Naturally ventilated and mixed-mode buildings—Part I: Thermal modeling

Mixed-mode cooling strategies rely on several different means of delivering cooling to the occupied spaces of buildings. These different means, or modes, of cooling include different forms of natural ventilation through operable windows, ventilation assisted by low-power fans, and mechanical air conditioning. Control of mixed-mode cooling systems requires a thermal model tuned to accurately predict the dynamics of a specific building. This paper presents a flexible system-identification framework for linear thermal models that is well suited to accommodate the unique features of mixed-mode buildings. The effectiveness of this framework was demonstrated on a multi-zone, mixed-mode building, with model-prediction accuracy shown to exceed that published for other naturally ventilated or mixed-mode buildings, none of which exhibited the complexity of this building. A companion paper employs the thermal model in an efficient algorithm to optimize control strategies over extended planning horizons.