Paper Conference

Proceedings of eSim 2018: 10th Conference of IBPSA-Canada


Investigating the Thermal Performance of Expanded Polystyrene as a Function of Core Temperature using Static and Dynamic Thermal Conductivity Values

Tyler Kenneth Ulmer, Alex Hayes, Brock Conley, Christopher Baldwin, Cynthia Ann Cruickshank

Abstract: When designing and modelling building enclosures, static values for the thermal conductivity of wall materials are used. However, in practice the thermal conductivity of insulating materials is dynamic and increases as temperature increases. Failing to account for the dynamic properties of insulation can introduce errors into the performance simulation of buildings. This paper investigates how the thermal resistance and performance of an expanded polystyrene (EPS) insulation panel varies as a function of core temperature. In order to accomplish this, a guarded hot plate was used. The relationship between thermal conductivity and core temperature was then combined with the Canadian Weather for Energy Calculation data to understand how using a dynamic value for thermal conductivity versus using a static value will affect the heat transferred across the building enclosure. This comparison was accomplished by approximating a wall section using a simplified resistance network model. The results show that considering a dynamic RSI value for EPS results in a 5% difference in predicted yearly heating loads for homes in cold climates such as Ottawa and Edmonton.
Keywords: Thermal conductivity, RSI value, building envelope, uncertainty, material properties, heat transfer
Pages: 568 - 574