Pattern 1: Floor Plate Geometry

Proper building organization at the schematic level is a precursor to using daylight as a functional source of illumination. The perimeter to core depth, aspect ratio, and programmatic organization relative to floor plate geometry all play a critical role in effective daylighting. In most cases, one of two conditions must be met. In multi-story buildings this means that areas where daylight is desired must be located directly adjacent to the building perimeter, usually within 20’-0” (7m) of a window or directly under a roof with skylight access. It should be noted that while effective floor plate design and orientation create the potential for successful daylighting, it does not provide a guarantee of persistent performance. It can, however, be stated categorically that to achieve daylighting success the building organization and footprint geometry must place key program elements within the reach of daylight.

Floor plate geometry has varied widely over time. Historic buildings generally had relatively thin plans out of necessity. Limitations in lighting and ventilation technology required designers to use daylight and passive ventilation strategies to simply make their buildings habitable. As energy sources became more reliable and less costly and electric light sources and HVAC technology matured, designers were released from the constraints of narrow floor plates as a means of access to light and air. Ultimately, this led to buildings that sought to maximize immediate return on investment through the creation of very large floor plates with minimal access to daylight and views, and consequently led to a complete reliance on electric lighting for interior illumination. Recent efforts to include daylight and views as part of sustainable design strategies have somewhat reversed this trend.

One of the particular challenges faced by designers today is the fact that the starting assumptions about many building types were developed in a time when response to daylight was not a design consideration. Subsequently, this means that achieving daylight performance in contemporary building types requires a fundamental re-thinking of the building morphology and programmatic arrangement.

These case studies show common multi-story floor plate configurations for buildings constructed between the late 19th century and the early 21st century. To illustrate the “daylight potential” of each floor plate, all window areas have been normalized to a 40% window-to-wall ratio (WWR) with glazing set to 60% visible light transmission. In some cases this varies substantially from the as-designed condition. Illuminance plots are provided for September 21st under clear and overcast skies at noon to show the intensity and distribution of horizontal daylight illumination on an average day.