Human Comfort in the Urban Environment
Solar loading impact on human thermal comfort
M + Qn + C – LE = 0
Metabolic Rates for various activities
The metabolic rate, or human body heat or power
production, is often measured in the unit "Met". The
metabolic rate of a relaxed seated person is one (1)
Met, where
1 Met = 58 W/m2 (356 Btu/hr)
The mean surface area, the Du-Bois area, of the
human body is approximately 1.8 m2 (19.4 ft2). The
total metabolic heat for a mean body can be
calculated by multiplying with the area. The total
heat from a relaxed seated person with mean surface
area would be
58 W/m2 x 1.8 m2 = 104 W (356 Btu/hr)
Activity
W/m2
W1)
Bt
u/ Me
hr t
1)
Reclining
Sleepimng
46
83
282 0.8
Seated relaxed
58
104
356 1.0
Standing at rest
70
126
430 1.2
Sedentary activity
(office, dwelling,
school, laboratory)
70
126
430 1.2
Car driving
80
144
491 1.4
Graphic profession Book Binder
85
153
522 1.5
93
167
571 1.6
Teacher
95
171
583 1.6
Domestic work shaving, washing and
dressing
100
180
614 1.7
Walking on the level,
2 km/h
110
198
675
Standing, light
activity (shopping,
laboratory, light
industry)
1.9
Running
http://www.shapesense.com/fitnessexercise/calculators/resting-metabolic-rate-calculator.aspx
8-9
Activity
Human Metabolic Rate
(W/m2)
(Met)
Laying down
46
0.8
Sitting, relaxed
58
1.0
Standing, relaxed
70
1.2
Sitting activity (office work,
school etc.)
70
1.2
Standing activity (shop,
laboratory etc.)
93
1.6
Moving activity (house
work, working at machines
etc.)
116
2.0
Harder activity (hard work
at machines, work shops
etc. )
165
2.8
Clothing and human comfort
The insulation of clothes are often measured in the unit "Clo", where
1 Clo = 0.155 m2K/W
Clo = 0 - corresponds to a naked person
Clo = 1 - corresponds to the insulating value of clothing needed to
maintain a person in comfort sitting at rest in a room at 21 ℃ (70 ℉)
with air movement of 0.1 m/s and humidity less than 50% - typically a
person wearing a business suit
http://www.engineeringtoolbox.com/clo-clothing-thermal-insulation-d_732.html
http://www.engineeringtoolbox.com/metabolism-clothing-activity-d_117.html
Heat Discomfort Zone
Maximum recommended work load
Temperature
Relative Humidity (%)
oF
oC
30
40
60
80
80
27
Very Heavy
Very Heavy
Very Heavy
Heavy
90
32
Very Heavy
Heavy
Moderate
Light
Moderate
Light
Not
recommen
ded
Moderate
Light
Not
recommen
ded
Not
recommen
ded
Light
Not
recommen
ded
Not
recommen
ded
Not
recommen
ded
100
110
120
38
43
49
Heavy
Heart rate, energy expenditure
Body
Energy
Expenditur
e
(watts)
Work
Duration
Restriction
(hours)
70 - 175
none
Effort Level
Typical Tasks
Heart Rate
Elevation
(beats per
minute)
Light
riding bicycle at 10 km/h, canning
paint, raking leaves, making
drawings, machining light objects,
sewing by hand
0 - 35
Moderate
building brick wall, cleaning boiler,
planing softwood, sheet-metal
35 - 55
working, soldering, using
screwdrivers, walking on level
175 - 260
>2
Heavy
digging trenches, using sledgehammer, stoking furnace, metal
grinding, walking up 5% gradient
55 - 75
260 - 420
< 1 to 2
Very Heavy
shoveling sand, using
jackhammer, stacking concrete
blocks, stone masonry, climbing
normal stairs
75 - 90
420 - 700
< 1 to 2
Extremely
Heavy
sawing wood, climbing vertical
ladder
> 90
> 700
< 0.25 to
0.3
Heat Index in degrees Fahrenheit
The heat index can be calculated as
tHI = -42.379 + 2.04901523 t + 10.14333127 φ
- 0.22475541 t φ - 0.00683783 t2 - 0.05481717 φ2
+ 0.00122874 t2 φ + 0.00085282 t φ2 - 0.00000199 (T φ)2
where
tHI = heat index (oF)
t = air temperature (oF) (t > 57oF)
φ = relative humidity (%)
(1)
Caution - Fatigue is possible with prolonged exposure and/or physical activity
2) Extreme Caution - Sunstroke, heat cramps and heat exhaustion are possible with prolonged exposure and/or physical
activity
3) Danger - Sunstroke, heat cramps and heat exhaustion are likely. Heat stroke is possible with prolonged exposure and/or
physical activity
4) Extreme Danger - Heatstroke/sunstroke is highly likely with continued exposure
Wind Chill Index - Wind Velocity km/h and degrees Celsius
The "Chilled" air temperature can also be expressed as a function of wind velocity and
ambient air temperature as
twC = 13.12 + 0.6215 ta - 11.37 v0.16 + 0.3965 ta v0.16 (1)
where twC = effective "wind" temperature (oC)
ta = air temperature (oC); v = wind velocity (km/h)
"Chilled" Air Temperature (oC)
Ambient Wind Velocity (km/h)
Air
Tempera 5
10
15
o
ture ( C)
20
30
40
50
60
10
10
9
8
7
7
6
5
5
5
4
3
2
1
0
-1
-1
-2
0
-2
-3
-4
-5
-6
-7
-8
-9
-5
-7
-9
-11
-12
-13
-14
-15
-16
-10
-13
-15
-17
-18
-20
-21
-22
-23
-15
-19
-21
