101: Electrification of Domestic Hot Water in Multifamily Buildings

Electrifying domestic hot water in multifamily buildings is a tough nut to crack—and one of the most critical challenges on the path to low- and zero-carbon buildings. In this session, we’ll explore the current landscape of electric DHW solutions for large multifamily projects, with a clear-eyed look at what works, what doesn’t, and where the real tradeoffs lie. Through real-world case studies, the presentation will examine system types, costs, sizing strategies, energy use, embodied carbon, mechanical space demands, metering approaches, and ongoing maintenance considerations.

Providing electric DHW at scale introduces significant technical and planning hurdles, particularly when transitioning away from fossil fuels in both new construction and existing buildings. This event is designed to help project teams better understand the options available today and evaluate whether central air-source heat pump DHW systems can realistically meet performance, space, and carbon goals. The discussion will also address how to design systems that allow for future electrification where full conversion may not yet be feasible.

Learning objectives include:

-Understanding the range of electric DHW system options for large multifamily buildings

-Evaluating opportunities and obstacles for central ASHP DHW systems in new and existing projects -Identifying key space-planning considerations and strategies for future system conversion

-Assessing a project’s feasibility for achieving net-zero carbon using central ASHP DHW systems

James Petersen, PE, is Owner and Principal of Petersen Engineering, an 18-person MEP/FP firm, with over four decades of experience designing integrated building mechanical systems. He brings a holistic approach that combines MEP design, building science, and enclosure coordination, and has served as principal-in-charge on more than 70 large Passive House projects. James currently volunteers as President of Passive House Mass and serves on the HCA Portsmouth Hospital Board of Directors.

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