Applying Natural Cooling to Slab Floors

Richard C. Bourne and Marc A. Hoeschele, Davis Energy Group, Inc.

Keywords

Abstract

“Natural cooling” systems use evaporative or night sky radiative processes to cool water for building comfort conditioning. Hydronic tubing in concrete floors facilitates operation of the natural cooling source at night when wet-bulb temperatures are lowest. Heat is thus discharged from the concrete slabs at night, and the cooled slab passively cools the building the next day. The major benefits of natural slab floor cooling are reduced (or eliminated) compressor energy consumption, reduced peak demand, and reduced blower operation for forced air cooling delivery.

This paper reviews the design and operation of three Northern California projects completed in 1997 and 1998, each using a different approach to natural cooling via the slab. All three were monitored with financial support provided by Pacific Gas and Electric Company through California public goods charges. Monitoring work evaluated key issues for these systems including performance, economics, water use, maintenance, and latent cooling. After summarizing the projects, the paper compares them and discusses their relative merits.