Housing type and location are the biggest determinants of life-cycle energy demand for new housing
In Massachusetts, residential buildings account for approximately a fifth of total greenhouse gas emissions. On a per-unit basis, single family homes use [y] more energy than multifamily housing. [X percent] of statewide emissions are generated by [household transportation]; the locations of homes relative to jobs, retail, amenities, and other destinations affects levels of transportation emissions. Growth of household-related[DA1] energy demand depends in large part on the type and location of new homes.
Smaller units in multifamily homes use less energy than single-family homes
[summarize per-unit energy demand for various housing unit types (new) and sizes.
Transportation-efficient land use patterns reduce VMT and foster sustainable transportation.
Carbon emissions associated with dense, mixed-use, transit-served, walkable settlement is much lower than emissions associated with low-density, car-oriented sprawl. As shown in this map, Boston and its adjacent urban areas have lower average household carbon emissions than households than households in low-density suburbs.
{Map}
Massachusetts has hundreds of walkable, mixed use, transit-served downtowns, centers, squares, and Main Streets where dense housing can be concentrated. Massachusetts also has car-oriented growth centers where the infrastructure can be upgraded for walking, biking, and transit. The state supports zoning reform and infrastructure investment towards these ends.
40R requires districts to be in a suitable location. MBTAc requires certain percentage near transit. Other existing metrics of transportation accessibility could support more targeted zoning changes designed to facilitate low auto ownership and usage.
The Administration supports efforts to protect open space and agriculture, and to keep areas that are far from job hubs, retail spines, and civic institutions low density overall, even as they add housing diversity.
The Qualified Allocation Plan is a key state policy document that guides the allocation of federal Low-Income Housing Tax Credits within the state. It sets the criteria for awarding these tax credits to developers that build or rehabilitate affordable housing. The criteria include a focus on environmental justice and sustainability.
The Administration supports full implementation of the MBTA Communities zoning law, which requires cities and towns served by the MBTA to allow construction of multi-family housing near public transportation. The Commonwealth funds local planning efforts and infrastructure development that accommodates residential growth. The Administration also supports zoning reform that minimizes or eliminates parking requirements for new residential developments.
Compact, coordinated growth can enable innovative technologies
[Dense development can support creation of shared geothermal and perhaps other shared energy infrastructure (solar, storage, DERs/load flexibility)….]
Preventing development in carbon sequestration
[Encouraging compact development in already built-up areas can accommodate housing demand without conversion of undeveloped areas and loss of carbon sinks….]
Energy efficiency, renewables, Decarbonization and resilience investments improve long-term affordability
The state is making progress toward housing sustainability goals
[describe state’s CECP and other goals for housing sector carbon reduction. What has been accomplished in terms of residential energy consumption, adoption of efficient practices, new construction meeting certain standards. What are the results in terms of carbon reduction and reduced energy consumption/costs? What are the current areas of focus for residential efficiency and decarbonization?]
When building and energy codes change often, it’s hard for the construction industry to keep up
The 2023 Massachusetts Building Energy Code Update established three energy codes: the Base Code, the Stretch code, and the Specialized Code. The Stretch and Specializes codes are more stringent and can be adopted by individual communities on an opt-in basis. As of end of 2024, only 50 of Massachusetts’ 351 communities (accounting for less than 10% of the Commonwealth’s population) use the Base Code, while 253 have adopted the Stretch Code and 48 have adopted the Specialized Code.55
The Stretch Code requires builders to meet more stringent building performance standards. Housing in Stretch Code communities must be built to a lower Home Energy Rating System (HERS) rating than in a Base Code community (representing a more energy efficient home) or receive Passive House certification. Homes must also be pre-wired for electric vehicle charging (“EV Ready”), use energy or heat recovery ventilation, and must be solar-ready if solar PV is not installed. The Specialized Code encourages further steps towards net zero buildings, including on-site solar installation and electrification readiness for homes built using gas. Based on feedback from contractors, municipalities, and other stakeholders, these codes were also recently amended in February 2025 to increase flexibility and relax HERS requirements for homes built using low-embodied carbon materials.
State agencies and Mass Save Program Administrators continue to provide technical assistance to municipalities considering adopting the Specialized Opt-In code as well as training for local building code inspectors and contractors. Experience and training can help to dramatically reduce the cost premiums of meeting standards like Passive House. The Passive House Institute of the United States found that cost premiums decreased from +5-10% for first-time Passive House contractors to +2-4% for experienced Passive House contractors. Implementation of these different codes can add to already high housing development costs. Communities that allow more density, leverage subsidies from Community Preservation Act funds or other resources to offset development costs, reduce parking requirements, and utilize other cost savings measures can help advance both housing and climate goals more effectively.
