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Men, microclimate and society
Energy and Buildings, 4 (1982) 149 - 154
149
Men, Microdimate and Society Physiological Requirements of the Human Body for Comfortable Indoor Climate E Z R A S OHAR
Tel-Aviv University Medical School, Heller Institute of Medical Research, Chaim Sheba Medical Center, TelHashomer (Israel) "Architects build walls People live in the spaces between them" -
The basic principles of the human thermo. regulatory mechanism will be presented as background for understanding requirements of climatic comfort in hot and cold, humid and dry environmental conditions. Examples will be presented of various basic approaches, past and present, to climatically acceptable solutions for indoor comfort in seoere and even extreme climatic conditions. The influence of indoor climate on the development of human societies will be discussed. In this lecture I intend to discuss the heat regulating mechanism of Man, as a basis for the determination of comfortable indoor conditions. "Physiological Man" is presented in Fig. 1 [1]. Although we live in an exterior environment which is gaseous, the environment within the body ("milieu intdrieur") is liquid.The components of the internal liquid medium must remain at all times within well defined and narrow limits. This includes the water content, the osmotic pressure and its electrolyte composition -- and what is of major interest for us here, the core temperature. Core temperatures below 32 °C or above 43 °C are incompatible with life, but normal functions of the body require a still narrower range, between 36 and 38 °C [2]. The barrier between the internal and exterior environment is the skin. It has important functions in keeping the body temperature constant, mainly by regulating radiation, by adjusting the diameter of peripheral blood vessels and by sweating. Skin temperature is not constant. It is higher in summer than in winter and lower in the extremities than in the trunk (Fig. 2). Changes in skin temperature are part of the heat regulating mechanism. 0378-7788/82/0000-0000/$02.75
FLUID E N V I R O N M E N T AIR ENVIRONMENT FIXED TEMPERATURE SUMMER
AIR ENVIRONMENT WINTER
d
~
~
//\
~ 6 8
8 6 6
'~-PA'c-J6.~; I a~% t I FOOD
WASTE
L
." ~
1
+40"
SKZ~
¢~
Fig. 1. Schematic representation of "physiological Man" [1]. TEMPERATURE SKIN
INTERIOR
iii ,~..1~R
WINTER
SU~',~R
WINTER
Fig. 2. Skin and core temperature in winter and summer [ 1 ] .
To maintain the manifold functions of the body energy is needed. Metabolic processes within the body produce about 20% energy and 80% heat. The basic functions of the body at rest require 40 kcal/h/m 2 of body surface area. When muscles are activated, heat production rises steeply. During strenuous © Elsevier Sequoia/Printed in The Netherlands
150
exercise it m a y increase seven fold, putting a heavy load on the heat dissipating mechanism of the b o d y . Therefore, the combination of external heat and heavy physical work m a y become dangerous when certain limits are exceeded [ 2 ] . Under such conditions b o d y temperature cannot be kept within normal limits (Fig. 3) and heatstroke may ensue [ 2 ] . Mental effort, w h i c h does not in itself increase internal heat production significantly, is also affected b y external heat and performance deteriorates. Re~al Tn~rature °C
15 39
13 30
60
9O
120
Time Fig. tion [2]. DBT
3. S t e e p rise o f body temperature by c o m b i n a o f e x t e r n a l h e a t a n d strenuous physical e f f o r t ( 1 3 = sitting, 14 ffi w a l k i n g , 15 ffi r u n n i n g uphill. = - - 4 0 °(3, W B T ffi - - 3 0 °(3).
Heat balance of the b o d y denotes the exchange of heat with the environment, which is regulated mainly b y physical means. Quantitatively, the most important is r a d i a t i o n transfer of heat from one object to another. The b o d y m a y gain or lose heat b y radiation, depending on the degree and direction of the temperature gradient between the b o d y and environmental objects. Conduction means transfer of heat through a surrounding medium. It is usually o f rather small quantitative importance if the medium is air. If the medium is liquid, the a m o u n t of heat gained or lost increases m a n y times (pilots, for example, who fell into cold water at temperatures easily bearable in an air medium, died within minutes in the liquid medium). This explains w h y wet clothing or walls lose much of their isolating power. The heat balance of the human b o d y in relation to the environment m a y be expressed as the heat load on the body. It is the sum of internal (metabolic) heat load and the outside climatic conditions which produce the external heat load. The total heat load m a y be positive (in summer) or negative (in winter) and core temperature m a y increase or d e crease accordingly.
