ZNE – The Story Continues…

NBI’s recently released 2014 Getting to Zero Status Update provides a snapshot of the advancing zero net energy (ZNE) market in commercial buildings. While the market is still very small, the number of buildings achieving ZNE Verified performance or those targeting ZNE has more than doubled in just two years – from 60 in 2012 to 160 projects in 2014. While the growing list of net zero energy buildings is definitely encouraging, this snapshot is only part of a rapidly evolving story.Low energy buildings are a challenge that doesn’t end when the design team has finished its work and the contractors and commissioning agents have gone home. Factors such as climate, building use patterns, occupant loads and photovoltaic production are all dynamic, causing electric meters to spin one way or another at varying rates all the time.In the 2014 Status Update NBI looked at energy use and renewable energy production over a 12-month period. If the 12-month renewable production equaled or exceeded the 12-month total building energy use, the building was recognized on the ZNE Verified list. If not, they were listed as ZNE Emerging – targeting, but not yet accomplished. But which 12 months you investigate matters. What was the weather like during that period? Was equipment functioning properly? How about the dashboards or meters? Were there any changes in the building or meter configuration? Did occupancy or hours vary? All these questions are pertinent to the net zero result.Another important lesson learned during this research is not necessarily anything new. Namely, collecting measured building performance information is a challenging undertaking, even for the best buildings. Not only is it difficult to gain access to the data, but it is often incomplete or contains errors. As John Scofield from the Department of Physics and Astronomy at Oberlin College asserts in the January 2013 Issue of HPAC Engineering, utility bill interpretation can be complicated for many reasons, and even well-cited case studies may not be using the most accurate data.Having an energy dashboard to report problems is not enough. ZNE, and even ultra-low energy buildings, require attention to ongoing use and consumption patterns. In other words, they need to be managed – and managed well – to achieve and sustain their goals.All these challenges have led us at NBI to believe that once a building is ‘on the list’ it must earn the right to stay there by providing updated measured performance and renewable energy production data. We have created an online registry (http://newbuildings.org/share) where building owners and design teams can share information about their ZNE or ultra low energy building. This ongoing attention to measured performance increases accountability and provides another snapshot. And those snapshots, when tied together over time, will tell the story of just how the commercial building industry got to zero.