In February, we reviewed some unintended consequences associated with the growth of renewable energy production on the grid, and how smart net zero buildings, combined with a smart grid, can enhance rather than undermine the carbon emission reduction benefits of net zero energy design. To recap, as the generating capacity of grid-connected renewable energy sources (e.g., wind, solar farms, rooftop solar) increases (as in California), there can be seasonal conditions and times of the day when there is a mismatch of energy generation and energy use. This can temporarily result in a wholesale electricity prices near zero or even negative. Quick responding solar farms, not wanting to pay grid operators to take their energy, immediately shut-off (economic curtailment). Discarding fully paid-for solar energy from solar farms reduces overall renewable energy production and increases energy costs. That’s a problem.
One solution that we reviewed in the February column was smart day-ahead electricity pricing, providing an inducement for consumers to adjust energy use, combined with smart buildings, able to automatically modulate energy use based on owner-defined preferences and utility pricing signals. This smart net zero approach ensures the carbon emission reduction potential of renewable energy resources is fully realized, provides greater economic incentive for renewable energy investments, large and small, and increases community resilience. The New Buildings Institute (NBI) recently launched the GridOptimal Buildings initiative to hasten the implementation of strategies for buildings and utilities to work together to achieve grid decarbonization. Let’s look at other ways to achieve smart net zero.
Another smart approach is scaling up—focusing on net zero neighborhoods rather than on individual homes and buildings. Due to trees, topography, and sub-optimal roof size and orientation, many homes are not ideal for solar arrays, especially when net zero is the goal. Fortunately, most urban and suburban neighborhoods are bounded by collector streets lined with commercial and public buildings that have larger, unshaded flat roofs and [potentially] covered parking lots, ideal for optimized solar, typically at a lower installed cost per watt compared to small residential arrays. (See image.)
Urban Neighborhood Rooftop Solar Potential. Image from Google Project Sunroof.
This opens up the opportunity to include a community solar model into these neighborhood projects. Community solar projects are generally located within the community they serve, with homeowners, renters and businesses able to purchase shares of the array, then receiving a return on their investment through utility bill credits based on solar production. These community solar project can be managed by the electric utility, a special purpose entity, or by a nonprofit organization. Community solar provides a cost-effective and equitable means for an entire neighborhood to transition toward net zero.
Larger buildings offer many other benefits, too. They are much more likely to need power in the middle of the day when solar production is at its peak. By consuming on-site solar output, the complications of back-feeding the distribution grid can be reduced or eliminated. These buildings tend to have significant HVAC and refrigeration needs—electrical loads that have operational flexibility. Together, building operators can reduce their energy costs by avoiding increasingly expensive morning and late afternoon electricity in favor of their own cheaper mid-day electricity.
Many of these larger buildings already have some type of building energy management system that can be used or upgraded to adapt their energy use to these emerging scenarios. Some buildings even have their energy managed remotely by a centralized or contracted service.
The growing number of electric vehicles (EVs) is also brings new challenges and opportunities. Although charging EVs at home can benefit from lower nighttime rates, connecting EVs to charging stations in the middle of the day provides the grid much-needed flexible loads able to cheaply purchase increasingly abundant, and occasionally excessive, mid-day solar power.
When you consider that grocery stores and schools are typically the neighborhood buildings with the largest roof areas, this model brings increased resilience to their communities. After a hazard event, schools often serve as shelters, and grocery stores are uniquely positioned as distribution locations for relief supplies of food and water. Often, these buildings already have standby generators. This is a good start. And with on-site solar, managed consumption, and a small amount of battery storage, these buildings can function as disaster recovery centers and emergency EV charging stations indefinitely.
Naturally, these smarter energy systems will require that the grid and building systems be able to communicate with each other. Given recent news of cyber-attacks and hacking, there are plenty of reasons to be cautious when advocating for the broad adoption of more web-connected devices in homes, businesses and utilities. However, unlike many casual consumers, larger buildings are more likely to take these cyber threats seriously and have both the means and savvy to aggressively manage potential vulnerabilities.
Designing buildings to use no more energy than can be produced by on-site solar is a good benchmark for all buildings but achieving this in isolation can sub-optimize the system. Smart net zero looks for system-wide approaches to optimize both the production and use of energy, maximizing the production and best use of clean renewable energy, while decreasing dependence on carbon-intensive generation as a back up when sun and wind are not plentiful. We have all the tools and we just need to use them smartly.
Alan Scott, FAIA, LEED Fellow, LEED AP BD+C, O+M, WELL AP, CEM, is an architect with over 30 years of experience in sustainable building design. He is a senior consultant with Intertek Building Science Solutions in Portland, Ore. Dan Bihn is an energy educator, communicator and consultant specializing in smart energy issues. To learn more, visit www.intertek.com/building/building-sciences/ and follow Scott on Twitter @alanscott_faia. Bihn can be reached at dan@danbihn.com.