Energy saving and economic analysis of a new hybrid radiative cooling system for single-family houses in the USA

Radiative cooling has received much attention as it generates “free” cooling to buildings and helps reduce energy consumption of mechanical air conditioning systems. However, most current radiative cooling materials either work for nighttime (nocturnal) cooling only or have high cost issues. A novel scalable-manufactured randomized glass-polymer hybrid metamaterial coated with silver has recently been developed and reported a 110 W/m2 cooling power on daily average. This metamaterial potentially provides passive cooling for both nighttime and daytime. Proposed is a hybrid diurnal radiative cooled-cold storage cooling system using this metamaterial for air conditioning purposes in single-family houses. Because single-family houses have a relatively low cooling load but high ratio of roof area to floor area, they are excellent end users of the hybrid radiative cooled-cold storage cooling system. The potential energy savings of the hybrid radiative cooled-cold storage cooling system in a typical two-floor single-family house with floor area of 204 m2 have been modeled using EnergyPlus for four locations in the U.S., including Orlando, FL, San Diego, CA, San Francisco, CA, and Denver, CO. In comparison with the electricity consumption of a split air conditioner alone, the hybrid radiative cooled-cold storage cooling system could save annual cooling electricity by 26% to 46% for the modeled locations, under a restriction of 8-year payback period. The corresponding simple payback periods for adoption of the hybrid radiative cooled-cold storage cooling system fall in a range of 4.8-8.0 years and the maximum acceptable incremental costs are $50.0/m2-$78.9/m2. The diurnal working hybrid radiative cooled-cold storage cooling system may provide a cost-effective solution for radiative cooling technology in residential building applications.