Evaluating dynamic thermal performance of building envelope components using small-scale calibrated hot box tests

• Published in: Energy and buildings Vol. 251; no. C; p. 111342
• Main Authors: Shen, Zhenglai, Brooks, Adam L., He, Yawen, Shrestha, Som S., Zhou, Hongyu
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.11.2021; Elsevier BV; Elsevier
• Subjects: Building envelopes; Calibrated hot box test; Calibration; Construction; Construction costs; Dynamic thermal performance; Experimentation; Finite difference method; Full scale tests; Heat transfer; Performance evaluation; Sandwich structures; Scaled-down specimen; Testing time; Thermal properties; Thermodynamic properties; Calibrated hot box test; Scaled-down specimen; Dynamic thermal performance
• ISSN: 0378-7788; 1872-6178
• DOI: 10.1016/j.enbuild.2021.111342

[Display omitted] The hot box test method has been applied to evaluate both the steady-state (U-value) and dynamic thermal properties of building envelopes. However, the high construction cost of full-scale hot box apparatus and the testing time required (usually several days) may prevent its wider adoption. To overcome the limitations of full-scale hot box tests, this paper proposes a novel method to evaluate the dynamic thermal performance of building envelope components using a small-scale calibrated hot box and scaled-down specimen. In this paper, the scaling relationships of thermal properties evaluated using a full-size specimen and a scaled-down specimen are established based on the Laplace transform of the heat transfer equations. In addition, dynamic thermal properties obtained from scaled-down experimental tests are compared to the values calculated by the EN ISO13768 (ISO) method. A small-scale hot box with a 355 mm × 355 mm metering area was constructed and calibrated to validate the correlations. Three scaled-down concrete sandwich wall panels were then tested and the scaling relationship was cross-validated using the experimental results, finite difference (FD) simulations, and the ISO method. The results indicate that the dynamic thermal properties obtained from a scaled-down hot box test can be correlated to its full-size counterpart when certain conditions are met. The scaled-down hot box test is demonstrated to be an effective yet economical alternative to a full-scale test with significantly reduced experimentation cost and turn-around time.