A comparative assessment of two HVAC plant modelling programs

A comparison is made between two thermal simulation modelling programs with particular reference to HVAC plant modelling. The two programs, APACHE and TRNSYS, were set up using identical building data, plant data and the same meteorological database. A seven zone constant air volume system with a further four heated and naturally ventilated zones was considered. Hourly time series results of a variety of plant and zone air conditions for a three-day winter period and three-day summer period were compared; each period containing a substantial plant shut down phase. Certain groups of results compared very well indeed - most notably zone air-conditions in winter, whilst comparative zone air and plant air conditions in summer contained some significant inconsistencies.