California’s Long-Term Energy Efficiency Strategic Plan for commercial buildings, implemented by the state’s Public Utilities Commission, mandates that beginning in 2030, all new commercial buildings and major renovations of existing buildings need to achieve zero net energy (ZNE) performance and support grid optimization. As noted in the plan, ZNE buildings will result in energy efficiency improvements of 60-70 percent, improve access to clean air, and reduce greenhouse gas emissions and resource dependency.
Although 2030 is more than a decade away, it’s important for architects in California to begin taking steps toward achieving zero net energy buildings now, so that when the date arrives, these goals are already a deep focus of their design strategies.
A ZNE building is one designed with systems and features that combine energy efficiency and renewable energy generation to result in the consumption of only as much energy as is produced onsite. As California’s population continues to grow and the need for new buildings increases, it’s easy to understand the importance of the mandate, especially as the state makes continued efforts to transition away from dependence on fossil fuels.
In addition to focusing on improved energy management, California has the pressing concern of bettering its water management. With several drought years in its recent history and no indication that pattern will change, the plan includes water efficiency as part of what a ZNE grid-friendly project should achieve.
There are essentially two types of strategies behind creating a zero net energy building: passive and active. Active strategies, such as high-efficiency mechanical systems and high-tech lighting controls are designed to reduce energy and must be carefully accounted for in the planning and design phase as added value to a building's life cycle cost. To balance cost, architects use passive design solutions, such as improved insulation and daylighting, natural ventilation, thermal mass, night flushing, solar shading, and thermal breaks. These relatively simple solutions can make a big impact on your project.
Some of the top active and passive design systems and features used by HMC Architects and others to achieve a zero net energy building are:
Geothermal
Depending on geographical location and soil conditions, ground source heating and cooling can be an excellent option, as it is extremely efficient. Below the earth’s surface, the ground is generally warmer in the winter and cooler in summer relative to the air temperature, and this can be used for heating and cooling within the building. One earth coupling approach is laying long tubes into the earth and running air or water through it, heat can be extracted from the ground in the winter and cooling can be achieved in the summer. While the temperature of the air and water that come back into the building might not be exactly what is needed for thermal comfort, less energy will be used to reach the target temperature.
Insulation
When you invest in high-performance wall and roof insulation, you reduce thermal transfer between the inside and outside, resulting in lower energy consumption to operate heating, ventilation, and air conditioning systems. The LEED Platinum-certified Kaiser Permanente La Habra Medical Offices in California achieved 74.2 percent energy savings by utilizing high-performance insulation in conjunction with several other sustainable strategies.
Water management
Interior and exterior water management is an important part of any sustainable project. At Clearwater Elementary School in Perris, California, our team aided in securing a grant from the state’s Water Resources Control Board that helped us implement several stormwater management strategies into the project. Stormwater capture systems, for example, allow storage of water, while bioswales reduce sediments, turbidity, and pollutants. The result serves as a wonderful sustainability teaching tool for the students.
Thermal mass
In areas where extreme temperature swings are common, utilizing thermal mass in a building’s design is a great ZNE tactic. Large, thick walls absorb the day’s heat and when the outdoor temperature drops at night, they slowly release it, regulating the interior temperature. In hot climates, combining thermal mass with night flushing results in precooling buildings for the following day and significantly reduce cooling needs.
Daylighting
Windows that reduce or eliminate the need for artificial lighting are sustainable features that lighten building load and positively affect occupant well-being. In the LEED Platinum-certified Evergreen Valley College Math, Science, and Social Science Building in San Jose, California, we utilized light wells in a long center corridor to bring in lots of natural light and create a bright and inviting communal space.
Natural Ventilation
Many architects have moved away from using operable windows in projects in recent years, but in certain climates, natural ventilation can be an effective year-round tool for passive cooling.
HMC strongly believes in leading by example. We use energy and water reduction strategies in all our recent work and always look forward to ZNE projects. We also feel that education is an important component of meeting California’s ambitious ZNE goals, which is why we’re so proud of our work on the Frontier Project in Rancho Cucamonga, California. Ten years ago, we succeeded in creating a demonstration building that makes consumers, other architects and builders, and ZNE advocates aware of design methods that encourage sustainability.
Ten years later, we apply new active technologies and optimize passive strategies on the ZNE. We are currently constructing what we hope will be our first true ZNE building—the North Coastal Health and Human Services Agency (HHSA) facility in Oceanside, California. This facility is powered entirely by the sun and uses no fossil fuels. Our design facilitates improved workplace health, productivity, and well-being by allowing for plenty of sunlight and natural ventilation, and by utilizing thoughtful hardscaping and landscaping features. By leading by example, we believe that we can be a part of the solution for a future in which we are all responsible in our energy consumption and take care to make our built environment harmonious with our natural surroundings.
HMC Architects looks forward to creating many more zero net energy buildings in California and beyond. Our designers are experts in the sustainable building practices that can help you achieve compliance with the California ZNE mandate and carbon neutrality goals. To learn more about our sustainable designs, contact HMC Architects. If you have specific questions about the state’s action plan and ZNE strategies, email Eric Carbonnier, PhD, our VP of Sustainability, directly. We look forward to working with you.