we want and need to stop. Spreading occurs through sneezing, coughing, shouting, singing and breathing hard by an infected person. Larger droplets infected with the virus will fall down immediately, but small droplets (also called droplet nuclei) form aerosols. These aerosols can spread over a larger distance and therefore have the potential to move through a building with air currents.

Despite initial resistance from official bodies such as the RIVM, it is now generally accepted that viruses can spread through the air.

Preventing the spread of viruses in buildings is currently the most important challenge in the field of indoor climate technology.

What is the advice?

Various institutes have published advices containing measures aimed at making the working environment as safe as possible. This mainly refers to measures that minimize the risk of contamination in buildings.

The core of the recommendations is ventilation with 100% outside air. In this case, all air added to a space must come from outside and therefore may not consist of recirculated air from the building itself.

While the Building Decree still assumes 25 m3/h per person, the recommendations for sufficient ventilation to be able to stay 'safely' go much further, even up to 50 - 60 m3/h per person.

The most important recommended measures are therefore to no longer recirculate (for example by closing the recirculation valves in the air handling unit) and to ventilate with sufficient outside air.

What is the practice?

More ventilation with 100% (treated) outside air is good for everyone and significantly improves human well-being. But what if the recirculation cannot be (completely) closed and what if the capacity is (far) insufficient to supply the recommended amount of fresh air per person? What options are left for a building owner?

Existing buildings have many different situations and installation concepts, each with their own specific properties. A QuickScan can quickly determine the current situation and which measures can be taken quickly. There are various market parties that offer these scans and advice.

What else is possible?

Supplying a large amount of outside air ensures that the contaminants in the air are mixed with the (polluted) room air and can then be removed via the return system.

If there is insufficient outside air available, there are various air purification solutions. In terms of contaminants, three main groups can be distinguished: solids (such as particulate matter), gaseous substances (such as nitrogen) and viruses, bacteria and fungi (such as COVID-19). The first two groups can be neutralized with various filter techniques and the last can be neutralized with UV-C solutions. All these techniques are already available on the market, but the correct application, selection, installation and maintenance of these is work for specialized technical service providers.

Advise advice remains: ventilate as much as possible with outside air and also seek appropriate advice. At FHI Gebouw Automatisering, expert and experienced technical specialists are affiliated who will be happy to help you with this.

For more information please contact Martin Hof Sr. Project Manager Building Automation