When the b o d y temperature stability is threatened, the following physiological mechanisms occur: in summer the sweating process is activated; in winter constriction of the peripheral blood vessels, decrease of temperature of the extremities and increase of the metabolic rate occur. There is, however, a basic difference between summer and winter. Physiological means are sufficient in a hot climate to keep the b o d y temperature within normal limits (provided that enough drinking water is available and that the subject does n o t engage in physical work). In a cold climate, however, physiological mechanisms are insufficient to protect us against cold and artificial means have to be applied: since prehistoric times the human race has resorted to housing, clothing, and heating to survive in a cold climate. Physical work which is dangerous in a hot climate, as we have seen, provides additional heat and can, for a limited time, protect the body from cold. In hot environmental conditions cooling is achieved not by sweating but by the evaporation of sweat. M a n is capable of sweating up to 4 liters per hour [4]. However, when climatic conditions are adverse to evaporation, no cooling ensues. The best example is a wet sauna. The temperature is high and the humidity close to 100%. People sweat profusely, but the sweat cannot evaporate and it drips off the body. N o cooling effect is achieved and the body temperature rises steeply [6]. The factors influencing evaporation of sweat are the physical laws which apply to evaporation in general: the higher the air temperature the easier the evaporation, while it is inhibited or even arrested when relative humidity is high. In a humid climate, when the body is surrounded b y a saturated layer of air, wind (0.5 - 1.5 m/s) facilitates evaporation. It follows that air temperature alone is n o t a good index of the ability of the human b o d y to cool in a h o t climate. Humidity and, possibly, other factors such as wind velocity and radiation have also to be taken into account. Many indices have been devised for the determination of the external heat load in an effort to integrate the relative influence of the various climatic factors [5]. Our group uses the Discomfort Index (DI) which has the advantage that it can easily and quickly be computed. The DI is the arithmetic mean of the dry bulb (DB) and wet bulb (WB) tempera-
151
tures [7]. The necessary data can be obtained from the meterological service or measured with a psychrometer. Many experiments in the field, in climatic chambers, and experience of 15 years led us to suggest the following physiological significance for the scale of the DI units [ 5] : Discomfort Index (units)
Physiological significance, (heat load)
< 22 22 - 24 24 - 28 > 28
none mild moderate severe
To determine a daffy profile of a given site the DI of every hour of the day is plotted vertically on a graph. Three horizontal lines, corresponding to 22, 24 and 28 units are drawn. Thus it can now easily be determined which hours have mild, moderate, or severe heat load (Fig. 4). Such a graph can be computed for a given day (e.g., for a weather fore: cast) or for a whole month, using hourly means obtained over a period of many years. In this way climatic discomfort in summer can be expressed in physiological terms [5]. .~o. 29.
TTT TT
,TT •
9 q)
17
! ol
o 2 co 04 olb ~
o./ o o ~ i
Io I i
cs l a 14 i o
HI. n? ¢I !
s o s l s¢ Rs s4
Fig. 4. Graphic representation of degree of heat load at every hour of the day [1].
