Windows need to be specified and sized appropriately, located in the most optimal locations and treated properly on the interior and exterior. Cardinal directions are important in determining window size, location and frequency. But with careful consideration and delicate balance, all of these goals can be addressed with positive results.

In the Northern Hemisphere, south-facing windows are the most critical and advantageous for daylighting and for moderating the indoor environment. Consider locating rooms that are used in daytime on the south side. Couple a dense floor with those rooms, and you can store heat during the day for re-radiation later at night.

East and west facing windows can allow morning and evening light into homes, but should be limited to avoid overheating and glare at those times of the day. Limited glass on the east side can achieve a pleasant opportunity for a breakfast nook to take advantage of the rising sun. Avoid lots of glazing on the west side in warmer climates or provide ample outdoor shading. Northside windows are a potential source for natural lighting of lesser intensity, but also presents the greatest potential for heat loss.

To determine proper overhang depth for optimal daylighting, the solar conditions of the specific location need to be analyzed and simulated by one of the following methods: calculations and simple tools, actual physical modeling or daylighting computer modeling.

Daylighting labs and computer models are also helpful resources as they provide more accurate designs.

Letting the sun do the work for you during daylight hours should mean that you can reduce reliance on electric lighting. Incorporate the ability to adjust the amount of light in spaces as needed, as natural light intensity changes. Overhangs can be designed so they block direct summer sun and allow an appropriate amount of winter sun into the living spaces.

Daylighting is tied to a multitude of attributes well-studied and noted in green schools. In a 1996 study in North Carolina, daylit schools were associated with increased attendance and fewer classroom disruptions. Better performance is widely noted in students in daylit schools along with the surprising finding that these students had better dental records and grew more than students in schools with average natural lighting due to the additional vitamin D produced by kids with increased exposure to full-spectrum light. The study showed nine times less dental decay, and students grew almost one inch more than their darker classroom counterparts over the two-year study period. With 90 percent of our time spent indoors these days, it’s no stretch to think that our homes have similar effects on kids and adults alike.

Rob Moody is a LEED-accredited professional and a licensed LEED faculty member. He may be contacted at rob@organicthink.com.