Old Homes can learn new energy efficiency tricks
The Administration supports the retrofit of existing homes for greater carbon efficiency, and the construction of new homes that meet high standards of sustainability. Both regulations and funding, among other policy tools, support this transition. The route to net zero in the operation of homes involves greater use of insulation, solar power, electric heat pumps, and other technologies, as well as the greening of the electric grid.
The Massachusetts 2025-2027 Energy Efficiency and Decarbonization Plan includes multiple strategies to move towards decarbonization including weatherization of 174,000 homes, installation of 115,000 heat pumps, and $4.5 billion for customer incentives to improve energy efficiency. The plan provides special consideration for low and middle-income residents and their needs, as well as strategies for renters to access these benefits through supporting weatherization of 48,000 homes and the installation of 16,000 heat pumps specifically for low- and moderate-income households and investing $1 billion in paying for incentives of low-and moderate-income customers and renters.53 The work towards decarbonization has already begun throughout the state, with many agencies and corporations supporting this work.
The state, municipalities, and other institutions have several programs that support green retrofits of market-rate and affordable homes. Programs include Mass Save, Solar Massachusetts Renewable Target Program (SMART), and Home Energy Assistance Programs. The City of Boston is running the Healthy and Green Retrofit Pilot Program. The state’s Climate Ready Housing Program has been funding retrofits of multi-family housing, The Affordable Homes Act authorized spending of $2 billion to support repair, rehabilitation, and modernization of public housing units, with $150 million specifically dedicated to decarbonization. The Allston Brighton Community Development Corporation offers one model for deep energy retrofits to eliminate on-site fossil fuel combustion of affordable housing, using a diverse funding portfolio. The Massachusetts 2025-2027 Energy Efficiency and Decarbonization Plan includes multiple strategies and goals.
Energy affordability is important for housing stability
[Energy cost burden is an issue for many low income households; adds to the burden posed by rent costs….]
Nontraditional housing types and building strategies can reduce emissions
The Administration supports adaptive reuse of existing buildings, to make use of carbon already embedded in structures and reduce reliance on carbon-intensive construction materials and work. Retrofitting old buildings is more environmentally sustainable than construction of new buildings. The Administration also supports the strengthening of the factory-built modular home sector, which has potential to reduce emissions over on-site builds. Also, use of low-embodied carbon materials in construction is needed.
Resilience - Climate events are a major threat to the housing supply
Climate resilience refers to people’s ability to anticipate, prepare for, adapt to, and recover from adverse climate changes and events. For housing, this means changing how we build new homes, and adapting old homes, as well as investing in infrastructure upgrades that support and protect old and new homes alike. Massachusetts' 2023 State Hazard Mitigation and Climate Adaptation Plan, Resilient Mass, identifies rising temperatures and extreme heat, coastal and inland flooding, and severe weather (including increased precipitation, strong winds and drought) as the biggest risks to Massachusetts.
Flooding is likely to affect more areas and homes in the future
Flooding happens both on the coast and inland. Tidal and storm-related flooding is projected to increase. Most homes in the state were built before current flood protections were added to the building code. More than a fifth of residential land in the state is located in FEMA-designated flood plains – and flooding is not isolated to such areas. Only 23% of properties deemed to be at high risk of floods in Massachusetts have flood insurance.
The Administration supports local adoption of floodplain overlay districts in zoning, where buildings have additional requirements that relate to elevation and setbacks. Also, the state, regional planning agencies, and municipalities should keep floodplain maps up to date with the latest information on flooding, precipitation, and property damage.
Low-income housing, public housing, EJ Communities are more at risk than others
[describe what is known about disproporationate climate risks to certain types of housing and communities…]
Managed Retreat
[Decisions about when to not rebuild or retreat are hard
The Administration is also studying options to manage retreat, as needed.]
Extreme heat is a growing threat even in Massachusetts
Hundreds of Massachusetts residents visit emergency rooms during each heat wave. Over the last decade, approximately 30 people died per year due to extreme heat. As temperatures rise, the health risks increase. Those most at risk include the unhoused population and those without resources to install cooling equipment in their homes, among others. Residents of neighborhoods with less tree cover and more pavement are at particular risk. Massachusetts also has the second oldest housing stock in the nation (measured by the median age of buildings).
Widespread weatherization of homes, which includes improving energy efficiency through measures like insulation, air sealing, and upgrades to HVAC (heating, ventilation, and air conditioning systems) is needed. Also, tree coverage, vegetation, and other shading can also keep residential neighborhoods cooler.
Current state programs such as Mass Save make cooling solutions accessible to more households. Other financial incentives are available from the Massachusetts Department of Energy Resources. Federal and state tax credits are also available. Individual municipalities and municipal light plants might also offer resources to help. The Resilient Mass Plan recommends establishing a multi-agency team that will assess opportunities to promote cooling in residential buildings, especially to assist renters and remote workers. [Do we say something about the Affordable Homes Act offering funding to address cooling of public housing?]