The New York Times Company saves energy at its 52-story headquarters by using the oldest lighting technology in the world: the sun. Floor-to-ceiling windows let daylight flood in, and sensors then dim internal lights to save electricity. Compared with other buildings in New York City, the Times Building has reduced its energy use by 24 percent, notes a new report from Lawrence Berkeley National Laboratory (lbnl).

The energy used to light, cool and vent buildings in cities around the world accounts for roughly 40 percent of humanity's carbon dioxide emissions, the greenhouse gas primarily responsible for climate change. Using more sunlight sounds like an obvious solution but turns out to be more complicated than one would think. A modern building in a city such as New York requires specific window glazing to control glare as well as shading to block at least some of the sunlight and enable employees to see computer screens.

An energy-efficient system requires self-adjusting dimmable lights that must be affordable, long lasting and easy to maintain, as well as the computer hardware and algorithms to run it. And the people using the building must like the system—or at least find it easy to control. Outfitting the Times's 20 floors of offices with daylighting equipment constituted “the largest direct procurement of innovative lighting and shading technologies in the U.S.,” the lbnl report says.

In the 35 years since lbnl's buildings guru Stephen Selkowitz began advocating the use of more daylight, the trend has actually gone in the opposite direction. “It has not been scalable,” he says, meaning the lessons learned in one building have not been translated into similar buildings or other cities.

The Times Building is an example of those challenges, too. The company itself inhabits slightly less than half of the 150,000-square-meter building, and not all the other tenants have opted for the new technology, which can cost from $2 to $10 per square foot (0.09 square meter) of office space.

For all that expense, there are savings. By Selkowitz's analysis, the New York Times's investment delivers roughly $13,000 in energy savings annually per floor. It took the company three years to recoup its costs, but it has been saving money ever since. That's “pretty darn good,” he notes.

Yet because of new buildings rising to the north and west, the sophisticated system now has to be retrained to deal with unexpected glare off of new windows. In the end, although using sunshine seems easy, “you can't fall out of bed and do this by yourself,” Selkowitz says.