Exterior of building

Commissioning to Net Zero

In May 2016, the state of California adopted the Zero Net Energy definition that the Federal Government uses.A building “produces as much energy as it consumes over the course of a year, when accounted for at the energy generation source.”This is a big deal for California, but also could impact the project’s ability to reach ZNE since the new definition will require approximately 39 percent less renewable energy generation capacity, save the project’s renewable energy dollars, and still achieve the requirements of the executive order, as compared with the “ZNE site” definition. With this common definition and supporting state and federal requirements, we are in a unique situation to implement ZNE into the design, construction and operations.The first step in pursuing ZNE is also the most difficult – setting the ZNE target as a project goal and one of the Owners Project Requirements (OPR).After agreeing on a common ZNE definition and making ZNE a goal and part of the OPR, the second step is designing to the ZNE target. In addition to the Design Teams hands-on ZNE experience, a number of strategies have been identified by the state of California for consideration in ZNE facilities whenever possible to ensure the highest output and efficiency possible, reducing long-term operating budgets and avoiding overgeneration.
  • Energy efficiency – Ultra-low energy use through energy conservation, passive systems and whole-building integrated energy efficiency measures should always be the initial focus for each building pursuing ZNE.
  • Share excess generation – Whenever possible, excess generation should be utilized on-site through energy storage, with other buildings on campus, or through utility agreements with other buildings in portfolio.
  • Install energy storage – Utilize on-site energy storage (batteries, thermal, etc.) to shift energy use for peak load reduction, limit overgeneration sent back to the grid, reduce demand charges, reduce energy costs by taking advantage of time-of-use (TOU) rates, and provide cloud cover and outage protection for the facility.
  • PV array orientation – To the extent possible, consistent with California Solar Initiative’s Flexible Installation (CFI) option, orient the PV arrays between 150 and 270 degrees from true north to delay the maximum generation to later in the day to better coincide with the CAL-ISO grid’s high peak periods. This approach should be reviewed and adjusted over time to provide alignment with the needs of the utility grid.
  • Use over generated energy for EVSE charging – Electric vehicle service equipment (EVSE) can utilize excess energy generated to charge electric vehicles. This will help reduce or avoid export of over generated electricity, and help agencies meet zero-emission vehicle charging infrastructure goals. Energy used for electric vehicle charging does not count toward building energy use, nor does it need to be included in ZNE building calculations. Energy generated through on-site renewables used for EVSE charging can be included in the annual calculation of ZNE using the same source energy factor as over generated energy delivered to the utility grid.
Simple box energy models and performing various ‘what-if’ scenarios using modelling and estimating is the most efficient way of determining which building systems should be considered and how much renewable energy is required to off-set the energy use. How the facility energy and water use will be tracked and monitored needs to be determined and documented during the design phase.Our approach to ZNE projects begins with an initial Energy Performance Options Report (EPOR) which will help the Project Team understand how all of the various envelope, daylighting, lighting, and mechanical elements, cost options, and financial opportunities fit together.  This will confirm the current and potential range of performance, based on the initial plans, while there is still time to make design adjustments.Recommendations for reducing costs and/or improving performance and ZNE targets will be provided, as appropriate.  Interactions with multiple related LEED credits will be identified and managed.The information in the EPOR will serve as a tool for the team to make informed decisions about the energy goals, design choices, and construction costs.  As the design proceeds, we will review the plans and update our calculations to identify if the project is on track to achieve the ZNE energy goals. Recommendations will become increasingly specific, to reflect the level of detail appropriate for a given phase.We have many years of experience working on various ZNE projects using different project delivery methods and understand risk mitigation from each team’s standpoint. We understand that LEED implementation and Energy Analysis is tied to the whole project process from pre-design to construction and well into the operations phase of buildings. We bring experience from each of these phases to the other, communicating the challenges and solutions of each. We call this “filling the gaps” and it’s a large part of the reason that owners, designers and contractors enjoy working with us. We understand how to integrate ZNE and LEED planning with the design process in an efficient but thorough manner and can assist with the Living Building Challenge (LBC) analysis and documentation for the Zero Net Energy petal.The third step is to construct to the ZNE design. Integrating the contractors team in the ZNE effort is critical and is often most effective when combined with the building commissioning quality process. Verification of energy using systems and their proper functionality is one of the most important elements of confirming zero energy use.The fourth step is to monitor, correct and validate. We do this by trending energy and water use, identifying any abnormalities, performing a post-evaluation survey, and implementing a deficiency resolution path. Independent tracking and monitoring of the energy and water use over a period of 12-months is both good practice but also a great opportunity for engaging visitors and staff in the ZNE goal.