The following demonstrates the mode of operation. The heat load in August in TelAviv, which has a Mediterranean climate,is compared with Beer-Sheba, situated on the brink of the desert. Tel-Aviv does not have a severe heat load, but a moderate heat load over prolonged periods, day and night (Fig. 5a). The profile of Beer-Sheba shows a different picture (Fig. 5b). Heat load is again moderate, but it is of shorter duration and the nights are cool. In other words, properly built flats in Beer Sheba retain a comfortable temperature
throughout the day, without mechanical cooling -- whereas this cannot be achieved in Tel-Aviv. It is extremely difficult to develop an equivalent of the heat load for a cold climate, the reason being that physiological mechanisms are insufficient to protect us from the cold, and external means must be employed. The method of "heating degree days" takes into account air temperature only, but it was found to be a reliable index of heating requirements, providing an indirect index of "cold load". The following data, condensed into one page, are used in order to provide a comprehensive climatic characterization of any given site. As an example, the climate of Beer-Sheba is represented in Fig. 6: (a) the heat load of every hour of the day, for each of the summer months; (b) the air temperature and relative humidity at 14.00 h; (c) the number of cool hours (DB below 22 °C) daily during each of the summer months; (d) the units of heating degree days during each one of the winter months; (e) the monthly and yearly rainfall. All the figures are monthly means obtained from the meteorological service. The monthly means of solar radiation are lacking, but should be included in order to permit planning for active or passive solar heating. It would be presumptious of me to suggest the methods which architects should apply to achieve the desired indoor climate. Being a physician this is neither m y intention nor is it within the scope of my work. I wish, however, to present a few prototypes of houses and to discuss their relation to climate: (1) The building presented in Fig. 7 is in Tel-Aviv. It could just as well have been photographed in almost any other modern city. This is the "international style". Its two large fronts face east and west. Two thirds of the front is glass and one third is painted black. A comfortable microclimate within the building can be maintained in winter and summer only by mechanical means, burning large quantities of fuel. It seems that the most suitable name for this house would be: "The onedollar-oil-barrel-house". (2) Thick walled mud houses with small windows, erected in the desert climate of
152
Fig. 5a. Mean heat load in Tell-Aviv (Mediterranean climate) during the month of August [ 5 ]. ~iiiii~i~i~i mild heat load; moderate heat load.
Fig. 5b. Mean heat load in Beer-Sheba (Desert climate) during the month of August [ 5 ].
HEAT
LOAD
MAY
JUN JUL AUG SEPT OCT
.o.Rs COOL
24-
HOURS
20o~ oc
16-
~ 12"
8" 4~ms
300-
HEATING
DEGREE
DAYS
250O
200.
Z 17~
..
50' 10
S
MONTHS
RAiN
I °313' 9
10
11
12
1
2
3
4
5
I
Fig. 6. Comprehensive climatic characterisation of Beer-Sheba [ 1 ].
Fig. 7. The "one-dollar-off-barrel-house".
153
(a)
Fig. 8. House built on water with large openings in
hot, wet climate.
,~ WIND
2 Fig. 9. Trapped and water cooled wind cools living
area in desert climate in Iran [ 1 ]. Egypt several thousand years ago, were found to have a microclimate within the c o m f o r t zone day and night t h r o u g h o u t the year. (3) In the Pacific, houses built on stilts on water have large open windows. They benefit from the cooling effect of the evaporation from the water b o d y below them and from the breeze coming through the large windows (Fig. 8). (4) In desert areas in Persia, wind was trapped, c o n d u c t e d underground to pass over a spring to cool it, and then led up again to create a comfortable microclimate in the living areas (Fig. 9). (5) The Igloo (Fig. 10) is the Eskimo's solution to the coldest o u t d o o r climates in which human beings live. The temperature inside the igloo is 15 - 20 °C, while the only heating consists o f the burning of seal oil in a small lamp. The low ceiling is n o t e w o r t h y (hot air, as is well known, tends to accumulate at the t o p of the room). Microclimate has influenced the development o f civilization in ancient as well as in
(b) Fig. 10. (a) Igloo; (b) Plan of igloo [4].
m o d e m times. The cradle o f civilization is on or a b o u t the 21 °C isotherm (Fig. 11) [4]. Along this isotherm, the winter is relatively mild, the summer h o t -- unless houses are well built t o provide a microclimate suitable for the development of culture. The climate of West and Middle Europe is mild in summer, n o t requiring any special arrangements to provide an agreeable indoor microclimate. In winter it is very cold and artificial means must be employed. Though known for many centuries, the chimney began to be widely used in Europe only in the 13th and 14th centuries. In this w a y an agreeable microclimate was achieved t h r o u g h o u t the year. It is believed that this adjustment of the microclimate was a s i n e q u a n o n for the develo p m e n t of the industrial revolution. It is interesting that the e n m a u e emigration of Europeans flowed almost exclusively to areas of similar climate. This permitted the immigrants to apply time proven solutions to achieve the microclimate conducive t o the
154
e
Crete
CyI~I$ ~ ' . ~don
Tuila •
•
Ecbatana
_
•
EGYP
E
P
R
$
I
A
Perlmpoli$
.y,~ Thebes
~Ib
Mohenjodaro"
,f Ml~fta
@ J
#
0 I
Miles 2OO 4O0 I
I
6OO I
Fig. 11. The cradle of civilization (on the 21 °C isotherm) [4].
