LEDs vs. Daylighting: How These Green Lighting Solutions Compare

By Torrin Greathouse | February 18, 2015

As electricity costs rise and the government pushes businesses to incorporate more sustainable technologies into their facilities, incandescent and compact fluorescent lighting is being phased out of the lighting market. Two newer, far more sustainable solutions stand poised to take the helm as the standard of lighting: light emitting diodes, commonly called LEDs, and daylighting devices, which harness the sun’s natural light to illuminate a building. The question is, how do these solutions stack up?

Quality of Light

While both LEDs and daylighting devices offer superior efficiency when compared to more traditional lighting methods, it is not enough simply to quantify the savings. One must also judge the quality of the light. The CRI, or color rendering index, measures how truthfully a light source replicates the full-spectrum of light, making it an accurate method to compare the light quality of the two devices. This scale goes from zero to 100, with 100 being equated with the quality of natural sunlight.

On average, LEDs reach a CRI in the high 80s, and daylighting devices reach 100 by using the best light available--sunlight. Statistically, this may seem like a minor difference, but it is not. Once you take into account the fact that the CRI must be compared to the color correlated temperature, we see that daylighting devices provide healthy, broad spectrum white light, while LEDs tends to fall toward a more narrow blue or red spectrum light. The broader spectrum light provided by daylighting is far preferable, not only because it offers the greatest level of color rendition, but also because it provides an array of health benefits.

Energy Consumption

Similarly, both LEDs and daylighting devices offer a significant reduction in energy consumption. An incandescent bulb consumes 60 watts per hour, wasting between 60-90% of the electricity it consumes by converting it into heat—which also raises the cost of indoor climate control--compared to LEDs which consume only 10 watts of energy per hour. Heat generation has also been a problem known to be caused by daylighting devices, however, more advanced daylighting designs can, in fact, provide thermal comfort which saves electricity.

While LEDs are more efficient than incadescent and compact fluorescent bulbs, they still consume electricity. More efficient still, certain daylighting devices consume zero watts, forever. Daylighting devices rely on natural light as the source of illumination. According to the U.S. Department of Energy, because of this fact, LEDs can reduce your energy consumption by around 50% yearly, and daylighting, because it provides light with zero energy expenditure and reduces cooling costs, can save up to 80%.

Return on Investment

The cost of the initial installation of any sustainable lighting option can be fairly steep. This makes finding a solution with a fast return on investment (ROI) especially important. The sooner the upgrade pays off the investment, the sooner you can collect the net profits of the upgrade.

While there are many variables that affect ROI, including building location and the time of year the device is installed, it is usually easy to generate a fairly accurate average. According to Jim Sweeney, a partner at the sustainable lighting firm EcoTronics and a panel member from the CE Pro 100 Summit on the future of LED lighting, the ROI of LEDs varies wildly from six months to as much as 4 years, depending on the details of the installation.

On the other hand, market testing has shown that while daylighting devices typically have an ROI of 3- 5 years, advanced systems such as the Ciralight SunTracker have an ROI between 2.5 and 4 years. This is due to the fact that the advanced, active daylighting that the SunTracker provides does not reduce daytime electricity use, it eliminates it entirely.

Potential Disadvantages  

Neither daylighting devices nor LEDs are a perfect match for any and every building. Each device has strengths as well as limitations, and works best when it is chosen according to its suitability for a particular location, building structure, and purpose.

While daylighting provides high quality natural light and consumes zero electricity, it is only viable during daytime hours. Even the most efficient devices can only provide light as long as the sun is above the horizon, so building owners will still have to utilize electrical interior lighting during the hours when the building is in use and the sun is down.

LEDs, on the other hand, are a relatively new technology, and as such, have received far less market testing and long-term research than other lighting technologies. Additionally, LEDs are made up of multiple parts, each one of which can malfunction and cause the lamp to stop working. There are also studies beginning to emerge shedding a negative light on LEDs. One Harvard study showed that LEDs that produce blue-white spectrum light can actually have serious side effects. Because the human brain perceives blue light as being the light from the sky, long exposure to blue light—especially at night—hampers the production of melatonin, a neurotransmitter tied to the human sleep cycle. This can create or worsen symptoms of both insomnia and seasonal affective disorder.

Understanding how LEDs and Daylighting devices compare is a big step towards efficient and environmentally sound lighting practices. Both forms of sustainable lighting have advantages and disadvantages that must be weighed before installation in order to ensure reliability and increase consumer confidence. The more that new construction and retrofit projects make proper use of each of these system’s function and design, the more widely will they be adopted. And once they are consistently installed across multiple industries, they will positively transform the future of lighting and energy-saving standards.

To learn more about Ciralight SunTrackers and find out whether they are the right product for you, visit our website or contact our sales team who are ready to assist you.

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