Bridging the energy gap between design and building performance
Contrary to popular opinion, new buildings don’t always perform among the best. Some studies even show that they may be slightly less efficient than older buildings.1
And believe it or not, buildings that market themselves as “green” aren’t always efficient, either. An analysis by the New Buildings Institute found that more than 50 percent of LEED-certified new buildings did not meet EPA criteria for superior energy performance. Additionally, 25 percent of LEED-certified new buildings showed below-average energy performance.2
Why the gap in performance? The most common reasons are:
- Energy use goals are not clearly communicated and monitored throughout the design process, and design strategies and construction methods do not create an energy-efficient building.
- Estimated energy use is not projected; actual energy use is not measured. The owner or architect may be reluctant to estimate the projected energy use of the building during design and construction and may also be hesitant to measure energy use once the building is operating. No one wants to be held accountable for discrepancies. But designing, constructing, and operating a building without estimating and measuring energy use throughout the process is like going on a diet without ever stepping on a scale.
- Improperly sized, installed, or integrated building systems. "Conventional engineering methods chronically overestimate loads for new facilities," according to Karl Brown, Deputy Director, University of California, California Institute of Energy and the Environment. Even the most efficient chiller will perform like a standard chiller if it is oversized and operating inefficiently at partial load. Thermal breaks in the building envelope mean that the most efficient triple-pane windows will still leak air. Unsealed air distribution systems will leak.
- A commonly used metric, "percentage better than code," falls short of assessing whole-building energy use. Building codes are indices, not estimates of the intended energy use in the building, making it difficult to project — and plan for — energy savings. "Percentage better than code" is based on a reference building determined by design project parameters and not the actual operating performance of your building. The code only addresses "regulated" energy in a building; it does not consider right-sizing equipment or integrated system designs.
- The building maintenance staff was not properly trained to operate systems. Change orders may replace efficient equipment with standard components.
Clear, open communications between the owner and the design team are essential to understanding what is intended in design and what happens after the building is operating. Bridging the gap as a team will greatly improve building performance and foster positive change in the design-construction-operation lifecycle.