IN;
/
oeeL
•
m o d e m urban society which will create an agreeable microclimate within houses through correct planning and the use of appropriate building materials and easily available energy sources.
I hope that this symposium will be a step in the right direction. REFERENCES Fig. 12. Massive European emigration to areas of similar climate [ 4 ].
d e v e l o p m e n t o f w h a t m a y n o w b e called t h e A t l a n t i c civilization (Fig. 12). T h e d i s t r i b u t i o n o f universities, a g o o d i n d e x o f W e s t e r n c u l t u r e , was v e r y sparse in t h e h o t areas o f t h e w o r l d u n t i l a i r - c o n d i t i o n ing became available a generation ago [4].
It is obvious t h a t the problem of microclimate within houses cannot be viewed in the same manner as it was two or three decades ago. No longer can houses be built catering to the whims o f architects or occupants, regardless of materials and style. Cheap energy is no longer available to compensate for every mistake. New solutions must be found for the
1 E. Sohar, Man And Climate, Keter Publishers, Jerusalem, 1980, pp. 11, 13, 96, 115, 120 and 204. 2 T. Gilat, S. Shibolet and E. Sohar, The mechanism of heatstroke, J. Trop. Med. Hyg., 66 (1963) 204212. 3 S. Shibolet, R. Coil, T. Gflat and E. Sohar, Heatstroke: Its clinical picture and mecbanilm in 36 cases, Q. J. Med., New Series XXXVI, no. 144, (1967) 5 2 5 - 548. 4 E. Sohar, Climate and society, Biometeorol., 4 (1) (1970) 99 - 104. 5 E. Sohar, C. Birenfeld, Y. Shoenfeld and Y. Shapiro, Deseriptlon and forecast of summer climate in physiologically significant terms, Int. J. Biometeorol., 22 (2) (1978) 7 5 - 81. 6 Y. Shoenfeld, E. Sohar, A. Ohry and Y. Shapiro, Heat stress: comparison of short e x p o ~ r e to severe dry and wet heat in saunas, Arch. Phys. IVied. RehabU., 57 (1976) 126 - 129. 7 EC. Thorn, Discomfort Index, Weatherwise, 12 (1959)
57.
149
Men, Microdimate and Society Physiological Requirements of the Human Body for Comfortable Indoor Climate E Z R A S OHAR
Tel-Aviv University Medical School, Heller Institute of Medical Research, Chaim Sheba Medical Center, TelHashomer (Israel) "Architects build walls People live in the spaces between them" -
The basic principles of the human thermo. regulatory mechanism will be presented as background for understanding requirements of climatic comfort in hot and cold, humid and dry environmental conditions. Examples will be presented of various basic approaches, past and present, to climatically acceptable solutions for indoor comfort in seoere and even extreme climatic conditions. The influence of indoor climate on the development of human societies will be discussed. In this lecture I intend to discuss the heat regulating mechanism of Man, as a basis for the determination of comfortable indoor conditions. "Physiological Man" is presented in Fig. 1 [1]. Although we live in an exterior environment which is gaseous, the environment within the body ("milieu intdrieur") is liquid.The components of the internal liquid medium must remain at all times within well defined and narrow limits. This includes the water content, the osmotic pressure and its electrolyte composition -- and what is of major interest for us here, the core temperature. Core temperatures below 32 °C or above 43 °C are incompatible with life, but normal functions of the body require a still narrower range, between 36 and 38 °C [2]. The barrier between the internal and exterior environment is the skin. It has important functions in keeping the body temperature constant, mainly by regulating radiation, by adjusting the diameter of peripheral blood vessels and by sweating. Skin temperature is not constant. It is higher in summer than in winter and lower in the extremities than in the trunk (Fig. 2). Changes in skin temperature are part of the heat regulating mechanism. 0378-7788/82/0000-0000/$02.75
FLUID E N V I R O N M E N T AIR ENVIRONMENT FIXED TEMPERATURE SUMMER
AIR ENVIRONMENT WINTER
d
~
~
//\
~ 6 8
8 6 6
'~-PA'c-J6.~; I a~% t I FOOD
WASTE
L
." ~
1
+40"
SKZ~
¢~
Fig. 1. Schematic representation of "physiological Man" [1]. TEMPERATURE SKIN
INTERIOR
iii ,~..1~R
WINTER
SU~',~R
WINTER
Fig. 2. Skin and core temperature in winter and summer [ 1 ] .
