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Using lighting to influence the mood

When Thomas Edison patented the first practical light bulb in 1879, the American inventor gave humans a way to artificially light spaces – and changed the world forever.

Since then, engineers and designers have stretched their imaginations to design lighting systems that not only show us the way, but also influence our thoughts and actions.

“Factors such as color temperature and color rendering of a light source affect how we experience a space,” said Jim McCarthy, senior market specialist for Eaton’s lighting division. “For example, in a bright room, children tend to be high-energy; dimming the lights may slow them down.”

Dimming the lights to relax a roomful of rowdy children might sound simple, but there’s much more to the science of lighting and how it can be used to influence feelings.

Why does lighting have such a powerful effect on mood?

Retail stores and restaurants have long used lighting to encourage their customers to behave a certain way. “There’s more to grocery store design than putting the milk in the back,” said McCarthy. “Store owners can use lighting design to influence how their customers move through the store – which aisles they visit and how much time they spend in those aisles or spaces.” Department stores are also known for using light to emphasize certain mannequins or expensive items in a jewelry case, or for making a red dress look more dazzling.

Kelvin temperature – the scale that measures the warmth or coolness of the light source – has a particularly strong effect on the look and feel of a space. Warm light, often preferred in hospitality, retail and residential settings, enhances wood tones and warm colors like red, orange and browns, contributing to a sense of calm. On the flip side, office lighting generally has a cooler temperature, because it encourages productivity.

Also important is color rendering index (CRI), or the measure of how a light source renders the colors of objects in comparison to an ideal or natural light source. “If a light source doesn’t have the optimal CRI, it will not render certain colors well,” said McCarthy. “This can affect our perception of quality.” For instance, a grocery store with lighting that has a CRI in the 70s will cause a beautiful apple to look dingy or dull, leading customers to think twice about buying it. Similarly, a restaurant known for its filet mignon will use warm lighting with a higher CRI in the 90s to bring out the rich reds of the meat – ensuring it looks as good as it tastes. This type of lighting may encourage guests to linger over their meals and order a second glass of wine and dessert.

How can lighting be used to change the way we perceive spaces and objects?

Lighting provides innumerable ways to transform a space – from understated to unmistakable.

In general, there are four ways to light a space:

  • General or ambient lighting brightens objects and surfaces in the lower part of the room. Indirect lighting directed toward the ceiling and upper walls gives the space a cooler, more spacious look.
  • Accent lighting creates drama by enhancing objects and surfaces with added light. This lighting draws the eye of the viewer. It creates excitement!
  • Wall wash lighting spreads out to illuminate our walls and provide overall light to the walls.
  • Task lighting provides higher levels of lighting in a space where work is performed.

General lighting, accent lighting, wall wash lighting and task lighting all have distinctly different effects on a space, the way we perceive it and how it makes us feel.

“Compare the ‘big box’ store to the ‘specialty store,’” said McCarthy. “Both retailers sell kitchen appliances and cooking utensils. The big box store is evenly illuminated, with very little contrast, no points of interest, and surface characteristics and textures that appear flat. This type of illumination says you’re getting a bargain. On the other hand, specialty stores may use lighting design techniques to draw attention to certain objects and areas. You can purchase the same stand mixer at either store, but consumers may be willing to spend more for it at the specialty retailer. A well-planned lighting design creates a certain perception of the space and of the products available for sale.”

Lighting controls are adding to the conversation as they become more important and increasingly advanced. By adding dimming controls, for example, you can adjust the intensity of a light source. However, that’s just one piece of the puzzle.

What are important things to consider when you’re lighting an area?

For most lighting designers, the first order of business is to determine the ideal Kelvin temperature for light sources in a given space.

“Lighting can make or break a room, and in residential spaces, kitchens and bathrooms tend to require more lighting design knowledge,” said McCarthy. If you’re working with stainless steel appliances and white cabinetry, McCarthy recommends lighting in the 3,000 Kelvin range. “If you drop to 2,700K, your cabinets might take on an almond color.” On the other hand, the lower Kelvin number is better suited to rich wood tones and warm colors. When lighting a space, think about the fabrics, colors and textures you want to enhance in order to determine if your light sources should be on the warm or cool side.

This also applies to LEDs. For example, LEDs in the 90 CRI range will cause paintings, fruit bowls and granite patterns to pop and make the colors more vivid. Once you’ve identified your ideal Kelvin temperature, it’s time to determine the required lumens, or intensity of the light source.

“Anyone can light a room, but designing with light in a room is a science and an art,” said McCarthy. “A good lighting consultant can help you create a beautiful, practical space.”

How have LEDs changed the conversation?

“Many lamp types are being phased out,” said McCarthy. “They’re all being replaced by LEDs.”

Extremely energy-efficient and long-lasting, LEDs can last more than 50,000 hours – up to 20 years in residential applications – compared to just 1,500 hours for standard household incandescent lamps. What’s more, LEDs can now be made to mimic any light source including its CRI, Kelvin temperature, distribution and lumen output

“LEDs are available as warm as 2,700K or as cool as 8,000K,” said McCarthy. “Plus, LEDs can be manufactured with superior optics to create almost any lighting distribution needed with great accuracy and efficiency. LEDs can provide accent and wall wash illumination. We can combine many LEDs with high lumens to create a powerful light source or, when needed, drop lumen levels for a calming atmosphere with wonderful lighting controls. Add the energy savings, ease of maintenance and lower initial LED prices, and suddenly other light sources no longer make sense.”

What’s on the horizon?

In the immediate future, LED technology will become even more advanced, while the price of LEDs will continue to fall. “LEDs are 25 to 50 percent of their original price,” said McCarthy. “In many cases, they have also doubled their lumen output for the amount of power consumed and have improved significantly in their CRI and Kelvin temps. Moving forward, prices will continue to fall; meanwhile, we should be able to double the efficiency of LEDs today.”

But the most exciting developments of all are in the area of illumination controls.

“Because LEDs are electronic, they’re inherently controllable,” McCarthy said. “Now, we can walk into a space and control virtually everything, from our lighting and HVAC to media, security and communication.

“George Jetson’s world is right around the corner.”