Building Performance Cooperative

Building Performance Cooperative — still trading as BPC Green Builders, which is how the domain and every federal record read — is a builder and construction manager, not an architect. Clients arrive with an architect already retained or take a recommendation, which is worth knowing because it shapes what the firm is good at: executing an envelope to a tested number rather than authoring the design. Mike Trolle founded it in Newtown, Connecticut in 1998, his brother Chris joined in 2000, and in 2023 it converted to a worker cooperative with five employee members and eligibility for every employee after two years.

The evidence behind the work is unusually good, and almost none of it originates with the firm. The Department of Energy's own winners pages confirm six Housing Innovation Awards — 2013, 2014, 2015, 2017, 2020 and 2021 — including a Grand Winner in the custom category. DOE and Pacific Northwest National Laboratory case studies document three of the houses down to the assembly: 0.45 ACH50 and a HERS index of 35 at the Trolle Residence in Danbury, 0.6 ACH50 and HERS 33 at the Taft School faculty residence, 0.75 ACH50 and HERS 34 at a house in Stamford. The airtightness figures are third-party tested. The HERS indices are modeled, which DOE says plainly and so should anyone citing them.

The most interesting document they publish is the Green Warranty, and it is interesting because it is contractual rather than promotional. It commits to holding every room within three degrees of 72°F year-round, a complete air change every four hours, sub-slab depressurization capable of keeping radon below 4 pCi/L, and meeting or exceeding EPA Indoor airPLUS. The public version is an overview and the full document is not available, so those are commitments the firm makes rather than outcomes anyone has audited.

What separates them from the category is a habit of disclosure that works against their own marketing. They built a house in Stamford to Passive House standards, named it Hillside Passive House, and state on the page that the owner declined certification — after publishing the rule that certification is what makes a Passive House a Passive House. They mark another project as built to a standard but not certified. They note that a health program they once used is defunct. They publicly corrected a magazine that mislabelled one of their homes. On air quality the ceiling is the same as everyone else's in this category: DOE documents an ERV with a MERV 8 filter and an indoor air quality monitor at Stamford, MERV 8 being a modest rating, and no measured air quality data has been published for any completed house.