Photo credit: JE Dunn
Building Within the Site
Before jumping into all of the numerous ‘Net Zero’ definitions that exist for one simple idea, lets go back in time briefly to examine how efficient home design has influenced one aspect of this famous buzzword today. Germany (with the help of Lund University in Sweden) was first to coin the design for an ultra energy-efficient home—the “Passivhaus.” The idea, still relevant today for all net zero energy structures, is to build a home or building in such a way so that the need for artificial heating and cooling is severely reduced. But how does a builder accomplish this?
Designing with the building’s exact location in mind—the site—is something many architects and designers, at least in the U.S., have forgotten up until fairly recently. Since the Passivhaus-Institut was founded in 1997, homes built with the intention to pass the voluntary Passivhaus standard are designed with passive solar techniques, superinsulation, utilization of wind for cooling and ventilation, and various other strategies that enable occupants in a home or building to remain comfortable through physical design alone.
The concept and strategies developed with the invention of passive homes now form the backbone for many modern net zero energy buildings (NZEB). Below, we will go over the definition of a “net zero building” and see how energy-efficient, site-specific strategies enable their creation. We will then review the two other important aspects of net zero that are equally important for creating a sustainable built environment.
There are various ways to think of net zero energy buildings (NZEB), but the most commonly used definition states that the building must produce as much energy as it consumes annually. And, the energy it produces on-site must be a form of renewable energy—solar, wind, and geothermal are all options. The energy the building consumes does not have to solely come from the on-site energy source—it can be obtained from the grid as well. For example, a strictly solar-powered building located in Phoenix, AZ would have some trouble keeping cool during summer nights when temperatures remain 100 degrees Fahrenheit without using some power from the grid.
One of the largest NZEBs in the world, if not the largest, is the National Renewable Energy Laboratory’s Research Support Facility (RSF) in Golden, Colorado. The idea for the RSF was to create a living lab and replicable model for the next generation of high performance buildings. How is such a large structure able to attain the net zero qualifications? Just like with the Passivhaus, the best way to save energy is to not need it. The primary building section design of the RSF is narrow—only 60ft deep. This design strategy enabled the primary section to have a 100% daylight footprint, effective cross ventilation, and solar and glare control. The primary south façade windows are a prominent feature in this climate responsive building—they have an upper daylight section, which includes a reflective louver system daylighting device that redirects sunlight up into the ceiling deep into the space. The list of sustainable design features in this building goes on-and-on. These strategies, combined with the three on-site photovoltaic systems totaling more than 1.6 MW per year, grant this living lab the NZEB title.
When explaining what net zero water means for buildings, Amanda Sturgeon, vice president of the Living Building Challenge, stated, “All of your water must be harvested on-site or sourced from a closed-loop system. For discharge, no water leaves your project site through city pipes—all waste water is treated and reused or infiltrated within your property.” Now, after hearing this definition, right off the bat you might think that this sounds close to impossible for some regions (nod to Phoenix again). While net zero water projects in semi-arid climates are very scarce (if there are any), sophisticated enough graywater systems and rainwater harvesting strategies enable buildings in most regions to accomplish this feat.
Photo credit: Casey Dunn
The Dixon Water Foundation’s certified Living Building, the Betty and Clint Josey Pavillion located in Cooke County, Texas, fully embodies the foundations mission: to promote healthy watersheds through sustainable land management. Just as the Research Support Facility in Colorado is used as a living energy lab, this pavilion functions as a living water demonstration lab. Water is collected and stored in a 13,000-gallon cistern, from which it is used for sewage conveyance and irrigation. The site has its own constructed wetland that cleanses and returns all of the water used back to the aquifer—forming that closed-loop system that Amanda Sturgeon mentioned; the groundwater pumped into the pavilion’s sinks eventually gets returned to the ground again, and the cycle continues.
According to the U.S. Department of Energy, a net zero waste building “means a building that is operated to reduce, reuse, recycle, compost, or recover solid waste streams (with the exception of hazardous and medical waste) thereby resulting in zero waste disposal.” While sewage waste isn’t directly mentioned in the DoE’s definition, the Living Building Challenge isn’t afraid to make it clear that all buildings seeking certification under their system must have infrastructure in place for reusing or infiltrating all wastewater on site as well. It turns out this can be pretty difficult, as many municipalities will not allow onsite treatment of graywater or blackwater.
There is a commercial office building out there that has successfully passed the net zero waste qualifications—composting toilets and all. In fact, it is certified in all net zeros listed above—it is completely self-sufficient in energy, water, and waste. Be sure to check out our next blog post to find out more about the Bullitt Center, located in Seattle, Washington.
Interested in all things net zero?
On August 19th, 2016, Verdical Group is hosting the first ever conference that covers all three Net Zeros—Energy, Water, and Waste. This is the 3rd Annual Net Zero Conference, and will be the largest ever, with projections of over 600 attendees. Go here for more details about the event, information on how to register, and sponsorship inquiries: https://www.verdicalgroup.com/net-zero-2016/