Comparison of clothing thermal comfort properties measured on female and male sweating manikins

Abstract

Thermal manikins simulating human body’s thermal regulatory system are essential tools for understanding the heat exchange between human body and the environment and also for evaluating the thermal comfort of clothing and near environment. However, most existing thermal manikins adopt a male’s body shape and no sweating female thermal manikin has been reported so far. Furthermore, it is unclear how body shape (viz. male vs female) affects the heat loss and perspiration from the body. We report on a novel female sweating thermal manikin “Wenda”. Thermal properties of the nude body and clothing ensembles measured on “Wenda” are compared with those measured on the male manikin “Walter”. It was found that, although the more curvaceous female body reduces the thermal insulation of the nude manikin, it increases the apparent evaporative resistance at the same time. This may be due to the fact that the more curvaceous female body increases the surface still air layer to add resistance to heat loss by conduction and evaporative water loss by diffusion, and significantly increases the percentage of effective radiative area and the resultant radiative heat loss per unit surface area. It was further shown that clothing thermal insulation and apparent evaporative resistance measured on Wenda are typically 0 ∼ 11% higher than those measured on the male sweating fabric manikin-Walter, probably due to the greater clothing microclimate volume on the female manikin resulting from the looser fitting of the garments on the smaller female body and the more curvaceous surface of the female body.

Keywords

apparent evaporative resistance clothing area factor clothing thermal properties female sweating thermal manikin thermal insulation

Thermal manikins are essential tools for understanding the heat exchange between human body and environment and the objective evaluation of thermal comfort of clothing and near environment. The use of thermal manikins makes it possible to accurately determine the heat exchange between the human body and its environment, from which the thermal comfort of the human subject in the environment can be predicted based on human physiology.

The development of thermal manikins started in early 1940s at the US ARMY Research Center after realizing the importance of thermal protection of soldiers in the battlefields from casualties in the Second World War.¹ The first heated manikin for military was built by Harwood Belding in 1942, which was an armless and headless manikin. Under the request of the US Army, a one-segment electroplated copper shell thermal manikin-“Harvard Copper Man” was constructed in 1943 by General Electric. The thermal manikin technology was later further improved by General Electric based on past expertise and the anthropometric study of nearly 3000 Army/Air Force personnel, and as a result, a six-segment thermal manikin-“Copper Man” was built for the Climate Research Laboratory in 1946.²

In the earlier years, thermal manikins were mainly used to evaluate military protective clothing, but they are now also widely used for civilian applications, such as evaluating the indoor environment, work wear and sportswear, etc. There are more than 100 thermal manikins in use worldwide.^3,4

Thermal manikins may be grouped into four generations. The first generation were standing (viz. not walkable) and non-perspiring ones.^5–7 The second were movable (viz. walkable), but non-perspiring ones such as the copper manikin “Charlie” in Germany⁸ and those in Denmark⁹ and Japan.¹⁰ With these non-perspiring manikins, past workers tried to simulate sweating by covering it with highly absorbent underwear and supplied water to it by sprinkling or water pipes.¹¹ The third generation was manikins which simulate perspiration, but no body motion. They include “Taro” developed in Japan by Yasuhiko et al. in 1992.¹² The fourth or latest generations of thermal manikins are the ones which can simulate both perspiration and body motion, which include, “Newton” from USA, “Coppelius” in Finland,¹³ “Sam” in Switzerland,¹⁴ “Kem” in Japan¹⁵ and “Walter” from Hong Kong.^16,17

Most existing thermal manikins are in male body shape with a few exceptions. The first female thermal manikin, nicknamed “Nille”, was developed at Danish Technical University in 1989.³ It was made of plastic and divided into multiple segments with individual temperature control. This female manikin had an additional function: the simulation of breathing, which was useful for indoor quality evaluation. Silva and Coelho¹⁸ later developed a female thermal manikin, nicknamed ‘Maria’, made up of fiberglass and polyester shell covered with a nickel wire wound around the body. Konarska et al.^19,20 developed a 16-segment female thermal manikin-“Diana” and used it measure clothing thermal insulation. Existing female thermal manikins, however, cannot simulate perspiration, which is critical to thermal comfort.

