Quite a bit has been heard lately of the net-zero energy concept as it has slowly gained traction in the North American construction industry. But there’s another concept that goes hand-in-hand with net-zero energy: net-zero water.
If you look at the research literature, you’ll find little before about 2011. Since then, though, it has been getting a few mentions, although it is still for the most part flying under the radar. It popped up recently, though, with the release of a study done in Washington, D.C. It was conducted by the New Buildings Institute, the International Living Future Institute, and Skanska’s commercial development arm.
The purpose of the study was to forecast how much extra it would cost a project owner to upgrade his building from LEED Platinum to net-zero energy, net-zero water and Living Building certification.
For the study, the researchers looked at new commercial construction, at new commercial renovation, and at a new multifamily building. They examined what would happen to the economic model of each when transformed from LEED Platinum into net-zero energy and water, and the Living Building standard, which is usually thought of as being more stringent than LEED Platinum. In new commercial development, they found that for an additional total expenditure of between one and three per cent, energy consumption can be reduced as as much as 60 per cent. Want solar energy? You can still achieve those dramatic savings, but the additional expenditure wold be between five and 19 per cent. Return on investment? That starts at between six and 12 per cent and rises to between 33 and 36 per cent when solar is included.
Advanced water conservation measures to both reduce water consumption and stormwater runoff could also yield savings. For an additional cost of between one and three per cent, water savings would be between 45 and 60 per cent, and return on investment would increase by between 5 and 15 per cent. Improved water management would also make buildings more resilient during catastrophic storms.
The idea of net-zero water poses important problems, since a building would have to collect as much water as it uses. That might not be possible during the prolonged droughts that are plaguing the U.S. desert southwest and California. Even net-zero energy isn’t always obtainable.
The study notes that while net-zero buildings are possible with today’s technologies, the research “uncovered” the challenge that goes with trying to achieve net-zero in the large buildings common to city core areas.
“When considered in isolation, even ultra-efficient, 300,000-square-foot buildings may not be able to generate as much energy or collect as much water as they consume over the course of a year, given common rainfall patterns and today’s on-site renewable energy technology.”
And Richard Graves, executive director of the International Living Future Institute, says his group wonders constantly what a good building does or does not do.
“The answers have varied from year to year and place to place,” he says.
And that observation brings me to the caveat that must be attached to this study:
It was done on buildings in Washington, D.C., and there are differences between Washington and wherever you’re doing business. There is more than just differences in climate between Washington and Toronto, for example, or Edmonton or Vancouver.
There will also be differences in labour and material costs, as well as differences in the regulatory framework.
Having said that, though, one still can’t help but be impressed by how little more it would cost an owner to take that step beyond LEED Platinum. As more and more people become aware of the environmental hole we’ve dug for ourselves, we can expect to see more such studies. I expect most of them will be worth reading.
You can download a copy of this latest one at http://newbuildings.org/sites/default/files/ZNECostComparisonBuildingsDC.pdf
Korky Koroluk is an Ottawa-based freelance writer. Send comments to firstname.lastname@example.org