The Distillery North Apartments in South Boston is a 28-unit complex that follows the passive house model, a building standard aimed at true energy efficiency, comfort, and affordability.

In 1984, Fred Gordon, principal owner of Second Street Associates LLC, bought an old, 100,000-square-foot rum distillery originally owned and operated by Felton Rum. Five generations of the Felton Family made distilled rum in New England for 150 years.

“I just fell in love with it,” said Gordon of the warehouse. “It was a building that nobody wanted in a part of the city that nobody wanted to be in, and I, in certain ways, predicted that the whole thing would turn around.”

Fast-forward to the mid-1990s, and Gordon was determined to use the space to contribute to the environmental movement. He then bought the rest of the city block. In 2009, he decided to build a multifamily passive house on the distillery property.

“The passive house movement involves a huge amount of discussion about products,” noted Gordon. “If you went to the conferences both in Germany and in the U.S., which I did, there was all this buzz about air [-source] heat pumps. Air [-source] heat pumps were a revolution in terms of technology, energy efficiency, and cost,” he said.

Richard O’Dwyer, consulting principal with ICON Architecture, was one of the architects brought on early to The Distillery North team. He explained that product research and selection was a collaborative effort.

“We were excited by the prospect of developing a project that would be intensely energy-efficient with a very low carbon footprint that would deliver very clean air to breathe,” said O’Dwyer. “[Fred] had a great team of experts in the field. He brought in a passive house architect from Germany who had extensive experience with the constructability of larger passive house projects and also local professionals who were familiar with smaller passive house structures to assist in the process.”

Targeting energy reductions of at least 60 percent, Gordon and his team had to tackle two issues to attain passive house status: cut energy loads down as much as possible and use green power to assist in covering those loads. The passive house standard, developed by the Passive House Institute, has strict benchmarks surrounding cooling and heating that require the building to have controlled mechanical ventilation with heat recovery (MVHR). After 100 photovoltaic solar panels were selected to help bring in green energy, Gordon knew a highly efficient HVAC system with air-source heat pumps and heat exchangers that could perform the necessary MVHR functions.

Sarah Carter, project manager for Petersen Engineering, was one of the engineers who helped specify Mitsubishi Electric’s ductless system for The Distillery North.

“The loads are greatly reduced in the [passive house] type of building, so there needs to be equipment that’s available in small capacities. A lot of equipment’s preset sizes would all be considerably oversized in a passive house building, especially if they are for one- and two-bedroom apartments.”

With this in mind, Gordon decided to create a trial period for all the equipment in the rum distillery before breaking ground on the multifamily complex.

“We took a tenth of the existing building and retrofitted that with all of the equipment,” he explained. “We had about four years’ experience with all of the [HVAC] equipment before we made a commitment to a really major construction.”

In its design, Petersen Engineering selected ductless M-Series systems for each unit of the complex. Utilizing inverter-driven technology, the M-Series was an ideal choice for a multifamily passive house, because each unit only uses the exact amount of energy required to cool or heat a space. Zoning allows for optimum occupant comfort with substantial energy savings for the building owner.

The Distillery North Apartments have been open for tenancy since April 2017. Gordon and his wife, who actually live in the building, have been quite pleased with the first round of energy performance figures. Between the solar panels, positioning of the complex, and an energy-efficient HVAC system, Gordon and his colleagues at Second Street Associates believe the utility savings are a real perk for residents.

“For heating and cooling, we’re talking $65 per unit, per year — that’s less than a monthly cappuccino from Starbucks,” said Gordon.

“I think we’ve demonstrated with [The Distillery North] that we have a very contemporary building that ties in very nicely with the existing distillery building, which dates back to the 19th century,” O’Dwyer said. “Although incorporating the constraints of the passive house model into the project was a challenge, with the right concept and a thoughtful design process, those constraints ultimately enhanced the aesthetics of the final product.”

Gordon is already developing another low-energy building on the property. This will add 37 apartment residences, six commercial spaces, an indoor theater, a grocery store, and a 2,600-square-foot greenhouse. He has big plans to turn his block into a community that celebrates both the arts and the outdoors. After being in the neighborhood for 30 years, local institutions and residents are embracing it.

“This is a place that is really protected; people feel really comfortable,” he said. “In the end, we’ll have 300 people on-site, so it’s big enough to actually create [a] culture of its own.”