Session: 12-04-01: Heat and Mass Transfer in the Natural and Built Environments

Paper Number: 166863

Translational Dynamic Insulation System for Switchable Building Envelopes 

A large percentage of residential and commercial energy usage is spent on indoor space conditioning. This includes the heating and cooling of indoor environments to benefit human comfort. To isolate the indoor environment from the ambient, insulation is used within external wall cavities. The measure of the insulation’s ability to impede heat transfer is generally given by a standard known as the R-value. The R-value measures a material's thermal resistance, helping to compare insulation effectiveness. A higher R-value signifies better insulation performance. Wall cavities with higher R-values are generally advantageous throughout the year, but in some situations, greater thermal resistance can make it harder to regulate indoor temperatures effectively. The purpose of this research is to introduce a novel dynamic insulation system with variable R-value, capable of using exterior climate conditions to sustain a set interior temperature. The system achieves this by moving a piece of insulation parallel to the wall, which allows for a variation in the wall’s thermal resistance. As the insulation moves, a gap within the wall cavity is created, allowing for radiative and convective heat transfer between the exterior cladding and interior finishing. An increase in the width of the gap allows for greater heat transfer rates, which in turn leads to a lower thermal resistance. This technology is meant to supplement conventional HVAC technology, as the system can be operated alongside standard heating and cooling systems. The system has also been designed to be retrofitted into pre-existing wall structures. In developing the system, a thermal resistance network was created to analyze the different heat rate paths present within the system. An analytical model was constructed using custom MATLAB scripts to evaluate the proposed system. The model employs a quasi-equilibrium approach to study the individual heat rate paths within the wall cavity based upon the geometric configuration of the system. Multiple geometric configurations were analyzed, and a final layout with eight distinct heat transfer paths was chosen. This configuration allows for thermal resistance values ranging from  1.56-2.88 m² K / W (8.83-16.37 ft² F hr / BTU). This is important because, when closed, the system can achieve the highest recommended R-value for zone four of the United States, while when fully opened, much lower R-values than recommended are observed. Based upon the findings with the analytical model, a proof-of-principle prototype is being constructed to test the system’s effectiveness. The prototype consists of one dynamic wall surrounded by three inactive walls. A heavily insulated ceiling and floor cavity are also present in the setup. The energy consumption conserved will be analyzed by testing the system with and without activating the dynamic wall over a range of ambient conditions. Overall, this research shows great potential in creating a system capable of reducing commercial and residential energy expenditure as well as increasing human comfort by way of varying the thermal resistance of a dynamic wall.

 

Presenting Author: Jonathan Barber University of Tennessee at Martin

Presenting Author Biography: Jonathan Barber is a senior Mechanical Engineering student at the University of Tennessee at Martin. With a strong interest in HVAC and building technologies, he aims to pursue a Ph.D. in Mechanical Engineering to conduct novel research in this field. He has research experience in building technologies, including a summer internship at Oak Ridge National Laboratory. His work is driven by a passion for advancing energy-efficient solutions for a more sustainable future.

Authors:

Jonathan Barber University of Tennessee at Martin
Joseph Rendall Oak Ridge National Laboratory
Seyedali Seyedkavoosi University of Tennessee at Martin