So far, male body sweating thermal manikins have been used to evaluate the thermal comfort of women’s clothing, however, such results may be misleading as differences between the male and female body shape may result in significant differences in thermal response and sweating accumulation. The development of a female sweating thermal manikin is essential to thermal comfort evaluation. The recently developed, male body shaped, sweating fabric manikin, “Walter”, provided a novel technique of accurately measuring the sensible and latent heat loss, and hence clothing thermal insulation and apparent evaporative resistance in one step. In the present work, the concept of sweating manikin-“Walter” is applied to build a female-body shaped sweating manikin, nicknamed-“Wenda”. The differences in terms of the sensible and latent heat loss from the manikins as well as the clothing thermal insulation and apparent evaporative resistance caused by the shape difference between the male and female manikins are investigated.

Method

Construction of female sweating fabric manikin-“Wenda”

The newly developed female sweating fabric manikin-“Wenda” is shown in Figure 1 and its body dimensions and weight are listed in Table 1. It resembles a medium-sized Chinese female adult with a B cup breast size, a waist-to-hip ratio (WHR) of 0.75 and a Body Mass Index (BMI) of 19.7. The body surface area of “Wenda” is 1.5 m², which is about the surface area of a real woman with a height of 164 cm and a weight of 53.2 kg.²¹

Figure 1.

Female sweating fabric manikin-“Wenda”. (a): The female sweating fabric manikin measurement system (b): The locations of 15 temperature sensors (c): The photographs of female sweating fabric manikin-“Wenda”.

Table 1.

Comparison of body dimensions and weight of female manikin-“Wenda” and male manikin-“Walter”

Body Dimension	Female Wenda	Male Walter
Height	164 cm	172 cm
Shoulder	40 cm	45 cm
Bust Girth (BL)	89 cm	95 cm
Under Bust Girth (UBL)	75.5 cm	95 cm
Waist Girth (WL)	67 cm	89 cm
Hip Girth (HL)	89.5 cm	100 cm
Weight	53 kg	75 kg

Like the male-body sweating manikin-“Walter”, the skin of “Wenda” was made by a waterproof but moisture permeable fabric to simulate perspiration, similar to the fabric used for male manikin-Walter. This fabric skin is a three-layer laminated fabric, consisting of a strong nylon woven fabric as the outer layer, a tricot knitted nylon backing fabric as the inner layer and a middle layer of a microporous polyteyrafluoroethene (PTFE) Gore-Tex membrane, which has about 1.4 billion tiny pores every square centimeter. The pore size of the Gore-Tex membrane is up to 200 nm, which is about 20,000 times smaller than a typical droplet of liquid water, but about 700 times larger than a vapor molecule. Therefore, the membrane pores are too small for liquid water to pass through, but are large enough to allow water vapor transmission.^10,22 In order to create the curvaceous female body shape, the fabric skin was composed of multiple uniquely shaped pattern pieces as shown in Figure 2.

Figure 2.

The block patterns of the female manikin skin.

Just as the male-body sweating manikin-“Walter”, the female manikin is filled up with water (DI Water) and its skin temperature is controlled at 35℃. Warm water is pumped from the core to the extremities (i.e. head, arms and legs). By regulating the pumping rate, a temperature distribution similar to a real person under varying levels of activity and environmental conditions can be simulated.

Two heaters (220 V, 750 W) were fixed at the center of the body to heat up the water within the manikin. Four pumps (24 V, 3 A) were mounted within the manikin body, one to supply warm water to the head, one to supply warm water to the arms and two to supply warm water to the legs.

The area-weighted mean temperature was calculated based on local skin temperatures of the 15 divided skin areas,^23–25 which were measured by 15 temperature sensors (RS, Platinum Sensing Resistor-Pt100, UK) attached on the manikin’s skin surface by elastic band. Figure 1(b) shows the locations of 15 temperature sensors. Surface area ratios of divided sections are shown in Table 2.

Table 2.

Surface area and area weighting of divided sections of female and male manikins and sensors locations

	Female manikin-Wenda		Male manikin-Walter
Locations	Surface area (m²)	Area weighting (%)	Surface area (m²)	Area weighting (%)	Temperature sensor
Head	0.154	10.28	0.215	12	T1
Chest	0.148	9.86	0.163	9.12	T2
Back	0.142	9.44	0.170	9.50	T2
Tummy	0.131	8.75	0.107	6.01	T4
Hip	0.128	8.54	0.114	6.37	T5
Left upper arm	0.077	5.14	0.088	4.93	T6
Right upper arm	0.073	4.86	0.088	4.93	T7
Left lower arm	0.051	3.40	0.059	3.30	T8
Right lower arm	0.054	3.61	0.059	3.30	T9
Left thigh-front	0.078	5.21	0.166	8.71	T10
Left thigh-back	0.091	6.04	0.083	4.35	T11
Right thigh-front	0.078	5.21	0.166	8.71	T12
Right thigh-back	0.091	6.04	0.083	4.35	T13
Left calf	0.102	6.81	0.113	6.33	T14
Right calf	0.102	6.81	0.113	6.33	T15
Total	1.500	100	1.790	100	15 sensors

