Striking a Balance: Housing Affordability and Decarbonization in Large Multifamily Buildings


Retrofitting homes and buildings to reduce greenhouse gas emissions is a big but necessary task for Northeast and Mid-Atlantic States and cities committed to climate stabilization goals. While significant gains have been made in building new homes and buildings to zero energy or passive house design standards, fixing our existing building stock to minimize greenhouse gas emissions is quite a different challenge. It requires significant investment to replace aging cooling and fossil fuel-fired space and water heating systems with advanced heat pumps, passive solar and deep thermal efficiency that minimize the need for active heating and cooling. As cities like Washington DC and New York City move forward new minimum energy performance standards or emission caps for existing commercial buildings, the technology and market capacities to reduce building GHG emissions at scale will have a major push to develop. But what will it take to bring these technical and market capacities to decarbonize the hundreds of large affordable multifamily buildings across of Northeast and Mid-Atlantic region?

Castle Square Case Study

My recent tour of a 1960’s era large affordable multifamily building in Boston’s South End offers some important insights to tackling this challenge. In 2012 the Castle Square Apartment building achieved LEED Platinum Certification following an extensive deep energy retrofit that reduced electric energy consumption by 22.5 percent and natural gas consumption 55 percent. This seven story brick and concrete multifamily complex with 192-unit affordable apartments was initially built without wall insulation as was typical of that era. As a result, while the building provided much needed affordable housing near public transportation, Castle Square tenants suffered the discomforts and health challenges of uncontrolled thermal losses on hot summer and cold winter days, high energy bills and a loss of privacy from the noise and cooking smells that traveled from unit to unit.

In 2009, the building owner, WinnCompanies, partnered with the Castle Square Tenant Organization (CSTO) to develop a vision, strategy and plan for a deep energy retrofit to coincide with a major planned building renovation. The secret to the project success – before, during and after the retrofit - was CTSO’s involvement of the resident community from the outset to design and undertake this extensive energy retrofit to improve the quality of life of residents and reduce energy costs while minimizing disruption to tenant’s lives. Funded in part by a grant from the American Recovery and Reinvestment Act (ARRA), the partnership leveraged resources and support from the Boston Housing Authority (BHA), U.S. Department of Housing and Urban Development (U.S. HUD), the Kresge and Enterprise Foundations, Massachusetts Housing and the Department of Energy Resources, gas and electric utilities (National Grid and Eversource), and the Bank of America. The retrofit included seven key components – super insulation, air sealing, right-sized heating and cooling equipment, improved indoor air quality, solar water heating, and reduced plug load (lighting, appliances). Exterior wall insulation was two-thirds of the total energy retrofit cost of $3.4 million. Post construction, WinnCompanies and CTSO engaged measurement and verification services along with ongoing building operator training and feedback to optimize building performance and energy savings. The success of this project is reflected in the multiple awards they have won

On the tour, I was struck by the level of pride of the key partners with the success of the Caste Square Apartments deep energy efficiency retrofit as a key element of a community development project. And while this deep energy retrofit project did not include full decarbonization of heating (e.g., with efficient electrification), the process of community involvement, deep energy efficiency as a core strategy to improve the quality of life for tenants, and strategic partnerships of “co-investors” at the time of planned building renovation are important strategies to successfully and cost-effectively reduce or eliminate GHG emissions in large affordable multifamily projects. The health, comfort and safety co-benefits of the retrofit, the timing to align with planned renovation, and tenant buy-in may be just as important for market rate multifamily projects.

Replicating Success

Building on this success, CTSO with WinnCompanies was recently selected by the BHA to oversee a two-year renovation project to redevelop the Eva White Apartments, a 102-unit, low-income elderly housing community directly adjacent to the Castle Square Apartments. The renovation will substantially upgrade apartment kitchens and baths, community spaces, common areas, the laundry room, mechanical systems, life-safety systems and energy-efficiency features in the Eva White Apartments – a 50-year-old, seven-story masonry building –identical in many ways to the Castle Square Apartment complex before its 2012 upgrade. Here, again, deep efficiency is being undertaken as part of a planned renovation in a community development initiative with multiple goals to improve the quality of tenant’s lives, reduce energy waste and maintain housing affordability. Given this approach, along with several additional factors, it is possible the Eva White Apartment renovation might go even further in reducing energy use and GHG gas emissions than the neighboring Castle Square Apartments. The additional wind at their back includes the benefit of Boston city leadership committed to carbon neutrality by 2050, the new Carbon Free Boston Report from the Green Ribbon Commission and Boston University that provides a pathway to that, the assistance of the Rocky Mountain Institute’s REALIZE team to guide the Eva White project towards zero GHG emissions, and the advent of advanced heat pump technology and manufactured insulating building panels that did not exist in 2012.   

Leadership by a Community Development Corporation (CDC) offers a similar pathway to achieve deep efficiency and decarbonization in affordable multifamily buildings. The multi-year Talbot Norfolk Triangle Eco-Innovation District of the Codman Square Neighborhood Development Corporation (NDC) is working to retrofit fifteen percent of the neighborhood’s homes and increase energy efficiency in local businesses while providing jobs, improving community health and safety and preserving housing affordability. Efficiency for All provides further best practice guidance to retrofit affordable multifamily housing.  See also NEEP’s Multifamily Energy Efficiency Retrofits: Barriers and Opportunities for Deep Energy Savings.

Join us August 27-29 at the NEEP Summit – the 2019 Electrification Symposium: Pathways to Decarbonization in the Northeast for a session devoted to solving the challenge of scaling up large affordable multifamily building retrofits while preserving housing affordability and improving the quality of people’s lives.


This blog is part of Building Decarb Central, a series of blogs and other resources aimed at providing a constant flow of information on building decarbonization. Be sure to check out our web portal for more stories, resources, and information.

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