How to cope with the environmental costs of COVID controls
School districts with sustainability commitments likely haven’t thought all that much about sustainability in the past year. Pushing through the pandemic and holding classes safely had to be the priority.
With vaccines rolling out, administrators and student groups alike may be starting to wonder: What is the environmental cost of all this infection control? Which COVID-19 prevention measures should we keep in the long term and which may hinder our sustainability goals?
The price of fresh air
A typical HVAC system might combine approximately 20% outside air with 80% recirculated air. When information about how COVID-19 spreads came to light, many districts looked to increase the outside air percentage.
Typical HVAC design provides some flexibility for the amount of outside air the system can handle. Often, an existing HVAC system can be configured to bring in about 10-15% more fresh air, but the energy cost can be significant and occupant comfort may be compromised.
Maximizing the outside input to a standard HVAC system could result in higher energy consumption, except on particularly temperate days. As a result, it’s best for sustainability purposes to return ventilation systems to their design settings once the pandemic subsides.
On temperate days or in temperate climates, there is one very cost-effective way to get 100 percent fresh air: Outdoor learning.
Many schools developed outdoor learning spaces during COVID-19 and, in fact, outdoor instruction areas were a rising trend in K-12 education before the pandemic. These spaces help students stay engaged and can be as simple as contours in patios or courtyards that allow for seating or writing.
Shedding light on filtration
Last year, administrators across the country suddenly had to become air-filtration experts and learn about MERV ratings, which is how the effectiveness of air filters is measured. MERV 13 seems to be a good start for limiting the aerosols that spread COVID-19.
If your district made air-filtration upgrades during COVID-19, you may be thinking, “Clean air is good. What’s the harm of leaving this in place?”
The stronger the filter, the harder HVAC systems have to work to push or pull air through it. This can increase energy consumption and reduce the performance of the system.
MERV 13 filters are required in many different occupancy types. Stronger air filters are typically the providence of hospitals, labs, or other spaces that require a high level of filtration.
UV systems have been another common upgrade to HVAC systems. While UV light can deactivate the virus on surfaces, its effectiveness on airborne particles should be reviewed before installation. UV systems can add a significant electrical load as well.
Take stock and build for flexibility
When the pandemic hit, many districts suddenly realized they did not have a detailed survey of their buildings, furniture, and infrastructure. This made it more difficult to make a game plan for complying with CDC guidelines.
For instance, districts that knew the specs of every HVAC system in their schools were better positioned to assess the need for upgrades and the likely cost. They also at least had the potential to factor in environmental concerns, as they set up tents for classrooms and temporary locations for temperature checks and testing.
More from DA
Living through COVID-19 will give a whole generation of administrators new questions to ask as they take on development projects. Whether it’s a pandemic, a storm or something else we haven’t thought of yet, how is it going to work when a gym needs to be something other than a gym?
Designing for flexibility will enable districts to avoid making tough calls that compromise sustainability in the future.
Richard Loveland, P.E. is vice president of BVH Integrated Services, a consulting engineering firm with offices in Bloomfield, Connecticut, and Newton, Massachusetts. Michael B. Tyre, AIA, LEED AP, is a principal at Amenta Emma Architects with offices in Boston, New York and