Hot Thermal Storage/Selective Energy System Reduces Electric Demand for Space Cooling As Well As Heating in Commercial Application

Abstract

Based on an experimental residential retrofit incorporating thermal storage, and extensive subsequent modeling, a commercial design was developed and implemented to use hot thermal storage to significantly reduce electric demand and utility energy costs during the cooling season as well as the heating season. To achieve air conditioning savings, the system separates dehumidification from sensible cooling; dehumidifies by desiccant absorption, using heat from storage to dry the desiccant; and then cools at an elevated temperature improving overall system efficiency. Efficient heat for desiccant regeneration is provided by a selective-energy system coupled with thermal storage. The selective-energy system incorporates diesel cogeneration, solar energy and off-peak electric resistance heating. Estimated energy and first cost savings, as compared with an all-electric VAV HVAC system, are: 30 to 50% in ductwork size and cost; 30% in fan energy; 25% in air handling equipment; 20 to 40% in utility energy for refrigeration; 10 to 20% in refrigeration equipment; and space savings due to smaller ductwork and equipment.