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Thermal effects of ventilated car seats
Industrial Ergonomics International Journal of Industrial Ergonomics 13 (1994) 253-258
ELSEVIER
Case study
Thermal effects of ventilated car seats Thomas Lund Madsen Thermal Insulation Laboratory, Technical University of Denmark, Building 118, DK-2800 Lyngby, Denmark (Received June 15, 1993; accepted in revised form December 2, 1993)
Abstract
In this paper a description is given of a new car seat designed for increased thermal comfort on hot summer days. The seat is supplied with a simple ventilating system blowing air from the bottom of the car through the seat and the back towards the person in the seat. The seat has been tested with a thermal manikin in order to find the cooling efficiency on the dry heat loss as well as the latent heat loss from a person seated in the seat. The test result is, that the ventilating system with an air flow of 2 l per sec has a significant influence on the dry heat loss, but mainly on the latent heat loss. Relevance to industry This car seat can be a c h e a p and effective solution decreasing discomfort after start in an o v e r h e a t e d car p a r k e d in the sun. In the winter, the system may d e c r e a s e the time of discomfort after start with electrical h e a t i n g e l e m e n t s in the seat and back.
Key words." Air flow; Automotive; Comfort; Ventilation; Cooling
1. Introduction It is a well-known fact that it is very u n c o m fortable to e n t e r a car which has b e e n p a r k e d in the sun on a hot s u m m e r day. Even in c o u n t r i e s where air c o n d i t i o n i n g in cars is u n c o m m o n , the seat is very w a r m a n d has a high i n s u l a t i o n value. W h e n these two items are p u t t o g e t h e r it causes a high degree of t h e r m a l discomfort for the body, in general, a n d for thigh a n d back in particular. O n e solution to r e d u c e the time s p e n t with a high degree of discomfort can be v e n t i l a t i o n of the car seat. A v e n t i l a t e d car seat of this kind has b e e n
developed by m e a n s of a special polyester fiber m a t e r i a l by a D a n i s h firm.
2. Description of the ventilating system T h e o u t e r 30 m m of the seat a n d back consists of pigs' bristles, which gives a good d i s t r i b u t i o n of the air; the back a n d u n d e r part of the seat is covered with an airtight lining with a t u b e which is c o n n e c t e d to a fan. Two types of covering are tested, o n e m a d e of wool a n d a n o t h e r of polyester fibres. In this simple way it is possible to create
0169-8141/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved SSDI 0 1 6 9 - 8 1 4 1 ( 9 3 ) E 0 0 8 0 - 8
254
T.L. Madsen / International Journal of Industrial Ergonomics 13 (1994) 253-258 polyester cover.
mm layer of pigs bristles Jbe for ventilation
The manikin is divided in 16 sections each with its own control system. This control system is designed to simulate the h u m a n skin t e m p e r a t u r e regulation in thermal comfort. The relation between the surface t e m p e r a t u r e of each section and the heat loss is given by Eq. 1.
tskin = 36.4 - 0.054"
Fig. 1. Car seat.
an air m o v e m e n t from the seat and back against the person who is sitting in the seat. T h e fan speed can be controlled to o p t i m u m comfort (Fig. 1).
3. Test method The efficiency of this simple system has been tested with a thermal manikin (Madsen, 1976; M a d s e n and Olesen, 1986) supplied with heat flux meters on the shoulder-blades and on the left and right thigh, which are the parts touching the seat when the manikin is seated.
d)d~
( 1)
where tskin is the mean surface t e m p e r a t u r e in °C and 4~d~y is the dry heat loss in W / m 2. The manikin's heating system consists of nickelwire w o u n d a r o u n d each section and interspaced by less than 2 mm. This establishes an extremely even distribution of heat from each section. It is possible to make a record of the heat loss and the surface t e m p e r a t u r e from each of the 16 sections every 30 seconds. A n area weighed m e a n of the total dry heat loss from the manikin is calculated as well (Bischof et al., 1991; T a n a b e et al., 1994). Finally, it is possible to make a record of the difference between the area weighed m e a n heat loss from two selected groups of sections, e.g. to c o m p a r e the left leg and arm with the right leg and arm in an asymmetric temperature field. The manikin was clothed in a suit with an insulation value of 0.6 clo and placed in the car seat in a climatic c h a m b e r with a constant room t e m p e r a t u r e and a constant relative humidity.
tair= tmrt = 20°C,
c < 0.1 m / s , R H = 55%
Fig. 2. Thermal manikin with heat flux meters, temperature sensors and "sweat gland" on shoulder-blade.
