Daylighting has been an integral part of the built environment throughout architectural history, and structures that are thousands of years old are still revered for their daylighting qualities. “The history of Architecture is the history of man’s struggle for light – the history of the window,” wrote Mies van der Rohe.

It’s only within the last 75 years or so that daylighting has been supplanted by electric lighting as the primary source of interior daytime illumination. Ever since the introduction of air-conditioning, and especially of modular gas-discharge lighting (i.e. modern fluorescent lamps), windows and skylights have been getting smaller and floor plates have been getting larger. Our luminous environments have been deemed adequate and appropriate based on a simple numerical criterion, horizontal footcandles. However, in recent years, especially with the ‘green’ movement, there has been much more pressure to re-introduce daylight back into our interiors and create daylit architecture once again.

But what exactly is ‘Daylit Architecture’? It’s difficult to define. For architects it may be about beauty and ergonomics; for engineers it tends to be focused on energy and economics. Fortunately, with recent studies, we finally have hard evidence showing that daylight in schools improves test scores, and daylight in the workplace improves productivity. In retail, it boosts sales; in hospitals, it reduces recovery time. These studies embolden the stance of the ‘quality’ seekers.

But, on the other side are the energy tyrants. They want to see fewer windows in architecture since windows are terrible insulators. The criticism is real. News stories are unfolding about LEED buildings and how they are not living up to their touted energy claims. But the LEED points for daylighting and views have nothing to do with saving energy. It’s all about interior environmental quality.

So now, there is a bigger push to improve energy usage and enforce ‘green’ building codes. LEED, CHPS, and other programs give you the option of getting daylighting points. A ‘green’ code will require it. There has been overwhelming support for some type of daylighting requirement or code, but the problem seems to be in writing one. Most would agree that, if introduced properly, daylighting can save energy associated with interior illumination. The more difficult aspect is quantifying quality. How do you require architecture to beautifully introduce daylight and sunlight into itself?

Codes requiring access to daylighting are relatively new to the United States. Title 24 in California already requires daylighting in certain buildings. There’s a rich history of codes requiring access to daylight. An English law dating back to 1663, Ancient Lights, is a form of easement that gives owners of a building with windows a right to maintain access to daylight. Justinian Code in the sixth century AD included sun rights, laws to ensure that every homeowner had reasonable access to the sun. And, many modern European codes require daylight and views for workspaces and classrooms.

Get ready for daylighting codes across the United States. Come late spring 2010, ASHRAE will have introduced its new Standard 189.1, which is basically a ‘green’ standard that goes beyond the energy-saving measures published in ASHRAE Standard 90.1. It also contains a lot of language about minimum amounts of windows and required illuminance from daylight. The other big player is the International Code Council, with their new proclamation, the IgCC, or ‘International Green Construction Code’. In that particular code, the daylighting portion will most likely be broken into two sections: energy and indoor environmental quality. This approach makes the most sense for both camps. We want enough daylight and views to elevate the human spirit, but not so much as to cause glare or unnecessary energy usage associated with excessive cooling loads.

It won’t just be footcandles and daylight factors anymore. Relatively new metrics such as Daylight Autonomy, Daylight Saturation Percentage, Useful Daylight Illuminance, and Daylight Glare Probability may become common language within these new daylighting codes.

It’s probably time that we have some sort of code that protects and even encourages our access to our greatest energy source, the sun. How it is written makes all the difference. It cannot reward poor design, or suffocate good design.

Great daylit architecture comes from the brilliant architects and designers who create it, not from a formula or code. But gone are the days of overly-glazed façades used in the name of ‘daylight’. Responsible practice must produce sustainable architecture, even if it has to be mandated.

Photo Credits: Elinnea (1), Roryrory (2), Stephen Lee (3), Lam Partners Inc (4)