Center for the Built Environment

This paper presents a new spreadsheet-based cooling load design tool for underfloor air distribution (UFAD) systems developed by the Center for the Built Environment at University of California, Berkeley. After briefly reviewing previous UFAD design tools, the main characteristics of the tool are described: transformation of the zone design cooling load calculated for a standard overhead (OH) mixing system into the design cooling load for a stratified UFAD system, splits of the total UFAD cooling load into three fractions, supply plenum (SPF), zone, or room, (ZF), and return plenum (RPF); prediction of the thermal comfort in a vertically stratified environment, air temperature profiles and setpoint temperature at the thermostat; modeling of air diffusers; prediction of the design airflow rate; and modelling of commonly used plenum configurations. A practical example is reported at the end of the paper. The design tool and detailed user notes are available at: .