Tool Compares Risk, Cost and Carbon Impact of HVAC Strategies

enVerid Systems has shared a tool to calculate energy, costs and carbon impact of various HVAC strategies for mitigating airborne transmission of COVID-19. The open-source enVerid COVID-19 Energy Estimator allows building owners, mechanical engineers, and facility managers to gain a more complete picture of the risk, costs, and carbon impacts of different ventilation and filtration approaches. The enVerid COVID-19 Energy Estimator is informed by enVerid’s decade-long focus on indoor air quality (IAQ) and energy efficiency.

The Energy Estimator gives building owners, mechanical engineers, and facility managers a picture of the risk, costs, and carbon impacts of different ventilation and filtration approaches.
The Energy Estimator gives building owners, mechanical engineers, and facility managers a picture of the risk, costs, and carbon impacts of different ventilation and filtration approaches.

The enVerid COVID-19 Energy Estimator was co-developed by enVerid Systems and Dr. Marwa Zaatari, P.E., an ASHRAE distinguished lecturer and member of the commercial team and building reopening team for the ASHRAE Epidemic Task Force. Dr. Zaatari is principal of Dzine Partners LLC and an advisor to enVerid Systems. Dr. Zaatari previewed the tool during a webinar for a large audience of building engineers and facility managers.

During a webinar hosted by enVerid, Prof. Bill Bahnfleth, chair of ASHRAE’s Epidemic Task Force, explained that initial guidance from ASHRAE released in the spring was conservative without consideration for cost, operational, and seasonal weather impacts. He went on to explain that ongoing assessment of the guidance, including consideration of equivalent outdoor air approaches, has led ASHRAE to conclude that high-efficiency filtration, when installed correctly, can be as effective and lower cost than ventilation and more feasible technically.

Why It Is Important

For existing commercial buildings, facility engineers and building managers need to make informed decisions about how to reduce the risk of airborne transmission of SARS-CoV-2, taking into account the energy costs associated with different approaches and planning for the impact on their operating budgets. New HVAC systems will need to be designed with the dual priorities of pandemic future proofing and maximizing energy efficiency to save money and lower carbon emissions. The optimal strategies will vary by climate zone and energy costs, and the COVID Energy Estimator can be used to evaluate these tradeoffs for different metropolitan areas taking into account local energy rates. 

For example, building engineers evaluating a 50,000 foot-squared office space in Boston with 250 occupants and a design supply air of 50,000 CFM and a 72 hour operating schedule can compare two approaches, switching to 100 percent outside air (OA) or upgrading to MERV 13 high-efficiency filters and bringing in minimum outside air as per the ASHRAE Standard 62.1 Indoor Air Quality Procedure (IAQP). The Energy Estimator shows that both strategies will deliver over five effective air changes per hour (ACH), but the 100 percent OA strategy will cost $85,827 per year compared to $12,261 per year for the MERV 13/IAQP approach. When reviewing the carbon impacts of the two approaches, the COVID Energy Estimator shows that the 100 percent OA strategy will generate 325 metric tons of CO2 per year versus 28 metric tons for the MERV 13/IAQP approach.  

Download the enVerid COVID-19 Energy Estimator.

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