A simple, yet correct and powerful, method of estimating the radiation performance of single spaces or of two coupled spaces is developed. This method is particularly useful for simplified numerical simulations of average lighting conditions and of radiant contribution to the heat balance of buildings. The article develops an example of the method and analysis of a room with an attached sunspace. The method is based on the properties of form factors. The form factors of two spaces coupled by radiation exchange are reduced to the form of a collapsed matrix. The form factors for each space are reduced to a 2 × 2 matrix subject to the principle of energy conservation. Radiation from one space is reflected from the surfaces and transmitted from one space to the other repeatedly in an infinite series. The result of the infinite series is obtained in explicit form for both the radiosity and the distributed form factor matrices. A parametric study of the interaction of a room with an attached sunspace is carried out explicitly. The results show a very weak dependence of the room absorptance on the surface reflectance and a very strong dependence of the illumination of the room on the same absorptance.

AUTHOR: Francisco Arumí-Noé, Ph.D.
CITATION: Thermal Performance of the Exterior Envelopes of Buildings VII
KEYWORDS: December, Florida, 1998
YEAR: 1998