Blog posts

Mojtaba Kamarlouei, 03 June 2020

8 min read

How to Operate Commercial Buildings during the COVID-19 Crisis?

I’m missing so much the time that I could work freely with my colleagues in our fantastic workspace in Lisbon. Working at home in Portugal is not something that you would like for so long. Social life is an important part of Portuguese culture and changing this behavior is very hard. However, respecting the COVID-19 regulations defined by governments is necessary. So, in this post, I am going to give some guidelines and insights on how to return to our offices without putting our health and comfort on serious risks. This would only be possible with direct collaboration between building tenants and managers.

Figure 1. Returning to work under the self and tenant care umbrella [1].

What are the possible contamination modes in the offices?

Before going into the details of virus transmission modes, let’s have an overview of the last updates on the study of the COVID-19 virus. According to [2], the size of the SARS–CoV particle is estimated as 0.08 to 0.14 μm. It is assuming that SARS-CoV-2 has a similar size. To have an imagination about the size of this virus, let’s say the diameter of SARS-CoV-2 is 600 times smaller than normal hair. In aerodynamics, such small size particles have higher lift forces compared to their gravitational forces. Thus, they can stay floating in the air even for several hours.
Three most known contamination modes inside business buildings can be categorized as Airborne, Droplet, and Contact. Figure 2 shows the different transmission routes [3]. Small droplets (D < 5 μm), also known as aerosols, are responsible for both short-range and long-range airborne transmissions (indirect infections). Medium (10 < D <50 μm), and large droplets (D > 50 μm) are respectively responsible for the direct spray and contact contamination modes.

Figure 2. Various transmission routes of COVID-19 [3].

How to avoid contamination?

Each transmission route suggests its practices for contamination avoidance. The best practice for airborne mode is to use masks, visors, and proper ventilation. The droplet transmission can be controlled by restrictions and social distancing (> 2 m). Also, the contact mode can be eliminated by hygiene, sterilization, and behavior change.

Figure 3. Building COVID-19 contamination control word cloud.

The above information is telling us that the contamination by aerosols is the most likely to happen (approved by the Federation of European Heating, Ventilation, and Air Conditioning (REHVA)) but hard to control inside the offices. Thus, besides providing hygiene kits, social distancing, and behavior awareness tooltips, the following instructions are advisable for office managers to ensure the minimum infections.

"It is declared by REHVA that until vaccine and medicament are not available, ventilation is No 1 infection control measure."

Thus, it is better to change the dress code restriction and encourage occupants to keep the windows open, especially in places with high-risk re-circulation systems.
Although it is known that Ozone sterilization will kill the Corona-virus, Ozone is a pollutant and it should not be used for indoor air breathed by humans. One may say that using UV lamps (UVC) can work as a sterilization solution, but requires correct design, installation, and management to be effective. Of course, people should not be exposed to this type of light.
There is a lot of contradiction about the effectiveness of different types of masks. However, considering the size of the virus and detail studies of airborne contamination, normal masks are not completely effective in preventing the small particles. The obligation of wearing a mask is more to decrease the transmission range of the particles coming out of the infected person’s mouth. In this regard, the visor can substantially increase the prevention effectiveness. Because it acts as a shield against the airflow with suspended particles. Thus, these particles can hardly reach to the surface of the mask.

Energy perspectives regarding post COVID-19 in commercial buildings

Energy analytic solutions like Builtrix can support building managers to track their energy profile, before and after the COVID-19 situation. This process may take less than half an hour to convert your raw data, from sensors or electricity bills, into meaningful insights. Builtrix database demonstrates that starting from March 2020, a considerable reduction is recorded in the electricity consumption of business buildings in Portugal. Thus, during the quarantine period, the energy savings in commercial buildings are noticeable.

Figure 4. Energy efficiency levels defined for a building [5].

The bright side of the story is the behavior change that is practiced during this period. For example, it is observed that:

Moreover, some retrofit actions are now in the top-priority of buildings due to risk reductions and national obligations. These types of renovations include using smart lighting, smart air-conditioning, and ventilation system. Solutions like Builtrix support the decision making and investment process associated with the deployment of new energy efficiency technologies by providing benchmarking, prediction, and insight services.


[1] Available online at [], accessed in 27th of May 2020.
[2] Bae, Seongman, et al. “Effectiveness of surgical and cotton masks in blocking SARS–CoV-2: a controlled comparison in 4 patients.” Annals of Internal Medicine (2020). [].
[3] Wei, Jianjian, and Yuguo Li. “Airborne spread of infectious agents in the indoor environment.” American Journal of Infection Control 44.9 (2016): S102-S108. [].
[4] Chin, Alex, et al. “Stability of SARS-CoV-2 in different environmental conditions.” medRxiv (2020). [].
[5] Available online at [], accessed in 27th of May 2020.