To maintain the manifold functions of the body energy is needed. Metabolic processes within the body produce about 20% energy and 80% heat. The basic functions of the body at rest require 40 kcal/h/m 2 of body surface area. When muscles are activated, heat production rises steeply. During strenuous © Elsevier Sequoia/Printed in The Netherlands
150
exercise it m a y increase seven fold, putting a heavy load on the heat dissipating mechanism of the b o d y . Therefore, the combination of external heat and heavy physical work m a y become dangerous when certain limits are exceeded [ 2 ] . Under such conditions b o d y temperature cannot be kept within normal limits (Fig. 3) and heatstroke may ensue [ 2 ] . Mental effort, w h i c h does not in itself increase internal heat production significantly, is also affected b y external heat and performance deteriorates. Re~al Tn~rature °C
15 39
13 30
60
9O
120
Time Fig. tion [2]. DBT
3. S t e e p rise o f body temperature by c o m b i n a o f e x t e r n a l h e a t a n d strenuous physical e f f o r t ( 1 3 = sitting, 14 ffi w a l k i n g , 15 ffi r u n n i n g uphill. = - - 4 0 °(3, W B T ffi - - 3 0 °(3).
Heat balance of the b o d y denotes the exchange of heat with the environment, which is regulated mainly b y physical means. Quantitatively, the most important is r a d i a t i o n transfer of heat from one object to another. The b o d y m a y gain or lose heat b y radiation, depending on the degree and direction of the temperature gradient between the b o d y and environmental objects. Conduction means transfer of heat through a surrounding medium. It is usually o f rather small quantitative importance if the medium is air. If the medium is liquid, the a m o u n t of heat gained or lost increases m a n y times (pilots, for example, who fell into cold water at temperatures easily bearable in an air medium, died within minutes in the liquid medium). This explains w h y wet clothing or walls lose much of their isolating power. The heat balance of the human b o d y in relation to the environment m a y be expressed as the heat load on the body. It is the sum of internal (metabolic) heat load and the outside climatic conditions which produce the external heat load. The total heat load m a y be positive (in summer) or negative (in winter) and core temperature m a y increase or d e crease accordingly.
When the b o d y temperature stability is threatened, the following physiological mechanisms occur: in summer the sweating process is activated; in winter constriction of the peripheral blood vessels, decrease of temperature of the extremities and increase of the metabolic rate occur. There is, however, a basic difference between summer and winter. Physiological means are sufficient in a hot climate to keep the b o d y temperature within normal limits (provided that enough drinking water is available and that the subject does n o t engage in physical work). In a cold climate, however, physiological mechanisms are insufficient to protect us against cold and artificial means have to be applied: since prehistoric times the human race has resorted to housing, clothing, and heating to survive in a cold climate. Physical work which is dangerous in a hot climate, as we have seen, provides additional heat and can, for a limited time, protect the body from cold. In hot environmental conditions cooling is achieved not by sweating but by the evaporation of sweat. M a n is capable of sweating up to 4 liters per hour [4]. However, when climatic conditions are adverse to evaporation, no cooling ensues. The best example is a wet sauna. The temperature is high and the humidity close to 100%. People sweat profusely, but the sweat cannot evaporate and it drips off the body. N o cooling effect is achieved and the body temperature rises steeply [6]. The factors influencing evaporation of sweat are the physical laws which apply to evaporation in general: the higher the air temperature the easier the evaporation, while it is inhibited or even arrested when relative humidity is high. In a humid climate, when the body is surrounded b y a saturated layer of air, wind (0.5 - 1.5 m/s) facilitates evaporation. It follows that air temperature alone is n o t a good index of the ability of the human b o d y to cool in a h o t climate. Humidity and, possibly, other factors such as wind velocity and radiation have also to be taken into account. Many indices have been devised for the determination of the external heat load in an effort to integrate the relative influence of the various climatic factors [5]. Our group uses the Discomfort Index (DI) which has the advantage that it can easily and quickly be computed. The DI is the arithmetic mean of the dry bulb (DB) and wet bulb (WB) tempera-
151
tures [7]. The necessary data can be obtained from the meterological service or measured with a psychrometer. Many experiments in the field, in climatic chambers, and experience of 15 years led us to suggest the following physiological significance for the scale of the DI units [ 5] : Discomfort Index (units)
Physiological significance, (heat load)
< 22 22 - 24 24 - 28 > 28
none mild moderate severe
To determine a daffy profile of a given site the DI of every hour of the day is plotted vertically on a graph. Three horizontal lines, corresponding to 22, 24 and 28 units are drawn. Thus it can now easily be determined which hours have mild, moderate, or severe heat load (Fig. 4). Such a graph can be computed for a given day (e.g., for a weather fore: cast) or for a whole month, using hourly means obtained over a period of many years. In this way climatic discomfort in summer can be expressed in physiological terms [5]. .~o. 29.