The water within the manikin is compensated through a real-time automatic water supply system.^17,26 The perspiration rate of the manikin was measured in real time by monitoring the water loss of a small container connected to the manikin body through a siphon. The measurement and control system of the female manikin-Wenda, used for recording measurement data and regulating the heating and pumping rate, is the same as that of the male sweating fabric manikin-Walter.

Determination of thermal insulation and apparent evaporative resistance using the female manikin

The thermal insulation of the naked manikin or a garment ensemble (I_t) is determined using the following formula¹⁶

I_{t} = \frac{A_{s} (T_{s} - T_{e})}{H_{d}} (\circ Cm 2 W - 1)

(1)

where A_s is the total surface area of the manikin, which is 1.50 m² compared to 1.79 m² for the male manikin; T_s is the areas weighted mean temperature (℃); T_e is the environment temperature (℃); and H_d is the dry heat loss of the manikin (Watts).

The dry heat loss of the manikin (H_d) can be determined by

H_{d} = H_{s} + H_{p} - H_{e} - H_{a}

(2)

H_{e} = Q λ

(3)

where H_s is the power of heaters (W); H_p is the power consumption of pumps (W). As the pumps are totally immersed into water, the influence of them on the external environment of the manikin is slight. All power input to the pumps is assumed to be converted to heat energy.¹⁰ H_e is the evaporative heat loss of the manikin (W); H_a is the power consumed for heating the supplied water to the manikin body temperature (W); Q is the water loss per hour (g h⁻¹); λ is the heat of evaporation of water at the skin temperature (W h g⁻¹), which is equal to 0.67 W g⁻¹.

The mean skin temperature is the area-weighting average temperature of all divided skin sections. The area-weighting mean skin temperature (T_s) is calculated by using the following formula

T_{s} = \sum_{i}^{n} A_{i} T_{si}

(4)

where A_i is the area percentage of a division of manikin skin surface, which for the developed female manikin is shown in Table 2; T_si is the temperature of a division of the manikin surface area (℃).

The apparent evaporative resistance of the clothing (R_e) is calculated by

R_{e} = \frac{A_{s} (P_{SS} - P_{as} {RH}_{a})}{H_{e}} - R_{es} (P_{a} m 2 W - 1)

(5)

where A_s is the surface area of the manikin (1.5 m² for female manikin; 1.79 m² for male manikin); P_ss is the saturated vapor pressure at the skin temperature (P_a); P_as is the saturated vapor pressure at the ambient temperature (P_a) and RH_a is the ambient relative humidity (%); H_e is the evaporative heat loss (W); R_es is the apparent evaporative resistance of the skin which was calibrated in advance by conducting nude test under various air velocity conditions. It was determined as 8.60 P_am²W⁻¹ for male manikin.^25,27

To determine the apparent evaporative resistance of the skin of the female manikin (R_es), we conducted the experiments of nude female manikin under different windy conditions (viz. 0.22, 1, 2, 5 and 6 m/s). Figure 3(a) plots the total apparent evaporative resistance (including the resistance of the manikin skin and surface air layer) against the air velocity. The trend can be fitted with an exponential curve. As shown in Figure 3(b), it can be extrapolated that, when the air velocity is infinite (corresponding to a zero resistance of surface air layer), the total apparent evaporative resistance, which is the apparent evaporative resistance of the female manikin skin (R_es), is 8.2 P_a m² W⁻¹.

Figure 3.

The experiments of nude female manikin under different windy conditions. (a): The apparent evaporative resistance of nude female manikin under various air velocities. (b): The change of the thickness of the surface air layer under different air velocities.

Comparison of measurements made on male and female sweating manikins

Five clothing ensembles were tested on the male manikin-Walter and the new developed female manikin-Wenda. Table 3 describes the details of clothing ensembles. All tests were carried out in a climatic chamber with the temperature controlled at 20 ± 0.5℃, relative humidity at 50 ± 3% and air velocity at 0.2 ± 0.1 m s⁻¹. The mean skin temperature of the manikins was set at 35℃. Before testing, all samples were conditioned in the chamber for at least 24 hours. All tests were repeated three times, the garment samples were put off and on again between repetitions.

