For several years, systems consisting of radiant ceiling panels coupled to air-to-water heat pumps have been tested in a California laboratory house with the goal of evaluating radiant delivery as an alternative to installing ducts in conditioned space as a means of reducing distribution loss. The house includes two conventional, high efficiency air-to-air systems with ducts in conditioned space used as references for comparisons with the radiant system. Recently, an experiment was conducted at the house to determine how effectively afternoon cooling loads can be shifted by adding chilled water storage to the radiant system. The tests compared the energy and comfort impacts of two load shifting methods: precooling using a conventional air conditioner vs. incorporating chilled water storage into the radiant system. Water storage was chilled during the night, to take advantage of cooler condensing temperatures, and used to cool the house the same day during the peak cooling hours. Results showed that the radiant system was able to operate entirely off peak while maintaining more comfortable conditions and using less energy than the air-to-air system. Radiant ceiling and air-to-water heat pump systems with storage can provide utilities with the ability to leverage residential heating and cooling loads in load shifting and demand response programs without significant negative impacts on comfort or efficiency.