T.L. Madsen / International Journal of Industrial Ergonomics 13 (1994) 253-258
Heatloss in percent. 350 300 250 200 150 100 50
0
0
6.8
10.1
14.4
21.0
Ventilation rate (m3/h)
• Heatloss from back [ ] Heatloss from Thigh Fig. 3. Correlation between heat loss and ventilation rate.
The test seat was equipped with a centrifugal fan with variable speed. The amount of room air introduced to the seat was measured by a gasmeter.
4. Measurement Two car seats were tested; the only difference was that one seat had a wool cover and the other a polyester cover. During all tests the thermal manikin (weight: 35 kg) was seated as a normal person in the test seat. The heat loss variation was measured by four heat flux meters, two on the back (Fig. 2), and one between each thigh and the car seat. The correlation between the ventilation rate and heat loss for the back and thigh measured by heat flux meters in direct contact with the car seat is given in Fig. 3. It is seen that only a small increase is obtained for ventilation rates higher than 7 m 3 / h ~ 2 l/see. This rate of ventilation is used for the investigation.
4.1. Measurement of dry- and latent heat loss In order to have an idea of the increase of the latent heat loss caused by ventilation, the thermal manikin is equipped with two "sweat glands" (Fig. 2), one on one of the shoulder-blades and the other under one of the thighs where they are in contact with the car seat. The "sweat glands" consist of two small capillary tubes connected to two small pumps with a capacity of 15 m l / h ensuring 0.025 m 2 of wetted area under the cloth-
255
ing for each tube. 60, 120 and 180 ml per m 2 are added per hour if the pumps are running 10, 20 or 30 percent of the time. The running frequency is 2 min. To be able to measure the influence of the humidification on heat loss and skin temperature a heat flux sensor and a temperature sensor have been installed on each shoulder-blade, one set close to the "sweat gland". Heat flux meters and temperature sensors have also been placed between the thigh and the seat. Under one thigh the sensors are placed close to the second "sweat gland". The reason for using this method and not the usual measurement of area weighed mean of each section is that only a small part of the thigh and maybe 50% of the back section of the manikin is in direct contact with the car seat. It is now possible to compare "skin" temperature and heat loss from the dry and the humidified area of the back as well as of the thigh. All measurements are recorded each minute by a 12-bit datalogger. During all the tests the ventilation rate was 2 1/see, and the perspiration was 60, 120 or 180 m l / m 2 per hour.
5. Measuring results The increase of the heat loss for sweat rates of 60, 120 and 180 m l / m 2 per hour in the wool seat for back as well as for thigh is shown in Fig. 4. In Fig. 5 a comparison is given between the wool and the polyester seat for back as well as for thigh. This comparison shows the increase of the heat loss for ventilation only, sweating only and ventilation + sweating. Fig. 6 shows the recording of the skin temperature at the dry and wetted shoulder-blade and thigh.
6. Evaluation of the measuring results
6.1. Back The increased heat loss by humidification is almost independent of the added amount of wa-
T.L. Madsen / International Journal of lndustrial Ergonomics 13 (1994) 253-258
256
Increase of heatloss (percent)
BACK.
350 f 300 250 200
6.2. Thigh
150 100 50 60
120
180
Increase of heatloss (percent) THIGH.
200 150 100
0
crease of temperature can be seen from Fig. 6. This figure shows the surface temperature of the two shoulder-blades by a humidification of 120 ml/mZh.
6O
120
The two thighs are two separately independent sections of the thermal manikin. Fig. 6 shows the temperature variation between thigh and seat during a test (120 m l / m 2 h ) . It can be seen that the temperature of the dry thigh only varies when the ventilation is started. From Fig. 5 it can be seen that the increase of the heat loss by ventilation both with and without humidification is smaller for the thigh than for the back but the temperature decrease is biggest for the thigh. One reason for this discrepancy can be that only a small part of the total area of the thigh is in direct contact with the insulated seat.
180
Sweat rate (ml/m*m pr. hour)
• ventilation [ ] sweating [ ] ventilation +sweating Fig. 4. Correlation between perspiration (sweat rate) and heat loss from back and thigh. Wool Seat.
Increase of heat loss (percent).
BACK.
