Natural ventilation for crown court: developing statistical assessment techniques at the design stage.

The ventilation performance of a proposed naturally-ventilated court-room was predicted and assessed on a statistical basis with regard to the local meteorological conditions. Summertime ventilation was to be provided via an underfloor duct and controllable vents at roof levels, under the action of wind and buoyancy forces. Wind pressure coefficients expected on the external facade of the building were obtained from wind tunnel measurements on a scale model. Treating the court-room as a single cell, a computer prediction program was used to determine ventilation flows into the building for various configurations of ventilation openings, and a range of meteorological conditions and internal temperatures. For each wind direction, ventilation flows versus windspeed were presented in a convenient compressed form, in which the temperature dependence was removed. A new approach was developed to predict the statistical occurrence of design ventilation levels by using the above results with correlated frequency distributions of the local meteorological data.