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Nothing But Net – Zero Net

BY LISA KOPOCHINSKI

Over the past 20 years, green and sustainable construction has evolved from what many called a fringe movement to one that has achieved mainstream status. Reducing energy and water usage remains the top environmental issue driving these types of construction projects.

Now, we are hearing much more about zero-net construction. Exactly, what is this and how does it differ from green and sustainable construction?

Essentially, a zero-net energy building is a structure with zero-net energy consumption, meaning the total amount of energy used by the building on an annual basis is roughly equal to the amount of renewable energy created on the site.

“Zero-net energy is a more holistic approach to design and construction,” explains Andy Feth, P.E., project executive at C.W. Driver Companies, a premier building company founded in 1919 and member of AGC of California and San Diego Chapter.

“Rather than designing a building and installing a photovoltaic system after the fact, energy efficiency must be incorporated into all aspects of the planning and construction process,” says Feth.

“For instance, smart use of glazing, daylighting, shading and window placement are all important parts of the planning process, as is the appropriate amount of insulation. Lighting sensors and controls help minimize energy usage for the end-user. Variable refrigerant flow (VRF) systems can also reduce energy usage significantly compared to traditional HVAC systems.”

Ash Awad is chief marketing officer at McKinstry, a member of multiple AGC chapters. A national leader in designing, constructing, operating and maintaining high-performing buildings, McKinstry provides a single point of accountability across the entire building lifecycle from new construction and ongoing operations to adaptive reuse and energy retrofits.

Awad says today’s built environment is needlessly inefficient, resulting in buildings that cost too much to design, build, operate and maintain.

“It is our firm belief that half of all building construction costs are wasted, and half of all energy consumed in facility operations is wasted. Construction productivity and building performance need to improve, which is why we are focused on accelerating that change to eradicate waste and ensure facilities keep pace with rising energy and occupant demands.”

NOTABLE ZERO-NET PROJECTS

Over the years, McKinstry has been part of several projects that changed how energy and sustainability is looked at.

“For instance, the McKinstry-Clise Eco District in Seattle challenged us to take a neighborhood view instead of designing and constructing each building as a standalone island,” says Awad.

“The unique project moves waste heat from the Westin Building Exchange data centers across the street to heat Amazon’s corporate campus. That waste heat sharing will save over 180 million kWh over the next 20 years.”

Awad also mentions the South Landing development in Spokane which amplifies the neighborhood eco-district approach.

“Every building in the development will share energy resources and work together to set a new vision for the built environment. The result creates a grid-optimal eco-district that benefits both the buildings and the utility grid.”

He explains that South Landing is only possible because of a unique approach to partnerships.

“Avista set the vision, partnering with McKinstry to bring it to life. From there, we engaged Katerra to deliver efficient, modular construction and secured Eastern Washington University (EWU) as the primary tenant. Engaging all stakeholders early allowed us to focus on outcomes to achieve the zeroenergy and zero-carbon vision.”

Calling the technologies used to build the zero-energy and zero-carbon building standard, off-the-shelf components, he adds that, “it is the unique partnership that pulls it together in an innovative way, delivering a zero-energy and zero-carbon building at market cost.”

Essentially, he says South Landing sets a new vision for what the built environment must become.

“It will transform the way buildings are designed, operated and maintained by unifying the complete energy value chain. The Catalyst building and Hub facility are the first buildings under construction within South Landing.”

When completed in September 2020, the five-story Catalyst building will span 159,000 square feet and be the largest zero-energy building ever certified by the International Living Future Institute. The building will also be zero carbon, combusting zero fossil fuels on-site.

The Catalyst building is being constructed of sustainable cross-laminated timber (CLT). The 4,000 cubic meters of CLT within the building will store 3,713 metric tons of carbon. Using CLT instead of steel and concrete avoids another 1,437 metric tons of carbon.

“That roughly 5,000 metric tons of carbon dioxide equates to 1,100 cars off the road for a year. U.S. and Canadian forests can regrow that 4,000 cubic meters of CLT in just 11 minutes,” says Awad.

