Boston's first ground-up mass timber building.
11 E Lenox: Mass Timber & Passive House Multi-Family
Currently under construction, 11 E Lenox St is a 7-story, 34 unit multifamily project in Roxbury, Boston, MA. With a projected Fall 2022 occupancy, it will be the first ground-up mass timber Passive House project in the City of Boston. The project combines the multiple benefits of mass timber construction and Passive House design (currently seeking PHIUS+ 2018 Precertification) to create an incredibly energy efficient and low embodied carbon building.
The building utilizes several strategies and systems that work to decrease it’s overall carbon impact, holistically designed to lower both its embodied carbon footprint and its operational consumption. Starting from its construction materials, the mass timber from Nordic is sustainably sourced and is a carbon sink while also being a less carbon intensive material to produce than concrete or steel. Working in tandem with the excellent thermal insulating properties of mass timber, the building is seeking and expecting Passive House PHIUS+2018 Certification - with a passive thermal envelope and novel active building systems designed to be as energy efficient as possible.
The project was conceived of 2019 and precedes the recent launch of the Boston Mass Timber Accelerator Program, which seeks to provide assistance and funding for the use of mass timber in the City of Boston, underscoring the development and design team's early commitment to bringing low carbon design to the booming Boston area housing market.
The building utilizes several strategies and systems that work to decrease it’s overall carbon impact, holistically designed to lower both its embodied carbon footprint and its operational consumption. Starting from its construction materials, the mass timber from Nordic is sustainably sourced and is a carbon sink while also being a less carbon intensive material to produce than concrete or steel. Working in tandem with the excellent thermal insulating properties of mass timber, the building is seeking and expecting Passive House PHIUS+2018 Certification - with a passive thermal envelope and novel active building systems designed to be as energy efficient as possible.
The project was conceived of 2019 and precedes the recent launch of the Boston Mass Timber Accelerator Program, which seeks to provide assistance and funding for the use of mass timber in the City of Boston, underscoring the development and design team's early commitment to bringing low carbon design to the booming Boston area housing market.
Location
Boston, MA
Type
Mass Timber, Multi-Family Residential
Status
Completed 2022
Details
- • 43,000 sq. ft
- • 7 stories
- • Passive House Certification pursuant
Team:
- • Haycon
- • BLW Engineers
- • H+O Structrural Engineering
- • Passive to Positive
- • Code Red Consultants
- • Charlotte Nakhoul
A Boston first: mass timber proof-of-concept
With the mass timber due to be installed on site in October 2021, 11 E Lenox will be the first ground up mass timber project in the City of Boston. The realization of a mass timber concept was culmination of proactive and collaborative efforts from the entire development team. Through precedent study, research, and visiting mass timber projects in the northeast region; the team connected with industry experts and liaisons to guide our initial fact-finding efforts through a rigorous feasibility phase, eventually leading to the final mass timber design that is implemented in the diagram below.
a practical hybrid approach
While the majority of the structure is mass timber, a hybrid approach was utilizied to meet the specific conditions of this project. A parking garage at grade, with its vehicular design and clearance restrictions, necessitated the use of 7 steel posts for structural transfer and clearance height, for which a mass timber solution would have pushed the building over the high-rise threshold.
A vast reduction: embodied carbon & operational carbon
The building utilizes several strategies and systems that work to decrease it’s overall carbon impact, holistically designed to lower both its embodied carbon footprint and its operational consumption.
12.8 kBTU/sf pEUI
81% energy reduction
the passive house building projects to use 81% less energy than a baseline building EUI of 65, according to the 2030 Challenge baseline metric
844 tons of CO2 stored
327 tons of CO2 offset
the mass timber superstructure stores 844 metric tons of CO2 during its building lifecycle, while saves 327 tons over conventional steel or concrete alternatives
2030 Challenge score, created with ZeroTool
PHIUS+ 2018 building metrics
A winning combo: mass timber + Passive House sustainable design
Passive House design seeks to lower the overall consumption of operational energy with a combination of passive and active systems, while also encouraging the use of ecofriendly materials and products that are less carbon intensive to produce. Mass timber is the ideal structural system choice in reducing a building's overall embodied carbon, and with its excellent thermal properties it also contributes in creating a robust passive building envelope that reduces thermal bridging and heat loss.
Holistic & integrated design
Utilizing a novel structural system for its vertical space utilization benefits requires proactive coordination and management of systems integration. MFDS led the design team in vetting and coordinating the various systems approaches to maximize space utilization and mitigate unknown factors and potential pitfalls/pain-points, designing efficient vertical stacks and ensuring that horizontal MEP systems ran high and tight within the structural plenum.
For this particular project, MFDS realized the a double glulam beam system provided both structural and MEP systems benefits. In addition to its architectural flexibility, the double beam system provides a 6” clear gap at gridlines, allowing for vertical MEP stacks to run in walls located along the gridlines. In more conventional steel and concrete construction, MEP verticals are typically avoided along these structural gridlines.
For this particular project, MFDS realized the a double glulam beam system provided both structural and MEP systems benefits. In addition to its architectural flexibility, the double beam system provides a 6” clear gap at gridlines, allowing for vertical MEP stacks to run in walls located along the gridlines. In more conventional steel and concrete construction, MEP verticals are typically avoided along these structural gridlines.
Conceptual imagery