Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc.

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 2 Human Factors A quality lighting environment is planned to optimize the person-in- environment system Involves a knowledge of current research and a thorough assessment of the project

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 3 Physiological Factors Research shows light has negative and positive effects on health: –Negative effects: Eyestrain, headaches, dizziness, skin cancer, and premature aging of skin and eyes –Research is exploring effects of lighting on growth and development of infants

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 4 Physiological Factors Circadian rhythm coordinates bodily functions for being awake and sleeping Light therapy successful in helping to regulate biological clock associated with circadian rhythm

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 5 Physiological Factors Problems related to circadian rhythms are associated with seasonal affective disorders (SAD) SAD: –A condition associated with an individual’s inadequate exposure to sunlight –Effects of SAD: Depression, weight gain, lack of concentration, and sleeplessness –Many people experience SAD during time of year when days are the shortest

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 6 Physiological Factors Bureau of the Census estimates 16 million people in US have a visual impairment: –People with vision impairments require special lighting accommodations –Population includes all age groups, but dominated by elderly

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 7 Physiological Factors Age –Reduction in size of pupil –Decreased elasticity of muscles –Yellowing and thickening of the lens Presbyopia: –Decrease in eye’s elasticity and thickening of lens –Affects visual acuity and ability to see objects at close range

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 8 Psychological Factors Research Topics include: –Characteristics of natural and electrical light sources and their behavioral and psychological effects on people –Lighting effects on special populations, including individuals with Alzheimer’s disease, cancer, AIDS, infants, and the elderly

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 9 Psychological Factors Research Research focused on understanding which characteristics of electrical light sources affect people: –Specific lamps –Color rendering index –Color temperatures –Quantity of light –Intensity –Spectral composition –Distribution patterns

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 10 Psychological Factors Research Early lighting research investigated effects of quantity of light on productivity in the workplace: –Demonstrated that quality lighting improved worker productivity and the increase in performance offset the cost of lighting systems

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 11 Psychological Factors Research Current research regarding effect of lighting on productivity is inconclusive: –Improved performance may be the result of a higher level of satisfaction with working conditions –Control over one’s environment, including lighting, is a significant factor in employee satisfaction

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 12 Psychological Factors Research Generally, the type of luminaire and light distribution patterns does not affect worker performance Proper lighting for the computer’s VDT is required to enhance worker productivity

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 13 Psychological Factors Research Light affects emotions, cognitive processes, memory, communication, and perceptions Effect of lighting on moods Differences in moods for men and women Flynn concluded people prefer warm and dim lights, compared to cool and bright sources

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 14 Psychological Factors Research Mood can also be affected by lighting patterns in a space: –Uniform lighting patterns viewed as monotonous and boring –Becomes more pronounced when tasks are repetitive and require a long period of time to complete

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 15 Psychological Factors Research A connection between stimulation and the spectral distribution of a light source: –Rea reported a blue spectrum stimulates rods in eyes –Navvab suggests bluer light should be used in workplace

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 16 Psychological Factors Research Proper amount of stimulation can: –Increase attentiveness –Reduce fatigue –Alter perceptions of time –Promote positive moods Too much stimulation can cause anxiety and stress

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 17 Psychological Factors Research People with visual impairments and dementia are more inclined to be adversely affected by stressful lighting environments

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 18 Psychological Factors Research Stress can occur: –In a dark space –A building that is unfamiliar –An emergency situation To help alleviate stress wayfinding lighting and adequate signage should be well planned

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 19 Universal Design Consider –Visual acuity –Manual dexterity –Placement of luminaires, switches, and outlets Visual acuity affected by: –Illumination level –Type of lamp –Distribution –Color temperature and color rendering –Ballast –Ability to control lighting

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 20 Universal Design Wall switches and luminaires should be intuitive to use and easy to operate Rocker or touch switches are the easiest Switches and dimmers should be accessible

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 21 Universal Design Placement of luminaires, switches, and outlets should be accessible to people with disabilities, including individuals in wheelchairs: –Average range of reach is 24” ADA specifies: –Wall-mounted luminaires mounted 27”- 80” AFF should not extend more than 4” from wall –Luminaires at or below 27” AFF may protrude any amount

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 22 Universal Design ADA specifies: –Lowest element of a suspended luminaire should allow for 80” of clear headroom –Freestanding luminaires mounted on posts may overhang 12” horizontally and 27”- 80” AFF

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 23 Universal Design Wall switches and outlets - Universal access is 15” to 48” AFF Electrical receptacles on walls mounted no less than 15” AFF Convenient location for wall switches and outlets is 38” and 18” AFF

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 24 Universal Design ADA requires signage in the 100 to 300 lux range (10 to 30 footcandles) Elevator thresholds should be a minimum of 50 lux (5 fc)

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 25 Universal Design Need knowledge of specific needs of individuals Requires observations, interviews, and often researching special situations People with visual impairments require illumination levels ~20% higher People with visual impairments often excessively sensitive to glare

Chapter 13 Illumination and Human Factors © 2006 Fairchild Publications, Inc. 26 Universal Design The RGIE study indicated that people with visual impairments need luminaires: –Easy to adjust –Remains fixed in desired position –Distributes light over a large area –Conceals lamp from view