4686 – Sensitivity Study of Slab-on-Grade Transient Heat Transfer Model Parameters PDF

Heat transfer between a building and its surrounding soil is a complex and transient phenomenon. Due to the unknowns and long time scales involved, predictions of the heat transfer rates to and from buildings via their ground contact tend to be somewhat or significantly inaccurate. Physical experiments with an actual building over a short time period give good insight into its long-term thermal characteristics, but due to variations in building operation and weather conditions, long-term predictions will vary from the actual heat transfer rates. For buildings yet to be constructed, modeling of the ground-coupled heat transfer can give reasonable time-averaged first-order predictions if the input data are sufficiently accurate. However, due to the range of variables involved and the unknowns, such as actual subgrade site conditions and future weather, these models can give very inaccurate results too. This paper presents the results of a sensitivity study on some of these variables. These conditions and a detailed slab-on-grade construction were examined using a fully transient FORTRAN code that evaluated heat transfer over an entire typical weather year.

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