Above is an image of The Lumberyard – an affordable housing complex located in the heart of Northampton, Massachusetts. At first glance, it may look like any new apartment complex, but this building is a highly energy efficient multifamily building. The efficiency of the Lumberyard was measured using the Home Energy Rating System (HERS), a nationally recognized system for measuring and calculating the energy performance of a building. The first and fourth floors of The Lumberyard achieved a HERS score of 39 while the second and third floors achieved a score of 40. To put that into perspective, a standard new home that is built to code is typically awarded a score of 100.

The lower the HERS score, the more energy efficient a building is. Therefore, a building with a score of 40 is 60% more energy efficient than a standard new home! To increase the efficiency of a building and lower the HERS score, a builder can install energy efficient lighting systems and efficient heating, ventilation, and air conditioning equipment. A multifamily building, typically considered in Massachusetts to be a building with more than 5 units, with a HERS score as low as The Lumberyard’s can be more broadly defined as a high performance building.

Multifamily high performance buildings certainly present unique challenges in comparison to single-family high performance buildings. There are typically multiple architects, engineers, developers, and investors involved in multifamily projects, requiring that good lines of communication are established from the very start. Once the construction process begins, collaboration between different groups of people are necessary to carefully plan out the integration of efficient mechanical systems. Mark Newey, one of three HERS raters on the Center for EcoTechnology’s High Performance Building Team, states that “it’s important to catch any issues in the plans before construction starts since everything is driven off those construction documents.” Meanwhile, with single-family homes, it is much easier to fix any problems as they emerge. John Saveson, another HERS rater on CET’s High Performance Building team, agrees with Newey, saying that “multifamily buildings usually have more complex central mechanical systems that are challenging to model and test.”

Casey Simpson (left) and Mark Newey (right) conducting a blower door test on a building.

In spite of the challenges that multifamily projects present to builders and HERS raters alike, multifamily buildings are becoming increasingly popular as cities become denser and tenants seek affordable housing options. The National Multifamily Housing Council (NMHC) has a Housing Affordability Toolkit which includes a Multifamily Benefits section. NMHC highlights the environmental benefits of multifamily buildings, stating that the energy intensity of constructing an individual unit is significantly lower and that less energy is required to maintain individual units over time. As demand for multifamily buildings increase, some builders are incorporating high performance building standards to increase these benefits.

Leyden Woods Affordable Housing, ENERGY STAR-certified. The Community Builders, Inc. Greenfield, MA.

Newey has recently secured an agreement with the Valley Community Development Corporation (Valley CDC) for a 28-unit project that is striving for a Passive House certification. The goal of Passive House is to make conventional heating, ventilation, and air conditioning equipment obsolete by constructing a building that will require minimal energy to achieve a comfortable temperature year-round. CET’s High Performance Building team will be involved in every step along the way, from the diagnostic and mechanical testing up to the certification process. Newey states that he is particularly excited for this project because, while he has worked with Valley CDC over the years, this is the first Passive House project he has worked on with them. Newey has already gotten a jump-start on the process and is working on the Passive House Feasibility Study to determine the amount of insulation and the level of efficiency other features of the building will require to meet Passive House certification standards.

To learn more about CET’s high performance building services and projects, click here!