Climate surfaces: a quantitative building-specific representation of climates

Based on the power balance equation, an analytical tool for the calculation of the free-run-temperature of a room has been developed and a universally valid energy-strategy derived. The description of the thermal behavior of a room is traced back in this approach to three parameters only: the generalized loss-factor K, the time constant tau and the gain-to-loss ratio gamma. By an appropriate inclusion of solar gains the usual definition of 'heating-degree-days' is extended to 'generalized heating-degree-days', represented graphically as a function of tau and gamma. These two parameters yield the 'climate surface' of the room under consideration, A comparison with measured data from actual buildings confirms the validity of this approach. In order to illustrate its practical value, the method of climate-surfaces is applied in this paper to generate surfaces for design-temperature differences and to deduce optimized heating, cooling and control strategies, as well as strategies for the night set back, solar shading, night cooling etc. (C) 1998 Elsevier Science S.A. All rights reserved.