Comparison of Outside Air and Sol-Air Design Temperatures for Estimating Insulation Needs

Abstract

Highlights Design air temperatures disregard ambient weather effects such as convective heating/cooling and solar radiation. Design air temperatures may not yield accurate estimates of heat transfer for broiler houses during warm conditions. The use of sol-air temperature as a design parameter could serve to optimize estimates of heat transfer. Sol-air temperatures can be predicted with historical meteorological data and used as a design parameter. This study supports the appropriateness of using sol-air temperature as a design parameter. 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: (1) to 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) to 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. Keywords: Broiler house, Design temperature, Heat transfer, Insulation, Poultry, Solar radiation, Sol-air temperature, Thermal envelope.