350 I 3001 250"
F i
200
ter, which is due to the fact that already at 60 m l / m 2 h , the area round the measuring point will be wet. When the ventilation is started the heat loss from the moist area will be about doubled. A very strong cooling will, consequently, arise maybe too strong. A comparison between the wool and the polyester seat (Fig. 7) shows that the polyester seat gives a stronger cooling than the wool seat; the reason may be that for the chosen voltage to the ventilator (110 V) corresponding to 2 1/sec through the wool seat, a little more air than 2 l / s e c will pass through the polyester seat than through the wool seat. As all the back makes one section of the thermal manikin, a local cooling of part of this section will give an increased voltage to the hot wires, which are equally interspaced over all the surface, and the temperature of the dry part of the back will therefore be increased. This in-
150 100 50 0
Wool seat
Polyester seat
Increase in heat loss (percent).
THIGH.
350 I 300 / 250] 200 / 150 100 50 0
Wool seat
Polyester seat
• ventilation only [ ] sweating only [ ] ventilation + sweating
Fig. 5. Comparison of the increase of heat loss from back and thigh when using wool or polyester seat.
257
T.L. Madsen / International Journal of lndustrial Ergonomics 13 (1994) 253-258
On Fig. 6 it can be seen that the skin temperature between thigh and seat without ventilation and humidification is 40°C, on the back it is only 33°C. When the ventilation starts the temperature decrease will be bigger between the thigh and the seat than between the back and the seat. The heat loss from the thigh, which was high without ventilation because of the high temperature, will be increased with a smaller percentage than the back. This example shows the limitation of the thermal manikin, and it indicates that the result from the back is best correlated to the human situation. The main result of the investigation can be seen from Fig. 7. For each seat, calculations have been made of the mean heat loss and temperature fall on the basis of two "sweat glands" located at two different places (back and thigh). This comparison shows no significant difference between the two seats of the ability to remove the
Increase of heatloss in percent. 300 250 200 150 100 50 0
Wool
Polyester
temperature decrease (C). 0
-6 -8 -10
WOOL
POLYESTER
• ventilation D sweating [ ] ventilation+sweating
Fig. 7. Increase of heat loss and decrease of "skin" temperature during ventilation and/or perspiration for wool and polyester seat. Mean of back and thigh and mean of 60, 120 and 180 ml/m 2 per hour sweat rate. Ventilation: 2 l/see.
°C 35 ---'¢-'-"'-----~'~"~ DRY SHOULDERBLADE k.,___.,_. . . . . . . .
surplus heat. Ventilation of the polyester seat causes a little higher increase of the heat loss and consequently also a little higher decrease of the "skin" temperature of the person in the seat.
30 BACK 25 VENTILATION
.
PERSPI
20
*C
. . . . . . .
7
0 . . . . .
-- . . . . .
......
r
5
7. C o n c l u s i o n
ON
10
1'5
2; hour
"7
40
DRY THIGH
x
30
WEATINGTHI i\
20 ~
10
~
THIGH
~ VENTliATIO N PERSPIRATION - -
L
V
~
I
[~P
0 5 10 15 20 hour Fig. 6. Recorded "skin" temperature of wett and dry shoulder-blade and thigh, during ventilation and/or perspiration.
The measurements prove that it is possible, with a ventilated seat, to remove the surplus heat from part of the body (thigh, buttocks and back), which is very difficult to remove with a normal car seat. Especially when a car has been left standing in the sun and the driver therefore is perspiring the seat will be efficient. The differences between the wool and the polyester cover of the seat are only small and can be adjusted by a correct choice of ventilation.
8. References
Bischof, W., Madsen, T.L. and Banhidi, L., 1991. Physiological adaptation of thermal manikins. ICHES'91. Interna-
258
T.L. Madsen / International Journal of lndustrial Ergonomics 13 (1994) 253-258
tional Conference on Human-Environment System, December 1991, Tokyo. Madsen, T.L., 1976. Description of thermal manikin for measuring the thermal insulation values of clothing. Thermal Insulation Laboratory Report No. 48, 16 pp. Madsen, T.L. and Olesen, B.W., 1986. A new method for
evaluation of the thermal environment in automotive vehicles. A S H R A E Transactions, Vol. 92, Part 1B, pp. 38-54. Tanabe, S., Arens, E.A., Bauman, F.S., Z~ing, H. and Madsen, T.L., 1994. Evaluation of thermal environments with a skin surface temperature controlled thermal manikin. (For presentation at the A S H R A E Meeting in New Orleans 1994.)
