October 16, 2015
by Brandon Tinianov, PhD, PE, LEED AP
It is no secret architects have an affinity for glass. The sheer number of full-glass buildings emerging all over the United States speaks to the material’s panoptic appeal and its ability to create openness and connectivity to the outdoors. Most of our time—approximately 90 percent—is spent inside, meaning an exposure to natural light and a visual connection with the outdoors is more important than ever.
This fascination with glass comes at a time when there is also growing a mindfulness of architecture’s vital role in environmental accountability. Although visually stunning, windows are the ‘Achilles’ heel’ of the building envelope. Commonly regarded as one of the least energy efficient building components, they are responsible for up to 40 percent of the total heating and cooling energy consumption, due to the need to offset both hot and cold temperatures. Organizations such as American Society for Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE), International Energy Conservation Code (IECC) evaluate the total energy benefit of glazing applications. Their findings highlight the challenges of traditional all-glass buildings. In the end, these shining structures not only need to meet current market desires, but also comply with design codes and efficiency requirements.
Because of this, revisions to building codes have limited the allowance of glass filled designs. New code language lays strict ground rules for building design, prioritizing efficiency, and minimizing negative environmental effects of buildings. With these performance objectives in mind, architects have turned to two major strategies to increase or recover lost glazing area. The first is reducing the total internal building loads (i.e. key equipment and outlet loads), to create a more efficient facility. While once very effective, this approach has recently proven to be difficult. The loads from permanent office fixtures and equipment (e.g. HVC, LED lighting managed by occupancy sensors, copiers, etc.) have been slashed, so the remaining savings require requires a drastic modification occupant plug loads and behavior. Additional savings will come from personal, portable office equipment and user training. There is a considerable body of occupant research underway attempting to improve these outcomes, but it still remains difficult.
The second is to design more efficiency into the building envelope using elements such as window blinds, shades, and fins, as well as emerging technologies such as vacuum-insulated glazing and panels (VIGs and VIPs), and electrochromic (EC) glass. This approach is advantageous because it does not require a behavioral change from building occupants, and the benefits are additive to energy load efficiencies.
VIG technology is composed of two closely spaced sheets of glass with a deep vacuum drawn in the cavity. The vacuum, though difficult to fabricate, is highly insulative because it eliminates the conductive heat exchange between the glass panes. VIG is the next development of insulating glass technology designed to address large differences between outdoor and indoor temperatures (either in hot climates like Phoenix, Arizona, or cold climates such as Fargo, North Dakota).
Ongoing research and development has shown vacuum-insulated glazing can insulate a home (i.e. prevent conduction) five times better than standard double-pane glass. While this represents a significant step forward for thermal efficiency, the technology is largely targeted at residential applications and has not yet experienced widespread market adoption.
Electrochromic (or ‘dynamic’) glass has become a key component of high-performance buildings by making fenestration a responsive façade solution for solar control. The technology itself has been in development for nearly 50 years, but dynamic glass was only recently commercialized on a large scale. This ‘smart’ glazing solution leverages embedded nanotechnology and building sensors in the glass to change from clear to tinted on demand, providing superior control over the amount of light and heat (i.e. solar gain) entering a building. This dynamic power significantly reduces lighting and HVAC electricity consumption, as well as peak load, allowing for HVAC equipment downsizing.
One notable real-world example of this envelope-based approach is a commercial office retrofit at 415 Mathilda in California’s Silicon Valley. Via full market repositioning, the building went from a 5 percent window area to more than 40 percent window area while maintaining a highly efficient building skin. The team accomplished this by utilizing rigid foam insulation in the walls and employing dynamic glass to meet both its vigorous energy-efficiency and occupant-focused objectives. During periods of high solar heat load of glaring daylight, the dynamic glass tints to minimize energy usage and disruption. When the problem sunlight passes beyond the building face, the glass untints to save lighting energy and stimulate the tenants.
The completed 415 Mathilda Project building is both ZNE and Zero Net Carbon (a ‘Z2 building’), and was recently awarded the Best Green Project designation by the Silicon Valley Business Journals Structures Awards. Beyond public accolades, it resonates with building owners and developers due to the design’s immediate financial payback, including a net-positive cash-flow for the owner and a return on investment 20 percent higher than that of conventional, non-sustainable construction projects. Using an integrated package of three emerging and five mature technologies, including dynamic windows, the project can be easily replicated in most commercial and residential buildings.
Beyond commercial market recognition, the strategy of dynamic, energy efficient envelopes was recognized by the California Energy Commission as a demonstration project and technology platform for the state’s future mandate of Net Zero commercial buildings.
Given the perennial preference among architects to install large glass surface areas, it is critical the glazing industry commit itself to sustainable solutions that curtail design concessions and boost energy efficiency. To meet increasingly strict energy regulations, both existing and emerging technologies need to be integrated to advance architectural design freedom and maximize energy savings.
Brandon Tinianov, PhD, PE, LEED AP, is the senior director of business development at View, and an expert in energy efficiency and building sciences. His 20 years of experience in the construction industry (including ASTM and International Organization for Standardization [ISO] development) span various materials and systems including insulation, wallboard, glazing, and software controls. Tinianov will serve on the 2016 U.S. Green Building Council (USGBC) Advisory Council and as an expert in the California Technical Forum (Cal TF). An accomplished inventor, he has been issued 26 patents, with more than 20 pending.
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