-23
-24
-26
-27
-29
-30
-20
-24
-27
-29
-30
-33
-34
-35
-36
-25
-30
-33
-35
-37
-39
-41
-42
-43
-30
-36
-39
-41
-43
-46
-48
-49
-50
-35
-41
-45
-48
-49
-52
-54
-56
-57
-40
-47
-51
-54
-56
-59
-61
-63
-64
Wind Chill Index - Wind Velocity mph and degrees Fahrenheit
The "Chilled" air temperature can also be expressed as a function
of wind velocity and ambient air temperature as
twF = 35.74 + 0.6215 ta - 35.75 v0.16 + 0.4275 ta v0.16 (2)
"Chilled" Air Temperature (oF)
Ambient Wind Velocity (mph)
Air
Temper
5
10
15
ature
o
( F)
20
25
30
35
40
40
36
34
32
30
29
28
28
27
35
31
27
25
24
23
21
21
20
30
25
21
19
17
16
14
14
13
25
19
15
13
11
9
7
7
6
20
13
9
6
4
3
0
0
-1
15
7
3
0
-2
-4
-7
-7
-8
10
1
-4
-7
-9
-11
-14
-14
-15
5
-5
-10
-13
-15
-17
-21
-21
-22
0
-11
-16
-19
-22
-24
-27
-27
-29
-5
-16
-22
-26
-29
-31
-37
-34
-36
-10
-22
-28
-32
-35
-37
-41
-41
-43
-15
-28
-35
-39
-42
-44
-48
-48
-50
-20
-34
-41
-45
-48
-51
-55
-55
-57
-25
-40
-47
-51
-55
-58
-62
-62
-64
-30
-46
-53
-58
-61
-64
-69
-69
-71
-35
-52
-59
-64
-68
-71
-76
-76
-78
-40
-57
-66
-71
-74
-78
-82
-82
-84
Hypothermia
1. Hypothermia - "a decrease in the core body temperature to a level at
which normal muscular and cerebral functions are impaired." - Medicine
for Mountaineering
2. Conditions Leading to Hypothermia
Cold temperatures
Improper clothing and equipment
Wetness
Fatigue, exhaustion
Dehydration
Poor food intake
No knowledge of hypothermia
Alcohol intake - causes vasodilation leading to increased heat loss
Hyperthermia is an abnormally high body temperature caused by a failure of the heat-regulating mechanisms
of the body to deal with the heat coming from the environment. Heat fatigue, heat syncope (sudden dizziness
after prolonged exposure to the heat), heat cramps, heat exhaustion and heat stroke are commonly known
forms of hyperthermia. Risk for these conditions can increase with the combination of outside temperature,
general health and individual lifestyle.
Lifestyle factors can include not drinking enough fluids, living in housing without air conditioning, lack of
mobility and access to transportation, overdressing, visiting overcrowded places and not understanding how
to respond to hot weather conditions. Older people, particularly those with chronic medical conditions,
should stay indoors on hot and humid days, especially when an air pollution alert is in effect. People without
air conditioners should go to places that do have air conditioning, such as senior centers, shopping malls,
movie theaters and libraries. Cooling centers, which may be set up by local public health agencies, religious
groups and social service organizations in many communities, are another option.
Health-related factors, some especially common among older people, that may increase risk of hyperthermia
include:
Being dehydrated.
Age-related changes to the skin such as impaired blood circulation and inefficient sweat glands.
Heart, lung and kidney diseases, as well as any illness that causes general weakness or fever.
High blood pressure or other conditions that require changes in diet. For example, people on salt-restricted
diets may be at increased risk. However, salt pills should not be used without first consulting a doctor.
Reduced sweating, caused by medications such as diuretics, sedatives, tranquilizers and certain heart and
blood pressure drugs.
Taking several drugs for various conditions. It is important, however, to continue to take prescribed
medication and discuss possible problems with a physician.
Being substantially overweight or underweight.
Drinking alcoholic beverages.
Heat stroke is a life-threatening form of hyperthermia. It occurs when the body is overwhelmed by heat and
unable to control its temperature. Heat stroke occurs when someone’s body temperature increases
significantly (generally above 104 degrees Fahrenheit) and has symptoms such as mental status changes (like
confusion or combativeness), strong rapid pulse, lack of sweating, dry flushed skin, faintness, staggering, or
coma. Seek immediate emergency medical attention for a person with any of these symptoms, especially an
older adult.
How Cities Use Parks To Improve Human Health
Parks provide people with contact with nature, known to confer certain
health benefits and enhance well-being.
Physical activity opportunities in parks help to increase fitness and reduce
obesity.
Parks resources can mitigate climate, air, and water pollution impacts on
public health.
Cities need to provide all types of parks, to provide their various citizen
groups with a range of health benefits.
Central Park, NY