Sep 24, 2020

The trouble with formulaic designs driven by increased efficacy

By Willard Warren

Commodity vs. QualityIn the May issue of LD+A, IES Industry Relations Manager Mark Lien compared the “arts and crafts” of the music field to the “art and science” of lighting. In music, he wrote, some craftsmen create great art while others produce “commodity” music. In lighting, where science is a significant factor, some lighting designers can still evoke feelings in spaces, while others just produce “formulaic” lighting, especially in spaces that by their very nature are more concerned with function than form.

Perhaps the production of formulaic designs goes hand-in-hand with our embracing of LED sources for their energy reduction, but we cannot ignore aesthetics and the necessary comfort and visual performance of occupants. LEDs are now the source du jour, as they can reduce electrical energy usage by 90% when replacing incandescent sources and 50% when replacing fluorescents. These tiny, efficacious, solid-state devices, whether embedded in long plastic tubes (TLEDs) or installed in long strings in fixture housings with diffusers, are visually attractive in their various shapes, but they are very thin and can become glare bombs.

Of course, we do have our craftsmen. Classroom lighting, for example, can get pretty formulaic, but when the lighting guru professor Dr. Domina Eberley Spencer designed classroom lighting some years back, she chose decorative luminous ceilings that provided a soft uniform 100 footcandles for best performance, appearance and comfort.

Furthermore, the IES has adopted systems for glare control such as Scissors Curves, Glare Factor, ESI and VCP over the years, and we employed prismatic lenses to refract light rays downward or used parabolic louvers to cut off those high-angle light rays for glare reduction. However, with no glare reduction limitations in our current lighting codes, ultra-thin stick lights of all shapes are bringing back the era of bare lamps.

Beyond code limitations, there are also issues related to the impact of the energy reduction brought about by the adoption of LEDs. Here’s an excerpt from the promotion for a lighting design webcast: “According to several government sources, up to 40% of the total energy used in commercial buildings is used for artificial lighting.” What it should have said was: “up to 40% of the total electrical energy in commercial buildings is used for artificial lighting”— and even that would have been severely outdated.

In 2012, the U.S. Energy Information Administration (EIA) did an in-depth study of electricity usage in commercial buildings where the breakdown was: lighting (17%); refrigeration (16%); ventilation (16%); cooling (15%); computers (10%); office equipment (4%); cooking, space heating and water heating (5%); and other (18%).

While the lighting load had the highest percentage share in 2012, its percentage has decreased since then because of the use of LEDs and renewable energy. Simultaneously, there’s been an increase in non lighting sectors including computer usage and data storage.

In 2020, the EIA revised their data to reflect that lighting usage now constitutes only 10% of the total electrical load in commercial buildings. Both electrical and HVAC loads each account for approximately 40% of the energy consumption in commercial buildings. With the Zero Net Energy (ZNE) efforts of the DOE, the lighting portion will continue to decrease, so today lighting is only 4% of the total energy usage of the building—a far cry from 40%. However, bear in mind that the DOE is only concerned with the quantitative or “formulaic” lighting design—it’s up to us to be the crafts-men and women of lighting.


Willard Warren

Willard Warren

Willard L. Warren, PE, LC, Fellow IES, DSA, is principal of Willard L. Warren... More info »