Center for the Built Environment

We studied a combination of heating system measures in two large commercial officebuildings in San Francisco (110,000 and 120,000 ft 2 respectively) within a project funded by the California Energy Commission’s Public Interest Efficiency Research program. We retrofitted theexisting heating plants and updated the HVAC controls to ASHRAE Guideline 36-2021 as closely as possible while retaining the existing controller hardware. These measures decreased annual natural gas consumption by about 70 percent while also reducing HVAC electricity consumption. The results reinforce previous work showing significant natural gas reductions in 3 other buildings that underwent full controls retrofits (including controller hardware), and large savings from another 3 buildings that underwent partial controls upgrades. We show that on today’s electricity grid, which is quite dirty during the winter and early morning hours when most heating occurs, the carbon emissions reduction from these measures exceeds the reduction from fully electrifying the existing heating system’s load with today’s air-to-water heat pumps. More importantly, these solutions are mutually beneficial. Acknowledging that we also need to electrify HVAC loads to meet our climate goals, replacing controls first will reduce the size, weight, first cost, and ongoing operating cost of the subsequent heat pump installation requiredto fully electrify, and will make it more feasible to do so. This paper highlights an overlooked opportunity for enormous decarbonization in the existing commercial building stock using a solution that is available, cost effective, and scalable. We should prioritize these measures first,and then electrify, rather than focusing solely on electrification.