Passive House in Massachusetts.
Massachusetts has the clearest Passive House policy in the country. We bring the international standard and the experience of the world's tallest Passive House to teams building there.
The United States is building Passive House faster than ever, and Massachusetts is leading it. A specialized stretch energy code gives large multifamily a Passive House route to compliance, and Mass Save helps fund the design and certification. We are an Irish practice with thirty years at the standard and a place on the certifying team for the world’s tallest Passive House, in New York. We bring that experience to US projects and work alongside the local team.
Why Massachusetts moved first.
Code, incentive, standard, proofA Passive House pathway
Where a municipality adopts the specialized stretch code, larger residential buildings must clear a higher bar, and certifying to Passive House is an accepted way to meet it. The code rewards fabric and form before equipment, the order Passive House has always followed.
Mass Save behind it
Utility incentives offset a meaningful share of the design and certification cost for multifamily Passive House. With a compliance route and a programme that helps fund it, the standard has moved into the mainstream of new housing.
PHI and Phius
US projects usually target the Phius standard, alongside the international PHI Passivhaus standard. The physics is the same in both. We work to PHI and are comfortable supporting either, bringing PHPP modelling built to certification level.
Measured in use
A certificate says a building should perform. Monitoring shows whether it does. Our Pulse service tracks energy, comfort and air quality after handover, so the result can be checked against the model rather than assumed.
What we bring to a US team.
How we workEnergy modelling that holds up
A PHPP model built to construction level, by people who certify buildings for a living, gives a submission that stands up to scrutiny and a design that can actually be built to the standard.
Certification at height and scale
We have taken Passive House to 26 storeys. Tall and large buildings change the airtightness detailing, the ventilation strategy and the overheating risk, and we have worked those out before.
Alongside your local team
We complement the local architect and certifier rather than replacing them: building physics, modelling, detailing review and the judgement that comes from delivering the standard, not just reading it.
Proof after handover
Through Pulse we keep measuring real energy, temperature, humidity and air quality, so the in-use performance feeds back into the next building rather than being taken on trust.
The House at Cornell Tech, New York.
A 26-storey residential tower on Roosevelt Island that was, at completion, the world’s tallest Passive House. Our founders were among the certifying team. It proved the standard scales to a high-rise in a dense American city, and the lessons travel directly to the multifamily towers Massachusetts is building now, and to a New York market where Local Law 97 has started charging large buildings for the carbon they emit.
Common questions for the US.
FAQWhy is Massachusetts a leader in Passive House?
Two things came together. Municipalities that adopt the state’s specialized stretch energy code give larger residential buildings a Passive House route to compliance, and Mass Save offers incentives toward the design and certification of multifamily Passive House. With a clear compliance pathway and a programme that helps fund it, Passive House has become a mainstream way to build new multifamily in the state rather than a niche choice, and the pipeline is among the largest in the country.
What is the Passive House pathway in the specialized stretch code?
Where a municipality has adopted the specialized stretch code, larger residential buildings have to meet a higher performance bar, and certifying to Passive House is an accepted way to meet it. It rewards getting the fabric right, continuous insulation, airtightness, good windows and heat recovery, rather than offsetting a leaky building with extra equipment. That is the order Passive House has always worked in.
What about New York and Local Law 97?
New York now puts a price on building emissions. Under Local Law 97, large buildings that exceed their carbon cap have been accruing penalties since January 2026, at $268 for every tonne of CO2 over the limit, with the caps tightening again in 2030. A Passive House cuts the energy that drives those emissions at the fabric, so the building sits well inside the cap rather than paying its way out. The House at Cornell Tech, on Roosevelt Island, showed the standard holds at high-rise scale in exactly this market.
Phius or PHI: which Passive House standard applies?
In the United States, Passive House usually refers to the Phius standard, alongside the international PHI Passivhaus standard the rest of the world uses. Massachusetts programmes are concerned with Passive House performance rather than a single badge. We work to the international PHI standard and bring that experience to US teams; the building physics is the same either way, and we are comfortable working to whichever standard a project is targeting.
Why bring in an Irish practice for a project in the United States?
Because the physics does not change with the postcode, and because we have done it at the top end. Our founders were among the certifying team for The House at Cornell Tech in New York, the world’s tallest Passive House at completion. We bring PHPP energy modelling, certification experience and post-occupancy monitoring, and we work alongside the local architect and certifier rather than in place of them.
Do the incentives make the numbers work?
For multifamily, Mass Save and related programmes offset a meaningful share of the design and certification cost, and the energy savings then run for the life of the building. The honest answer is that it depends on the building, so we model the trade-off early, at feasibility, where it can shape the form and fabric rather than surprise the budget later.
Have you worked in the United States?
Yes. The House at Cornell Tech, a 26-storey residential tower on Roosevelt Island in New York, was the world’s tallest Passive House at completion, with our founders among the certifying team. Our US work is growing, and Massachusetts, with the clearest Passive House policy in the country, is where we see most of it heading next.
Building Passive House in the US?
Whether you are working to the Massachusetts stretch code or aiming for certification elsewhere, bring us in early and the fabric, the model and the target are aligned from the start.