25 Sixth St.


25 Sixth St.

Residential: Affordable Multi Family

Chelsea , MA | 2023

  • 71.5K GSF
  • 2 Companies


Located near the heart of downtown Chelsea, 25 Sixth Street is a 62-unit, transit-oriented project for The Neighborhood Developers that will be built on a previously developed site adjacent to the newly constructed MBTA Silver Line station near Bellingham Square. The project is pursuing certification under the PHIUS+ 2018 Passive House standard as well as the MassSave Multifamily Passive House Incentive Program. The design process involves integrated energy modeling to facilitate a robust thermal envelope, uninterrupted air barrier, and high performance glazing that works to minimize energy loss and better control heating and cooling loads. The building’s mechanical equipment includes centralized energy recovery ventilation and cold-climate VRF heat pump systems. Additionally, the building will be made solar ready for future inclusion of photovoltaic arrays to cover a portion of the building’s electrical load.

Project Owner

The Neighborhood Developers

Is the project achieving or targeting net zero energy?


Is the project Net Zero or Net Zero Ready?

Net Zero Ready

Project Size in GSF


Category of height


How is the building all-electric for heating?

Air-source Heat Pump

Is the service hot water all-electric?


On-site renewable energy


Is the owner purchasing off-site renewable energy to offset all electricity consumption?


The construction cost difference from "conventional" to being net zero "ready" (including incentives) for this building is

>-1% to 1%

Site EUI

19.2 kBtu/sf/year

Net Site EUI

0.0 kBtu/sf/year

What is the climate zone for this project?

5A Cool Humid

Project Team

Plumbing Engineering
Mechanical Engineering
Electrical Engineering
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    In Business Since 2023

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