Table 3.

The specification of five clothing ensembles

Clothing ensemble	Garment	Content	Mass (g)
A	Short sleeves polo shirt	100% polyester	209.78
	Underpants	100% cotton	18.75
	Short pants	100% polyester	149.93
B	Long sleeves T-shirt	100% cotton	206.6
	Underpants	100% cotton	18.75
	Trousers	100% cotton	458.54
C	Long sleeves T-shirt	100% cotton	206.6
	Underpants	100% cotton	18.75
	Trousers	100% cotton	458.54
	Jacket	Shell 100% nylon; lining 100% polyester	342.47
D	Suit	100% polyester	265.44
	Vest	100% cotton	96.54
	Underpants	100% cotton	18.75
	Trousers	100% cotton	458.54
E	Hoodies	100% cotton	477.98
	Vest	100% cotton	96.54
	Underpants	100% cotton	18.75
	Cropped trousers	100% cotton	213.14

Clothing area factor (f_cl), closely related to clothing fit,²⁸ design and thickness, may play an important role in the heat exchange between the clothed body and the surrounding environment. The photographic method was used to measure the clothing area factors of the five clothing ensembles.^29,30 Clothing area factor (f_cl) is determined using the following formula

f_{cl} = \frac{A_{cl}}{A}

(6)

where A_cl is the surface area of the clothed manikin; A is the surface area of the nude manikin. Three photographs were taken for each clothing ensemble and the garments were lifted to re-drape before taking new photographs.

Statistical analysis

All the statistical data analyses were carried out with SPSS (IBM SPSS Statistics, v.19.0, IBM, US). Independent-Samples T Test was carried out to compare the clothing thermal insulation and evaporative resistance on Walter and Wenda. Regression analysis was employed to examine the relationship between thermal insulation/apparent evaporative resistance and clothing area factor. All the statistical analyses were performed at a level of 95% statistical significance.

Results and discussion

Heat loss, thermal insulation and clothing area factor

Table 4 compares the dry heat loss (H_d), thermal insulations (I_t) and clothing area factors (f_cl) of the male manikin-Walter and female manikin-Wenda when in nude or covered with one of the five clothing ensembles. As can be seen, the coefficients of variance of I_t values are below 4%, meeting the requirement of ASTM F1291-15. It is also seen that, the surface thermal insulation of nude female manikin is 0.074℃ m² W⁻¹, which is 11.9% lower (p = 0.009) than that of the male manikin (0.084℃ m² W⁻¹). I_t values of nude female manikin-Wenda and male manikin-Walter are within the range of the I_t values of those nude thermal manikins (from 0.051 to 0.104℃ m² W⁻¹) located in different laboratories in the world³¹. The variation is caused by differences in the body shape of the thermal manikins as well as differences in environmental conditions. Since the surface insulation of the nude Wenda and Walter were measured under the same environmental condition, the difference is most likely caused by the differences in body shape. With the more curvaceous body surface of the female manikin, the percentage of the chest and bottom area over the entire body surface area is increased and that of the side body area shaded by the arms is reduced, leading to greater percentage of effective radiative area and increased radiative heat loss. This finding is in contrast to what is reported by Kuklane et al.,³² who found no significant difference between a non-sweating female and male manikin in surface insulation. Perhaps this is because the differences in body shape between the female and male manikin in Kuklane et al.’s work is not as much as that in our current study.

Table 4.

Dry heat loss (H_d), thermal insulations (I_t) and clothing area factors (f_cl) of the male manikin-Walter and female manikin-Wenda when in nude and covered with one of the five clothing ensembles

Sample	Female manikin – Wenda						Male manikin – Walter
	I_t	SD	CV	H_d	SD	f _cl	I_t	SD	CV	H_d	SD	f _cl
	(℃m² W⁻¹)	SD	CV	(W)	SD	f _cl	(℃m² W⁻¹)	SD	CV	(W)	SD	f _cl
Nude	0.074	0.002	2.82	284.2	8.41	–	0.084	0.002	2.38	290.8	7.72	–
A	0.113	0.004	3.67	183.9	6.19	1.14	0.106	0.001	0.94	229.8	2.41	1.09
B	0.152	0.001	0.49	137.2	0.8	1.25	0.136	0.002	1.17	181.2	4.13	1.14
C	0.203	0.002	0.7	105.5	4.56	1.38	0.177	0.002	1.2	139.6	1.35	1.23
D	0.160	0.002	1.3	131.6	3.02	1.29	0.146	0.001	0.68	168.6	0.63	1.16
E	0.139	0.004	2.69	148.5	4.11	1.13	0.122	0.002	1.63	199.3	2.75	1.09

