Heat and Hot Water for All-Electric Homes

Presented by Robb Aldrich

Scheduled for Presentation on Tuesday, May 2, 2017 (Time TBA)

In New England, all-electric homes have had a bad reputation – and this was often deserved. Older, poorly insulated homes using electric resistance heat are notoriously expensive to operate. People who own them often try to switch to a more affordable heating system using oil, gas, propane, or wood. But some big things have changed in the past decade:

  • With better building practices and codes, new homes have MUCH lower heating loads;
  • New electric equipment (especially heat pumps) can be very efficient even in colder climates;
  • To mitigate indoor air quality concerns, some try to avoid on-site fuel storage and combustion;
  • To address carbon and environmental concerns, there’s a movement to meet more energy needs with renewable energy.

With these changes, there are times when going all-electric can be both practical and cost effective. This workshop will focus on mechanical system options to meet the biggest thermal loads in homes: space heating and water heating.

Space heating discussion will focus on newer air-source heat pump (ASHP) technologies. We will begin with basic terminology and descriptions of how ASHPs operate. With this basic foundation, we’ll cover findings from some detailed evaluations of ductless heat pumps in homes around New England. Overall, ASHPs did provide the promised heat output at low temperatures, but efficiencies were generally lower than expected. We’ll also review resources available for selecting appropriate equipment in cold climates, especially NEEP’s Cold-Climate Heat Pump Specification. Attendees will learn best practices for sizing, selecting, installing, and operating ASHPs to get the most reliable and efficient performance.

The water heating portion will begin with a review of hot water consumption and conservation measures. Moving on to heating systems, we will cover several options: simple electric tanks, tankless electric heaters, solar thermal, and heat pump water heaters. The presentation will include basics of operation as well as real cost and energy data from several research & evaluation projects. Participants will learn to select the most appropriate system to match their application and project goals.

Learning Objectives

  • Learn ASHP basics and how reliably and efficiently they can provide heat in very cold weather (near or below 0°F).
  • Learn key criteria (equipment specs, sizing, installation, and operation factors) that can result in higher ASHP efficiencies.
  • Understand the capabilities and limitations of several non-fossil fuel water heating systems (including resistance, heat pump water heaters, solar thermal).
  • Learn how to select water heating systems as part of a whole-building strategy.

Intended Audience

This session may be useful to anyone interested in new systems for all-electric homes. The session will begin with enough basics that interested homeowners should find it useful, but it is intended more for building professionals: builders, designers, developers, building owners, building managers, engineers, HVAC contractors, etc.

Relevant Resources:

NEEP’s cold-climate heat pump specification:


DOE report on the cold-climate heat pump evaluations:


NEEP ASHP market strategy report:


Home Energy article on water heating in all-electric homes:


Blog posts on ASHP efficiency and best practices:


About the Presenter

Robb Aldrich, PE
Senior Mechanical Engineer
Steven Winter Associates, Inc.

Robb has been with Steven Winter Associates in Connecticut since 2000. At SWA he has specialized in building energy systems: researching new technologies, monitoring performance of systems, and working with builders and developers across the country to create better, healthier, more efficient buildings. Before joining SWA, Robb received a Master’s degree from the Building Systems Program at the University of Colorado and worked for several years designing, commissioning, and repairing solar electric and solar thermal systems.