Daylighting is the use of windows and skylights to bring sunlight into buildings and homes. Daylighting in businesses and commercial buildings can result in substantial savings on electric bills, and not only provides a higher quality of light but also improves productivity and health. Daylighting in schools has even improved student grades and attendance. For homeowners, daylight can also reduce electricity usage. If you work outside of home and are away most of the day, you probably will not notice the big difference. But if you stay at home or work from home, daylighting can make a big difference from light to heat.
Today’s highly energy-efficient windows, as well as advances in lighting design, allow efficient use of windows to reduce the need for artificial lighting during daylight hours without causing heating or cooling problems. For older homes, the windows are not well insulated and usually were designed in small sizes. If you have the means to replace them, you should take advantage of the solar energy. If you happen to live in the northeast where winters are long and cold, new and energy efficient windows can save you a lot in the long run.
Source: EERE