The 2020 COVID-19 outbreak has deeply redefined our relationship to public spaces. Fear of transmission (both direct and indirect) has closed schools, restaurants, office buildings, and transportation hubs, and has limited access to other densely populated locations and shared spaces. We have also learned that COVID-19 primarily transmits through the spread of water droplets from infected individuals, especially in scenarios of close contact, such as prolonged indoor activities. As a result, new building regulations have been put in place that reduce the circumstances in which the disease can spread. These safety precautions include mask mandates, redesign of ventilation systems, and social distancing policies. In this article, we will focus on social distancing.
Social Distancing is the practice of maintaining a 6-foot separation from other individuals. The Center for Disease Control and Prevention (CDC) has recommended social distancing as one of the best strategies, along with mask-wearing, to curtail the spread of COVID-19 in all indoor & outdoor environments - specifically in public buildings as they begin to reopen during the ongoing pandemic. The reoccupation of buildings post-COVID-19 outbreak has produced a new set of challenges and requires careful reconsideration of building design and occupant distribution. In other words, businesses will need to change their current layouts to ensure physical distancing is feasible, to promote a safe environment.
To address this need for redesign in accordance with the CDC Physical Distancing Requirements, cove.tool has developed a new grid-based analysis method that provides a quantitative metric for evaluating floorplan layouts, called the COVID Occupancy Assessment Score (COVID Score). The COVID Score Analysis calculates the social distancing potential in a given configuration and density to provide a COVID Score Percentage, which is based on the safety spectrum: from 0% social distancing potential being very risky, to 100% social distancing potential for a safer design layout. The score indicates whether two individuals would be able to maintain a radius of at least 6 feet of separation at each point on the floor.
The COVID Score also analyzes the floor area of the entire building to provide recommendations for the maximum number of building occupants who can safely reoccupy the building, along with a heatmap visualization of risky locations. One approach to converting the CDC’s 6-foot separation into a practical occupancy load factor is by dividing the area of space by the area of a circle with a 12-foot diameter, which is 113 square feet. cove.tool's method of occupancy rate calculation is based on this approach and also takes into account situations where a person is not in the center of the circle or is standing along a wall.
To learn more about the COVID Occupancy Assessment methodology, read cove.tool's COVID Occupancy Assessment article.
Case Study: Modifying Office Layout to Maintain Social Distancing
In the early days of the COVID-19 outbreak in the US, cove.tool established a data-based risk assessment process for their office which immediately led to switching to work-from-home. Based on the health security measures proposed by the CDC and other public health organizations, cove.tool created a robust “return-to-work” playbook to provide each employee with a safe and healthy work environment to meet in the office one day per month. This approach worked to balance the mental health risks that come with isolation as well as the physical risks that come with being exposed to COVID-19.
To assess the potential for social distancing in cove.tool's own office, their team evaluated 3 different layouts with the COVID Occupancy Assessment feature in cove.tool to achieve the safest furniture arrangement and an occupancy rate that could maintain a safe distance between employees. The office floor plate of 3,452 SF can accommodate up to 34 employees based on the 100 SF per person occupancy rate given for an open office. However, dividing the cove.tool office area by the occupant factor calculated based on the CDC’s 6-foot separation (113 SF) suggests that the current office area can only accommodate up to 30 people. After running the COVID analysis, the team got the following results:
Alternative 1:
This alternative demonstrates the normal pre-COVID layout which can accommodate up to 29 individuals based on the number of desks. Among all the options, this layout got the lowest score, which translates into a less-reliable option for maintaining social distancing. The maximum recommended occupancy for this option is 20.
Alternative 2:
To provide more separation between employees, the desks in each room were positioned farther away from each other and facing toward the walls. Also, the number of employees was reduced from 29 to 25 persons. Compared to the pre-COVID layout, these considerations enhanced the overall safety of employees and brought the COVID Score to 61%. However, the maximum recommended occupancy rate stayed the same.
Alternative 3:
In this alternative, the team further decreased the number of desks, which resulted in more distance between the desks and a higher COVID safety score. This layout can accommodate 22 employees based on the number of desks. However, the conservative occupancy suggested by the tool is 21.
A quick look at the results shows that as we move toward denser layouts:
1. The COVID score decreases
2. The Recommended Occupancy rate decreases
3. The purple spots on the heat map increase
Denser layouts constrict the spaces for safe physical separation and result in a lower occupancy rate. If we center a circle with a 6-foot radius on each point of the plan, the less densely furnished spaces cause fewer obstructions to the circles and ensure a safe physical distance is maintained. In the case of the cove.tool office, as the team increased the number of desks in small rooms, the intersections between the safe circle zones, and therefore the risk of COVID transmission, increased. Laying out the furniture with data can reduce the risk of spread and result in safer back-to-work plans.
Another Strategy for COVID-Ready Office Design: Ventilation
In addition to modifying the interior furniture layout, teams that are retrofitting their spaces to be COVID-ready can also utilize strategies that modify their ventilation systems and operation. There has been a lot of discussion about running the ventilation system 24/7. It is important to keep in mind that the energy impact of running a system 24/7, roughly double the normal schedule for non-residential buildings, is significant. This is especially true with constant volume systems where fan energy would double. The following chart compares the Energy Use Intensity (EUI) of the cove.tool office when the system is running 24/7:
As seen in the diagram above, the EUI increases by 81%. Instead of running the system at full capacity 24/7, a better solution would be to keep the ventilation on 24/7 but at lowered capacity when the building is not occupied to remove the particles outside the building. Additionally, as part of the retrofit, the team upgraded the filters to have a Minimum Efficiency Reporting Value (MERV) of 13. Lastly, the cove.tool office is in a renovated historic building with operable windows available for natural ventilation. The team studied the model and actively used operable windows for at least 60 minutes after entering a room to further reduce the risk of transmission.
While COVID-19 has been unpredictable throughout 2020, utilizing data-driven design allowed the cove.tool team to test varying retrofitting strategies alongside using healthy practices like mask-wearing, meeting fewer times in smaller groups, and sanitization, to create a safe work environment.
