Every successful project starts with a framework. A vision statement. A blueprint. The staff of Engineered Systems is proud to present The Blueprint — a monthly Q&A interview with HVACR engineering’s leading voices. These one-on-one discussions examine the trade’s history, current industry trends, the factors shaping the sector’s future, and more.

In the most recent installment, Christian Weeks, CEO, enVerid, discusses the decarbonization movement, introduces us to the company’s “Clean First” approach, defines the effectiveness of sorbent filtration technologies, and much more.

Engineered Systems: enVerid addresses the dual priorities of indoor air quality and building decarbonization through its innovations. Let’s start with IAQ, what stands out for you as the most important lesson learned from COVID-19?

Weeks: A key lesson from the COVID-19 pandemic is that just relying on outside air to deliver healthy, safe IAQ is very energy-intensive. As buildings increased their ventilation rates, their energy usage also went way up, which obviously doesn’t help with decarbonization goals. The second and related lesson is that layered mitigation strategies that combine filtration and outside air ventilation can be as effective at reducing risk, more feasible technically, and more efficient environmentally than just relying on outside air. This insight is important because it provides a pathway to achieve good IAQ in an efficient manner going forward, especially when outside air is not “fresh.”

In the early days of the pandemic, ASHRAE and other guidance focused on maximizing outside air to decrease the risk of airborne transmission. This initial guidance was very conservative without consideration for cost as well as operational and seasonal weather impacts. Concerns about surging energy usage were voiced immediately. This pushback led ASHRAE and others to evaluate the combined effectiveness of filtration and ventilation as an alternative to relying only on outside air to reduce airborne transmission. And, as it turns out, combining ventilation and filtration is very effective and more energy efficient. As Bill Bahnfleth, chair of ASHRAE’s Epidemic Taskforce, said during a webinar in October of 2020, “The ongoing  assessment of the guidance, including consideration of equivalent outdoor air approaches, has led ASHRAE to conclude that high-efficiency filtration can be as effective and lower cost than ventilation and often more feasible technically.”

Based on this insight, in January 2021, ASHRAE announced new COVID-19 guidance based on the concept that “ventilation, filtration, and air cleaners can be combined flexibly to achieve exposure reduction goals.” Updated in October 2021, ASHRAE’s core recommendations advise at least minimum outdoor airflow rates for ventilation and a combination of filters and air cleaners that achieve MERV 13 or better levels of performance for recirculated air. According to this latest guidance, designers and building operators should select control options that “provide desired exposure reduction while minimizing associated energy penalties.”

So, the most important lesson from COVID-19 as it relates to IAQ and building decarbonization is that mechanical filtration and air cleaners that target specific contaminant classes can substitute for higher volumes of outside air to achieve good indoor air quality energy efficiently.

Read the entire interview on Engineered Systems’ website.