Open AccessThermal resistance of the ventilated air-spaces behind external claddings; theoretical definition and a parametric study
Author(s) -
Mohammad Rahiminejad,
Dolaana Khovalyg
Publication year - 2021
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/2069/1/012197
Subject(s) - cladding (metalworking) , thermal , building envelope , thermal resistance , parametric statistics , mechanics , structural engineering , materials science , airflow , envelope (radar) , ventilation (architecture) , environmental science , mechanical engineering , meteorology , engineering , composite material , physics , mathematics , aerospace engineering , radar , statistics
The presence of a ventilated air cavity between the external cladding and the wall core of a wall assembly can have a varying contribution to the thermal performance of the building envelope. In particular, the thermal resistance of a ventilated air-space is a dynamic parameter that is influenced by various thermo-physical parameters. In this study, a theoretical definition of the thermal resistance of a ventilated air-space behind an external cladding is introduced, employing a non-linear network of thermal resistances in the air-space. A numerical code is developed for the steady-state condition and verified with data from hot box tests available in the literature. Thereafter, a parametric analysis is performed based on the air change rate in the cavity (0 to 1000 1/h), type of the external cladding (brick and vinyl siding), seasonal variation (summer and winter conditions), and presence of the reflective insulation. The results are compared with a closed cavity to see the efficiency of the ventilation in the air-space. The results confirm that the theoretical thermal resistance of the ventilated air-space is a function of multiple factors, and its magnitude varies under different conditions.