As more federal buildings target zero energy, leading designers tell us that day-to-day choices make all the difference
Automatically operated shades and a passive transpired solar collector could help bring the NREL research support facility to net-zero energy use--but it takes intentional conservation too. (Photo: Frank Ooms)
If you build it, they will plug. They will plug in drip coffee makers, halogen lamps, personal DVD players, aquariums, space heaters, and maybe even hair dryers. They will leave computers, lights, and printers on all night. How many of them will it take to screw in incandescent light bulbs before we realize that net-zero is not just about design?
That was the big takeaway from a net-zero press conference I attended during the AIA Convention. The conference, sponsored by Building Design+Construction to promote its new white paper on net-zero buildings, focused on an AIA/COTE Top Ten winner, the National Renewable Energy Laboratory (NREL) research support facility in Golden, Colorado. Completed in June 2010, the NREL facility could become the largest net-zero building in the country.
Unlike with Energy Star, LEED, or even Passivhaus certifications, a zero-energy building (ZEB) doesn't get to call itself that until it has shown for a whole year that it produces at least as much energy as it consumes (subscribers can read Tristan Roberts' feature on energy metrics for an in-depth comparison of various systems). This is where some designs targeting net-zero have run into trouble: buildings don't use energy. People use energy.
The obvious way to get to zero energy, then, is to have zero occupants. Problem solved!
Unfortunately, the purpose of 99.9% of buildings is to have occupants living or working in them. So ZEB designers are feeling their way toward three main strategies for balancing the net-zero equation to account for us humans and our crazy need for "comfort":
- Engineer for maximum efficiency. According to David Eijadi, FAIA, who worked on the net-zero Science House, targeting net-zero needs to begin with efficiency--a minimum of 50%–70% above ASHRAE 90.1. This involves right-sized mechanical systems, tight envelopes, daylighting, and other features that are fundamental to good, energy-efficient design and construction. Tom Hootman, AIA, added that it was key to "start with passive strategies" for heating, cooling, ventilation, and lighting.
- Automate. Tagging along right behind passive strategies are automated systems that turn lights on and off using motion sensors, close and open louvered shades based on sunlight conditions, or even sense indoor and outdoor temperatures and automatically open windows. For safety or comfort reasons, most of these automated systems will need the flexibility of human override, which is why you need to...
- Talk to owners and occupants. A lot. Because they need to understand that achieving net-zero requires constant, intentional conservation. In the case of the NREL building, the client was 100% on board with this. "Set aggressive goals," emphasized NREL's Paul Torcellini, P.E., Ph.D. "Get behind it, set the budget, and unleash the creativity" of the design team. Still, there are a lot of people using this building every day, and each one has to take some responsibility as well. They are alerted at their work stations when a central computer thinks it's a good time to close a shade or open a window--but that doesn't mean they'll do it. You may be going for zero, but buy-in has to be one hundred.
'Embrace your limits'
The panel was made up of industry leaders who have helped design multiple net-zero buildings. From left to right: Tom Hootman, AIA, of RNL Design; Paul Torcellini, P.E., Ph.D., of NREL; David Eijadi, FAIA, of the Weidt Group; Mary Ann Lazarus, FAIA, of HOK; Mark L'Italian, FAIA, of EHDD Architecture; Philip Macey, AIA, of Haselden Construction.
The stringency of achieving net-zero might seem daunting, but the whole panel here seemed really excited about the possibilities. "Embrace your limits," emphasized Mary Ann Lazarus, FAIA. Lazarus, one of the designers of Net Zero Co2urt, also served as a judge for this year's AIA/COTE Top Ten awards. "Rethink your process," she said, "and be pushed to a new set of processes."
Other panel members concurred, and added that if you try really hard to get to net-zero and you don't make it, you've still made a much more efficient building than you would have if you hadn't had this goal in mind.
What about the renewables?
Distinctly missing from this conversation was the thing that puts the Z in ZEB: energy produced on the site. Aside from photovoltaics (PV) on the roof and on an adjacent parking structure, the NREL building also uses some interesting strategies like a transpired solar collector and a thermal labyrinth to make use of solar energy for heating. While very creative, the design intentionally employs established technologies and off-the-shelf products and does not incorporate any funky, cutting-edge renewables. This is partly for budgetary reasons and partly as an object lesson: if the nation's largest net-zero-to-be can get there on a low budget, so can you!
What do you think? Would you have gotten to zero a different way? Or is getting to zero even important, considering that old-fashioned (and some new-fashioned) conservation is doing so much of the work?