The four-story, 40,000-square-foot Hub facility will house a central energy plant to power the facility and its neighboring Catalyst building. Its central energy plant transforms South Landing into a shared energy eco-district. McKinstry engineers performed 40,000 energy models to design the central energy plant and eco district. Deployed systems will include solar photovoltaic (PV) arrays, thermal energy and battery storage systems, high-performance variable air volume (VAV) systems and dedicated outdoor air systems (DOAS).

“The South Landing eco district unifies the entire energy value chain,” says Awad. “Thousands of IoT sensors will be deployed across South Landing backed by machine learning and analytics. The resulting technology infrastructure will allow Avista to see beyond the meter to balance on-site energy demand and energy generation with overarching grid operations. Excess energy can then be used to meet demand elsewhere on the grid or stored in the on-site thermal energy and battery storage systems.”

Feth says, to date, C.W. Driver completed one zero-net energy project — the Alpine Branch Library in 2016, and is currently underway working on the County of San Diego’s Assessor, Recorder, County Clerk Office (ARCC) in Santee, which is scheduled for completion this November.

“To accomplish zero-net energy — and generate enough renewable energy to meet its own consumption requirements — the single-story, 25,000-square-foot ARCC building and parking lot will support approximately 375 highly efficient photovoltaic cells and incorporate all building systems on electrical power. The ARCC building will also leverage natural daylight and breezes from the surrounding environment to maintain warm and cool temperatures in the building. It will be the nation’s first zero-net energy archive facility and will maintain strict temperature and humidity conditions to preserve delicate archive materials properly.”

He adds that both of these projects have been a highly collaborative effort involving energy modeling with the input of an electrical engineer, close discussions with the county and a third-party review from a county consultant to ensure that everyone is aligned to the projected energy input/output and that the required 10 percent buffer set by the county is met.

ZERO-NET CHALLENGES

While zero-net projects certainly have great advantages, they are not without their challenges.

Feth says it can be difficult to implement zero-net energy for buildings that require higher energy use, but it’s not impossible.

“For example, for our current project for the County of San Diego’s Assessor, Recorder, County Clerk Office, the building requires very strict temperature and humidity conditions to preserve the delicate archive materials properly. This requires a high-energy standalone HVAC system, rather than energy-saving VRF. To offset this higher energy use, we are using an efficient building envelope and robust photovoltaic system. The building, which will be the nation’s first zero-energy archive facility, demonstrates that there are solutions to making even the most challenging projects zero-net energy.”

He also says that one challenge people don’t think about is training the end-user. When doing energy efficiency calculations and determining whether zero-net energy is feasible, assumptions must be made about how the building will be used.

“Space heaters, fans and other unexpected electrical usage can add up quickly and make it difficult to offset energy usage. To avoid this, it’s important to educate the end-user to regulate energy usage and maintain efficiency, and this could mean encouraging changes in habits. Often, it’s as simple as changing settings on computers so they go to sleep mode when not in use or adjusting the temperature controls so people are more comfortable without the use of space heaters. It’s a small change in mindset that quickly becomes habit once users understand why these choices make a difference.”

Awad says that zero energy traditionally requires as much on-site energy generation as the building consumes over the course of the year.

“Under this definition, zero-energy operations would be very difficult to reach even with an incredibly efficient building,” explains Michael Frank, vice president of engineering and design for McKinstry. “Approximately half of all the building square footage that currently exists in the U.S. is a candidate for zero energy.”

Frank adds that while it is technically an achievable goal to make all building construction projects zero energy, the growing number of zero-energy projects in the market can put strain on the utility grid.

“This means there is the opportunity to locate/connect the renewable energy in a part of the grid that can handle the surplus load that solar photovoltaic (PV) systems creates in the summer months, as well as make your building as grid optimal as it can be through the use of on-site storage (thermal and battery). Additionally, while it might not make sense for every building to go the final mile of adding renewable energy sources, there are fundamentals of zero energy that remain valid for any construction project.”