Paper Conference

Proceedings of Building Simulation 2021: 17th Conference of IBPSA


Deteriorate: a model to simulate envelope r-value fluctuations in natural porous insulation

Yasser El Masri, Tarek Sherif, Tarek Rakha
Georgia Institute of Technology, United States of America

Abstract: As the threat of climate change is exacerbated by increasing energy demand and the carbon emissions linked to it, driving down energy consumption is a goal that building professionals must seek to prioritize due to the key role that buildings play in global energy consumption. The use of insulation to drive down building energy consumption is an effective strategy in climates where a large temperature variation exists between indoor and outdoor conditions. While inorganic types of insulation may offer high resistivity (R Values) per square unit, their embodied energy might make their use pointless from a climate change perspective. Naturalbased insulations, which are typically porous, offer an insulation solution with low to negligible embodied energy. The porosity of these materials however can decrease thermal performance due to moisture build-up. Simulating these effects generally requires Building Energy Modelling (BEM) software that utilizes advanced algorithms to factor this variability. Due to the need to employ these materials more commonly and to anticipate their behavior for more informed decision-making, we propose a computationally efficient model that discretizes porous insulation into three distinct layers: Solid, Air, and Moisture. The model associates moisture build-up in the pores using material-specific Sorption Isotherms. We run a simulation using our model on a building utilizing cellulose insulation. Results show that the model is validated by matching experimental data reported by other authors in terms of thermal conductivity and RValue changes. Comparing the outcome to experimental values shows promise in mimicking thermal conductivity fluctuations in porous materials.
Keywords: Building Envelope, Variable Thermal Conductivity, Sorption Curve, R-Value
Pages: 2039 - 2046