EFFICIENT LIGHTING: Can sunshine be used to cut down on lighting costs in skyscrapers, like the New York Times Building, shown here at night with lights on.
Image: Flickr / Digiart 2001 / Jason Kuffer
More In This Article
-
Overview
Special Issue: Cities
-
The Best Science Writing Online 2012
Showcasing more than fifty of the most provocative, original, and significant online essays from 2011, The Best Science Writing Online 2012 will change the way...
Read More »
The radiometer tracks the sun's progress across the Manhattan skyline and sends a signal from the roof to the command computer on a floor 90 meters below. Blinds fall slowly with the buzz of an electric motor, cutting off the sun's glare on computer screens. Another computer triggers the shades on the opposite side of the building to rise while another system shuts off the air-conditioning and adjusts the internal lights.
The New York Times Co. saves energy at its 52-story headquarters using the oldest lighting technology in the world: the sun. Floor-to-ceiling windows let sunlight flood into the office space and sensors then dim the internal lights to save energy. In the process, compared with other buildings in New York City, the Times Building has reduced its energy use by 24 percent, according to a new report prepared by Lawrence Berkeley National Laboratory (LBNL).
Letting the sun do the work of lighting up buildings is obvious. It's cheap, it's free and it's as easy as a window. Or, as managing director of Sustainable Energy Partnerships Adam Hinge says, "there are lessons we can relearn" from the building practices of the time before cheap fossil fuels and ubiquitous air-conditioning. As it stands, the energy used to light, cool and vent the buildings of the world's cities accounts for roughly 40 percent of humanity's carbon dioxide emissions, the greenhouse gas primarily responsible for climate change.
But using daylight turns out to be more complicated than building floor-to-ceiling windows. A modern building in a city like New York requires specific glazing on its windows to control glare as well as some form of shade to block at least some of the sunlight and enable employees to see their computer screens. An energy-efficient system requires dimmable lights that must be affordable, long-lasting and easy to maintain. And the people using the building must like the system—or at least find it easy to control.
In a bid to gain a better understanding of all those factors, the Times built a full-scale model of 400 square meters of the building in College Point, Queens, to test various systems before going ahead with final construction in Manhattan. Even then, outfitting the Times’s 20 floors of office space with daylighting equipment constituted "the largest direct procurement of innovative lighting and shading technologies in the U.S.," according to the LBNL report.
New York City boasts some 10 percent of all the office space in the entire U.S.—more than 50.1 million square meters—and could save $70 million a year in power costs, or roughly 340 gigawatt-hours of electricity, by relying more on sunshine (as well as even simpler fixes like turning off the lights that are not needed at night.) That's according to another recently released report dubbed "Let There Be Daylight" from Green Light New York, an advocacy group, which notes that more than a quarter of the energy used in New York City's buildings goes to interior lighting, which is often used even in the middle of a sunny day.
All the way back in 1977, when LBNL's buildings guru Stephen Selkowitz began working on energy-efficient construction, his very first project advocated the use of more daylight. Yet, in the 35 years since then the trend has been in the opposite direction. "I'm a failure, because we should have solved the problem by now," he says. "It has not been scalable," meaning the lessons learned in one building have not been translated into other similar buildings or even other cities.
The Times Building is an example of that as well. Whereas the company itself employs a sophisticated daylighting and energy savings system, it only inhabits slightly less than half of the 140,000-square-meter building. The remaining space is rented out to tenants by co-owner Forest City Ratner—and not all the tenants opt for such systems, which can cost from $2 to $10 per square foot (0.09 square meter) of office space.
Of course, that cost does deliver roughly three kilowatt-hours of energy savings per square foot per year, by Selkowitz's analysis of the Times Building, or roughly $13,000 saved annually per floor. That's "pretty darn good," he notes. But building managers are often skeptical. Even New York Times facilities director Patrick Whelan thought the new system, especially the under-floor air-circulation vents, would be a "nightmare" when the company moved in back in 2007. (Under-floor vents save energy by requiring fewer pumps to move the air as well as relying on the natural warming of the internal building air to allow circulation. Cold air comes up from floor, warms and rises to the ceiling.)
