The Path to Net Zero Through Ongoing Performance Analysis
Carbon neutral facilities must be the norm by the year 2030. The AEC profession has been working with building owners to fulfill this imperative for over a decade. However not every building owner is in a position to achieve net zero energy construction today, often through lack of budget or similar scope limitations. So in working with our clients towards the 2030 Challenge, we’ve developed tools and tactics to help our clients and their projects be on a Path to Net Zero Energy.
Think of the Path as a tee up. We take facilities as far as possible toward net zero goals today within the project’s constraints. But we employ design and construction strategies that easily accommodate future additions or improvements that fulfill final net-zero operational needs as soon as the owner is able.
The Energy Pyramid
When we work with a client, the Path to Net Zero Energy begins with the Energy Pyramid. The lower levels of the pyramid have the biggest impact on energy efficiency (especially building orientation and envelope). They’re also the easiest to achieve within any given project’s scope, which means it’s critical to investigate net-zero opportunities at each and every level. We do this through ongoing performance analysis.
Ongoing Performance Analysis
Performance analysis is a term we use to cover diverse modeling and analysis tactics that we perform to evaluate the energy efficiency of design, systems and construction options. There are various ways we can optimize a building’s energy usage by implementing ongoing performance analysis throughout design:
- Building Shape and Orientation: Early in the project we host an integrated design charrette to specifically explore options for how the very form, size, and orientation of a building influences energy consumption. For example, our design team for Valencia College’s Poinciana Campus (Poinciana, Fla.) not only used performance analysis to fully understand how their design decisions would impact the energy consumption, but further presented findings to the owner as the schemes were developed. This approach makes energy consumption an integral part of the early design decision making.
- Building Envelope: As our understanding of the building shape and orientation grows, we then explore options for the building envelope, with specific analysis of how materials and systems impact energy consumption. Our Zellwood Elementary project team (Zellwood, FL) tested various performance criteria for the building walls, glazing and roof selection. The project team presented the return on the investment for improved envelope design and the project owner elected items with a payback within 5-8 years and the overall energy consumption was reduced by 18% over ASHRAE 90.1-2007.
- Lighting/Daylighting: The next step in ongoing Performance Analysis is understanding lighting (both natural and electric). We can verify our selection of glazing by looking at daylighting and lighting within the building. For example, the Valencia Poinciana project team modeled several glazing options along with the location of daylight sensors. It was determined that if we implemented multiple types of glazing, depending on orientation, we could save an additional 5% in energy consumption.
- HVAC Equipment and Architectural Impact: With building shape, orientation and envelope determined, the next step in modeling would be to test various approaches to mechanical design. If the building structure itself sets a baseline optimization for user comfort and wellness, then mechanical systems don’t need to do as much work, and we can explore the most efficient systems possible. For example, on the Valencia Poinciana project, the design team tested various options and overall went with a hybrid chilled beam and traditional VAV mechanical system. By implementing the chilled beam system in a majority of the building, it not only had a significant impact on the energy consumption, but it impacted the architecture. We were able to reduce the floor area dedicated to mechanical equipment giving it back to programmable space and we reduce the overall building height which saved the project money keeping it on-budget. By modeling the savings, it helped the owner team to justify moving towards a new approach to mechanical design.
- Controls: Although controls occupy their own level on the pyramid, in ongoing performance analysis we typically investigate controls concurrently with both lighting and HVAC.
- Renewables: Most often, this is where an owner’s project constraints prevent them from fulfilling net-zero. But by implementing ongoing performance analysis, a project team reduces the energy use intensity (EUI) to a point where the addition of renewables is the only step needed to accomplish that goal. The key is to masterplan the renewables now in the building design, so that the infrastructure can accommodate the additional renewables in the future.
Our project teams who have implemented ongoing performance analysis have noticed design estimates come in on-target. The increased accuracy of estimating comes from this approach of balancing architectural and engineering decisions against the budget. We implement value engineering throughout the design, and it’s tested against performance criteria. And clients who request a Path to Net Zero Energy have found testing the design against performance criteria allows them to justify the money spent upfront.
So now I’d ask you this question: will you implement ongoing Performance Analysis on your next project?