An energy and sustainability case study
Electrochromic (EC) glazing has the reversible ability to change its visible light transmission and solar heat gain coefficient creating a dynamic building skin, capable of actively responding to the ever-changing exterior environment. In doing so, EC glass can minimize cooling and heating loads, maintain a thermally comfortable environment and control sunlight glare for the occupants. EC glazing has the potential to enable net zero energy façade systems[1] while maintaining sufficient glazing area for needed daylight and views.
The newly renovated, state-of-the-art, approximately 194,000-square-foot headquarters for Saint-Gobain in Malvern, Pa., demonstrates the potential of EC glass in office designs that support both the long-term sustainability of the planet and the longterm well-being of the humans who occupy them.
In this case study the key goals for the building owner were to:
- Create a next-generation work place, which supports cross-collaboration and a state-of-the-art environment, which could attract and retain top talent.
- Create a high-performance building. Achieving USGBC v3 Platinum for both Core and Shell (CS) and Commercial Interiors (CI) and U.S. EPA Energy Star certification were key targets.
In addition, Saint-Gobain wanted to use this as a living laboratory to measure the impact and experiences of its employees in its next-generation workspace.
After stripping down an existing structure to the bare steel and concrete frame, the building was completely re-clad, re-finished and the HVAC system upgraded. Knowing the sustainability goals, a focus for the design team from The Sheward Partnership LLC, Philadelphia, was how to use enough glass to achieve good daylight admission and views to the surrounding countryside without impacting energy use and occupant thermal comfort. This was especially challenging because of the fixed orientation of the building, which has one long west-facing façade where heat gain and glare would be major issues. To solve this problem they installed EC glass on both west and south elevations, including the highly glazed atrium at the entrance.
Energy modelling was used to compare the design with the EC glass with the code compliant baseline, which showed a 34 percent reduction in energy usage and a 30 percent reduction in energy costs. As a result the project was awarded 14 points under the EA credit. The use of EC glass is not responsible for the entirety of this energy performance since the simulation model included a range of other energy efficiency strategies that were implemented. EC glass was estimated to have attributed to a quarter of the energy savings over the baseline[2].
In addition, to sufficiently capture the benefits of load reduction allowed by the dynamic nature of the EC glass, EQuest, an energy-modelling tool based on DOE 2.1 was used. The energy-modelling tools developed by the U.S. Department of Energy‘s National Laboratories, DOE 2.1 and EnergyPlus have very flexible, capabilities for modelling dynamic fenestration systems. According to Grey Fowles of Seattle-based Paladino and Co., who supported the design team with energy modelling expertise, the use of EQuest allowed the project team to achieve two to four more LEED points in the Energy and Atmosphere credit than if they had used the original Trane Trace software, which does not yet have the sophistication to deal with dynamic systems.
The project has achieved LEED Platinum for both CI and CS, the latter including points under the Views credit which were achieved because of the ability to provide substantial glazed area over all façades which provided 94 percent of all regularly occupied spaces with a view to the outside. The EC glass (photo above) can be controlled to provide glare control and daylight admission simultaneously, while also maintaining a clear view to the outside. In this project, because of the re-use of an existing deep building floor plate, sufficient daylighting of 75 percent of the space, and thus points for daylighting, could not be achieved.
The building has been occupied since Fall 2015 and actual energy consumption data is currently being collected to compare with the data originally predicted. Focus groups have also been initiated with occupants to determine user acceptance of the EC glazing. Initial results suggest that occupants universally love having views to the nature just outside the building and the EC glass is preventing them from feeling thermal and visual discomfort from sun penetration.
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Dr. Helen Sanders is vice president, technical business development at SAGE ELEctrochromics Inc., Faribault, Minn. Sanders has more than 19 years’ glass industry experience and more than 13 years’ experience in dynamic glass technology and manufacturing. She is active in codes and standards development, and leads SAGE’s technical services organization. To learn more, visit www.sageglass.com.
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References:
[1] Arasteh, D., Selkowitz, S., Apte, J., LaFrance, M. 2006. Zero Energy Windows, Proceedings of the 2006 ACEEE Summer Study on Energy Efficiency in Buildings, August 13-18, 2006. LBNL report number 60049.
[2] Communication from Chloe Bendistis of The Sheward Partnership LLC, Philadelphia.
Photos: Jeffrey Totaro