"Basically, things are working really well," Whelan says. The under-floor vents proved easier to access and quieter than traditional pumped vents in the ceiling and, in five years, only 5 percent of the energy-saving, dimmable fluorescent lights have had to be replaced—proving that the bulbs are durable. "To tell you the truth, we get very few complaints," he adds.
Yet, thanks to new buildings rising to the north and west, the sophisticated system now has to be retrained to deal with unexpected glares off of new windows. That requires a comprehensive study of reflections and then reprogramming the computer control system. In the end, although using sunshine seems easy, "you can't fall out of bed and do this by yourself," Selkowitz says.
See what we're tweeting about
14 Comments
Add CommentThey pay about $0.20 a kWh ($70M / 340M kWh), and since these rennovations can save 3 kWh per square foot (gawd I hate mixing metric and irrational units!) per year, the payback period is somewhere between 3 - 15 years. After that period, it's almost as if they put a little oil rig on their building that just spits out money from the energy savings!
Reply | Report Abuse | Link to thisOne way to reduce glare would be to put solar panels on the south-facing windows. There's gotta be a way that they can keep people on the street from getting blinded while still letting in enough daylight to keep this system running. Since First Solar is installing and SELLING solar power for 5.8 cents a kWh, they can save the NYT 14 cents a kWh compared to grid electricity:
http://cleantechnica.com/2013/02/03/thin-film-solar-power-to-be-sold-for-less-than-coal/
This probably has not caught on for two reasons. One is that it only works for the tallest building in the area. If all the buildings are the same height, then the only available sun is what hits the roof--not enough to make a serious difference if it is more than a few stories tall. So the tallest building can get a significant cost saving on lighting, but only because it is stealing natural light from the surrounding area. this is something that Japan has understood for decades. The owners of tall buildings have to pay for the reduced light that falls on the other, nearby buildings. I wounder how much of a savings would be realized if this was required for this building.
Reply | Report Abuse | Link to thisThe other is that another solution is to let the people in the buildings regulate their own light by adjusting the blinds and artificial lighting themselves. Low tech, but also low cost.
What about fiber optics to interior spaces in the building?
Reply | Report Abuse | Link to thisShading is very dependent on the time-of-day and time-of-year. Even when shaded, indirect light from surrounding, taller buildings can still be very bright.
Reply | Report Abuse | Link to thisThere are several reasons why we have a lot of untapped potential for energy savings. First of all, tenants usually pay the energy bills but are unable to install efficiency and / or conservation equipment on property they don't own. Landlords usually DON'T pay for their tenants' energy consumption so they have little incentive to enact major energy-saving measures. Additionally, these measures usually have a sizeable up-front cost that is either unaffordable to some people or the payback period is too long for companies focused on short-term profits. Finally, most utilities have a large incentive to keep energy sales increasing instead of decreasing. They are directly compensated for energy sales and are allowed to capture a decent profit margin on capital equipment investments like new power plants and such. California has "decoupled" utility revenues from energy sales and has structured their operations such that they can capture some of the benefits of energy efficiency / conservation. As a result, the state has kept per capita energy usage flat since 1980 while the rest of the country has increased a great deal.
Provide the right incentives and correct for market failures and you'll see smarter energy use like the NYT's building take off in a hurry!
No mention of the "greenhouse effect" warming the building in the summer when the sun's rays are strongest, and prompting an increase use of air conditioning.
Reply | Report Abuse | Link to thisNo mention of the short days of winter or cloudy days.
Could it be that the NY Times is exempt from such obvious potential problems that they don't need to be addressed in the story?
Or would these be an "inconvenient truth"?
[Solar lighting could actually be a reasonable idea, but why not address the obvious?]
TTLG: Shadow casting by tall buildings certainly impacts access to direct sunlight and is among the reasons that photovoltaic panels have limited viability in a dense place like Manhattan, but "daylight" comes from the entire skydome so the blocking of direct sun is less of an issue. Offices can be entirely daylit from windows that face only north, for instance. Tall buildings can certainly limit daylight access at lower floors but due to the narrow blocks and relatively wide streets in NYC the vast majority of office spaces (even those on lower floors in an area like midtown) can benefit from using daylight in lieu of electric lighting for significant portions of the year. The real impediment is the high cost of the ballasts and controls required for fully functioning system.