TTT TT
,TT •
9 q)
17
! ol
o 2 co 04 olb ~
o./ o o ~ i
Io I i
cs l a 14 i o
HI. n? ¢I !
s o s l s¢ Rs s4
Fig. 4. Graphic representation of degree of heat load at every hour of the day [1].
The following demonstrates the mode of operation. The heat load in August in TelAviv, which has a Mediterranean climate,is compared with Beer-Sheba, situated on the brink of the desert. Tel-Aviv does not have a severe heat load, but a moderate heat load over prolonged periods, day and night (Fig. 5a). The profile of Beer-Sheba shows a different picture (Fig. 5b). Heat load is again moderate, but it is of shorter duration and the nights are cool. In other words, properly built flats in Beer Sheba retain a comfortable temperature
throughout the day, without mechanical cooling -- whereas this cannot be achieved in Tel-Aviv. It is extremely difficult to develop an equivalent of the heat load for a cold climate, the reason being that physiological mechanisms are insufficient to protect us from the cold, and external means must be employed. The method of "heating degree days" takes into account air temperature only, but it was found to be a reliable index of heating requirements, providing an indirect index of "cold load". The following data, condensed into one page, are used in order to provide a comprehensive climatic characterization of any given site. As an example, the climate of Beer-Sheba is represented in Fig. 6: (a) the heat load of every hour of the day, for each of the summer months; (b) the air temperature and relative humidity at 14.00 h; (c) the number of cool hours (DB below 22 °C) daily during each of the summer months; (d) the units of heating degree days during each one of the winter months; (e) the monthly and yearly rainfall. All the figures are monthly means obtained from the meteorological service. The monthly means of solar radiation are lacking, but should be included in order to permit planning for active or passive solar heating. It would be presumptious of me to suggest the methods which architects should apply to achieve the desired indoor climate. Being a physician this is neither m y intention nor is it within the scope of my work. I wish, however, to present a few prototypes of houses and to discuss their relation to climate: (1) The building presented in Fig. 7 is in Tel-Aviv. It could just as well have been photographed in almost any other modern city. This is the "international style". Its two large fronts face east and west. Two thirds of the front is glass and one third is painted black. A comfortable microclimate within the building can be maintained in winter and summer only by mechanical means, burning large quantities of fuel. It seems that the most suitable name for this house would be: "The onedollar-oil-barrel-house". (2) Thick walled mud houses with small windows, erected in the desert climate of
152
Fig. 5a. Mean heat load in Tell-Aviv (Mediterranean climate) during the month of August [ 5 ]. ~iiiii~i~i~i mild heat load; moderate heat load.
Fig. 5b. Mean heat load in Beer-Sheba (Desert climate) during the month of August [ 5 ].
HEAT
LOAD
MAY
JUN JUL AUG SEPT OCT
.o.Rs COOL
24-
HOURS
20o~ oc
16-
~ 12"
8" 4~ms
300-
HEATING
DEGREE
DAYS
250O
200.
Z 17~
..
50' 10
S
MONTHS
RAiN
I °313' 9
10
11
12
1
2
3
4
5
I
Fig. 6. Comprehensive climatic characterisation of Beer-Sheba [ 1 ].
Fig. 7. The "one-dollar-off-barrel-house".
153
(a)
Fig. 8. House built on water with large openings in
hot, wet climate.
