From retrofitting a ranch built in the ’40s to conditioning massive multi-family Passive House developments, air source heat pumps are being selected as the primary method to heat and cool an ever-growing variety of housing stock. While this technology is remarkable in its affordability, efficiency, and ability to offset a major contributor to greenhouse gas emissions, there are often unmet challenges in selecting the most appropriate piece of equipment.

Today’s climate crisis requires us to bring innovation to every part of the construction process, including our use of existing building stock. Where older buildings can be retrofitted rather than replaced, we can reinvest embodied energy and drastically reduce first costs in building energy and carbon.

Maine Passive House (MPH) has used two different strategies in retrofitting existing homes. One strategy involves adding insulation to the outside of the building; the other strategy is to add insulation to the inside of the building. Most projects involve a mix of the two strategies. Along with added insulation and eliminating thermal bridging, MPH increases air tightness, installs high performing windows and doors, and adds mechanical ventilation systems in their projects.

As electrification grows as a tool to reach greenhouse-gas reduction goals, so do the risks of using electricity at times when it is most dirty and costly. To ensure that the benefits of long-term electrificaton of residential buildings are balanced with the short-term impacts on the grid, Massachusetts has begun testing consumer value propositions through tools like the 2017 Peak Demand Management Grant Program, Mass Save Connected Solutions, and the Clean Peak Standard.

Triple-decker homes, built in the late 19th and early 20th centuries to house immigrant workers, are an important New England housing resource. However, their energy performance is typically poor: they are often leaky, under-insulated, and heated with outdated fossil fuel systems. In this session, three organizations will describe scalable, replicable models to upgrade these iconic buildings. ABCD, which retrofits triple-deckers that house low-income individuals, will present on cost and energy savings achieved and challenges encountered.

This session will provide concrete tools and answers on how to draw down carbon in our buildings starting today. We’ll focus on low-rise buildings, where most new construction and renovations happen and which are currently under-represented in embodied-carbon design and analysis. We will present critical construction details such as band joist insulation selections and sloped ceiling retrofits, as well as whole-building design strategies.

Central ventilation systems in multifamily buildings are a vital building system with significant implications for energy, sustainability and occupant health and safety. In this session, we compare and contrast the building stock in Boston and NYC and explore a variety of techniques for restoring and improving these systems.

Urgent climate goals require state programs such as Mass Save to better target comprehensive decarbonization – applying efficiency, electrification, demand response, and solar+storage – in an equitable manner that addresses differences in local building characteristics. Meanwhile cities and towns, including low income/urban, suburban, and rural communities, are making commitments to local climate neutrality and social equity for their citizens.

Energiesprong and practitioners selected by RetrofitNY are developing standardized and scalable methods to achieve whole-building near-zero energy retrofits while maintaining multifamily tenants in place. Energiesprong, based in Europe, has successfully transformed 4,500 affordable units and RetrofitNY is currently in proof-of-concept phase.  The session will provide an introduction to standardized retrofits for multifamily housing, an overview of the best practices in Europe, and the practical implementation in the US market.

Should we be trying to electrify everything? Is it practical for existing and new buildings with the technologies we have now? Two engineers with different takes on these questions will debate electrifying residential buildings, from small single-family to high-rise apartments. Both speakers have years of experience with heat pump technologies (mini-splits, PTHPs, water-source HPs, VRF, and several types of heat-pump water heaters). They’ll present examples of buildings where these systems worked wonderfully, where performance was less than ideal, and a few absolute failures.