Energy, power, and office buildings : design and analysis of an off-peak cooling system using structural mass storage

Abstract

As the electric utilities face ever increasing peak power production requirements, (mostly from the commercial sector) scheduled "time-of-day" pricing schemes have become imperative. At present, most conservation strategies for commercial buildings focus on the reduction of energy consumption orchestrated (justifiably) by t he expense of electrical energy for lighting and cooling which dominate their loads. However, these conservation schemes, such as higher efficiency lamps, various glazing techniques, etc., do not alter the time of consumption nor do they utilize the lower off-peak electrical rates. The results are as before; high energy costs due to peak (daytime) consumption, and projected savings from the various conservation strategies are overshadowed or not realized. This thesis investigates a decentralized off-peak cooling system for commercial office buildings utilizing the structural mass as the thermal storage medium. The system incorporates an exposed concrete ceiling slab cooled at night with imbedded chilled water pipes and taking full advantage of off-peak electrical rates. The ceiling/slab - waterpipe system is modeled via two-dimensional finite difference methods for transient analysis. The sensitivity of the system to pipe size and spacing, internal loads, water temperatures, and surface geometry is assessed. The analytical results suggest the potential for application, however, additional research must be undertaken to investigate the economic implications of fabrication and to more adequately determine the effects of non-planar surface geometry.