Reply | Report Abuse | Link to thisIt is definitely true that the low tech/low cost approach works in many small offices. But our analysis found that these systems were almost never used properly in large, open plan office spaces- which are the vast majority of office spaces in NYC and most central business districts.
Charlie,
Reply | Report Abuse | Link to thisThere is definitely a balance to be found between providing enough glazing to deliver daylight and not having so much glazing that the AC systems are overburdened. Our report is really about retrofitting buildings with control systems that allow offices to take advantage of the daylight from existing windows. They are already paying an energy "penalty" for having windows- might as well take advantage of them. By offsetting electric lighting by the use of daylight you are saving energy by limiting the hours of electric lighting use but also saving energy by eliminating he heat from that lighting, a major factor in the sizing of AC systems in commercial buildings. And you are doing it at the time of peak demand- which has significant additional environmental benefits. In the specific example of the New York Times building there is an external screen of ceramic rods that keep the majority of the direct sunlight from meeting the facade, considerably reducing the greenhouse effect you speak of.
Winter and cloudy days have little impact on the efficacy of daylighting. "Daylight" is the light from the entire skydome, not just direct sunlight. In fact, cloudy days often provide the optimum time to take advantage of daylight because the light is diffused and you do not have the direct sunlight to deal with (which is typically too bright for office tasks and must be shaded.) In fact, north facing offices are the easiest spaces to daylight.
Does this prove that spending money on costs that will not be realized for 30 or more years and rarely equal the Green engineering estimates. solar out of photo voltaic cells rarely achieve the designed output capacity - they promise 100 gigawatts but produce only 85% due to climate conditions or in very bad overcast times maybe only 35% so the cost of a 100 gigawatt gas or coal must be standing by at idle to ramp up and prevent a grid failure.
Reply | Report Abuse | Link to thisPaying for two 100 gigawatt plants makes zero economic sense nor can it = Solar and wind are failed premises.We are not advanced far enough down the energy road of technology to go Green . .
Side Issue the Lawrence Berkeley National Laboratory (LBNL). It's first name was LAWRENCE "RADIATION" NATIONAL LABORATORY. Yes they were Nuclear researchers - plutonium was all over the place in the early days.
Responsive Design ... Works for software, works for buildings and everything in between!
Reply | Report Abuse | Link to thisThat would be the most logical answer wouldnt it, but does this article mention.??????
Reply | Report Abuse | Link to thisFiber optics light could be individualised to an office or an individual as well as general lighting.
Yes, daylighting and solar activated shades and dimming are great and will pay for themselves eventually. We have the technology to do these things and have for some years. I am a lighting designer and know the system that was put into the NY Times building and it wasn't cheap. That's the problem with these systems is that the initial costs are so high that they only exist in buildings that have unlimited resources for the initial expense or need/want the PR. Eventually the ROI will be such that it won't make sense not to do this but right now, they're cost prohibitive in the short term.
Reply | Report Abuse | Link to thisAnother technology which is little used and could probably be developed in many radical ways is the light tube. Most simply employ reflective surfaces but with the application of optical fibres this should be a technology which can direct natural light into the darkest corners of any building.
Reply | Report Abuse | Link to thisWith the huge advantages of energy savings over increased fossil fuel use, surely this is a technology which should be more widely employed and sponsored.
How does this compare to switching to LED light bulbs?
Reply | Report Abuse | Link to thisHaving worked on the project, I would like to point out that the New York Times occupies the lower half of the building, not the top, clear half. We and LBNL analyzed the shadows from other buildings and understand that there are huge amounts of time where there is no shadow on large areas of glass, as well as times when some zones or areas have long periods of time in shadow. When in shadow for sufficient time, the SolarTrac shade system raises the shades up automatically. Which brings me to your second point. I would generally state that people are pretty good at lowring shades or blinds down when they are in direct sun or glare. But not very good at raising them. They do have a day job, after all. It was the team at New York Times who realized that the automation was equally, if not more important,tasked with raising the shades as often and as high as possible,while maintaining comfort, in order to maximize the natural light in the building, and allow the dimming system to work more effectively.
Reply | Report Abuse | Link to this