What is daylighting?
Most simply, daylighting is the practice of using natural light to illuminate building spaces. Rather than relying solely on electric lighting during the day, daylighting brings indirect natural light into the building. Daylighting reduces the need for electric lighting and connects people to the outdoors. And it provides pleasing illumination at a fraction of the cost of the most efficient electric lights.
What is GOOD daylighting?
Good daylighting creates beautiful, appropriately lit spaces while saving energy. A successfully daylit building is the result of a combination of art and science, of architecture and engineering. It is the result of an integrated design process, and is not simply a technology that is installed once the building is complete.
The daylighting designers toolbox includes concepts of lighting power density (W/ft2), illuminance levels, contrast ratios, window to wall ratios, ceiling to skylight area percentages, and reduction in glare. However, we don’t have prescribed values for these concepts that designers can use knowing they’ll result in good daylighting. While there are efforts underway to establish metrics for good daylighting, they aren’t available yet.
Even with proven metrics, daylighting will always be a mix of art and science, of logical thinking and common sense. Climate and geographical region, building type and use and building orientation are big factors in designing a successfully daylit building. Designers must always apply basic lighting and building performance principles to successfully employ daylighting.