Zero Net Energy (ZNE) buildings are designed with greatly reduced energy loads so that over the course of a year their energy use can be completely met through on-site renewable energy generation.
To be verified as ZNE construction by a utility’s energy efficiency program or from a third-party verifier such as the New Buildings Institute, the International Living Future Institute, or the U.S. Green Building Council, this new construction must be designed with two separate elements in mind. First, the building’s design must prioritize strategies for maximizing energy efficiency options to reduce energy usage. Second, the building must replace any remaining energy needs with on-site renewables such as solar photovoltaics.
In recent years there has been tremendous growth in building designs and technology innovations, as well as codes and regulations, to support architects and building owners in achieving each of these two areas. Below we’ll take a brief look at some of the options architects have available to support their ZNE strategies.
Designing to Reduce Energy Demand
ZNE strategies generally become cost-effective when all avenues have been exhausted for maximizing a building’s energy efficiency before making use of on-site renewable generation. Many organizations advise reducing energy needs as much as possible through design strategies before addressing renewable energy supply. As a result, reducing energy loads through design strategies and energy-efficient technology must be prioritized as early as possible.
Based on our experience, cooling and lighting demands account for up to 75% of a commercial building’s energy load. These systems present a clear starting place for architects to minimize a project’s energy demands and costs. Reducing the load on these systems begins with prioritizing the use of daylighting and ventilation wherever possible to reduce lighting, heating, and cooling demands.
Strategies for reducing these loads may include optimizing building orientation, passive ventilation, windows that balance natural light with low solar heat gain, and selecting high-performance building envelope materials that provide excellent insulation and optimal thermal mass, among other design strategies. Studies have shown that natural light also has a positive effect on occupant health and wellbeing.
It’s important to recognize that the bulk of work needed to achieve ZNE happens through design strategies. As a result, energy reduction must be a clear priority early on. Integrating design, engineering and sustainability work together at the earliest onset of a project will help to ensure energy-efficiency measures are not just effective, but also economical. The best part is that once this early design work has been done it can serve as a template for future projects.
Technologies for Energy Efficiency
The next step toward reducing energy loads comes through an investment in energy- efficient building materials and technologies. This includes both familiar, low-hanging fruit such as a LED lighting, as well as more significant investments, such as higher SEER heat pumps, more efficient hot water heaters, better insulation, and Energy Star-rated appliances.
Once these avenues toward energy-efficiency are exhausted, architects can begin to integrate smart building automation or management systems that improve operation based on certain conditions. These ZNE strategies can include a wide range of integrations, from optimizing HVAC operation based on the time of day to adjusting lighting based on occupancy sensors or automating window shades to open and close based on the amount of sunlight entering. indicates that energy management systems can reduce energy consumption in facilities by as much as 50%.
While these investments have higher initial costs, they can make a tremendous impact on operational costs throughout the building useful life.
Supplying Energy with Innovation
The next step toward achieving ZNE is for a building to produce as much energy in a year as it uses through the use of on-site renewables such as solar photovoltaics, water-powered microturbines or geothermal energy. As the U.S. Energy Information Administration notes in its 2020 Energy Outlook report, rapid cost declines are driving an increase in renewable technology adoption.
While many ZNE strategies rely on the utility grid for energy storage, battery storage options are also becoming more efficient and cost-effective. Energy storage options not only benefit the building owner by meeting critical power needs in the event of outages and eliminating the dramatic peaks and valleys of demand changes, but can also benefit the utility grid by reducing grid-wide load fluctuations.
Striking the Right Balance
While ZNE buildings are increasingly a goal of large A&E firms, there remain a number of challenges to broadening acceptance of these ZNE strategies. Chief among these challenges remains a lack of awareness around the resources increasingly available to support the shift toward ZNE.
This is an area where working with an energy and sustainability consultant like Lincus can help. Our team members carry unique skillsets that combine technical and regulatory expertise, helping guide projects of all sizes toward more energy-efficient design and technology solutions. If you’re ready to take the next step and support this market transformation, contact Lincus today.