When shopping for lighting, there are lighting design terms that are used to differentiate lighting. While these terms may deem daunting, they actually make intuitive sense when you understand the concepts behind them.
Why To Consider Designing With Light
One base human need is to "see it all" or to have a complete view of ourselves in a styling space. Since people habitually check on their appearance in the bathroom, they expect to have a complete view in good lighting.
When preparing a space, you should design a styling space that is appropriately lit for the activities desired. Lighting allows you to properly see your reflection, eliminate glare, avoid eye strain with no dark/hot spots.
Glare Control
Non-diffused lights can cause uneven spots of brightness and darkness across a space. The light sources appear too bright and cause excessive contrast between bright and dark areas. This can result in visual discomfort, fatique, visual impairment or injury to the eye. Therefore, electric lights are recommended to be shielded.
An example is if you are outside and the sun is shining with no clouds. The light is harsh and there is a lot of shadows around you. However, if there are clouds in the sky, they block out the harsh sunlighting making the light shielded or diffused.
Direction of Light
Poor mirror lighting is unflattering. The usefulness of a mirror depends mostly on lighting and quality of light. Poor lighting, as you can see from the smaller of the two images above, can be unflattering. The glare and harsh shadows cast on the face are bad for makeup application and grooming. Lighting can do a great job of illuminating the bathroom, yet a terrible job of lighting the face. This is the difference between ambient and task lighting (click here to learn the difference).
Task lighting should illuminate the face from at least two directions - ideally, from the sides for minimal shadows. The face should be bright enough for good visibility, while the light source should be soft and diffused to avoid discomfort caused by glare.
Lighting Measurements
How bright should lighting be? When selecting lighting, there are two measurements to consider: the intensity (foot-candles) and the amount of light output (lumens).
Foot-candles are a measurement of light intensity. More specifically, foot-candles measure how much visible light is falling on a surface (brightness).
Lumens measure the total visible light output of a light source. One lumen is equal to one foot-candle falling on one square foot of surface area.
Here is an example. Let's say you have a lighted mirror and a ruler. Put the ruler up to the mirror and turn out the lights. Foot-candle of light is the amount of light the lighted mirror generates one foot away. A lumen measures how much light is generated in the room.
Brightness
Now that you understand foot-candles and lumens, you should select lighting that emits suffiecient lumens to produce the desired amount of foot-candles on the target surface. With bathroom lighting, the task is relatively fixed. The user typically stands 18 inches from the mirror's center and lighting should produce satisfactory illumination on the user's face at this distance.
In residential spaces, the use of dimmers and controls allows settings to be adjusted to the homeowner's needs. Dimmers offers a choice of soft mood lighting or bright task lighting via a smooth, continuous dimming. Solutions such as controls or products that feature dimming and tuning can provide balanced lighting for activities. To learn more about dimming and tuning options, visit Lighting Controls (click here).
Color Temperature
Direction, intensity and quantity are important factors in good lighting. Another variable of good lighting is lighting color.
Correlated Color Temperature (CCT) defines the color appearance of white in degrees Kelvin and tells you what hue and tone of white to expect from a light source. Different temperatures on a kelvin scale represent different colors.
- 2700 = a warm white that is more orange/yellow in color (typical for incandescent lamps and home environments)
- 4000 = a neutral white that is more of a paper white
- 5000 or higher = a cool white that is more of bluish white (typical of flourescent lamps and work environments)
More About Color Temperature
Warm white lights enhance reds and oranges for a more relaxing and intimate atmosphere. Cool white enhances blues and greens, creating a more invigorating public atmosphere. The right choice depends entirely on user preference.
Residential lighting is typically warm (i.e., incandescent), whereas workplace lighting is typically cooler (i.e., flourescent). Ideally, lighting will provide flexibility to examine one's appearance under both warm and neutral white CCTs. Traditionally, this would have been addressed with duplicate light fixtures - one set with warm white lamps and one with neutral lamps.
Recent advances in LED lighting technology allow users to change the color temperature of a single fixture. New control methods allow users to easily adjust CCT (known as tuning) using a wall control or smartphone app.
Color Rendering - CRI
Color temperature can be a matter of personal preference. Color accuracy, on the other hand, is a more objective standard.
Color Rendering Index (CRI) measures an artificial light source’s ability to reveal the colors of objects faithfully in comparison with natural light. Sunlight has a perfect CRI of 100. The higher the number of CRI to 100, the more the person will be clear, bright and as close to how they would appear in an outdoor, natural setting. Using lighting with low CRI results in a flat, dull appearance.
Color Rendering - R9 Value
CRI is determined by averaging the color rendering for eight color samples (R1 through R8) that are light in saturation. Manufacturers may test another six colors, including R9 through R14, which are saturated colors. These don't contribute to CRI, though some manufacturers report R9 (saturated red) to demonstrate that their source effectively renders skin tones and wood finishes.
An R9 value of 50+ in conjunction with a CRI of 90+ is needed to accurately render colors, bring out skin tones and accurately match makeup to skin tone.
Circadian Lighting Design
The circadian system regulates physiological systems, including hormones and sleep cycles. Light received by receptors in the eyes plays a major influence on circadian rhytms. Light can influence well-being, notably non-visual effects on the body's circadian system via the daily change from light to dark. The circadian system produces and regulates bodily functions such as the sleep-wake cycle based on circadian rhythms, or 24-hour cycles. Studies of shift workers have shown that disrupting natural circadian rythms cause poor sleep, inability to sleep, loss of cognitive funtion, and increased risk of elevated blood pressure and cholesterol levels (and therefore, cardiovascular disease).
According to the Lighting Research Center, there are four primary factors that affect how light influences the circadian system. These include quantity of light falling on the eye's photoreceptors (vertical illumination), spectrum (spectral power distribution or color), timing and duration.
Mirror lighting provides an opportunity to adjust light output and CCT at influential times of the day. In the morning, the lighting can be adjusted to its maximum intensity setting and a cooler CCT to prepare you for the day. This produces 30 - 40+ footcandles of vertical illumination that is heaver in short (blue) wavelengths, which is more effective at producing a cirdadian response.
In the evening, the lighted mirror can be adjusted to its lowest intensity and a warmer CCT to wind you down for the evening. Specific outcomes will vary by individual, due to variables such as schedule, overall light exposure during the day, and use of electronic devices before bed. However, bathroom mirror lighting is one strategy for supporting a more natural circadian rythm.
Source: Lighting Research Center (Mariana Figueiro, Kassandra Gonzales, and David Pedler), “Designing with Circadian Stimulus,” LD+A, October 2016