In order to create a simulation model of a building, it is usually necessary to make a number of assumptions and/or approximations about the building being simulated. Many physical quantities cannot be known precisely when the building is being simulated. For example, the real amount of infiltration is almost never known because it is impossible to predict accurately and difficult to measure. Other examples include quantity and type of internal mass, thermophysical properties of building materials, ground temperatures, and equipment efficiencies.
In thermal simulation codes for buildings, aeraulic transfers are computed either with very simplified models (fixed air distribution) or with sophisticated models (based on the computation of the pressure fields). The simplified models are not accurate enough and the sophisticated models are too complicated for only thermal computations. An intermediate model has been developed. This new model is based on the computation of the temperature fields and on the knowledge of an average air distribution due to air leakage and specific ventilation.
Much research has been directed towards development of software environments that allow easy construction of building simulation models of widely varying structure and purpose. For example, TRNSYS has been in use for a number of years. Recently, several new such environments have been proposed. In spite of a considerable variation in model description formats among environments, the underlying mathematical models of physical processes are very similar.
This papers introduces an emulation system for simulation of the thermal process of building and plant named ESAC (Emulation Set for Air-Conditioning systems) developed in 1984, and a prototype system was presented in 1985 (1), since then a great progress has been made and several applications have been explored.