Daylighting 101: Sunshine on Your Shoulder Does More Than Make You Happy

By: Jon Null, LC, LEED, Product Marketing Manager, Legrand Shading Systems

​​​​​​​We spend 80% of our lives inside buildings. So it’s no wonder that maximizing the benefit of windows—for natural light and outdoor views as well as for ventilation and thermal comfort—is a goal for building owners and designers alike. Windows are essential in creating an inspiring space for living and working indoors, connecting a building’s occupants with the natural world outside, while also providing the daylight so vital to internal circadian cycles that regulate health and well-being.

But for all its benefits to overall indoor experience, a window is always subject to the constant, sometime unpredictable changes in the amount of daylight it lets in. A soft morning sun can become a hot glaring annoyance in a matter of hours. A desk with a stunning view of autumn’s changing colors can become the last place anyone wants to sit during summer. Window blinds and shading (let’s call them “shades” for short) are an obvious solution. Adjusted throughout the day, a proper shade system can easily regulate light, heat, and glare from any window and even contribute to the efficiency of building energy consumption. But only so long as building occupants use them properly. Which, alas, they don’t.

The truth is, building occupants are far from ideal in the way they operate window shades. A study funded by Pacific Gas and Electric Company of California found that individuals generally operate the shades available to them based on their own unique preferences or priorities. Some leave the shades down most of the time to reduce the need to move them every few hours. Others leave them open because they “like the view” or are not bothered by the sun for a few hours on their desks and computer screens. Still other occupants admit to leaving shades open or closed for days, or even months, at a time— because they lack easy access to the controller or simply find the whole thing too cumbersome to deal with. Of course, any of these examples result in suboptimal conditions—for both the occupants as well as the building mechanical systems that are designed to provide comfortable lighting or thermal conditions for them.

Research shows that the unpredictability of human behavior is sometimes the biggest challenge to maximizing the daylight control and energy savings promised by even the most innovative window design. In 2005, a field study funded by the Northwest Energy Efficiency Alliance looked at over 120 buildings with window equipped daylighting controls and found that only 23 percent of the lighting energy savings expected in side-lit daylit spaces were being realized on-site. Additionally, the study found that in 52 percent of the spaces, controls had been disabled or were non-functional.

An automated window shade system can do what building occupants cannot— consistently produce an optimal indoor environment, and the energy savings that come with it. In fact, in an emerging technologies evaluation report funded by Pacific Gas and Electric Company in 2014, a side-by-side comparison of automated and manually-operated shades in an open office situation revealed just what kind of energy savings potential automated shades can deliver. Measuring on-field daylight levels continuously for several months in two similar side-by-side open offices, the report found that the consistent daylight levels delivered by windows with automated shades increased lighting energy-savings by 37 percent above those with manually-operated window shades.

Perhaps the most well documented example of energy savings from automated shades is the New York Times building in Manhattan, where an advanced sun tracking and glare management system is integrated into automated shades across the building’s curtain wall façade. Studies since the building was first occupied in 2007 have documented energy savings from dimming controls of 20 percent relative to the 2007 baselines as set by the American Society of Heating, Refrigerating and Air-Conditioning Engineers. And while this project may feature a control system with a higher degree of sophistication than what is necessarily required for all automated shade systems, it clearly illustrates what can be achieved in energy savings when utilizing such technology, even if in a simpler form. At the end of the day—and in fact, on every day of every year— the reliability and predictability of automated shades is what makes them the best choice for ensuring successful daylighting control and energy savings in an indoor environment. Working with a window’s design, automated shades help building owners and designers achieve their goals for daylighting and energy efficiency and let building occupants get back to simply enjoying the view of the great outdoors.