Indoor fresh air ventilation strategies have become all the more urgent, given the respiratory COVID-19 pandemic. We have learned that not only coughing or sneezing, but breathing, talking and singing all easily spread the virus — particularly indoors where air is trapped and recirculated. Read on to discover what indoor situations to avoid while learning time-tested strategies that optimize good health in your home, school, workplace, hospitals and community.
Photo: Fia Tharp
Fresh air ventilation has been a human-centric design principle throughout the ages. By necessity, builders of the past have worked with nature to create indoor comfort. Thus, health and wellbeing are protected by ensuring ample sunlight, temperate environments, optimal humidity levels and, above all, fresh air.
Photo: Cosmic Timetraveler
Shuttered windows open up to light and breeze or close down to insulate.
Photo: Hiroyuki Oki
This open staircase funnels hot air up and out, while filtering the connection between indoor and outdoor space with greenery. Architecture by Vo Trong Nghia.
Photo: Frank Eiffert
The Pantheon's oculus (Latin for "eye") acts like an operable skylight, offering dramatic illumination and heat relief in Rome's blazing summers.
Mechanical Heating and Cooling Can Compromise Wellbeing
As our reliance on mechanical heating and cooling has increased, our buildings largely ignore nature. "Tight" interiors are well-insulated, which does save energy, yet without fresh air, they threaten health and wellbeing. Rooms are built with windows that do not open, or worse, no windows at all.
Photo: Sheila Sund
Rise of the Glass Giants: Skyscrapers Must Evolve
The Problems with Blowing Mechanical Systems are Magnified during a Pandemic
A false sense of fresh air is created by HVAC systems that blow and recirculate. HVAC stands for Heating, Ventilation and Air Conditioning, yet the Ventilation part is often left out for cost-savings. To make things worse, systems blow not only air, but make particulates such as dust, allergens and lead dust airborne, sending them and any chemical off-gassing farther than they would otherwise go. Ductwork is a breeding ground for mold, given its typical mix of dust and central air-conditioning condensation. It is no wonder that asthma and other health issues are on the rise in the U.S. since cheap forced-air systems became the dominant system of choice.
The impacts of blowing systems to our health become magnified during a pandemic. Coronavirus droplets and aerosols are proven to spread through the air, which is why indoor transmission is much higher than out of doors.
Studies Highlight COVID-19 Risks of Poor Indoor Air Design
Blowing Air Conditioning System Spreads Coronavirus
In this field study, an asymptomatic restaurant diner infected with the coronavirus sat at Table A, within the air flow exchange of the air conditioner. The air conditioning draft bounced off the far wall and recirculated among Tables B, A and C, but not around Tables E and F.
Diners sharing the air conditioning draft with infected diner A1 (yellow circle) were sickened, while diners at tables out of the draft stayed healthy, despite closer physical proximity to diner A1 by some at Tables E and F. Study here.
Duration of Indoor Air Sharing Matters in Coronavirus Transmission
In this telemarketing call center study, the blue desks indicate 44% of workers on the 11th floor as confirmed Covid-19 cases. This chart demonstrates how the sharing of indoor air spreads the virus. "Despite considerable interaction between workers on different floors... in the elevators and lobby, spread of COVID-19 was limited almost exclusively to the 11th floor, which indicates that the duration of interaction (or contact) was likely the main facilitator for further spreading." Study here.
Six Foot Distancing and Surface Cleaning is Not Enough, Particularly Indoors
As the transmission animation above illustrates, ventilation is critically important. Many months into a respiratory pandemic, this article rightly asks how is it that "we are still doing so little to mitigate airborne transmission?"
6 Fresh Air Strategies Can Help Prevent Coronavirus Spread
What follows are six strategies for better building practices as well as simple actions we can all take to ensure good health:
#1. Avoid or Replace Blowing Forced-Air Systems: Passive heating and cooling design uses the position of sun, breeze, shade to optimize comfort and minimize or even eliminate reliance on mechanical systems. Non-blowing mechanical heating, such as radiant underfloor heating or radiators, provides comfortable healthy heat that does not blow particulates or viral aerosols nor dry out mucosal membranes (which can make one more susceptible to infection).
#2. Install Fresh Air Ventilation Systems with Filtration: The one time I do recommend ductwork is in the case of a mechanical fresh air system. In fact, we installed this system in our award-winning Concord Green Healthy Home. (For more, see DIY Network | This New House video on Videos webpage.) Energy Recovery Ventilators cleverly pass stale indoor exhaust air by fresh intake air to pre-heat or pre-cool the incoming air using the temperature of the outgoing air. HEPA and carbon filters added to this set-up will ensure clean air filtration of particulates and aerosols. When installing, zone systems to isolate rooms from one another in order to control viral transmission via the ductwork.
Photo Credit: Philipp Kester/ullstein bild via Getty Images
Open Air Schooling - New York City
Photo Credit: Paula Burch-Celentano
First Day of Class - Tulane University
#3. School Outdoors: As proven during the 1918 flu pandemic, classrooms can effectively be hosted outside. College campuses typically have more land, making it even easier to spread out.
Photo Credit: Nathan Dumlao
#4. Shift School Calendars to Local Climate: Education can work with nature by adapting local school calendars to the most temperate months of each climate. Northern states could school outdoors April through October, while southern climes could educate throughout the winter months. All climates can supplement online to achieve a full nine months.
Photo Credit: Haut Risque
#5. Work Outdoors Too: If you are lucky enough to have a covered porch, yard, roof deck, garage or even just a shade tree, set up your outdoor space. Communities can designate sections of parks as work space, with off-grid solar panels for powering devices. They can also trade out parking spots for expanded outdoor street dining.
Photo Credit: Library of Congress
#6. Open Windows Regularly: Open up, even in colder weather. Wear a sweater and sacrifice a bit of fuel efficiency to get through this health emergency. And if you are commissioning new construction or renovation — either for yourself, for a business, school or for your community — INSIST there be operable windows throughout the design plan.
Email us at hello@lisatharp.com if you need help with fresh air design strategies. I hope that you find this post helpful, and that you and yours stay safe.
Be well.
Lisa
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