Abstract

This thesis presents a study aimed at thermally massive high-rise buildings equipped with fan-assisted hybrid ventilation through corridors linking controlled motorized inlets on opposing façades and an atrium (solar chimney) consisting possibly of stacked atria. During the cooling season, hybrid ventilation is used when outdoor air conditions satisfy a set of criteria in order to reduce cooling energy consumption, especially at night when the outdoor air temperature drops. Additionally, this reduction can be greater when the system is controlled in a predictive manner by incorporating forecast weather in anticipation of a warm or cool day. Without compromising thermal comfort, the result from this study proposes 8 °C and-12 °C as the lower limit for allowing cool outdoor air during unoccupied and occupied hours respectively. Furthermore, replacing the existing criterion of relative humidity range of outdoor air by its humidity ratio is proposed. Using an institutional building in Montreal as the site for full-scale tests during the cooling season, the cooling potential of using the hybrid ventilation system and considerations for thermal comfort when admitting cool outdoor air are studied. To this effect, a calibrated transient thermal network model, based on the measurements from 4 hours of night ventilation and focusing on the first 10 m of the corridor at one of the motorized inlets, is developed to study the behaviour of the main building thermal mass - the 0.4 m thick concrete floor and how the temperature evolves with distance from the inlets and the resulting effect on thermal comfort. The effect of the outdoor temperature setpoint at which air is admitted into the building on potential energy savings is also studied.