Room Lighting Design
by: David Gray • 2
By the time you reach 75 years old, you will need four times as much light as a 20 year old, in order to see satisfactorily
.INCANDESCENT, full spectrum is the most desirable type of light. It can be achieved with energy efficient “T” series FLUORESCENT bulbs with a high color rendering index (CRI) 90-100.
For bulb selection
1. you need to know the dimensions of the room;
2. how BRIGHT you want room lighted as measured in LUX;
3. the COLOR of light in KELVIN;
4. and the QUALITY of the light measured by the color rendering (CRI) index.
5. select the appropriate bulb and note how many LUMENS of light it will produce.
Then calculate the number of florescent bulbs with the your CRI rating as necessary to accomplish the task and with power consumption in mind (WATTS), select the type of fixture.
LUX (Lx) BRIGHTNESS IN LUX
One Lux - is one lumen per square meter.
3.4 lux - twilight
50 lux - living room
80 lux - office hallway
100 lux - overcast day
350-500 lux - office lighting
400 lux - sunrise
1000 lux - overcast day
10,000-25,000 - daylight
32,000-130,000 - sunlight
KELVIN (K) is the COLOR of the LIGHT
called COLOR TEMPERATURE
3000K – warm white
4200K – cool white
5000K - daylight
2700 K - residential lighting (Incandescent light)
3000-3500 K - neutral-white
4100 K - cool-white in offices
5000-6500 K - blueish-white
CRI is the QUALITY of the light
called the COLOR RENDERING INDEX
and is a measure of how well colors can be perceived.
100 CRI - incandescent lamp
50-100 CRI - fluorescent tubes
82-100 CRI - natural color (full spectrum)
as measured in Watts. Incandescent lights are full spectrum but are energy hogs. Florescent lighting is more energy efficient.
The high efficiency bulbs are labeled with “T” - T12, T8, T5 etc..."T" is the diameter of the tube in the lamp. Typically narrower the lamp diameter the more efficient it will be.
T12’s have not bee manufactured since 2012.
Seniors - Printed materials are not as clear as before, in part because the lens in your eye becomes less flexible with time. Changes within the lens in your eye cause light entering the eye to be scattered rather than focused precisely on the retina, thus creating more glare. The normally clear lens located inside your eye may start to discolor making it harder to see and distinguish between certain shades of colors. The tear glands in your eyes will produce fewer tears.
Increasing the the amount of light, brightness called LUX can improve vision.
Bright Light Therapy - is used to gradually shift sleeping patterns to what we consider normal. For treatment, the timing of light exposure uses a full-spectrum light (90-100 CRI) usually 10,000 LUX in intensity, for 30-90 minutes.
Blue wavelengths -- boost attention, reaction times, and mood are about 5000 degrees Kelvin.
As published in the The Journal of the American Medical Association researchers learned that bright light resulted in a modest improvement in dementia symptoms. Specifically, the use of bright daytime lighting:
· Reduced cognitive decline on a mental status exam by a relative 5%.
· Cut depression symptoms by a relative 19%.
· Calmed slow increases in functional limitations by slightly more than half (53%).
Dementia and Alzheimer's - For these people shadows in a darkened room can become something else, often menacing, and can lead to confusion and depression. A dark rug in a dimly lighted room before a door may become a deep well.
I installed 800 LUX of light – when I throw the light switch, I feel a burst of energy like I am waking up and my mind becoming clear.