A planned 78-apartment affordable housing development in Northeast Portland will use geothermal energy to heat and cool residents’ homes, a design intended to limit utility expenses and support housing stability. The Sandoval development will use a closed-loop system that circulates water through pipes extending about 600 feet underground. The system draws on the relatively steady temperature below ground to help regulate indoor temperatures, said Sander Kohler, an architect with Scott Edwards Architecture. The apartments are intended for households earning 50% to 60% of the area median income. Sabin Community Development Corp., the Portland nonprofit behind the project, plans to pay the building’s utility bills rather than pass those costs on to tenants, said Nathalie Hansen of the organization. Residents “never have to choose between turning the heat on and putting food on their table,” Hansen said. She said covering utilities could make monthly expenses more manageable and reduce the risk that unpaid bills lead to housing loss. The geothermal equipment takes up less roof space than conventional heating and cooling systems, leaving room for more solar panels. Hansen said the added solar capacity will help support the nonprofit’s plan to hold the utility accounts in its name. Project officials say the geothermal approach would be a first for the Portland area and could inform future housing projects. “It’s not a commonly used system, but it’s a great testing ground,” Kohler said. Project information estimates the geothermal equipment could last 50 to 100 years, compared with 15 to 20 years for conventional systems. The geothermal portion is funded by the Portland Clean Energy Fund; Metro, the Portland Housing Bureau and other partners are also contributing to the housing development. The building is expected to open in 2028.