It is important to determine the view factors between internal heat source surfaces and their environment in order to better understand the thermal radiation in rooms. With reasonable approximation to the theoretical derivation, this paper presents a simple approach to evaluate the view factors between internal heat sources and their surroundings. The approach is based on the contour-integral representation and the superposition principle of view factors. The integral intermediate value theorem is applied to reduce the complexity of calculation. The simple approach is validated through comparison with a theoretical method for several basic configurations. A comparison to numerical results obtained by the Monte Carlo method is also presented. In addition, four typical configurations between human postures and the surroundings are presented. Compared to Fanger's experimental data, the simple approach produced satisfactory results. Based on this approach, thermal radiation heat exchange between internal heat sources and their surroundings can be easily predicted with sufficient accuracy.

Units: SI