It can be seen from Table 4 that the same clothing ensemble tested on the female manikin-Wenda has relatively greater thermal insulation and Clothing Area Factor than that tested on the male manikin-Walter. The differences are statistically significant (B: p = 0.001; C: p < 0.001; D: p = 0.02; E: p = 0.008) except for ensemble A. This finding is consistent with what is reported by Kuklane et al.³² The increase in thermal insulation on the female manikin may be caused by the fact that the body of the female manikin is more curvaceous and smaller in size, creating greater air gap or microclimate volume between the body and clothing.

The differences in I_t between the manikins were 11.6% for B, 14.6% for C, 9.7% for D and 14.2% for E, respectively. On the other hand, the difference for clothing ensemble A is not significant (p = 0.102). This could be due to the fact that the fitting of ensemble A on the female manikin is very loose, causing natural convection within the air gap. So, the increase in insulation due to increased air gap is off-set by the reduction due to natural convection. Spencer-Smith³³ mentioned that natural convection is predicted to occur as the air gap thickness exceeds 8 mm.

Water loss (perspiration rate) and apparent evaporative resistance

Table 5 presents the water loss and apparent evaporative resistance (R_e) of the male manikin-Walter and female manikin-Wenda when in nude and covered with one of the five clothing ensembles. The coefficients of variance are below 4%, lower than the 5% accepted by the ASTM F 2370-15 for tests using sweat manikin in a single lab. The R_e values of the nude male manikin-Walter and female manikin-Wenda are within the range of R_e values (from 11.0 to 20.0 P_a m² W⁻¹) measured on nude sweating manikins located in different laboratories in the world.³¹ The apparent evaporative resistance value of nude female Wenda is 12.6 P_a m² W⁻¹, which is just slightly (∼3.7%, statistically significant at p = 0.003) higher than that of the male manikin-Walter. The increase in apparent evaporative resistance may be caused by the greater surface air layer on the more curvaceous female body surface. It is interesting to note that the thermal insulation of the nude female manikin is lower than that of the male manikin, while the opposite is true for the apparent evaporative resistance. This may be explained by the fact that, although the greater surface air layer on the more curvaceous female body surface reduces heat loss by conduction and convection, and evaporative water loss by diffusion and convection, the more curvaceous body surface of the female manikin increases heat loss by radiation. For the more curvaceous female body, the percentage of the chest and bottom area over the entire body surface area is increased and that of the side body area shaded by the arms is reduced, leading to greater percentage of effective radiative area and radiative heat loss.

Table 5.

The apparent evaporative resistance (R_e) and water loss of the male manikin-Walter and female manikin-Wenda when in nude and covered with one of the five clothing ensembles

Sample	Female manikin-Wenda					Male manikin-Walter
Sample	R_e (P_a m² W⁻¹)	SD	CV	Water loss (g h⁻¹)	SD	R_e (P_a m² W⁻¹)	SD	CV	Water loss (g h⁻¹)	SD
Nude	12.60	0.09	0.69	438.1	4.0	12.14	0.06	0.49	555.0	2.2
A	19.32	0.62	3.29	341.8	7.5	18.37	0.13	0.71	438.3	2.4
B	26.58	0.40	1.56	277.6	3.4	24.21	0.38	1.57	348.0	3.7
C	36.66	0.49	1.44	218.5	2.5	35.45	0.26	0.72	257.8	1.5
D	30.39	0.76	2.58	251.2	6.7	26.52	0.72	2.70	324.7	3.5
E	26.12	0.35	1.36	280.4	4.5	22.89	0.16	0.72	363.0	1.6

Independent-Samples T Test results show that all five clothing ensembles have significantly different (A: p = 0.007; B: p = 0.005; C: p = 0.048; D: p = 0.006; E: p = 0.001) R_e values measured on the female and male manikins. With increasing weight of the clothing ensembles, the R_e values measured on the female and male manikins tends to be greater with exceptions depending on garment design and construction.

