The Challenge: Generate Ideas for Decarbonizing Triple Deckers
Triple Deckers are one of the most predominant and widely recognized residential building typologies in Massachusetts. Tens of thousands of triple deckers were built during the late 19th and early 20th centuries across New England, with an estimated 8,900 in Boston, 4,000 in Fall River, 4,000 in Worcester, and many others in Lowell, Lawrence, and other communities. These three-story, wood framed structures consist of three apartments with generally identical floor plans and a mix of flat and gable roofs. They are typically very energy-inefficient. Many are owner occupied, some are investor owned, and many have been converted to condominums. But all share building retrofit challenges and opportunities regarding electrification and decarbonization.
About the Triple Decker Design Challenge
The Triple Decker Design Challenge harnessed building energy retrofit technical expertise and design excellence to help identify scalable renovation and electrification strategies for existing triple deckers.
The competition, sponsored by MassCEC and supported by a generous grant from the Barr Foundation, awarded prizes to various designers, developers, and students in the Commonwealth for the designs that best balanced upfront cost, long-term operational savings, and Greenhouse Gas (GHG) emissions reduction. The winning submissions offer the greatest potential to be replicated and scaled across tens of thousands of triple decker homes throughout the state and to help the Commonwealth meet its commitment of Net Zero emissions by 2050.
See the press release.
Program Accomplishments
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The Challenge stimulated scores of architects, engineers, and design professionals to focus on this important building retrofit sector and collaborate on 14 creative and practical submissions.
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The winning designs offer a variety of approaches that can be implemented on real-world buildings. Some designs include the addition of a fourth unit to the building.
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Lessons learned contributed to MassCEC’s design of the Triple Decker Retrofit Pilot, launched in 2022.
July-November 2020
Design Competition and Evaluation
Design Challenge Winners
Check out the features of these winning projects!
Details on additional submissions are provided under Program Outputs, below.
Zephyr Architects
WINNER: Triple Decker Retrofit Design
- This Triple Decker Retrofit Design provides a series of tools to help homeowners and contractors decide the most effective ways to renovate their buildings, balancing immediate costs and lifetime performance.
- Estimated construction cost: $152,149 (and $16,700 Solar PV)
- 94% decrease in annual energy use; HERS rating change: 174 to 11
- 3,500 kg CO2e embodied carbon emissions in proposed building materials
- Solar PV: 5.6 kW
- Heating & Cooling: Air-source heat pumps (ducted), Hot Water: Hybrid heat pump water heater
MERGE Architects, Inc.
WINNER: 3+ Retrofit Design
- This 3+ Retrofit Design adds an additional 3 story unit (of 1,100 sq. ft.) and additional outdoor spaces for existing tenants at the rear of the building.
- Estimated construction cost: $620,010 ($288,210 to retrofit the existing space and $331,800 to add an additional unit)
- 80% decrease in annual energy use; HERS rating change: 173 to 34
- 3,900 kg CO2e embodied carbon emissions in proposed building materials
- Solar PV: 4 kW
- Heating & Cooling: Air-source heat pumps (ductless), Hot Water: Heat pump water heater
DiMella Shaffer Associates, with RW Sullivan as consultant
WINNER: Bring Your Own Building
- This Triple Decker Retrofit Design seeks to prove that a "carbon drawdown" building is feasible and cost effective with existing technology and construction techniques by testing a replicable design and modeling approach which prioritizes a low-infiltration Passive House envelope, thermal comfort, and resiliency.
- Estimated construction cost: $326,408 (and $42,000 for Solar PV)
- 92% decrease in annual energy use; HERS rating change: 176 to 15
- 2,200 kg CO2e embodied carbon emissions in proposed building materials
- Solar PV: 10 kW
- Heating & Cooling: VRF heat pump, Hot Water: Heat pump water heater
Gunnison Company
WINNER: Student Prize and People's Choice Award
- This Triple Decker Retrofit Design focuses on making a net zero renovation as compelling as possible to an owner by aligning the project incentives with their tenants and providing the most cost efficient-solution.
- Estimated construction cost: $247,464
- 2,800 kg CO2e embodied carbon emissions in proposed building materials
- Solar PV: 17.1 kW
- Heating, Cooling, & Hot Water: Air-to-water heat pump
Past Program Details
Notable Program Features
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The Design Challenge sought replicable, scalable designs for all-electric energy retrofits with attention to both construction and operational costs.
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The competition offered two tracks:
A. “Triple Decker Retrofit Design”, focused on retrofitting a typical triple decker building using the existing building square footage; and/or
B.“3+ Retrofit Design” focused on retrofitting a typical triple decker while also adding additional unit/units. This track provided opportunities to deliver additional value and income to the building owner while addressing regional housing supply shortages.
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Embodied carbon was incorporated in the judging criteria.
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For baseline, participants could use either of two standard buildings with provided drawings and construction details, or “bring their own” building.
For details of the Challenge, please refer to the Invitation for Proposals and associated documents.
Application Materials
Triple Decker Retrofit Designs Webinar
MassCEC and the Boston Society of Architects co-hosted this webinar to introduce the retrofit designs submitted to the 2020 Triple Decker Design Challenge. Enjoy opening remarks by Kevin O'Connor from This Old House!
Program Outputs and Resources
ZH Architects
RUNNER-UP: 3+ Retrofit Design
- This 3+ Retrofit Design renovates an existing triple decker and in the side yard adds two additional prefabricated modular townhouses (of a total of 2,400 sq. ft.), that can be customized in unit size and coun to reflect the needs of the owner.
