Zero net energy buildings are growing in popularity. By 2030, the goal is to have all new commercial construction and 50% of existing commercial construction in California meet this standard. The commercial and residential building sector represents more than 40% of the national energy consumption. But zero net energy buildings are either energy neutral or produce more energy than they use, through a combination of on-site generation and energy-efficient measures.
Case in point: San Diego County is already paving the way with a commitment that every new project meets these standards. In 2018, it broke ground on the nation’s first zero net energy archive facility. The 25,000-square-foot, the single-story structure was designed using a “reduce before you produce” methodology, which focuses on minimizing energy usage, so less renewable generation is necessary. To achieve this goal, it incorporated approximately 375 highly efficient photovoltaic cells that provide enough energy to support the current building, plus 10% growth. It also included a combination of passive systems to reduce energy consumption by the end-user, including strategic building orientation, high-efficiency envelope and mechanical systems, lighting power reductions, plug-load reductions and operational changes.
This once seemed ambitious but is now becoming achievable even within typical construction budgets — with proper planning and execution.
Identify Your Goals
The decision to go zero net energy needs to be made at the start of a project, as it dictates all aspects of the project, including the team, design and materials. Because not all designers and builders are equipped to complete zero net energy buildings, it’s critical to inquire about recent projects and understand each party’s expertise. It’s also important that the architects and contractors collaborate upfront to help identify the most cost-efficient solutions. Having the end goal in mind can help everyone stay on track when making design and material decisions.
For example, San Diego County’s archive facility required special care and attention on the archive’s mechanical systems and design to ensure a climate-controlled space suitable for delicate documents, including hand-drawn maps; birth, marriage and death certificates; deeds and parcel maps from the 1800s, as well as a letter from President Abraham Lincoln granting land to the Mission San Luis Rey de Francia. Planning allowed the team to select the best HVAC system and create proper insulation and vapor control for the space. Since the team anticipated the HVAC system would require more energy usage early on, they had to explore other opportunities to save energy throughout the building.
Design & Materials
A common misconception is that you need a large budget to achieve zero net energy. However, more projects can achieve this designation under typical construction budgets with proper consideration for design and materials. In recent years, zero net energy projects have become more cost efficient, as key supplies, such as photovoltaic equipment, are being mass produced and therefore are more affordable. But some materials still have higher upfront costs, such as a Variable Refrigerant Flow (VRF) system. A VRF system allows you to control temperature in specific spaces based on needs, which is especially important in buildings where there are constant shifts due to usage or time of day, such as a cafeteria in a K-12 school where you might need cooling only during the lunch hour or west-facing office spaces in the afternoon when the sun is shining brightly. While it has a higher sticker price, a VRF system can help reduce energy usage compared to a traditional HVAC system, resulting in long-term savings. To buy in on these initial investments, it’s key to share predicted energy cost savings upfront.
For buildings with more upfront material and equipment costs, design teams can help identify and implement prefabricated design and construction strategies to keep projects within budget. Other considerations that can help buildings achieve their long-term energy goals include design decisions on window placements and coverings. These can have an impact on thermal loads without increasing material or construction costs and passive energy efficiency strategies, such as lighting sensors and controls, so that lights are not on when the space is not in use. Dimmers can also help reduce energy.
Zero net energy is an ongoing goal and can’t be forgotten once the project is complete. It is important that end users understand the long-term energy usage goal and are engaged to help achieve it. This can include educating all the occupants on the features so they can get the most value out of them — for example, showing how the window coverings will help minimize the use of energy-draining personal fans and heaters. In addition, building owners should perform ongoing assessments of the energy usage. In the case of San Diego’s Alpine Branch Library, the facility was seeing higher energy consumption than expected after completion. The culprit: idle computers were consuming a significant amount of energy. After the assessment, employees were trained on how to properly power down or set up equipment to automatically go into sleep or power-saving mode, and they were able to get back on track to meet their goals.
Zero net energy is the next evolution in sustainability. Not only are these projects becoming achievable within typical construction budgets, but the return on investment is well worth the time and energy.
Andy Feth is a project executive at C.W. Driver Companies, a builder serving California since 1919. C.W. Driver Companies serves a broad spectrum of industries, including education, commercial/office, technology, healthcare/biomedical, mixed-use, assisted living, entertainment, retail, industrial and civic. Feth can be reached at firstname.lastname@example.org or 619-696-5100.