Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 1
Workplace Design and
Glare Reduction
Professor Alan Hedge
Dept. Design & Environmental Analysis,
Cornell University, Ithaca, NY 14853, USA.
© Alan Hedge 11/00
Slide 2
Indoor Environmental Quality
IndoorAir
Air Quality
Quality
Indoor
Lighting
Lighting
Workstation
Workstationdesign
design
© Alan Hedge 11/00
Slide 3
Workstation Design:
Deviated Work Posture
Inappropriate
viewing
distance and
monitor height
Knee
compression
Flexed neck
Unsupported,
kyphotic back
Abducted
arms
Ankle
compression
© Alan Hedge 11/00
Extended
wrists
Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 4
Keyboard on Desk
Unsuitable for sustained keyboard work:
(after Stack, 1987)
70° acute elbow
angle will increase
upper limb fatigue
and nerve
compression.
© Alan Hedge 11/00
Slide 5
Keyboard on Lowered Tray
Unsuitable for sustained keyboard work:
Wrist extension
Fingers cannot
rest on keys
~90° elbow
angle
(after Stack, 1987)
© Alan Hedge 11/00
Slide 6
Keyboard on Negative Slope Tray
Ideal for sustained keyboard work:
Wrist neutral
Fingers can
rest on keys
(after Stack, 1987)
© Alan Hedge 11/00
>90° elbow
angle
Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 7
Cornell/Honeywell Study
(Hedge et al., Ergonomics,
Ergonomics, 1999)
Before and after study of keyboard systems.
Tiltdown group
Desk group
Tray group
Keyboard tray slope 10°
© Alan Hedge 11/00
Slide 8
Cornell/Honeywell Study
Control Group Wrist Extension
© Alan Hedge 11/00
Slide 9
Cornell/Honeywell Study
Test Group Wrist Extension
© Alan Hedge 11/00
Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 10
Cornell/Honeywell Study
(Hedge et al., 1999)
Conventional Tray
Extension
Flexion
Tiltdown system
Extension
Ulnar
Radial
Flexion
Ulnar
Radial
© Alan Hedge 11/00
Slide 11
Cornell/Honeywell Study:
Reported discomfort
(Hedge et al., Ergonomics 1999)
Control group
Survey 1
Survey 2
PT Test group
Survey 1
Survey 2
<25%
25-50%
>50%
© Alan Hedge 11/00
Slide 12
Keyboard Slope and Wrist Extension
(Simoneau et al., 1999)
• 10 female Ss typed on
keyboard at different
slope angles.
• Wrist extension
decreased 1° for every
2° decrease in keyboard
angle.
• Optimal wrist position
was when the keyboard
tilted down in a range
between 7-15°.
© Alan Hedge 11/00
Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 13
Keyboard Position
• Lowered, negative-tilt tray for neutral
wrist posture.
© Alan Hedge 11/00
Slide 14
Encourage Neutral Posture
Relaxed,
balanced
neck
Preferred
viewing
angle,
distance
and
monitor
height
Relaxed,
supported
shoulders
Supported,
lordotic
back
Neutral
wrist,
supported
palm
Open knees,ankles
Open elbow
© Alan Hedge 11/00
Slide 15
Indoor Air Quality Problems
• 1 in 3 workers
may be in a
"sick"building.
© Alan Hedge 11/00
Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 16
Office Indoor Air Quality
Concerns
Combustiongases
gases
Combustion
(COx,,NO
NOx,,SO
SOx))
(CO
x
x
x
Volatile
Volatileorganics
organics
(VOCs,
(VOCs,MVOCs)
MVOCs)
Biogenic
Biogenicparticles
particles
(bacteria,
(bacteria,fungal
fungal
spores,
spores,
allergens)
allergens)
Particulates/fibers
fibers
Particulates/
(ETS,SMF,
SMF,Asbestos)
Asbestos)
(ETS,
Thermalconditions
conditions
Thermal
© Alan Hedge 11/00
Slide 17
Breathing Zone Filtration
• Energy efficiency - not all office air needs to be treated, only
that in the breathing zone.
