The high cost-effectiveness of cool storage in new commercial buildings

In new commercial buildings with demand meters, thermal storage is already cost-effective. The cheapest strategy, partial storage, displaces two-thirds of cooling demand and can displace 3 GW each year in new U.S. buildings. The more expensive strategy of full-demand avoidance can shift another 2 GW. Partial storage uses a chiller, sized to run continuously. On a summer night, the excess chiller capacity goes to storing coolth, then the next afternoon this coolth is used to supplement the chiller. (This strategy requires the samllest capacity chiller and the smallest volume storage, i.e., the least first cost.) Demand-limited storage minimizes cost of operation by installing a somewhat larger chiller, sized to be able to turn off when power is most expensive. Both chiller and storage must be about 40% larger than what is required for partial storage. Many builders will go only as far as partial storage, which has a payback of less than three years. But from the point of view of society and the utilities, full-peak avoidance will in the long run save money and power plants. We discuss the attractiveness of both strategies for the customer and for the utilities.