ELSEVIER
Case study
Thermal effects of ventilated car seats Thomas Lund Madsen Thermal Insulation Laboratory, Technical University of Denmark, Building 118, DK-2800 Lyngby, Denmark (Received June 15, 1993; accepted in revised form December 2, 1993)
Abstract
In this paper a description is given of a new car seat designed for increased thermal comfort on hot summer days. The seat is supplied with a simple ventilating system blowing air from the bottom of the car through the seat and the back towards the person in the seat. The seat has been tested with a thermal manikin in order to find the cooling efficiency on the dry heat loss as well as the latent heat loss from a person seated in the seat. The test result is, that the ventilating system with an air flow of 2 l per sec has a significant influence on the dry heat loss, but mainly on the latent heat loss. Relevance to industry This car seat can be a c h e a p and effective solution decreasing discomfort after start in an o v e r h e a t e d car p a r k e d in the sun. In the winter, the system may d e c r e a s e the time of discomfort after start with electrical h e a t i n g e l e m e n t s in the seat and back.
Key words." Air flow; Automotive; Comfort; Ventilation; Cooling
1. Introduction It is a well-known fact that it is very u n c o m fortable to e n t e r a car which has b e e n p a r k e d in the sun on a hot s u m m e r day. Even in c o u n t r i e s where air c o n d i t i o n i n g in cars is u n c o m m o n , the seat is very w a r m a n d has a high i n s u l a t i o n value. W h e n these two items are p u t t o g e t h e r it causes a high degree of t h e r m a l discomfort for the body, in general, a n d for thigh a n d back in particular. O n e solution to r e d u c e the time s p e n t with a high degree of discomfort can be v e n t i l a t i o n of the car seat. A v e n t i l a t e d car seat of this kind has b e e n
developed by m e a n s of a special polyester fiber m a t e r i a l by a D a n i s h firm.
2. Description of the ventilating system T h e o u t e r 30 m m of the seat a n d back consists of pigs' bristles, which gives a good d i s t r i b u t i o n of the air; the back a n d u n d e r part of the seat is covered with an airtight lining with a t u b e which is c o n n e c t e d to a fan. Two types of covering are tested, o n e m a d e of wool a n d a n o t h e r of polyester fibres. In this simple way it is possible to create
0169-8141/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved SSDI 0 1 6 9 - 8 1 4 1 ( 9 3 ) E 0 0 8 0 - 8
254
T.L. Madsen / International Journal of Industrial Ergonomics 13 (1994) 253-258 polyester cover.
mm layer of pigs bristles Jbe for ventilation
The manikin is divided in 16 sections each with its own control system. This control system is designed to simulate the h u m a n skin t e m p e r a t u r e regulation in thermal comfort. The relation between the surface t e m p e r a t u r e of each section and the heat loss is given by Eq. 1.
tskin = 36.4 - 0.054"
Fig. 1. Car seat.
an air m o v e m e n t from the seat and back against the person who is sitting in the seat. T h e fan speed can be controlled to o p t i m u m comfort (Fig. 1).
3. Test method The efficiency of this simple system has been tested with a thermal manikin (Madsen, 1976; M a d s e n and Olesen, 1986) supplied with heat flux meters on the shoulder-blades and on the left and right thigh, which are the parts touching the seat when the manikin is seated.
d)d~
( 1)
where tskin is the mean surface t e m p e r a t u r e in °C and 4~d~y is the dry heat loss in W / m 2. The manikin's heating system consists of nickelwire w o u n d a r o u n d each section and interspaced by less than 2 mm. This establishes an extremely even distribution of heat from each section. It is possible to make a record of the heat loss and the surface t e m p e r a t u r e from each of the 16 sections every 30 seconds. A n area weighed m e a n of the total dry heat loss from the manikin is calculated as well (Bischof et al., 1991; T a n a b e et al., 1994). Finally, it is possible to make a record of the difference between the area weighed m e a n heat loss from two selected groups of sections, e.g. to c o m p a r e the left leg and arm with the right leg and arm in an asymmetric temperature field. The manikin was clothed in a suit with an insulation value of 0.6 clo and placed in the car seat in a climatic c h a m b e r with a constant room t e m p e r a t u r e and a constant relative humidity.
tair= tmrt = 20°C,
c < 0.1 m / s , R H = 55%
Fig. 2. Thermal manikin with heat flux meters, temperature sensors and "sweat gland" on shoulder-blade.
