By Jay Fox

The Northeast Sustainable Energy Association (NESEA) hosted BuildingEnergy Boston last week, March 20 and 21, at the Westin in Boston’s Seaport District. The well-attended conference and trade show brought together an array of people from across the real estate and construction industries to learn how to build more efficiently, more sustainably, and more resiliently. The conference was also a celebration of NESEA’s 50^th anniversary, and the content was centered around the appropriate theme of Building the Movement.

Before describing some of the more pertinent lessons shared during the presentations I was lucky enough to attend, it’s important to note that the in-person format of the conference helped amplify the theme. Building the Movement is not simply about sharing technical knowledge with one’s colleagues; it’s about connecting people with different professional and regional backgrounds who share a passion for decarbonizing the built environment.

While virtual events and platforms are certainly capable of uniting people around an idea or purpose, there is an added dimension to social interactions that occur in person. As BuildingEnergy Boston Chairs Jacob Deva Racusin of New Frameworks and Keirstan Entriken of the Electric Power Research Institute (EPRI) reminded those in attendance at the beginning of the second day, it’s important to remember to look up from our work every once in a while, and to take time to appreciate art and moments of spontaneity and creative joy. For Deva Racusin, this translated into an impromptu Mingus session after lunch, but for most of those in attendance, it was the art of small talk. At in-person events, one is more likely to initiate a chat with whoever happens to be sitting nearby than to start a private chat over Zoom, and this can lead to introductions, conversations, and possibly even collaborations that wouldn’t happen otherwise.

Expanding the Movement

The effort to de-silo the industry and create more communication between groups and individuals working to decarbonize the built environment could not come at a better time. Climate action is needed throughout the AEC industry and policymakers at the state and local level should be looking to borrow from successful programs that have been enacted in states like Massachusetts and cities like Boston. Given the local successes of policymakers and green builders throughout the state (as well as states like New York), the theme of Building the Movement is as much about building upon this momentum as it is about making the community more interconnected and preaching to more than just the choir.

It was therefore fitting that the keynote presentation for the second day of the conference was “From Silos to Synergy: Toward Inclusion and Thriving Communities.” The two speakers were Heather Ferrell, Executive Director of Prism Design Lab, and Laura Calvin Bailey, Climate Economy Program Manager at the Vermont Council on Rural Development.

Ferrell and Bailey stressed how vital it is to extend the benefits of high-performance building to more communities and individuals who are far too often overlooked or deprived of representation when conversations about sustainable development arise. They also highlighted that improving the built environment has implications beyond creating durable, healthy, and efficient homes for owners and occupants. The necessary upskilling to create these buildings generates good-paying jobs for working and middle class people. Meanwhile, better planning and building methodologies allow entire towns impacted by catastrophic weather events to rebuild their communities in ways that make them more resilient.

Technical Details

On the more technical side are issues of retrofits, refrigerants, and code. With respect to retrofits, the focus is on increasingly difficult typologies to update and modify because of their size and regulatory obstacles. In one session, “Historic Buildings, Modern Solutions: Decarbonization Strategies for Multifamily Landmarks,” the session revolved around the retrofit of three large-scale historic projects in New York City. These buildings date back to either the 1930s (the Harlem River Houses I) or the 1920s (New York University’s Rubin Hall and Three Arts).

One of the main takeaways covered by presenters Ryan Esparza (Associate, Curtis + Ginsberg Architects), Dylan Martello (Senior Building System Consultant, Steven Winter Associates), and Crystal Ng (Director of Sustainability, Curtis + Ginsberg Architects) is that teams have found that the use of packaged terminal heat pumps (PTHPs) is frequently preferable to centralized systems. However, two drawbacks noted by Esparza are that these units require far more penetrations in the building façade and can take up significant amounts of living room, especially in units that are relatively small. On the plus side, they are lower in cost than centralized systems and minimize the amount of refrigerant lines within the building.

As Neil Donnelly (Senior Energy Engineer, New Ecology), Maciej Knieczny (Director of Green Building Technologies, New Ecology), JS Rancourt (Principal, DXS), and Tom Secondo (Principal, R.W. Sullivan Engineering), noted during their panel, “Refrigerants: Rethinking their Role in Electrification,” cutting down on the amount of refrigerant lines in a building can make a significant impact in reducing embodied carbon. Especially in a large-scale multifamily building, you can have what amounts to miles of line in a centralized system and all those lines add up.

However, embodied carbon was not the focus of the discussion. Instead, the topics that got the most attention were refrigerant leaks and technical issues about the conversion from R-410A to newer refrigerants with lower global warming potential (GWP). The panelists were clear that air source heat pumps are extremely beneficial and a necessary part of the decarbonization effort, but they also stressed that there needs to be more of an effort to prevent and stop leaks, as R-410A has a GWP over 2,000 times worse than CO2. True, R-410A is being phased out and newer refrigerants like R-32 have a lower GWP (675), but the industry is still many years away from fully adopting refrigerants with very low GWPs, such as CO2 (1) and propane (0.02). Therefore, workforce training to ensure these units are properly installed and maintained is absolutely critical. Even small leaks can add up very quickly.

One tip that Rancourt noted is that flare joints are a common source of leakage. He advised checking for leaks one year after system installation (i.e., after one heating season and one cooling season), and then retightening (but not overtightening) if needed.

In “Scaling Embodied Carbon Through Building Codes,” Ariel Brenner (Project Manager, New Buildings Institute) and Andy Buccino (Manager of the Energy Division, Stephens and Company) described how the regulation of embodied carbon is beginning to appear in code throughout the country. As Brenner noted, embodied carbon from buildings makes up 7% of greenhouse gas emissions worldwide; and though it may seem like a relatively new concern, treating it like a niche subject is not an option for governing bodies, companies, and organizations that recognize anthropogenic climate change as an existential threat.

Jurisdictions are still determining the best way to codify embodied carbon, and there are several examples that have emerged in recent years. These include CALGreen, Portland, Oregon’s Low Carbon Concrete Initiative, and Marin County’s Low Carbon Concrete Code. Additionally, RESNET is currently developing a standardized method of calculating and reporting embodied carbon in buildings under Standard 1550. For more information, see RESNET’s page about Standards Development Committee 1500.

Scaling Up

Finally, in “Scale Up/Carbon Down: A Regenerative Approach to the Housing and Climate Crises,” Croft Founder Alexander Frederick and GO Logic Founder Alan Gibson took a far more theoretical and wide-angle view of many of the intersecting problems confronting the AEC industry. Frederick and Gibson both manufacture prefabricated panels for high-performance homes and also strive to reduce the embodied carbon of their projects. As just one example, GO Logic uses dense-pack cellulose and wood fiber insulation, while Croft uses straw insulation. Straw in particular is highly regarded for its ability to absorb carbon during growth and sequester it when used as a building material, and Frederick says he likes to think of Croft as a carbon capture company with food and housing as byproducts.

The presentation centered on the fact that the State of Maine Housing Production Needs Study, a paper published by several state agencies, reported in 2023 that Maine will need approximately 84,000 housing units by 2030 to satisfy growing demand. Maine is also working to drive down greenhouse emissions—45% by 2030 and 80% by 2050.