The perspiration rate (or water loss) of nude female manikin-Wenda is 18% less than that of the nude male manikin-Walter, which is mainly caused by the difference in the surface area of the two manikins. The surface area of the female manikin-Wenda and that of the male manikin-Walter are 1.50 and 1.79 m², respectively. This is consistent with those of real persons as reported by Bar-Or³⁴ and Havenith et al.³⁵ The perspiration rates of nude male and female manikins are 310 g m²h⁻¹ and 304 g m²h⁻¹, which are approximately to the perspiration rate of real persons doing moderate activity (e.g. walking at a speed of 5 km h⁻¹ to 6 km h⁻¹) based on ISO standards.^36,37

Relationship between thermal insulation/apparent evaporative resistance and clothing area factor

Since both clothing thermal insulation and clothing area factor relate to the air gaps between the body and clothing as well as the air gaps between the clothing layers, clothing thermal insulation and clothing area factor is related. As Figure 4 shows, for the female manikin-Wenda, the following relationship exists

I_{t - Wenda} = 0.291 \cdot f_{cl - Wenda} - 0.207 (R 2 = 0.863, p = 0.023)

(7)

Figure 4.

Relationship between clothing area factor (f_cl) and thermal insulation (I_t).

For the male manikin-Walter, the following relationship can be found

I_{t - Walter} = 0.451 \cdot f_{cl - Walter} - 0.377 (R 2 = 0.955, p = 0.004)

(8)

The relationships described in equations (7) and (8) are only approximate. They may be used as approximate estimation when either the female or male manikin is available, but the thermal insulation or apparent evaporative resistance on the other gender type should be estimated.

There is also an approximately linear relationship between the apparent evaporative resistance and clothing area factor for the male and female manikin, respectively. As Figure 5 plots, the apparent evaporative resistance measured on the female manikin-Wenda is related to the clothing area factor by

R_{e - Wenda} = 53.989 \cdot f_{cl - Wenda} - 39.025 (R 2 = 0.8, p = 0.041)

(9)

R_{e - Walter} = 104.082 \cdot f_{cl - Walter} - 93.373 (R 2 = 0.916, p = 0.011)

(10)

Figure 5.

Relationship between clothing area factor (f_cl) and apparent evaporative resistance (R_e).

It can be seen from the above relationships that the thermal insulation or apparent evaporative resistance increases with clothing area factor regardless of manikin shape. But the slope of increase is more gradual for the female manikin. Clothing ensemble A and E have a similar f_cl value, however I_t and R_e value of clothing ensemble E are 24.6% and 34.8% higher than those of ensemble A tested on the male and female manikin, respectively, which can be attributed to the differences in fabric property and the multilayer construction of the clothing ensemble. Clothing ensemble A includes a polo shirt and sport short pants made of 100% polyester, which is light and thin, while clothing ensemble E is composed of 100% cotton hoodies and cropped trousers, together with an extra vest. The mass of ensemble E is about double of that of ensemble A. It must be noted that equations (7) to (10) were based approximate trends found among the five typical clothing ensembles, further investigations involving more varieties of clothing ensembles are required to establish such relationships of broader applicability.

Conclusions

We have demonstrated that the newly developed female sweating manikin-Wenda can provide reproducible measurements of the thermal insulation and apparent evaporative resistance of clothing ensembles. The repeatability of the measurements meets with the respective standard requirements.

It is interesting to find that, in comparison with the male body, the naked female body has lower surface insulation, but higher surface apparent evaporative resistance. Reduced heat loss and perspiration from the more curvaceous female body surface may be understood by the increased surface air layer at female body surface, creating more resistance to heat loss by conduction and convection or evaporative water loss by diffusion and convection. However, heat loss from the more curvaceous female body is actually increased, which is probably due to the fact that, with the more curvaceous body surface of the female manikin, the percentage of the chest and bottom area over the entire body surface area is increased and that of the side body area shaded by the arms is reduced, leading to greater percentage of effective radiative area. It was also found that clothing area factor, thermal insulation and apparent evaporative resistance of the same clothing are greater on the female body than those on the male body, probably due to the greater clothing microclimate volume on the female manikin resulting from the looser fitting of the garments on the smaller female body and the more curvaceous surface of the female body.

For the five typical clothing ensembles tested, it was shown that, for a specific type of manikin, the thermal insulation and apparent evaporative resistance are almost linearly related to the clothing area factor, respectively. However, since these five clothing ensembles are only single or double layers and made of relatively permeable fabrics, such relationship may not apply to relatively heavy and impermeable clothing. Further tests should be carried out using the newly developed female manikin-Wenda for a wider range of clothing ensembles.

Footnotes

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors would like to thank the funding support of Hong Kong Research Grant Council through a GRF grant (PolyU515111) awarded to Professor Jintu Fan.

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