Optimizing daylight with motorized window treatments

by Scott Blue

Images courtesy Nice S.p.A.
Images courtesy Nice S.p.A.

Since the beginning of this millennium, architects and owners have increasingly adopted a daylighting design approach when constructing or redesigning buildings. This design concept promotes natural light through the use of windows and other openings, the strategic placement of walls, and with other tactics such as motorized window treatments (MWTs).

Daylighting has been shown to benefit both building occupants and businesses. For workplaces, the addition of sunlight to interior rooms sparks a satisfied, productive workforce while leading to a greener workplace. Developments in MWTs are increasing yields from sunlight.

For architects and building owners, many of their decisions on daylighting can be based on the desire to save money on lighting and heating costs. However, there is another factor.

Since most people spend 85 to 95 percent of the workday inside buildings, daylighting is a step in the right direction for increasing one’s connection to the outdoors and creating a more stimulating work environment. The Construction Specifier author Michael J. Holz points out, it is important to consider the non-energy as well as the energy benefits of daylighting. Though return on investment (ROI) analysis may not give the nod to non-energy impacts, it is the occupants who count. Comfort, health, and workplace productivity are essential to design strategy.

Let the sunshine in

As an example of how approaches to room illumination have changed throughout the years, one must consider the history of the manufacturing plant. In the early days of the industrial revolution, factories had an abundance of windows. Eventually two factors led to the replacement of glass by solid walls—management’s desire to keep what was going on inside their plant undercover and improvement in artificial lighting technologies, a boon for 24-hour factories.

Tubular motors operate window treatments and can be controlled remotely by sensors.
Tubular motors operate window treatments and can be controlled remotely by sensors.

Then came the oil crises of the 1970s and ’80s, forcing building designers and managers to find new ways to produce illumination using less energy. One significant change was the introduction of compact fluorescent lamps (CFLs). Light-emitting diode (LED) lighting started to find its way into general use in the early 2000s.

The search for natural replacements for carbon-based energy sources led to a fresh look at daylighting in the ’90s. Sunlight was re-introduced, bringing natural illumination back into buildings through the strategic placement of the structure and an increase in the number of apertures such as windows, glass doors, and skylights.

The savings make sense

The electricity to power interior lights can eat up a considerable amount of energy—as much as 17 percent of a total energy budget. Effective daylighting design can significantly knock back the energy used for lighting by up to 75 percent.

Most people, other than night-shift workers, are up and busy during the day. This increases demand on electrical power utilities, particularly in the late morning and early afternoon hours, thereby raising the cost of providing power. Daylighting enables building managers to peak-shave their power usage for substantial savings on the power bill.

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