STP922: In Situ Measurement of Wall Thermal Performance: Data Interpretation and Apparatus Design Recommendations

    Modera, MP
    Staff scientists, Energy Performance of Buildings Group, Lawrence Berkeley Laboratory, University of California, Berkeley, CA

    Sherman, MH
    Staff scientists, Energy Performance of Buildings Group, Lawrence Berkeley Laboratory, University of California, Berkeley, CA

    de Vinuesa, SG
    Research scientist, Ciudad Universitaria, Madrid,

    Pages: 16    Published: Jan 1987


    Abstract

    Although the U values of many building materials have been determined by laboratory testing, the in situ thermal performance of walls, under either static or dynamic conditions, is not so well documented. This report examines the use of field measurements of heat flow and surface temperatures to determine the dynamic as well as static thermal performance of walls. The measurement strategies examined include both active devices, which generate their own heat fluxes on the wall surfaces, and passive devices, which rely on the weather to induce the required fluxes and temperature differences. Data obtained with both devices are analyzed with the simplified thermal parameter (STP) model, which was designed to characterize a wall from flux and temperature measurements rather than from assumed material characteristics. The active measurement data are also analyzed with a modified version of the STP model that takes into account lateral heat losses. Some possible sources of error for both active and passive measurement strategies are also examined, and recommendations for both measurement strategies are given.

    Keywords:

    walls, dynamic response, heat transfer, in situ, measurement, U, value, R, value, time constant, periodic heat flux, Fourier transform, thermal insulation


    Paper ID: STP18476S

    Committee/Subcommittee: C16.30

    DOI: 10.1520/STP18476S


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