Center for the Built Environment

This multi-year project generated significant new and improved software design tools and commissioning guidelines for underfloor air distribution (UFAD) systems, new performance guidelines for radiant slab cooled buildings, and an updated advanced Berkeley thermal comfort model. This final report presents detailed results in four major task areas as summarized below.

Recommended commissioning guidelines were developed for the following three key elements affecting UFAD system performance: (1) procedures for measuring, adjusting, and optimizing room air stratification; (2) a new test protocol for determining air leakage from underfloor plenums; and (3) strategies and methods for controlling and managing thermal decay (temperature gain) in underfloor plenums. Emphasis is placed on commissioning procedures that are practical and as simple as possible for use by commissioning agents, and promote energy efficient operation while maintaining thermal comfort. The guidelines were developed through a combination of field and laboratory experiments, fundamental energy simulations, computational fluid dynamics (CFD) modeling, and simplified design tool studies.

A number of improvements were made to EnergyPlus/UFAD, a version of the publicly available whole-building energy simulation program, EnergyPlus (developed under a previous PIER contract), which greatly enhanced its capabilities for modeling the more complex heat transfer processes found in UFAD systems. The improved version of EnergyPlus was in turn used as a basis for developing a more comprehensive simplified design tool for determining design cooling loads for UFAD systems, the first of its kind.

Radiant slab cooling systems were found to demonstrate strong energy saving performance and improved occupant satisfaction in dry western U.S. climates based on a combination of occupant satisfaction surveys, two case studies, and whole-building energy simulations.

The usability of the Berkeley thermal comfort model was improved by developing a user tutorial and demonstrated by conducting a case study of a building with a radiant floor slab.