From San Diego to Singapore, Columbus, OH to Copenhagen, municipalities have been making a variety of smart city moves, all centrally controlled to improve safety, traffic congestion, energy-consumption and habitability.

In light of those advancements, the most glaring missed opportunity to reduce energy consumption and improve indoor habitability in smart cities is the use of the right kind of glass.

Just look up. Glass windows are everywhere. Glass dominates the striking facades of the urban, built environment but causes all manner of eyebrow-raising issues: 70% of a city's electricity is consumed by buildings, and HVAC loads comprise 40% of a building's energy use to compensate for the heat gain or loss through windows.

For this reason, coupled with rising temperatures and increasing concerns about global warming, glass towers are now the targets of lawmakers. In London, sustainability advocates at the Royal Institute of British Architects have urged ending the construction of all-glass skyscrapers, citing the difficulties and cost to cool such glass towers as the main culprits. In New York City, Mayor Bill de Blasio proposed a flat-out ban on new construction of all-glass towers.

There is a smarter solution to allay the legitimate downsides of all-glass or heavily glass-fronted structures so we can keep our access to natural light while lessening a building's environmental impact.

A general trend in all industries is to look to technology to improve efficiency and performance, and the construction industry is no exception. Stricter building energy codes have been driving the adoption of electrochromic glass (EC) in glass facade design to create "smart windows." These windows sense the level and intensity of natural light, tinting automatically (or on demand) to moderate solar heat and glare.

At the same time, smart windows, based on chosen efficiency settings, differentiate light levels that let in needed warmth in winter months, and clear views to the outdoors when sunlight isn't a liability to indoor, thermal and visual comfort.

The intelligence built into this type of smart window can adjust — at will, or automatically — for cloudy days or shadows from other buildings, depending on weather conditions or the time of day. In a sense, it's always the perfect time of day inside, whatever the conditions outside.

Smart windows also seamlessly integrate with existing and upcoming smart city technologies. Through cloud connectivity, smart windows integrate with building networks and municipal infrastructures. By intelligently optimizing tinting in response to weather conditions, you can reduce the load on indoor lighting, heating and cooling systems, saving up to 20% in energy consumption.

By linking smart windows to a building's HVAC system, the two systems work hand-in-hand to decrease energy demands on the utilities and smart grids. And an ever-growing library of cloud-based learning algorithms for smart windows improve performance over time, as the smart windows learn local weather patterns and consumer preferences.

Simple voice commands or manual controls can be invoked to change the smart windows' automatic tinting levels, overriding the weather data and roof-mounted sensors as needed, for special occasions or personal preferences.  Each window has its own IP address, so an individual window can be modified while the rest are set to automatically respond to pre-set controls.

On the security front, smart windows act as the first line of defense in the event of an outside intrusion, or when a window has been compromised, alerting the security console of a breach for each window.

Shortcomings of earlier generation smart glass have been radically improved making these windows more attractive than ever. Today's most advanced EC smart glass can shift from clear to glare-reducing, neutral gray in mere seconds. And even the largest smart glass window can go from clear to total-darkest within 3 minutes—a 10-fold increase over earlier smart glass technologies. 

For smart cities aiming to effect real change, smart windows are clearly one of the most impactful elements for attaining greater sustainability without compromising comfortable conditions; enabling glass buildings and the environment to coexist in an intelligent, efficient, and natural way.