The Power of Zero
In 2007 Congress passed and President Bush (somewhat shockingly) signed legislation that required all commercial buildings to be energy neutral. According to the U.S. Department of Energy, “Net-zero buildings generate as much energy as they consume through efficiency technologies and on-site power generation.” Unfortunately, the law set such ludicrously long deadlines that it undermined what could have been landmark legislation.
The law did, however, create a framework for more immediate action, establishing within the DOE the Net-Zero Energy Commercial Building Initiative. The program partners with private developers, research laboratories, non-governmental organizations, and other federal agencies to advance the cause of sustainable construction. On the eve of the DOE’s Lighting Supplier Summit, to be held next month in Las Vegas in conjunction with Lightfair, Metropolis’s executive editor, Martin C. Pedersen, spoke to Drury B. Crawley, a trained architect and engineer who is the lead DOE researcher for the commercial-building initiative. Crawley talked about the challenges of energy neutrality, the future of PVs, and the curse of high-rises.
What is the Net-Zero Energy Commercial Building Initiative?
The initiative was authorized in the Energy Independence and Security Act of 2007. That law directed the Energy Department to push energy efficiency in the commercial sector. The legislation specifically mandated that all new commercial buildings should be zero-energy by 2030, half of the remaining stock should be zero-energy by 2040, and all commercial buildings by 2050.
The initiative is great, but the timelines aren’t stringent enough.
I would agree, but I think there’s a real issue with the capacity in the market to support this. We’re having difficulty finding buildings that push 30 percent energy savings, so the question becomes: How are we going to be able to push beyond that?
What do you hope to achieve in the near term?
By 2015 we want to see buildings achieve 60 to 70 percent energy savings, and even some zero-energy buildings. We’re seeing some buildings that are already zero today. We’ve verified eight and have a database of those buildings online [at www.zeb.buildinggreen.com].
The good news, I guess, is that these buildings prove zero energy is not a pipe dream.
That’s right. The bad news is they are all one and two stories, and the largest building is only 13,600 square feet. A lot of these buildings have very low energy intensity to begin with. But if we’ve got, say, an electronics retailer, where half of the energy is used in the displays, then that’s a completely different animal.
Outline for me the complete package for a zero-energy building.
First off, a substantial reduction in lighting. We’re seeing systems today that offer 40 to 50 percent savings, but we’re looking to achieve 70 to 80 percent. Right now there’s great potential in solid-state lighting. I won’t say it’s there for interior solutions, but we’re beginning to see it make sense for exteriors. Unfortunately, there’s a lot of not very good product on the market. People need to be careful about what they’re choosing. The department has a program called CALiPER, which buys and then tests a product in a laboratory to see how it’s performing.
What are the other systems for achieving net-zero buildings?
Ground-source heat pumps, radiant heating and cooling, integration of lighting controls and daylighting, natural ventilation when it makes sense …
All of those systems may get you to 20 or 30 percent energy reduction, but you can’t get all the way to zero without making your own electricity.
Yes, that’s what we found. We’ve done studies to look at what point it makes sense to bring renewables in to achieve zero energy. For commercial buildings, it seems to be when a building has reached somewhere between a 60 and 80 percent reduction.
Then you use renewable energy to make up the difference and come out at zero?
Is renewable energy cost effective yet?
If you look at energy prices in New York or California or Hawaii, where prices are about 15 to 20 cents per kilowatt-hour, renewables are cost effective. We’re probably ten-plus years out on this, but there are a lot of people willing to rent out roof space. Some grocery-store chains in the Northeast are renting their roofs to PV providers. They’re getting long-term contracts because there’s enough profit in that for the financiers to make money and still give a benefit back to the building owner.
Will we eventually see PVs on every roof in America?
We did a study a few years ago and found that we would need to cover half of the roofs in the country to get almost to zero for all commercial buildings. But the difficulty is, once you get above three stories you may not have enough roof area to support the loads.
What does that mean for larger buildings?
It’s going to be tough. In Manhattan, there’s not enough surface area to generate the power to handle all those tall buildings. We’re going to have to look at grid solutions. And that also means that our low-rise buildings are going to become significant energy producers. Warehouses with low-energy needs are going to be mini power plants. They may make more money selling their roof space than being warehouses or distribution centers.
True or false: engineers will be the key to getting us to net zero.
It’s going to take a change in mindset for all parts of the real estate and design community. Engineers sometimes get in their own way. And engineers are by nature very conservative. We have leading firms out there pushing the envelope—Arup, Buro Happold—but that’s because they’ve been willing to put in the time to understand what’s going on.