What are some ways to effectively improve the quality and quantity of natural light in a house? Small skylights can be very helpful at bringing natural light into a dark hallway or room, but be careful. As Architect Kristine Anstead points out, “During the summer, when you don’t want heat and you have the sun directly overhead, they allow an abundance of heat. In the winter, when the sun is at a low angle, you get the least amount of available sun.” As an alternative to skylights, she suggests investigating clerestory windows or roof monitors.

Indeed, the trick with glazing is usually to admit as much light as possible without causing excessive winter heat loss or summer heat gain or glare—the factors that in the past have limited window numbers and sizes. Heat moving through windows destroys a building’s energy efficiency and wastes our natural resources. In fact, according to the Rocky Mountain Institute, more energy is lost through American windows every year than flows through the Trans-Alaska oil pipeline.

The good news is that many new types of high-performance glazing have been developed in recent years that make it possible to use a lot more glass while minimizing heat loss, heat gain, and glare. If you’re building a house, remodeling, or replacing windows, you can choose from a wide range of options, selecting glazing best suited to a particular window.

Talk with a window dealer about the specific properties and values available. Generally speaking, if you want to minimize heat transfer, pick high-performance glazing that has a high R-value. For maximum light, choose a type with a high visual light transmittance value or, to cut glare, with a lower light transmittance value. To cut heat gain, select glazing with a high shading coefficient. Glazing with a high UV value will block nearly all furniture-fading ultraviolet rays.