,~ WIND
2 Fig. 9. Trapped and water cooled wind cools living
area in desert climate in Iran [ 1 ]. Egypt several thousand years ago, were found to have a microclimate within the c o m f o r t zone day and night t h r o u g h o u t the year. (3) In the Pacific, houses built on stilts on water have large open windows. They benefit from the cooling effect of the evaporation from the water b o d y below them and from the breeze coming through the large windows (Fig. 8). (4) In desert areas in Persia, wind was trapped, c o n d u c t e d underground to pass over a spring to cool it, and then led up again to create a comfortable microclimate in the living areas (Fig. 9). (5) The Igloo (Fig. 10) is the Eskimo's solution to the coldest o u t d o o r climates in which human beings live. The temperature inside the igloo is 15 - 20 °C, while the only heating consists o f the burning of seal oil in a small lamp. The low ceiling is n o t e w o r t h y (hot air, as is well known, tends to accumulate at the t o p of the room). Microclimate has influenced the development o f civilization in ancient as well as in
(b) Fig. 10. (a) Igloo; (b) Plan of igloo [4].
m o d e m times. The cradle o f civilization is on or a b o u t the 21 °C isotherm (Fig. 11) [4]. Along this isotherm, the winter is relatively mild, the summer h o t -- unless houses are well built t o provide a microclimate suitable for the development of culture. The climate of West and Middle Europe is mild in summer, n o t requiring any special arrangements to provide an agreeable indoor microclimate. In winter it is very cold and artificial means must be employed. Though known for many centuries, the chimney began to be widely used in Europe only in the 13th and 14th centuries. In this w a y an agreeable microclimate was achieved t h r o u g h o u t the year. It is believed that this adjustment of the microclimate was a s i n e q u a n o n for the develo p m e n t of the industrial revolution. It is interesting that the e n m a u e emigration of Europeans flowed almost exclusively to areas of similar climate. This permitted the immigrants to apply time proven solutions to achieve the microclimate conducive t o the
154
e
Crete
CyI~I$ ~ ' . ~don
Tuila •
•
Ecbatana
_
•
EGYP
E
P
R
$
I
A
Perlmpoli$
.y,~ Thebes
~Ib
Mohenjodaro"
,f Ml~fta
@ J
#
0 I
Miles 2OO 4O0 I
I
6OO I
Fig. 11. The cradle of civilization (on the 21 °C isotherm) [4].
IN;
/
oeeL
•
m o d e m urban society which will create an agreeable microclimate within houses through correct planning and the use of appropriate building materials and easily available energy sources.
I hope that this symposium will be a step in the right direction. REFERENCES Fig. 12. Massive European emigration to areas of similar climate [ 4 ].
d e v e l o p m e n t o f w h a t m a y n o w b e called t h e A t l a n t i c civilization (Fig. 12). T h e d i s t r i b u t i o n o f universities, a g o o d i n d e x o f W e s t e r n c u l t u r e , was v e r y sparse in t h e h o t areas o f t h e w o r l d u n t i l a i r - c o n d i t i o n ing became available a generation ago [4].
It is obvious t h a t the problem of microclimate within houses cannot be viewed in the same manner as it was two or three decades ago. No longer can houses be built catering to the whims o f architects or occupants, regardless of materials and style. Cheap energy is no longer available to compensate for every mistake. New solutions must be found for the
1 E. Sohar, Man And Climate, Keter Publishers, Jerusalem, 1980, pp. 11, 13, 96, 115, 120 and 204. 2 T. Gilat, S. Shibolet and E. Sohar, The mechanism of heatstroke, J. Trop. Med. Hyg., 66 (1963) 204212. 3 S. Shibolet, R. Coil, T. Gflat and E. Sohar, Heatstroke: Its clinical picture and mecbanilm in 36 cases, Q. J. Med., New Series XXXVI, no. 144, (1967) 5 2 5 - 548. 4 E. Sohar, Climate and society, Biometeorol., 4 (1) (1970) 99 - 104. 5 E. Sohar, C. Birenfeld, Y. Shoenfeld and Y. Shapiro, Deseriptlon and forecast of summer climate in physiologically significant terms, Int. J. Biometeorol., 22 (2) (1978) 7 5 - 81. 6 Y. Shoenfeld, E. Sohar, A. Ohry and Y. Shapiro, Heat stress: comparison of short e x p o ~ r e to severe dry and wet heat in saunas, Arch. Phys. IVied. RehabU., 57 (1976) 126 - 129. 7 EC. Thorn, Discomfort Index, Weatherwise, 12 (1959)
57.