OT-88-15-1 (RP-453) -- Thermal Transmittance of Opaque Building Assemblies PDF

This paper presents the methods used to develop the ASHRAE "Manual of Heat Transmission Coefficients for Building Components" under ASHRAE Research Project RP-453. The analytical methods used to evaluate the steady-state hot box test results are described, especially the thermal analysis building assembly (TABA) heat transfer computer program that was used as the criteria for acceptance of the experimental hot box results. The computer program is capable of analyzing the heat flow through opaque building assemblies (walls, roofs, ceilings, and floors) that are bounded by hot and cold air masses. The building assembly can be made of various building materials and may also include enclosed air spaces. In all situations except for concrete block products, the thermal properties (solid thermal conductivity, air space thermal resistance, air surface heat transfer coefficients) used were taken from the appropriate values given in Chapter 23 of ASHRAE Fundamentals unless they were measured experimentally in conjunction with the hot box tests. In most cases the analytical results compared quite well with the experimental data (within the ± 10% acceptance criteria). The experimental results were then modified to have standard ASHRAE air surface heat transfer coefficients included in the reported thermal transmission coefficients for use in the manual. Examples of the resulting manual data sheets for four building assemblies and recommendations relative to the need for improved thermal property data are presented.

Units: I-P