Methodology for the Evaluation of Natural Ventilation in ... - Cham

Table 8. Prototype Building Window CharacteristicsWidth Height Horizontal LocationOpeningSingle Window Opening 130 cm 90 cm 6.5 cm South Half-Floors, Second NorthDouble Window Opening 2 x 90cm 90 cm 11.5 cm First NorthSingle Vent Opening 130 cm 45 cm 5.0 cm South Half-Floors, Second NorthDouble Vent Opening 2 x 90cm 45 cm 6.0 cm First NorthThe stack vents have a series of louvers on each face of the stacks, which are controlled byorientation (e.g. all of the eastern louvers for all five stacks are either open or closed). Thelouvers do not modulate, and are therefore either fully open or fully closed. There also is a rainand wind sensor located on the roof that is tied into the simple control system for the fans in thestacks; if there is any rain indicated, then the louvers are closed, and likewise if the wind outsideexceeds 4m/s the louvers are closed in the direction of the wind. The louvers are kept open if thefans located in the stacks are on. The fans are three-blade, 0.746kW fans that are unidirectional.On still days, the airflow is driven by buoyancy flow, with the louvers open in the stack vents toenhance the stack effect. On windy days, the airflow can be more similar to single sidedventilation on the ground and second floors, with the potential for some cross ventilation on thefirst floor. In part this is dependent on the interior loads, number of windows open and solarradiation. In automated mode, the fans and louvers are controlled by a single temperature pointlocated in the atrium just above the ceiling level of the second floor. If this thermocouplereaches 26ºC or more, the louvers are allowed to open and the fans are turned on. If thetemperature drops below 26°C, then the fans turn off and below 22°C the louvers close.The occupants are located on all three levels of the building: the south half of the ground floor,both north and south halves of the first floor, and the north half of the second floor. Within eachhalf floor there are approximately 25 occupants, each with a computer and monitor, and adesktop printer for every three people. There are energy efficient T-8 fluorescent lamps locatedthroughout the building, with the exception of the bathrooms and the ‗street lighting‘ in theatrium. The lighting fixtures in the occupied space, each with two lamps, are connected in banksof two to a combined occupancy and photosensor control mechanism. This feature allows for thelighting to be shut off when the space is unoccupied, and continuous dimming from 100 percenton, down to 10 percent to achieve further reduction in energy usage when the space is occupied.3.3 Monitoring ProcedureLong-term monitoring of Houghton Hall was conducted for internal temperature and relativehumidity throughout the occupied spaces, energy consumption by sub-system, and externalconditions. The equipment was installed at the beginning of the summer season and removedeighteen months later. This extended period provided time for troubleshooting equipment duringthe first summer prior to recording a complete data set for a twelve-month period. Problems thatneeded to be addressed included ensuring that data loggers were recording properly andthermocouples remained in position. Through some trial and error and data analysis after twomonths, the equipment was working properly. The measurements, both long term and short-term,47