• Thermal comfort - eliminating 'dead zones' improves thermal
comfort conditions.
• Personal control - most HVAC systems have only crude control
mechanisms.
© Alan Hedge 11/00
Slide 18
Cornell Study:
Statistics Canada
(Hedge et al., Indoor Air,
Air, 1993)
© Alan Hedge 11/00
Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 19
Statistics Canada
(Hedge et al., Indoor Air,
Air, 1993)
Control floor
BZF Test floor
© Alan Hedge 11/00
Slide 20
BZF and VOCs
(Hedge et al., Indoor Air,
Air, 1993)
ppm
2 .5
2
1 .5
1
0 .5
0
p recontrol
p ostcontrol
p re-BZ F p o st-BZF
© Alan Hedge 11/00
Slide 21
BZF and Airborne Particulates
(Hedge et al., Indoor Air,
Air, 1993)
P r e -po st c ha n ge in p a rtic u la te le v e ls
co unt/cc
(< .2 5 µ m )
60
40
20
52
36
0
Control
© Alan Hedge 11/00
BZF
Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 22
BZF and Perceived Environment
Conditions
(Hedge et al., Indoor Air,
Air, 1993)
Pre-control
100
90
80
70
60
% 50
40
30
20
10
0
Poor I A Q
Too little
air
Po st-con trol
Insufficient
ventilation
Pre-BZF
Stale air
Air too
du s ty
Post-BZF
A ir too dry Unp leasant
od ors
m ovem ent
© Alan Hedge 11/00
Slide 23
BZF and PIAQ Effects on Productivity
(Hedge et al., Indoor Air,
Air, 1993)
P re -con tro l
P ost-con tr ol
P re-BZF
P os t-B ZF
% repo rting dec reased produ ctivity
10 0
90
80
70
60
50
40
30
20
10
0
P oor IA Q
T oo little air
m ovem ent
I ns ufficient
ve ntilation
Stale air
A ir too
d us ty
A ir too dry
© Alan Hedge 11/00
Slide 24
BZF and SBS symptoms
M ean PSI
(Hedge et al., Indoor Air,
Air, 1993)
5.00
4.50
4.00
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0.00
P re c on trol
© Alan Hedge 11/00
P ostc o ntro l
P re -B ZF Po st- BZ F P la ceb o
Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 25
BZF and SBS Effects on Productivity
(Hedge et al., Indoor Air,
Air, 1993)
P re -c ontr ol
Po s t-c o ntr ol
P re -BZ F
P os t-B Z F
100
90
80
70
60
% 50
40
30
20
10
0
Dry eyes
Irritated,
sore eyes
Tir ed,
strained
eyes
Stuffy nose Runny nose
© Alan Hedge 11/00
Slide 26
Benefits of BZF
• BZF provides continuous,
controllable, clean air to each
employee.
• BZF compliments HVAC
performance and improves air
mixing in cubicles.
• BZF protects employees against
transient air pollutants.
• BZF reconfigures with "office
churn".
• BZF improves IAQ and reduces
SBS complaints.
• BZF improves productivity.
© Alan Hedge 11/00
Slide 27
Office Lighting Issues
• Computer
Vision
Syndrome
is the #1
complaint of
computerized
office
workers
© Alan Hedge 11/00
Lethargy
Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 28
Lighting and Eyestrain:
Sources of Glare
• Overhead lights
• Task lights
• Windows
• Reflective sources
(clothing, paper)
• Computer screen
© Alan Hedge 11/00
Slide 29
Computer Use and Eye Symptoms
(Hedge et al., ASHRAE Proc., 1991)
2
M ea n # eye sym ptom s
1 .8
1 .6
1 .4
1 .2
Men
1
W om en
0 .8
0 .6
0 .4
0 .2
0
0 .5
1
2
3
4
5
H rs. c o m pu te r use
6
7
7 .5
(n=4,479)
© Alan Hedge 11/00
Slide 30
Office Lighting Systems
© Alan Hedge 11/00
Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 31
Indirect vs. Direct Lighting
• The eye doesn’t see illuminance!
