Before this year, most people felt that if someone in their home had a cold or the flu, there wasn’t much they could do to avoid catching it. Stay away. Don’t kiss them. Don’t drink from their glass or eat from their plate. That may be about it.
Oh, how much difference a pandemic can make. Now, in addition to those things, we all would say:
- Sneeze and cough into your elbow.
- Wash your hands–well and often.
- Disinfect doorknobs and other often-touched surfaces.
- Don’t touch your face.
- Wear a mask.
- Stay at least 6 feet away from someone who may be infected.
But what else can you do in your home to keep viruses from spreading? The precautions above are helpful for combating the large virus-spreading droplets expelled by sneezing, coughing, or breathing. However, the smaller droplets, called aerosols, can float around in the air for hours. As a result, fighting these virus-spreading elements requires more careful planning and action.
Here are a few ways to improve indoor air quality and create a healthy home:
Filter out the small particles
If you have a forced-air heating and cooling system, upgrade your return air so you can filter out the small particles. The American Society of Heating, Refrigerating and Air-Conditioning Engineers recommends a Minimum Efficiency Reporting Value (MERV) of 14. This requires enough filter area to prevent air flow problems. Going to MERV-16 is even better.
Ventilate with outside air
If you know or suspect that someone in your home is sick with an infectious disease that can spread through the air, use your ventilation system more than usual. Run the fans in bathrooms and the kitchen range hood. If you have a whole-house ventilation system, make sure it’s on and consider increasing the rate if possible. This will remove some of the potentially contaminated aerosols and dilute the rest.
Use good HVAC design (don’t blow air on people)
One of the long-standing basic principles of good HVAC design is to avoid blowing air directly on people for comfort reasons. Now we know it helps with the spread of infectious disease, too.
Central heating and air conditioning systems recirculate indoor air throughout the home (or building). The movement of that air from supply vents to return vents may transmit virus-laden aerosols across a room, possibly infecting people who aren’t yet sick.
One way to avoid this is with ductless systems like radiant heating and cooling. Another option is ductless mini-split heat pumps. However, these can still result in someone getting sick from aerosols spread by the air currents within the room. But the spread would generally be confined to that single room.
When designing or retrofitting central heating and air conditioning systems, pay close attention to how the air moves.
Set up a quarantine room
If someone in the home is sick, have a special quarantine room for them. Ideally, that room will be independently heated and cooled. If it’s conditioned by a central forced-air heating and cooling system, it should have a dedicated return vent and good filtration. Having the room under negative pressure will ensure that contaminated air from the room does not come back into the rest of the house.
If the room has a dedicated return vent, close the supply vent partially or completely. If not, a small fan blowing air out of the window can work.
Determine if the room is under negative pressure by feeling for air movement with your hand at the undercut or with the door to the room partially open. A piece of tissue or nontoxic “smoke” may also indicate which way the air is moving. For negative pressure, the air should be moving into the room.
The good news
The fact that we even have to consider all this is a testament to the interesting and challenging times we live in. The good news is there are some things within our control. By continuing to educate ourselves and each other on issues like indoor air quality and healthy homes, we’ll emerge from the COVID-19 pandemic with increased understanding and empowerment when it comes to protecting the health of ourselves and our families–especially in our homes.
Allison Bailes is a speaker, writer, building science consultant, and founder of Energy Vanguard, a small firm that does residential HVAC design, building science consulting, training, and quality assurance in Atlanta, GA, and surrounding areas. He is also the author of the Energy Vanguard Blog. Follow him on Twitter @EnergyVanguard.
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