Modelling and simulation of building energy elements

A building energy system comprises building construction elements, hygro-thermal energy transfer processes or a combination of physical elements and processes. This chapter deals with explaining the various methods used to develop building energy system models and ways to analyze developed energy models. Energy transfer equations for a multi-layered building construction element are represented, and thermal resistor-capacitor networks are used to represent the element model. Reducing the order of the model and parameter estimation methods are also discussed. Similarly, energy models are developed for windows, building spaces and other elements. A single zonal energy model integrating all the developed element models as a resistor-capacitor network is then developed. A single-zonal test setup consisting of an external wall, internal partition walls, window, ceiling and floor is considered, virtually, for model development and simulation. The step response for a developed un-conditioned building energy system model is analyzed in terms of the performance characteristics such as rise time, settling time, delay time and maximum overshoot. Several approaches are available for developing building energy system models. In this chapter, the state space approach is explained due to its ease of development and linearity.