New Era of Energy Efficiency: Net-Zero Buildings
Part 3: Operations, Occupant Behavior and Plug Loads Can All Affect Net-Zero Goals
Operations, Occupant Behavior and Plug Loads Can All Affect Net-Zero Goals
By Greg Zimmerman, Executive Editor - October 2012 - Energy Efficiency
Myth #3. Only design matters — operations, occupant behavior and plug loads don't.
Most facility mangers would scoff at this notion, whether in regards to a showpiece net-zero energy office building or a parking garage. But it's a myth that persists.
"There needs to be a lot of engagement with occupants and facility managers," says Dakin. "You can design a net-zero energy building, but if it's not operated as designed, goals haven't been met."
In regards to operations, bridging the gap between design and operations with ongoing commissioning and measurement is the best way to ensure the building operates as initially designed, says Qualk, an expert on commissioning. "Design and construction only set up the opportunity for the building to be net-zero energy. All the marbles are in operations. Performance decay can degrade efficiency by 30 percent or more in the first year. That's why facility managers are my heroes."
Regarding occupants, the best solution is training on how the building operates, why it operates in those ways, the goals for the building and how occupants themselves can help, say experts. NREL has developed an eight-page occupants' guide for its RSF facility, for example, that includes about what would be expected for such a high efficiency building, Pless says: when to open and close the building's operable windows, how the facility's vacancy sensors work, etc.
But Pless cautions against relying on occupant training for maintaining long-term energy performance. "Training is really the last line of defense," he says. "Training's good, but you have to do it continuously forever." That's because occupants tend to revert to familiar or more comfortable behavior. "You want to minimize the hassle factor," says Pless.
Baker adds: "The best testament to the building is when occupants can talk about it being net-zero energy and also talk about how easy it is for them."
Minimizing plug loads is another critical component of achieving net-zero energy goals, and, in many cases, is the most difficult. That's because designers have almost no control over plug loads. "It's a tricky one to handle," says Dakin. "It's the Wild West out there."
What's more, because other loads have been minimized or altogether eliminated, plug loads represent the highest percentage of energy use in a building in many cases. That will be true at the Bullitt Center, where plug loads are expected to comprise about 50 percent of the building's energy use. The developers of the building — Point32 — have developed a system whereby each new tenant in the building will be given an energy budget based on the portion of the building they occupy, according to Kahn. If the tenant stays within its energy budget, it won't have to pay an energy bill. So it will behoove tenants to be as efficient as possible with their plug loads.
Schwer, one of the consulting engineers for Bullitt Center, says that a spreadsheet has been developed to help tenants predict their loads before they move into the building, so they'll know ahead of time if they'll have to reduce the number of computers or printers, or take other measures to trim plug loads. Schwer says his own firm has gone through this exercise, as it prepares to be one of the building's tenants, and was shocked to find it would be well over its energy budget.
According to Pless, NREL's plug loads, in the more than two years since its occupants have moved into the RSF, have declined by 50 percent from what they were in the organization's previous leased building.
Part of this was planning for the move to the new building by buying efficient equipment ahead of time, a strategy any owner can employ. "If you're getting ready to plan a new building, start buying energy efficient equipment now," says Baker.