T.L. Madsen / International Journal of Industrial Ergonomics 13 (1994) 253-258
Heatloss in percent. 350 300 250 200 150 100 50
0
0
6.8
10.1
14.4
21.0
Ventilation rate (m3/h)
• Heatloss from back [ ] Heatloss from Thigh Fig. 3. Correlation between heat loss and ventilation rate.
The test seat was equipped with a centrifugal fan with variable speed. The amount of room air introduced to the seat was measured by a gasmeter.
4. Measurement Two car seats were tested; the only difference was that one seat had a wool cover and the other a polyester cover. During all tests the thermal manikin (weight: 35 kg) was seated as a normal person in the test seat. The heat loss variation was measured by four heat flux meters, two on the back (Fig. 2), and one between each thigh and the car seat. The correlation between the ventilation rate and heat loss for the back and thigh measured by heat flux meters in direct contact with the car seat is given in Fig. 3. It is seen that only a small increase is obtained for ventilation rates higher than 7 m 3 / h ~ 2 l/see. This rate of ventilation is used for the investigation.
4.1. Measurement of dry- and latent heat loss In order to have an idea of the increase of the latent heat loss caused by ventilation, the thermal manikin is equipped with two "sweat glands" (Fig. 2), one on one of the shoulder-blades and the other under one of the thighs where they are in contact with the car seat. The "sweat glands" consist of two small capillary tubes connected to two small pumps with a capacity of 15 m l / h ensuring 0.025 m 2 of wetted area under the cloth-
255
ing for each tube. 60, 120 and 180 ml per m 2 are added per hour if the pumps are running 10, 20 or 30 percent of the time. The running frequency is 2 min. To be able to measure the influence of the humidification on heat loss and skin temperature a heat flux sensor and a temperature sensor have been installed on each shoulder-blade, one set close to the "sweat gland". Heat flux meters and temperature sensors have also been placed between the thigh and the seat. Under one thigh the sensors are placed close to the second "sweat gland". The reason for using this method and not the usual measurement of area weighed mean of each section is that only a small part of the thigh and maybe 50% of the back section of the manikin is in direct contact with the car seat. It is now possible to compare "skin" temperature and heat loss from the dry and the humidified area of the back as well as of the thigh. All measurements are recorded each minute by a 12-bit datalogger. During all the tests the ventilation rate was 2 1/see, and the perspiration was 60, 120 or 180 m l / m 2 per hour.
5. Measuring results The increase of the heat loss for sweat rates of 60, 120 and 180 m l / m 2 per hour in the wool seat for back as well as for thigh is shown in Fig. 4. In Fig. 5 a comparison is given between the wool and the polyester seat for back as well as for thigh. This comparison shows the increase of the heat loss for ventilation only, sweating only and ventilation + sweating. Fig. 6 shows the recording of the skin temperature at the dry and wetted shoulder-blade and thigh.
6. Evaluation of the measuring results
6.1. Back The increased heat loss by humidification is almost independent of the added amount of wa-
T.L. Madsen / International Journal of lndustrial Ergonomics 13 (1994) 253-258
256
Increase of heatloss (percent)
BACK.
350 f 300 250 200
6.2. Thigh
150 100 50 60
120
180
Increase of heatloss (percent) THIGH.
200 150 100
0
crease of temperature can be seen from Fig. 6. This figure shows the surface temperature of the two shoulder-blades by a humidification of 120 ml/mZh.
6O
120
The two thighs are two separately independent sections of the thermal manikin. Fig. 6 shows the temperature variation between thigh and seat during a test (120 m l / m 2 h ) . It can be seen that the temperature of the dry thigh only varies when the ventilation is started. From Fig. 5 it can be seen that the increase of the heat loss by ventilation both with and without humidification is smaller for the thigh than for the back but the temperature decrease is biggest for the thigh. One reason for this discrepancy can be that only a small part of the total area of the thigh is in direct contact with the insulated seat.
180
Sweat rate (ml/m*m pr. hour)
• ventilation [ ] sweating [ ] ventilation +sweating Fig. 4. Correlation between perspiration (sweat rate) and heat loss from back and thigh. Wool Seat.
Increase of heat loss (percent).
BACK.
