Beth Israel Auxiliary Building
Client
Beth Israel Congregation
Year
2025-2026
Location
Ann Arbor, MI
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Inclination Engineering helped Beth Israel Congregation turn a 2023 electrification study into a practical mechanical upgrade for their 2010 Washtenaw auxiliary building. The building is a converted two-story house used for classes, meetings, and events. Completed in 2026, the project replaced aging furnaces and air conditioners with hybrid heat pumps. The heat pumps use electrified heating to reduce greenhouse gas emissions most of the heating season. Gas furnaces serve as backup heat during very cold weather which avoided costly electrical service upgrades. The design also improved indoor air quality by adding Energy Recovery Ventilators that deliver fresh air only when the building is occupied, using heat recovery to improve energy efficiency.
$0 Upgrade
ELECTRICAL SERVICE
The new heat pumps' draw matches the air conditioners they replaced. Expensive underground electrical service upgrade avoided.
One-for-One
FURNACE REPLACEMENT
Hybrid heat pump furnaces sit where the old ones did, on the same ductwork. Electric heat most of the year, gas only in the coldest weather.
4×
WATER HEATER EFFICIENCY
A heat pump instead of a gas unit: no new circuit, one less gas line, and free dehumidification as a bonus.
0°F → 52°F
VENTILATION AIR
Energy recovery ventilators preheat incoming fresh air using exhaust air, and run only when the building is occupied.
Study – Design – Construction
In 2023 Inclination Engineering studied electrified replacement options for the 2010 Washtenaw Building and Beth Israel Congregation’s (BIC) Synagogue. The leadership team considered the recommendations, reviewed them with the congregation, and built a capital campaign. The design phase for the 2010 Washtenaw upgrades began in 2025, and were completed in the summer of 2026, in time to use the auxiliary building as swing space before renovating the main synagogue.
Previous under-performing ventilation relied on negative pressure in furnace’s return duct.
Hybrid Heat Pumps – An Affordable Solution for a Small Building
The 29-year-old furnaces and air conditioners were replaced with hybrid heat pump furnaces. These units look identical to a typical furnace and AC combination. However, the outdoor unit is a heat pump and will provide heating down to around 25 °F. When it is cold enough that the heat pump cannot provide enough heat, the gas furnace will automatically take over.
Electric heat coils were not a viable backup heat source for this building because of the limited electrical service size. The building’s main electrical connection is buried under a parking lot and upsizing it would have added significant costs. While the solution is not fully electrified, it provides significant greenhouse gas emission reductions at an affordable price.
The backup furnace and blower are in the dark gray housing in the lower right with a heat pump heating and cooling coil above.
Improving Ventilation
Energy Recovery Ventilators (ERVs) provide regulated fresh air for improved ventilation.
Another goal of the mechanical upgrades project was to improve the building’s ventilation so that it delivered the code required amount of fresh air when the building was in use. The furnaces had a typical setup with fresh air ducts connected to the return duct. This provides a pathway for air to enter, but does not control the amount and it does not provide a pathway for exhaust air to leave. This setup typically underdelivers on the amount of fresh air needed for a commercial building.
The upgraded system uses an Energy Recovery Ventilator (ERV) for each furnace to provide preconditioned, code required, fresh air flows. The ERVs have two fans and an energy recovery core where the fresh air and exhaust air pass through small channels. In the winter, the warm exhaust air preheats the cold fresh air from 0 °F to 52 °F. This significantly reduces the heating load on the heat pumps. An occupancy sensor triggers the ERVs to run only when the building is in use. During other times, the fans are off and mechanical dampers prevent warm air from escaping the building. This control was especially helpful since the building’s use schedule changes week-to-week.