Ask the Experts with CMTA’s Ray Beaufait and Brice Watson: Delivering Superior IAQ with DOAS + HLR Air Scrubbers

enVerid is debuting an “Ask the Expert” blog series featuring our CEO Christian Weeks’ conversations with design engineers, architects, IAQ authorities and other built environment thought leaders about their first-hand insights tackling two of the most pressing concerns for buildings today:  1) achieving good indoor air quality and 2) reducing building carbon emissions – and how to achieve these often conflicting goals cost effectively.

It seems only fitting to start this new series with an interview with CMTA, the innovative, national MEP known for its transformational projects and its expertise in the education sector. Recognized for its compelling net zero and LEED^® school projects, CMTA has earned accolades for its zero energy/LEED Platinum Alice West Fleet Elementary School project design. The project won the ASHRAE National Capital Technology Award, took second place for the ASHRAE International Technology Award and just this week won the USGBC National Capital Region’s Community Leader Green Schools Award. Architected by VMDO, the project is widely regarded to be the largest net zero school in the U.S.  Alice West Fleet is the third project designed by CMTA in the last year that incorporated enVerid’s HLR air scrubbers.

Christian caught up with CMTA engineers from the Louisville, Kentucky office Ray Beaufait and Brice Watson who designed the Alice West Fleet project.

CW – Congratulations on your ASHRAE Technology Award and USGBC Green Schools Award  for the Alice West Fleet Elementary School net zero project. Let’s start by talking about the overall energy and IAQ goals for the project.

RB/BW – Our main goal for Fleet Elementary School was to deliver a net zero design with excellent indoor air quality to ensure an efficient and healthy indoor environment for student learning. We also wanted a design that would reduce the maintenance burden on the owner. The challenge was to achieve stringent indoor air quality requirements, which often necessitate more outside air, while minimizing the energy impact to get to net zero. We incorporated enVerid’s air scrubbers into the design to help us achieve a very high IAQ standard more efficiently.

CW – Often there is a tension between better IAQ (often via more outside air) and energy efficiency (less ventilation energy consumption). How did you address this tension on this project?

RB/BW – Balancing the requirement for improved indoor air quality and energy efficiency is always at the forefront of our mind. For Fleet Elementary School, we were looking for options to enhance the IAQ to improve the health of the building and students’ ability to learn, but we needed to do it energy efficiently. We found that enVerid’s HLR air scrubbers could be used to achieve this increased IAQ with less outside air and thus reduce the energy used. The fact that enVerid’s air scrubbers can remove CO₂ from indoor air was especially appealing since the educational community puts great stock in the research that finds lower CO₂ levels leads to improved cognitive function in students. Increasing ventilation and bi-polar ionization were also considered for this project, but additional ventilation conflicted with our energy goals and bi-polar ionization is not a proven technology to reduce CO₂ levels.

CW – This project included a Dedicated Outside Air System (DOAS). How did you integrate the HLR air scrubber modules with the DOAS units?

RB/BW – At Fleet Elementary School the HLR air scrubbers are installed with DOAS units. Indoor air from the relief air stream passes through the HLR modules to remove CO₂ and VOCs from the air stream. This cleaned air is then mixed with outside air from the DOAS to provide building occupants with the cleanest air possible without having to rely on 100% outside air. Reducing the amount of outside air needed to maintain ideal space levels of CO₂ levels of around 800 ppm was key to achieving our net zero goals.

Having coupled DOAS units with HLR air scrubbers on this project, our view is that any project with DOAS units is an opportunity to use air scrubbers. Why not, you can make the air so much better and try to reduce what you are exhausting from the building. This is helpful because most of our high-performance projects use DOAS.

CW – Had you specified HLR air scrubbers before, or is this your first project using HLR technology? Would you specify HLR air scrubbers again, and if so, in what sort of building/project applications?

RB/BW – Some of our other offices have utilized HLR air scrubbers on projects, but this was the first project for our Kentucky office, and we would specify the HLR units again on the right projects to increase IAQ energy efficiently. In our view, schools are a great application.

The only challenge we foresee is space constraints in mechanical rooms, but where there is room on the roof enVerid’s rooftop air scrubber modules are also an option.

CW – We see the utilization of the ASHRAE’s performance-based ventilation design standard, the Indoor Air Quality Procedure (IAQP), as an untapped opportunity to design more efficient ventilation systems by incorporating air cleaning technologies with third-party validated cleaning efficiencies. Do you agree?

RB/BW – There is a lot of potential to reduce energy consumption by utilizing strategies such as the IAQP to minimize outdoor air being brought into the building. The key is selecting technologies that have been proven to be effective and that do not require a lot of maintenance. This is especially important when ventilation rates are reduced (via IAQP vs. VRP) to ensure one does not end up with an under ventilated space. Given our recent experience with COVID, it is critical to ensure the proper combination of ventilation and filtration to deliver at least four effective air changes per hour in classrooms.

CW – With CMTA’s demonstrated strength in the school market, what are the biggest challenges facing school districts concerning facilities? Are there any notable trends you are seeing in the school market?

RB/BW – Net zero design is a major trend in the K-12 market. The demonstrated long-term savings on net zero school buildings as well as reduced maintenance are “no brainers” when these goals can be accomplished for little to no increase over a more typical school design. The biggest challenge facing these districts is implementing these design elements at an effective cost and doing so while providing learning spaces that help strengthen the ability of students to learn and retain knowledge.

Learn more about how HVAC Load Reduction^® technology is helping schools deliver excellent indoor air quality while using less energy.