Energy and Buildings, 17 (1991) 7-12 7 Scale modelling of the built environment Mohammed Salah-Eldin Imbabi Department of Engineering, University of Aberdeen, Aberdeen AB9 2UE (U.K.) (Received July 24, 1989; accepted March 7, 1990; revised paper received April 24, 1990) Abstract Dimensional analysis was apphed to the design of a small-scale model building. The model was used to simulate the thermal response of a building and two-stage heating, ventilation, and air- conditioning (HVAC) system, operating under automatic control. Temperature variation, in the course of a series of heating and cooling cycles, was monitored by computer. The observed thermal response of the model was found to be fairly realistic. The modelling technique is currently being refined, and will include the effects of solar gains, humidity, and air movement. The method should offer an inexpensive and reliable means for evaluating the impact of new building materials and technologies on the built environment. Keywords: building, energy, HVAC, model, small-scale. 1. Introduction In a world of dwindling sources of conven- tional energy, the need for conservation, and hence for improved energy management pol- icies, has become the focus of considerable attention [ 1, 2]. Approximately 40% of the world's energy is used within buildings, to maintain the necessary environmental levels required for human com- fort [3, 4]. Building design must therefore take into account not only the cost of construction, but also the cost of maintenance and operation of the building throughout its useful life. Many parts of the world are subject to cli- matic extremes. In the Sudan, for instance, daytime temperatures approaching 55 °C have been recorded. Under such conditions, human safety, as opposed to comfort, is a major consideration. Energy-intensive methods of controlling the built environment, such as air- conditioning, are generally very expensive to procure and operate. Improved passive meth- ods of keeping the building cool (or warm) may offer a sensible solution to the problem. The scale modelling of a building and HVAC plant is outlined in the course of this presen- ration. This offers a useful means whereby the behaviour of the building, HVAC plant, and control system may be observed in the lab- oratory. A further incentive for using such models, as opposed to the current crop of building simulation models, is that non-con- ventional (or new) building forms, and new energy conservation strategies, can be rapidly examined and developed. In the present case, two important design criteria are: (a) the model building should be geomet- rically and thermally similar to the prototype. (b) the HVAC system should likewise com- pliment the model building. The number of parameters considered in this pilot study was limited to 23. Dimensional analysis was used to ensure that the values of these parameters, for the model, accurately reflect the properties of a real building. A series of heating and cooling cycles were used to assess the performance of the model. The results indicate that small-scale models may be used to simulate the thermal response of buildings. Quite complex phenomena, such as the thermal inertia of the building, are readily reproduced. The method has the advantage of 0378-7788/91/$3.50 © Elsevier Sequoia/Printed in The Netherlands