Validating the thermal behavior of an open-plan office in an innovative large scale commercial building

The 7.500 m² office building ENERGYbase in Vienna, Austria, was planned and built satisfying the "passive house" standard. The building utilizes innovative façade design as well as concrete core activation (CCA) supplied by heat pumps, solar heating and groundwater. Furthermore, the ventilation and air-conditioning (HVAC) systems are based on solar heating and solar cooling, with the heat pumps as backup. Approximately 500 sensors were installed for permanent monitoring in the whole building. A 250 m² open-plan office, directly influenced by the south-oriented façade, was chosen to assess the thermal comfort in the building with respect to planned uniformity objectives. The aim was to examine whether the indoor air temperature in the selected office can be deduced from the 20 permanent surface temperature sensors and the 4 permanent illumination sensors. Additional 49 air temperature sensors, one glass surface temperature sensor and 19 air velocity sensors were placed within the office. Most of the sensors were freely suspended, with a few in the overflow ventilation area and at air openings. Measurements were recorded every minute for approximately four months (July through November 2009). Linear statistical models were chosen to determine a direct relation between permanent and temporary monitoring. The collected data proved that the planned thermal homogeneity of the room air was nearly reached, showing increased sensitivity to solar radiation close to façade during the summer-winter transitional period. Consequently, the data from permanent and temporary sensors were well correlated, allowing good air temperature approximation based upon the wall sensor readings in the room. As part of prospective weather predictive control strategies the linear models used for approximating room air temperatures via recorded wall temperatures and illumination values will be implemented to improve the current building control strategies, since they are a viable state observer for the actual room air temperature.