Modeling peak load reduction and energy consumption enabled by an integrated thermal energy and water storage system for residential air conditioning systems in Austin, Texas

• Residential air conditioning (AC) often drives peak load on electric grid in Texas.
• Condenser-side thermal storage model developed for residential AC systems.
• Model estimated on-peak load reduction from air conditioners in range of 29–53%
• Model estimated total energy consumption increase of approximately 5–15%.

This paper discusses the development of a model for evaluating peak load reduction and change in overall energy consumption for a residential air conditioning (AC) compressor with and without condenser-side thermal storage. Stored rainwater (or any other type of on-site water storage) could be utilized as a heat sink for the condenser during peak hours, allowing for more efficient and lower power compressor operation, then re-chilled at night during off-peak hours. The system evaluated in this manuscript is referred to as ‘integrated thermal energy and rainwater storage’ (ITHERST).The model used simulated cooling load data for a typical home in Austin, Texas, based on summer 2011 historical and typical meteorological year (TMY) datasets. The analysis suggests that the ITHERST system with 3785–18,925 l of water could reduce on-peak compressor power demand by approximately 29–53%, as compared to a traditional AC with an air-cooled condenser. However, total compressor energy consumption increases 5–15% because of the inefficiencies of re-cooling the thermal mass, but this additional energy consumption occurs during low demand off-peak hours. System performance varied depending on weather data, the individual compressor, and thermal storage volume.