A study of the application of the BRE Average Daylight Factor formula to rooms with window areas below the working plane

In urban canyons where, apartment buildings can be beneficial in terms of their close proximity to offices, shops etc, causing less traffic congestion and pollution, saving fuel costs and bringing people in close proximity to city centres. At the same time trying to accommodate people in city centres, leads to the development of congested and confined narrow deep apartments which have to be mechanically ventilated and artificially lit. To reduce costs, in 1962 designers began building narrow structures with light curtain walls and thin frames to increase daylight and natural ventilation. These factors bought about overheating and noise pollution in buildings. More focus then went on to the design of windows and their fixtures to prevent heat loss, overheating and internal acoustical treatment of ceilings and floors to prevent acoustical reverberations1. The above views that windows were net energy debits disregarded the net solar heat gains in winters and reduction in electric lighting loads through out the year. Experience now shows that well day-lit buildings have lower running costs and are more energy efficient. In restricted sites, designers tend to design spaces with maximum window areas specifically using full height windows to compensate for deep spaces in maintaining daylight. This study lead to investigating the validity of the BRE Average daylight factor formula for how windows with increased areas below the working plane contribute to the ADF in Site planning,etc4.