Comparison of outside air and sol-air design temperatures for estimating insulation needs

Authors: CHESSER, D - Mississippi State University; Purswell, Joseph - Jody; DAVIS, J - Auburn University; WARD, J - North Carolina State University; TABLER, G - University Of Tennessee; ZHAO, Y - University Of Tennessee

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/23/2023
Publication Date: 9/15/2023
Citation: Chesser, D.G., Purswell, J.L., Davis, J.D., Ward, J.K., Tabler, G.T., Zhao, Y. 2023. Comparison of outside air and sol-air design temperatures for estimating insulation needs. Transactions of the ASABE. 39(4): 409-416. https://doi.org/10.13031/aea.15424.
DOI: https://doi.org/10.13031/aea.15424

Interpretive Summary: Thermal stress adversely affects poultry production efficiency, health, and welfare. Poultry house insulation requirements are typically specified based on engineering design air temperatures, which disregards ambient weather effects such as convective heating and cooling, and solar radiation. Sol-air temperature provides a simplified method to estimate exterior surface temperatures and subsequent heat transfer through walls using meteorological data. Ambient air, exterior surface temperatures, and solar radiation were recorded during two warm season periods (May and September) for an east facing sidewall of a broiler house in northern Alabama and used to calculate sol-air temperatures. Maximum daily surface and sol-air temperatures were significantly hotter than maximum air temperatures. Maximum surface and sol-air temperatures were not different during the monitoring periods. Additionally, simulations of conductive heat gain or loss using air and sol-air temperature were performed for a model broiler house located in ten different regions in the United States during daytime warm conditions using historical meteorological data. Conductive heat transfer calculated using sol-air was considerably higher than when using air temperature, indicating that using current methods to size insulation, heating, and ventilation for broiler houses may result in inadequate thermal insulation. Sol-air temperature provides improved estimates of conductive heat transfer during daytime conditions and allows for more accurate specification for broiler house insulation needs.

Technical Abstract: Thermal stress adversely affects poultry production efficiency, health, and welfare. Poultry house insulation requirements are typically specified based on engineering design air temperatures, which disregards ambient weather effects such as convective heating and cooling, and solar radiation. The objectives of this study were to: 1) Monitor external temperatures of a commercial broiler house to verify the suitability of using sol-air temperature as a design parameter for broiler housing design; 2) Use the sol-air temperature to simulate the effects of solar radiation on conductive heat gain during warm weather for a modeled broiler house in varying climatic locations using historical meteorological data. For two 7-day warm season periods (September and May), ambient air, exterior surface temperatures, and solar radiation were recorded for an east facing sidewall of a broiler house in northern Alabama and used to calculate sol-air temperatures. For both periods, maximum daily surface (Tsurface) and sol-air (Tsol-air) temperatures were significantly elevated (P<0.0001) as compared to maximum ambient air temperatures (Tair). Maximum Tsurface and Tsol-air were not significantly different for September (P=0.2144) and May (P=0.1544), respectively. Additionally, simulations of conductive heat transfer (gain/loss) using Tair and Tsol-air were performed for a model structure located in ten different broiler regions in the United States during daytime warm conditions using historical meteorological data. For each simulation, conductive heat transfer calculated using Tsol-air was considerably higher when compared to conductive heat transfer calculated using Tair. Methods currently used to specify design temperatures for broiler house design and construction can result in inadequate thermal insulation and Tsol-air provides improved estimates of conductive heat transfer during daytime conditions.