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Modeling the Performance of a Naturally Ventilated Commercial Building With a Multizone Coupled Thermal/Airflow Simulation Tool.


pdf icon Modeling the Performance of a Naturally Ventilated Commercial Building With a Multizone Coupled Thermal/Airflow Simulation Tool. (952 K)
Axley, J.; Emmerich, S. J.; Walton, G. N.

HI-02021-4;

ASHRAE Transactions 2002 Annual Meeting. Proceedings. 2002, Honolulu, HI, 1-16 pp, 2002.

ASHRAE Transactions, Vol. 108, No. 2,

Keywords:

calibration study; night cooling; natural ventilation; multi-zone model; envelope

Abstract:

Naural ventilation systems have long been employed in European residences to control indoor air quality and provide thermal comfort. European building designers have turned to natural ventilation to control air quality and cool commercial and institutional buildings as well, hoping to take advantage of the potential of natural ventilation systems to conserve energy associated with mechanical cooling and fan operation. Encouraged by the early successes of the past decade, European building designers have advanced natural ventilation technology, introduced promising hybrid ventilation technologies that combine mechanical and natural means, and developed analytical tools for the design of these systems. These systems may be adapted to the North American context, but much work will need to be done to realize the full potential natural ventilation may offer to North America. The needed work includes modeling studies which may require advanced modeling tools to adequately model the complex coupled thermal and airflow dynamics. A modeling study of a representative naturally ventilated building recently constructed in The Netherlands is presented. A multizone coupled thermal/airflow simulation tool CONTAM97R is used to investigate the performance of this building in two challenging North American climates. Comparisons of measured and predicted performance of this building in its native climate were performed as a validation exercise and to calibrate the building models used for subsequent analytical studies. Three models of a five-story segment of this building were formulated-a single-zone model with detailed representations of ventilation inlets and exhausts, a highly detailed 31-zone model accounting for all purpose-provided and infiltration flow paths, and a moderately detailed 11-zone model falling between these two extremes. The moderately detailed 11-zone model was then used to demonstrate the application of macroscopic coupled thermal/airflow performance evaluation to the design development of night ventilation cooling systems for the Enschede Tax Office placed in a hot-arid North American location-Los Angeles, California. Following a trial and error procedure using the overheated degree hour ODH performance metric, component sizes were adjusted to achieve the night cooling objective. This modeling effort demonstrated that a macroscopic tool like that provided by CONTAM97R provides essential spatial and temporal details that can guide system design relating to both whole-building and inter-room air distribution and thermal performance. In some cases, greater intra-room detail may be required. In these cases, performance evaluation would reasonably proceed to detailed computational fluid dynamic studies of individual rooms.