- Estimated construction cost: $722,844 ($233,644 to retrofit the existing space and $489,200 to add additional unit(s))
- 86% decrease in annual energy use; HERS rating change: 173 to 24
- -6,892 kg CO2e embodied carbon emissions in proposed building materials
- Solar PV: 15 kW
- Heating & Cooling: VRF heat pump, Hot Water: Heat pump water heater
Utile, Inc.
RUNNER UP: Triple Decker Retrofit Design
- This Triple Decker Retrofit Design, Plug-in +, is a holistic retrofit design approach that prioritizes resilient systems, locally available labor and materials, and minimal resident disruption.
- Estimated construction cost: $352,369 (and $38,606 for Solar PV)
- 84% decrease in annual energy use; HERS rating change: 173 to 27
- 14,000 kg CO2e embodied carbon emissions in proposed building materials
- Solar PV: 9.125 kW
- Heating & Cooling: Air-source heat pump (ductless), Hot Water: Electric resistance tank
West Faulkner and PlaceTailor
RUNNER-UP: 3+ Retrofit Design
- This 3+ Retrofit Design adds an additional unit (of 1,313 sq. ft.) to the top of the building. This design gets a triple decker to Zero Energy and pays for itself with added leasable space and future energy savings.
- Estimated construction cost: $699,875 ($338,800 to retrofit the existing space and $361,075 to add an additional unit)
- 104% decrease in annual energy use; HERS rating change: 107 to -5
- 18,000 kg CO2e embodied carbon emissions in proposed building materials
- Solar PV: 21.6 kW
- Heating & Cooling: Air-source heat pump (ductless & mini-splits), Hot Water: Solar assisted electric heat pump
Leupold Brown Goldbach Architects & Scott Payette Architects
RUNNER-UP: Triple Decker Retrofit Design
- This Triple Decker Retrofit Design emphasizes maximizing quality of life and increasing property values through three minimal, intelligent interventions: creating additional indoor and outdoor living spaces, tightening the building envelope, and eliminating operational costs with on-site photovoltaic panels.
- Estimated construction cost: $331,731
- 104% decrease in annual energy use; HERS rating change: 173 to -7
- 1,600 kg CO2e embodied carbon emissions in proposed building materials
- Solar PV: 18.2 kW
- Heating & Cooling: Air-source heat pump (ductless), Hot Water: Heat pump water heater
OPAL + TIMBER HP
HONORABLE MENTION: Lowest Embodied Carbon
- This Triple Decker Retrofit Design employs a carbon-sequestering, modular systems of building shell improvements to deliver net-zero energy performance with a negatve carbon footprint.
- Estimated construction cost: $424,509 (and $27,500 for Solar PV)
- 86% decrease in annual energy use; HERS change: 174 to 24
- -7,277 kg CO2e embodied carbon emissions in proposed building materials
- Solar PV system: 6.5 kW
- Heating & Cooling: Air-source heat pump (ductless), Hot Water: Air-to-water heat pump
University of Massachusetts, Amherst
HONORABLE MENTION: Most Innovative Design
- This Triple Decker Retrofit Design emphasizes continuous exterior insulation, maximum use of recycled materials, and innovative thermoelectric façade systems for all heating and cooling.
- Estimated construction cost: $329,952 (and $34,000 for Solar PV)
- 95% decrease in annual energy use; HERS rating change: 173 to 9
- 8,500 kg CO2e embodied carbon emissions in proposed building materials
- Solar PV: 10.1 kW
- Heating & Cooling: Thermoelectric Façade system, Hot Water: Heat pump water heater
DRAW Architecture + Urban Design
CATEGORY: 3+ Retrofit Design
- This 3+ Retrofit Design adds an additional unit (of 723 sq. ft.) in the basement of the building. The DRAW retrofit compliments the historical frontage with a renovated multi-faceted facade system, quickly becoming state-of-the-art while staying true to its design details both in its exterior and interior.
- Estimated construction cost: $512,297 ($465,302 to retrofit the existing space and $46,995 to add an additional unit)
- 61% decrease in annual energy use; HERS rating change: 174 to 67
- 15,000 kg CO2e embodied carbon emissions in proposed building materials
- Solar PV: 17.6 kW
- Heating & Cooling: Forced air electric furnace, Hot Water: Solar Hot Water
Sustainable Energy Analytics
CATEGORY: Triple Decker Retrofit Design
- This Triple Decker Retrofit Design focuses on improving the building envelope through reducing infiltration, proper compartmentalization, and increasing insulation and utilizing high-efficiency systems.
- Estimated construction cost: $529,564
- 79% decrease in annual energy use; HERS rating change: 297 to 34
- -261 kgCO2e embodied carbon emissions in proposed building materials.
- Solar PV size: n/a (not part of initial design, but the roof is designed to be solar ready for the future)
- Heating & Cooling: Air-source heat pump (ductless), Hot Water: Heat pump water heater
Design Build Boston Construction LLC
CATEGORY: Triple Decker Retrofit Design
- This Triple Decker Retrofit Design focuses on providing the owners the renovation tools necessary to achieve a net-zero home with concentration on tenant benefits.
- Estimated construction cost: $405,306 (and $57,458 for Solar PV)
- 80% decrease in annual energy use; HERS change: 173 to 34
- 18,000 kg CO2e embodied carbon emissions in proposed building materials
- Solar PV: 18 kW
- Heating & Cooling: Air-source heat pump (ductless), Hot Water: Electric water heater
Jayson Taylor - Carbon Cutters, LLC
CATEGORY: Triple Decker Retrofit Design
This Triple Decker Retrofit Design focuses on air-sealing a flat attic roof.