It has been impressive to witness the speed at which our collective efforts have generated research and discovery about the transmission of COVID-19. The global Coronavirus pandemic has instilled a sense of urgency in experts across the globe to put their knowledge and effort toward learning about and solving the myriad problems that this virus, SARS-CoV-2 presents to our species and our ways of living.
Our expertise is architecture and design thinking. This includes space and systems planning in a way that merges useful and beautiful. Much of the globe occupies what we would call “modern” spaces, with conditioned air, electricity, assembled walls that separate the indoor from the outdoor environment. We are finding that our indoor environments are not set up to reduce viral transmission. Architects design these spaces. Moving forward, architects can add viral transmission to the problems we design for.
There are two main types of design changes to our built environment that can reduce transmission of COVID-19 :
1 - radical changes in how we approach new spaces and buildings and
2- practical retrofits to our existing built environment.
Others are starting to explore potential radical societal and architectural changes. In this post, we explore two major transmission factors that architecture can address.
PHYSiCAL Distance
Many people have been using the term “social distance”, however this seems to imply being less social, which is not the goal of this strategy. Social cohesion is essential for our lives, so what we want to work towards is spreading out physically, while maintaining social connection. The CDC has been recommending that we keep six feet away from anyone who is not in our household. In Washington State, Governor Inslee announced near the end of June that masks or face coverings are not just recommended as they have been for months now, they are required when we go to public indoor settings and any outdoor setting where we cannot maintain six feet from other people.
Stores seem to have adapted decently well to physical distance requirements. By limiting the number of people in a space and providing markers on the floor, most places can effectively spread people out. People also do not spend a long time in stores and do not need to be in physical contact with others. Doctor and dentist offices and body work clinics present those issues that will require careful behavior modifications.
Spatial separation in an aisle to keep people physically distanced from each other. Source: Reuters
Another type of space that presents bigger challenges are schools, especially schools for younger students. How does a teacher manage mask wearing, face touching, and physical distancing in a classroom with 28 first graders? Classrooms cannot even accommodate spreading out a whole class. Like the grocery store, the number of students in the room needs to be limited to a lower number than before. That means more rooms and more teachers, which schools do not have. We have been working with our educational clients on space planning to maintain social distancing in their schools. This is an incredibly complex and challenging group of problems to solve for.
Airflow
Experts are becoming less and less concerned with surface transmission and more concerned with airborne transmission. Outdoor air behaves differently than indoor air, and we are quite certain that transmission outdoors is nearly zero, given that people keep a little bit of distance between each other. The main reason is that air moves more outdoors, diluting and spreading viral particles. The more wind the better. Stagnant, polluted urban environments are still a bit concerning. A windy beach is not.
In stagnant indoor environments, the virus can hang in the air for hours. Adding a little bit of air movement can still be dangerous.
A study in Guangzhou, China of an outbreak at a restaurant showed that people in the pathway of the air blowing from an air-conditioning unit were infected. What is remarkable about this study is that people who were upstream from the A/C airflow were infected because the virus laden air essentially bounced off the wall and flowed upstream along the same vector. The airborne virus traveled almost 30 feet in order to infect people sitting upstream. Meanwhile people who were sitting about 8 or 9 feet away from the index case-patient (the person who brought the virus into the restaurant) but not in the pathway of the A/C airflow were not infected.
This leads to two potential airflow solutions. Either move air around in multiple directions or use gravity and push it down. Both should attempt to mimic the outdoor quality of lots of movement. Ideally there is always at least a gentle breeze in the indoor space.
Design of spaces that are open to the public like restaurants, grocery stores, libraries, schools, and gyms could more carefully consider the flow of air through the spaces to limit the transmission of airborne viruses. While mask wearing has a significant impact on lowering transmission, restaurants and bars cannot rely on mask wearing. People are working on somewhat terrifying masks that allow you to eat and drink, but these are clearly imperfect.
Wall mounted blower units, or “mini-splits” are not ideal choices anymore for public spaces. These units are seen the most in restaurants because they are cheap, easy to install in existing spaces, and efficient. However, they blow the air horizontally in just one direction, the blowers are not very powerful, and they do not bring in fresh air. As the study in a Guangzhou restaurant shows, the conventional application of a mini-split pushes airborne particles toward anyone in the path of the air movement. Modifying their application to make a space safer could include installing multiple units on perpendicular walls, which would move air in multiple directions, constantly blowing a large volume of air to simulate an outdoor environment, and bringing in fresh air .
source: https://www.harthomecomfort.com/mitsubishi
There are wall mounted mini-splits in the top right of this image, blowing air diagonally down onto the people in the restaurant. Without a large amount of ventilation continuously adding fresh air into the space, this is a hazardous set up for airborne viral transmission.
To better reduce the risk of transmission, air should come from above and blow directly down, not at an angle, influencing particles to fall directly down, onto the floor. Particles above a table could still fall into your plate of food or cup of coffee, but this this is a better scenario to be in than horizontal air movement for two big reasons.
Surface transmission of COVID-19 is not as concerning as the early research showed. Although it still presents a low risk, it is pretty easily mitigated by frequently disinfecting surfaces and washing your hands before touching any part of your body, in particular your face.
There is no evidence to date of COVID-19 spreading through food or potable liquids .
Additionally and possibly alternatively, indoor air should be continuously exhausted outside and more fresh air brought inside. When the temperature outside allows, this can be done just by opening windows. In the hot summer or cold winter, the fresh air brought inside can be tempered, and the energy used to condition the indoor air can be conserved with any number of old and new technologies.