Despite the challenges that 2020 brought us, we continue to be impressed and humbled by our clients and the public sector’s resolve to push forward. One industry innovation that continues to attract attention is the design and construction of net zero energy facilities.
Over the past few years, B&D has guided multiple clients through the complex process of planning, designing, and implementing a net zero energy (NZE) building. It’s a multifaceted undertaking that can make what seems like a simple energy use problem into a much more complex equation.
In Case You’re Wondering
What makes a building net zero energy? NZE buildings generate as much energy as they use over the course of a year. They combine energy efficiency (using less) with on-site generation of renewable energy (producing more) to achieve the standing of ‘Net Zero.’ Buildings designed with the infrastructure to support becoming net zero energy in the future are known as net zero energy ready. Owners often explore this concept when navigating an energy infrastructure procurement process with uncertain timing or when funds are not currently available for additional energy infrastructure but may be in the future.
Whether you are involved in building an NZE facility or simply gathering information for a time to come, read on to discover four key considerations for planning and implementing an NZE building.
Using Less and Making More (Building Design Considerations)
The first piece of the net zero equation is reducing energy use. There are multiple ways to do this. Several high-efficiency mechanical, electrical, and plumbing (MEP) systems are available as well as system programming tools. This allows the systems to talk to each other and adjust to changing conditions in real time. Improving the building envelope’s efficiency by reducing the air and energy exchange with the outside environment can also dramatically reduce energy needs. Intentional selection of materials to passively absorb and transmit heat (or to block the absorption of heat) is another key component of net zero energy building design.
Offsetting energy use with on-site generation is specific to the site, building, and budget. Common options for site-specific energy production include geothermal systems, solar panels, wind energy, or a localized energy grid or “microgrid” supported by on-site infrastructure. Investigating and evaluating these options early is critical to delivering an NZE building. Sometimes, multiple on-site solutions will be needed to provide a building’s full energy demand.
For net zero energy ready facilities, the best plans account for both short- and long-term needs. It is important to make decisions that enable flexibility—such as designing the roof to have minimal equipment on it, so that it can hold solar panels or other green technologies in the future. Another example of planning for long-term use includes anticipating expanding infrastructure over time, and thus building larger mechanical rooms than the current system requires or ensuring roof access from the very beginning.
Balancing Competing Factors (Building Modelling Considerations)
Items benefiting one sustainable quality—natural light, heating efficiency, solar panel orientation—may impact others, and vice versa. For example, keeping HVAC equipment off the roof, while good for PV generation, may require additional interior space be dedicated to mechanical equipment, with the associated ventilation and enclosure costs. Orienting a building in a north-south direction may increase the viable area for photovoltaic arrays on the roof, but may also expose more of the building to direct southern sun, increasing the heat transfer and therefore the energy required to cool the building. B&D encountered both issues while working with a public sector client in Virginia. The final design included several large interior mechanical rooms, and the building design’s original north-south orientation was rotated slightly to reduce cooling load.
With so many pieces at play, comprehensive modeling is key to balancing the interrelated factors. Modeling energy use is both science and art. A model must accurately simulate changes to multiple building factors to identify the full impact of design choices. Models for multi-use projects must also be able to identify the level of building use, and then use that information to appropriately define net zero. For example, if a school is also used as a community center—primary and secondary purposes in the same building envelope—the model must decide whether to include the complete spectrum of uses or parcel out the net zero commitment for one user vs. the other. A building with school and community uses can be active up to 20 hours a day, making it hard to achieve net zero goals for all users. This delineation is particularly important for multi-use projects with distinct funding sources.
The key to all of these adjustments is timing. The earlier a development team can identify what is needed—both in the short- and long-term—the better. Engaging an experienced architect and / or energy modelling team early in the design process is critical. Also, keep the question “Where is your money better spent?” in mind when considering how to weigh benefits for changes that impact multiple project priorities.
The Schedule Factor (Design Process Considerations)
A wide range of industry professionals will be required to successfully design a net zero energy building and its on-site energy infrastructure. Determining the right project partners is key. Will the on-site energy systems be designed by your architect, your architect’s subcontractor, a separately hired specialized design and engineering team, or an experienced subcontractor hired by your general contractor? Determining which team members are ultimately responsible for these energy systems, and when they join the team, is an incredibly important factor in project success, especially for net zero energy ready buildings. Without early coordination, your facility may not be as “ready” for net zero upgrades (without costly or ugly retrofits) as you would like.
In addition to the team coordination aspects, a nimble procurement process plays an important role in achieving net zero energy status. As discussed above, multiple vendors may ultimately provide integral building systems (e.g., a geothermal vendor, a solar power vendor, etc.). This makes proper identification of resources and procurement options more important. One popular option is a Power Purchase Agreement (PPA), where you license or lease your roof to a company that puts solar panels on it. You then buy solar energy from that company for a set period (say 30 years), often at a lower rate than you would pay for electricity from your local utility. Alternatively, you might seek a rideable contract from a larger jurisdiction, allowing you to achieve economies of scale by buying into a bigger proposal. Finding creative procurement and infrastructure funding options can have a big payoff for a Net Zero Energy facility project.
An essential consideration relating to users and the operations of an NZE building is the education critical to encouraging behavior changes. Users of a building—e.g., library staff and patrons, rec center staff and visitors, office workers, school staff and faculty—must understand how the building functions and how their personal energy consumption affects the building output. For example, staff at a public school in the mid-Atlantic were accustomed to having appliances like personal microwaves, refrigerators, and printers in their classrooms or offices. In order to change this culture, the project management team led a campaign that emphasized the importance of personal behaviors that supported net zero energy priorities such as having only shared appliances in common spaces.
Ensuring user understanding can be achieved in a variety of ways, but signage that illustrates key facts about the sustainable features of the building is a common characteristic in net zero facilities. This signage can be static, dynamic and tied to the building’s systems (i.e., an interactive energy dashboard), or can change over time, using technology such as QR codes to provide links to additional building information. Education can also be incorporated into tours of the building that highlight sustainable features. These activities can also tie into relevant Leadership in Energy and Environmental Design (LEED) points—a benefit for the many NZE facilities that ultimately pursue certification.
When bringing a team together, it is important to combine smart building design and strategic decision making based on comprehensive modelling with the early involvement of trusted advisors, design experts, and educated users. As more and more entities look to install NZE facilities, using lessons learned from past projects is a great way to avoid painful—and costly—pitfalls along the way.