PNNL

Abstract

Efficiently managing energy usage to balance supply and demand on the power grid has become increasingly crucial, especially with the widespread deployment of distributed variable renewable electricity generation. This research paper introduces two duty-cycle control methods for heating systems, involving adjusting thermostat set points to limit and shift electricity demand. The control approaches employ innovative techniques, such as adaptive duty-cycling, to prioritize household thermal comfort while reducing peak demand. These control methods can respond to signals from the electric power grid, including demand targets and time-of-use tariffs, and were tested physically on an electric furnace and heat pump in a test home during winter conditions in 2021 and 2022. The results are given as average demand reductions and energy use impacts with respect to the average indoor-outdoor temperature difference during the control period. Heat pump findings reveal power reductions of 18.5\% and 23.3\% in 4-hour tests of demand limiting control for differences between the indoor setpoint and outdoor temperature of 30\degree{F} and 40\degree{F}. Demand shifting tests based on preheating the indoor space showed heat pump power reductions reached 34.8\% and 33.2\% respectively for the same indoor-outdoor temperature differences. Similar demand limiting tests on electric furnaces yielded power demand reductions of 33.8\% and 25.3\% under average indoor-outdoor temperature differences of 30\degree{F} and 40\degree{F}, respectively, while preheating-based demand shifting tests showed much greater average power reductions of 56.0\% and 45.7\% respectively for the same differences between the indoor setpoint and outdoor temperatures.