By Suzanne Robinson
I get asked all the time what’s the latest and greatest in the world of sustainability, especially with energy. The biggest trend of this year is total energy for the building, specifically Zero Net Energy (ZNE), Energy Positive (E+), Passive House, and Zero Energy Buildings (ZEB). ZNE is not new. It has been around for years, but this last year, clients who wanted to showcase a sustainable building gravitated towards a ZNE project. ZNE is the new LEED.
Design for ZNE has gone through an evolution these past few years. Personally, I loved the concept of ZNE buildings when I first came across the concept years ago: to produce the energy you consume on-site. I loved working on my first project that strived for ZNE with an owner who was up to exploring different concepts for occupying and operating the building, with an architect who fully embraced a design informed from energy decisions, and with a contractor who was involved during design. We had a truly integrated team.
I didn’t realize I lucked out. For the next series of projects, too often they were interested in ZNE without a full understanding, education, and mindset shift for all parties involved. To get to ZNE you have to let go of some of the old habits, thinking, rules of thumb, and expectations. We would go through the exercise of finding the path to ZNE design and then see other project agendas dominate.
I took away a personal mindset shift from the experience. The practice of designing to ZNE should be inherent on every project we work on, regardless of the energy targets. It provides the opportunity for true informed design decisions. Instead of tacking on extras from a baseline and building up your energy reduction number, start at ZNE. Even if the project does not end up being ZNE, you still will have a much better energy-performing building. All the projects that we were striving for ZNE are better for the process we went through even if they ultimately didn’t make it to ZNE.
There are two drivers that are emerging in this new wave of ZNE. The first driver is operation. True sustainability is designing and constructing a building that can actually be operated during its lifetime as a sustainable building. As we push our designs to be more high performance, we add layers of controls to only use energy when needed. A backlash has resulted because most high-performance buildings do not invest in high-performance operators. The more moving parts and complicated a system you have, the more risk you have for failure. The mantra Keep it Simple Stupid (KISS) is gaining ground.
ZNE refocuses design back to reducing the loads. For example, right-sizing the envelope shell should mean it is near energy-neutral and allows for the HVAC system to focus on the cooling and heating loads related to ventilation and internal load needs and not have to make up for the heating losses through the envelope. This results in smaller HVAC systems with simpler controls, and proper operation is more likely achieved.
The second driver is that ZNE is gaining legislative ground. There is a growing list of adoptions of ZNE requirements, from the European Union to California. In Massachusetts, the senate is reviewing Bill S.1587 that would establish ZNE building standards for new commercial buildings by 2030. There would be incremental increases of 30% better than the most recent international energy conservation code (IECC) to reach this 2030 requirement.
ZNE is not a fad. Between owner and legislative demands, we are shifting our practices as an industry. There are certainly growing pains, but the growing awareness, education, and energy intuition to effectively design and construct ZNE buildings is gaining momentum.
Suzanne Robinson, PE LEED AP, BD+C, is the director of sustainability at Vanderweil Engineers.