Building Envelope
Investing in something you don’t use seems like a waste of money and resources… but that’s what appears to be happening in New York City (and probably in other U.S. cities, too). A December 2013 study led by the Urban Green Council (UGC) looked at 55 buildings throughout Manhattan, Brooklyn, and Queens to see if the tenants in all-glass buildings actually took advantage of the views by keeping blinds, curtains, or shades open.

In many cases, more windows and better views translate to higher lease rates for commercial and multi-family high-rises; it’s likely that the tenants in these spaces are paying a premium to get their piece of the skyline.

Urban Green Council’s study, Seduced by the View, revealed that the blinds on many of these windows are closed, blocking out the cityscape. On average, of the 55 buildings studied, 59 percent of the window area was covered by blinds or shades. And over 75 percent of the buildings had more than half of their window area covered by blinds or shades.

[pullquote]High-rise tenants pay a premium for Views and energy, often wasting both.[/pullquote]To understand this phenomenon, the UGC team compared how often blinds were closed in the morning on east-facing windows with how often blinds were closed in the afternoon on west-facing windows. The results didn’t change based on this factor, ruling out the possible theory that blinds were closed only to reduce glare. Blinds were closed no matter what time of day, which direction the window faced, or whether the building was commercial or multi-family. This means that tenants are most likely closing their blinds for a variety of reasons: to stop fading, to decrease glare, to prevent uncomfortable solar heat gain, to maintain interior temperatures, and to reduce energy bills.

Not only do the tenants suffer (by paying for views they don’t get to enjoy), but the study points out that New York City suffers, too. Windows don’t insulate as well as walls, so these buildings are ultimately using more energy. They also have lower resiliency during power outages, since the glass doesn’t hold heat in during the night or keep it out during the day, energy costs (and the associated risk of blackouts due to increased power needs) can ultimately lead to carbon pollution.

To help overcome this problem, the study offers two helpful suggestions:

  1. Better design (use fiberglass window frame materials instead of aluminum, eliminate floor-to-ceiling windows and instead consider exterior walls with insulation on the lower two or three feet between the floor and the window, etc.)
  2. Better communication (make sure tenants understand the implications of working or living in an all-glass building)

Through efficient, sustainable design, buildings can offer tenants great views and also save energy. Better design is a great suggestion for new construction projects. But for the majority of existing buildings – many of which feature big windows with great views and exposure to the outdoors – better design isn’t a feasible option and building owners need to look at possible retrofit options.

Decades from now, after many other building systems have been upgraded to improve efficiency, these same windows will still be in place due to replacement costs, the slow return on investment associated with window replacement, and the overall disruption it can cause. Window replacement also requires disposal of old frames and window glass.

Over time, as Seduced by the View points out, the energy lost through the façade plays an increasing role in the overall performance of the facility. any change made to improve window performance can help make a significant difference in the energy wasted through the building envelope.

One solution high-rise managers are using is low-e window film. Window film can help building owners address many of the issues these New York City tenants seem to be dealing with: glare, uncomfortable temperatures, excessive heat during the summer, cold building walls in the winter, and fading of furnishings.

How much can window film improve the insulating performance of a window? The newest low-e window film technology can improve insulating performance by as much as 92 percent; in many cases, building owners see ROI on window film within three years of installation (vs. 15, 20, or more years for window replacement).

Window film was also recently found to be the most cost-effective choice for energy savings in retrofit applications for various California locations. An independent study from ConSol compared window film to other traditional energy-saving techniques like updating HVAC systems, air sealing and caulking, and adding R-38 insulation. Window film came out on top as the most economical way to save energy and reduce a buildingfs carbon footprint.

Not only can it improve energy efficiency, but window film also provides a barrier between harmful UV radiation and tenants, finishes, and furnishings. UVA rays can fade furniture, flooring, artwork, and wallcoverings. These rays are also responsible for initiating skin cancer development and causing signs of aging due to the effects they have on skin cells.

According to the Urban Green Council, daylighting and incredible views can be a valuable amenity for tenants – and a great selling point for owners and brokers. But it is possible to still get these benefits without experiencing the problems that arise from having too much glass by using the right retrofit technologies, such as high-performance low-e window film.

Steve DeBusk

Steve DeBusk is global energy solutions manager for the window film division at Eastman Chemical Company. DeBusk has 30 years of experience in energy efficiency. He is a Certified Energy Manager, a Certified Measurement and Verification Professional, and a Certified Sustainable Development Professional. You can visit his blog at or follow him on Twitter @greenbldgs.