350 I 3001 250"
F i
200
ter, which is due to the fact that already at 60 m l / m 2 h , the area round the measuring point will be wet. When the ventilation is started the heat loss from the moist area will be about doubled. A very strong cooling will, consequently, arise maybe too strong. A comparison between the wool and the polyester seat (Fig. 7) shows that the polyester seat gives a stronger cooling than the wool seat; the reason may be that for the chosen voltage to the ventilator (110 V) corresponding to 2 1/sec through the wool seat, a little more air than 2 l / s e c will pass through the polyester seat than through the wool seat. As all the back makes one section of the thermal manikin, a local cooling of part of this section will give an increased voltage to the hot wires, which are equally interspaced over all the surface, and the temperature of the dry part of the back will therefore be increased. This in-
150 100 50 0
Wool seat
Polyester seat
Increase in heat loss (percent).
THIGH.
350 I 300 / 250] 200 / 150 100 50 0
Wool seat
Polyester seat
• ventilation only [ ] sweating only [ ] ventilation + sweating
Fig. 5. Comparison of the increase of heat loss from back and thigh when using wool or polyester seat.
257
T.L. Madsen / International Journal of lndustrial Ergonomics 13 (1994) 253-258
On Fig. 6 it can be seen that the skin temperature between thigh and seat without ventilation and humidification is 40°C, on the back it is only 33°C. When the ventilation starts the temperature decrease will be bigger between the thigh and the seat than between the back and the seat. The heat loss from the thigh, which was high without ventilation because of the high temperature, will be increased with a smaller percentage than the back. This example shows the limitation of the thermal manikin, and it indicates that the result from the back is best correlated to the human situation. The main result of the investigation can be seen from Fig. 7. For each seat, calculations have been made of the mean heat loss and temperature fall on the basis of two "sweat glands" located at two different places (back and thigh). This comparison shows no significant difference between the two seats of the ability to remove the
Increase of heatloss in percent. 300 250 200 150 100 50 0
Wool
Polyester
temperature decrease (C). 0
-6 -8 -10
WOOL
POLYESTER
• ventilation D sweating [ ] ventilation+sweating
Fig. 7. Increase of heat loss and decrease of "skin" temperature during ventilation and/or perspiration for wool and polyester seat. Mean of back and thigh and mean of 60, 120 and 180 ml/m 2 per hour sweat rate. Ventilation: 2 l/see.
°C 35 ---'¢-'-"'-----~'~"~ DRY SHOULDERBLADE k.,___.,_. . . . . . . .
surplus heat. Ventilation of the polyester seat causes a little higher increase of the heat loss and consequently also a little higher decrease of the "skin" temperature of the person in the seat.
30 BACK 25 VENTILATION
.
PERSPI
20
*C
. . . . . . .
7
0 . . . . .
-- . . . . .
......
r
5
7. C o n c l u s i o n
ON
10
1'5
2; hour
"7
40
DRY THIGH
x
30
WEATINGTHI i\
20 ~
10
~
THIGH
~ VENTliATIO N PERSPIRATION - -
L
V
~
I
[~P
0 5 10 15 20 hour Fig. 6. Recorded "skin" temperature of wett and dry shoulder-blade and thigh, during ventilation and/or perspiration.
The measurements prove that it is possible, with a ventilated seat, to remove the surplus heat from part of the body (thigh, buttocks and back), which is very difficult to remove with a normal car seat. Especially when a car has been left standing in the sun and the driver therefore is perspiring the seat will be efficient. The differences between the wool and the polyester cover of the seat are only small and can be adjusted by a correct choice of ventilation.
8. References
Bischof, W., Madsen, T.L. and Banhidi, L., 1991. Physiological adaptation of thermal manikins. ICHES'91. Interna-
258
T.L. Madsen / International Journal of lndustrial Ergonomics 13 (1994) 253-258
tional Conference on Human-Environment System, December 1991, Tokyo. Madsen, T.L., 1976. Description of thermal manikin for measuring the thermal insulation values of clothing. Thermal Insulation Laboratory Report No. 48, 16 pp. Madsen, T.L. and Olesen, B.W., 1986. A new method for
evaluation of the thermal environment in automotive vehicles. A S H R A E Transactions, Vol. 92, Part 1B, pp. 38-54. Tanabe, S., Arens, E.A., Bauman, F.S., Z~ing, H. and Madsen, T.L., 1994. Evaluation of thermal environments with a skin surface temperature controlled thermal manikin. (For presentation at the A S H R A E Meeting in New Orleans 1994.)