The enVerid COVID-19 Energy Estimator: Revealing the Full Costs of HVAC Strategies

Published 11/23/2020
By Doug Engel
enVerid COVID-19 Energy Estimator Infographic

We were delighted to welcome our esteemed colleague, 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, and principal of Dzine Partners LLC, as the featured speaker in the last session of our very popular COVID and IAQ: New Best Practices Webinar Series.  During her Nov. 10th presentation, Dr. Zaatari reviewed existing methods for modeling COVID-19 mitigation strategies and previewed a new, open-source tool – the enVerid COVID-19 Energy Estimator – that she co-developed with enVerid. The COVID 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 that might be employed to address airborne transmission of SARS-CoV-2.

A number of excellent risk calculators have been shared with the industry in the past few months. While those tools are extremely helpful, the COVID Energy Estimator allows for a more informed view, uniquely combining risk with cost and carbon impact. We know for many of our customers, energy penalties associated with various ventilation and filtration approaches are a particular and timely concern as we head into the colder months. If you missed Dr. Zaatari’s webinar, an on-demand recording is available here.

In an earlier webinar in our series, Prof. Bill Bahnfleth, P.E., FASHRAE, FASME, FISIAQ and Chair of ASHRAE’s Epidemic Task Force, explained that initial guidance from ASHRAE released in the spring was very conservative without consideration for cost, operational, and seasonal weather impacts. He shared 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 often more feasible technically. According to Prof. Bahnfleth, who was one of the peer reviewers of the new tool, “The COVID Energy Estimator confirms these findings quantitatively by showing the cost and carbon tradeoffs of different ventilation approaches that deliver the same relative risk outcomes.”

Today we are sharing access to the open-source tool with the industry at large, (read our press release here). You can download the enVerid COVID-19 Energy Estimator at https://tinyurl.com/covid-energy-estimator.

enVerid COVID-19 Energy Estimator Infographic
Click the Infographic to view it at a larger size. Right click to save it.

We’ve created an infographic to show how the COVID Energy Estimator allows for different HVAC approaches to be modeled and compared. Calculations were performed across multiple U.S. cities on a commercial office space of 50,000 ft2 with 250 occupants, a design supply air of 50,000 CFM and a 72 hour operating schedule. The ventilation strategies shown include 100% outside air (OA), the Ventilation Rate Procedure (VRP) with MERV13 filters, and the Indoor Air Quality Procedure (IAQP) with MERV13 filters as per ASHRAE Standard 62.1 The effective air changes per hour (ACH) is > 5 for all ventilation strategies.  Comparing two approaches in the Boston area: 100% OA versus the IAQP + MERV13, the COVID Energy Estimator shows that the 100% OA strategy will cost $85,827 per year compared to $12,261 per year for IAQP + MERV13 approach. When reviewing the carbon impacts of the two approaches, the COVID Energy Estimator shows that the 100% OA strategy will generate 325 metric tons of CO2 per year vs. 28 metric tons for the IAQP + MERV13 approach.

We encourage building engineers and facility managers to download the enVerid COVID-19 Energy Estimator and begin to assess the operating costs, maintenance, first costs, and carbon costs associated with ventilation, filtration and air cleaners based on various HVAC strategies. Be sure to review the READ ME tab of the spreadsheet. Please offer any feedback, questions or findings by emailing us at [email protected].

Doug Engel

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