© Alan Hedge 11/00
Slide 32
Cornell Lighting Study: Xerox Facility
(Hedge et al., Ergonomics,
Ergonomics, 1995)
© Alan Hedge 11/00
Slide 33
Open--office K
K--12 Lighting
Open
(Hedge et al., Ergonomics,
Ergonomics, 1995)
© Alan Hedge 11/00
Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 34
Cornell/Xerox: Lighting Changes
(Hedge et al., Ergonomics,
Ergonomics, 1995)
K12 lens
Lensed-indirect
Parabolic
© Alan Hedge 11/00
Slide 35
Parabolic Gloom!
(Hedge et al., Ergonomics,
Ergonomics, 1995)
Private Offices
Open-Plan Offices
© Alan Hedge 11/00
Slide 36
Lensed--Indirect Lighting
Lensed
(Hedge et al., Ergonomics,
Ergonomics, 1995)
• Overwhelming preference
for indirect lighting.
L igh ting Prefere nces
• % reporting daily workrelated health complaints
twice as great with direct
PB lighting.
L IL
PB L
90
80
70
60
%
50
40
30
20
10
0
P re fe r LIL
P re fe r P B L
G roup
© Alan Hedge 11/00
Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 37
The Norwegian Trade
Council, NY.
TwoComponent
Lighting Study
© Alan Hedge 11/00
Slide 38
Pre--Installation Offices
Pre
Interior office
Perimeter office
Offices
© Alan Hedge 11/00
Slide 39
Office Photometrics
• Distribution of evening light levels in the
office space.
© Alan Hedge 11/00
Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 40
Cubicle Offices
• Individually controllable wall sconce indirect fixture
on side panel and on each mullion between
cubicles.
• Desktop adjustable, asymmetric task light.
© Alan Hedge 11/00
Slide 41
Lighting Quality Ratings
(P<0.05))
interes ting /b orin g
relaxed/tens e
hars h/soft
calm /aroused
D ir e c t
2 -c o m po ne n t
pleasant/u npleasant
attractive/un attrac tive
dim /bright
good/b ad
1
2
3
4
5
6
7
M ean ratin g
© Alan Hedge 11/00
Slide 42
Reactions to 22-component Lighting
Seeing screen graph ics
Seein g screen text
W ritin g on pap er
> G ood
Reading d ocuments
Meeting s at d esk
0
20
40
60
% Agr ee
© Alan Hedge 11/00
80
100
Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 43
Opinions of 22-component Lighting
E asier to read
s c reen
L es s ey es train
O ffice feels b rig h ter
L ike n ew lig h tin g
O ffic e look s n ic er
L ik e h av in g lig h tin g
c on trol
0
20
40
60
80
% A g re e
© Alan Hedge 11/00
Slide 44
Dual--component Lighting
Dual
• Worker reaction to the use of dual-component
lighting systems is very positive.
• Workers require training.
© Alan Hedge 11/00
Slide 45
Cornell
Glare Filter
Study
(Hedge et al., HFES Proc.,
1996)
© Alan Hedge 11/00
100
Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge
Slide 46
Reactions to Health Symptoms
(Hedge et al., HFES Proc., 1996)
Headache
Dry eyes
Itching/watering
eyes
Survey 3
Survey 1
Trouble
focussing eyes
Tired eyes
Lethargy
0
10 20 30 40 50 60 70 80 90 100
% response
© Alan Hedge 11/00
Slide 47
Good Ergonomics is
Great Economics
• Ergonomics is always a benefit.
• Ignorance of ergonomics is the cost!
© Alan Hedge 11/00
Slide 48
Cornell University Ergonomics Web
http://ergo.human.cornell
http://ergo.human.cornell.
cornell.edu
© Alan Hedge 11/00