Real controllers in the context of full-building, whole-year simulation

Study of complex control strategies plays an increasing role in building design. Discrepancy between the intentions of the designer, often expressed as nonformalized control laws, and the as-built implementation is a frequent source of malfunction and energy waste. Two approaches to remedy this problem in the context of equation-based, full-building, whole-year simulation are treated: (1) The availability of Modelica based libraries of functional blocks for typical objects such as integrator, gain, PID-controller and time-delay in a general system simulator enables offline testing and tuning of realistic control systems. (2) Efficient implementation of algorithmic discretetime controllers enables direct simulation of complex control algorithms described with the same source code in the simulator as in the real controller. The first approach is discussed and illustrated briefly. While not available in traditional building simulation environments, such block libraries have been available in other simulation domains for several years already. The second approach is treated more thoroughly,  since special methods are needed for buildings, where controller sampling interval is much smaller than the typical timescales of the equationbased building model itself. Initial implementation and testing of a new simulation approach is presented.