Introduction of Specific Laws in Zonal Model to Describe Temperature Fields and Air Flow Patterns in Mixed Ventilated Buildings

Abstract

In this paper, a zonal model used to predict the air movement, temperature distribution and air quality in a room is presented. It is based on a rough partitioning of the room: It is an intermediatc approach between one-node models (that consider an homogeneous temperature in each room, and, for that reason, do not permit to predict the thermal comfort in a room) and CFD models (that require great amount of simulation time). Where plumes, jets or thermal layers occur, air flow is described by empirical laws. In low velocity domains, flow rate are calculated in respect to the pressure distribution. This air flow model is coupled with a building envelope model including the calculation of radiant and conductive exchanges. The complete model is implemented in an object oriented enviroment, SPARK, in which modelling a room consists in connecting the different pre-design elementary models. Hence, the way of modelling is very modular, so that the zonal model can now be applied to a very large field of configurations. The strict syntax of SPARK permit having the simulation automatically generated. Now, imagining the creation of a very flexible tool that allows to represent a whole building is realistic.Results of simulations in a 3D-room will be given and it will be shown that this model yields rather accurate results even with a rough partitioning.