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European Journal of Applied Sciences – Vol. 11, No. 1

Publication Date: January 25, 2023

DOI:10.14738/aivp.111.13765.

Kurazumi, Y., Fukagawa, K. Sakoi, T., Yamashita, K., Naito, A. Imai, M., Yamato, Y., Kondo, E., & Tsuchikawa, T. (2023). Clothing

Thermal Insulation of Infant in Stroller Relating to Evaluation of Thermal Environment of Infant. European Journal of Applied

Sciences, 11(1). 42-59.

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Services for Science and Education – United Kingdom

Clothing Thermal Insulation of Infant in Stroller Relating to

Evaluation of Thermal Environment of Infant

Yoshihito Kurazumi

School of Life Studies, Sugiyama Jogakuen University, Nagoya, Japan

Kenta Fukagawa

Dept. of Environmental Science and Technology, Meijo University, Japan

Tomonori Sakoi

Dept. of Advanced Textile and Kansei Engineering, Shinshu University,

Ueda, Japan

Ken Yamashita

School of Life Studies, Sugiyama Jogakuen University, Nagoya, Japan

Akie Naito

Fac. of Human Life and Environmental Sciences, Ochanomizu University,

Tokyo, Japan

Motoe Imai

Graduate School of Life Studies, Sugiyama Jogakuen University, Nagoya, Japan

Yoshiaki Yamato

Dept. of Architecture and Structural Engineering, Kure National College of Technology,

Kure, Japan

Emi Kondo

Dept. of Comprehensive Engineering, Kindai University Technical College,

Nabari, Japan

Tadahiro Tsuchikawa

School of Human Science & Environment, University of Hyogo, Himeji, Japan

ABSTRACT

The clothing thermal insulation for individual clothing ensembles of infant and

strollers has been clarified. However, the clothing thermal insulation for the

combination of them has not been measured at all. The purpose of this study is to

examine the typical values of human factors such as the clothing area factor and

clothing thermal insulation of an infant in a stroller. As typical clothing ensembles,

seasonal combinations of infant clothing with a stroller were selected. The stroller

was treated as part of the infant’s clothing. The clothing area factors were measured

by using the photographic method. The clothing thermal insulations were

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Kurazumi, Y., Fukagawa, K. Sakoi, T., Yamashita, K., Naito, A. Imai, M., Yamato, Y., Kondo, E., & Tsuchikawa, T. (2023). Clothing Thermal Insulation

of Infant in Stroller Relating to Evaluation of Thermal Environment of Infant. European Journal of Applied Sciences, 11(1). 42-59.

URL: http://dx.doi.org/10.14738/aivp.111.13765

measured by using an infant’s thermal manikin. The typical clothing area factor of

an infant in a stroller is 3.67 for summer clothing, 3.75 for mid-season clothing, and

4.19 for winter clothing. The typical clothing thermal insulation of an infant in a

stroller is 1.23 clo for summer, 1.39 clo for mid-season, and 1.97 clo for winter. The

stroller was shown to significantly affect the body heat balance between the infant

and the thermal environment.

Keywords: Clothing area factor; Clothing thermal insulation; Infant; Stroller; Thermal

environment.

INTRODUCTION

Roads and public facilities are now being built on the Barrier-free. Therefore, in outdoor, the

usage of a stroller has been much easier. However, infants in strollers have become more

susceptible to short wavelength solar radiation and long wavelength thermal radiation.

Tsuchikawa et al. [1] examined the effects of reflected solar radiation and long wavelength

thermal radiation from the ground surface according to the evaluation height from the ground

surface. Tsuchikawa et al. [1] have made clear that the mean radiant temperature, which

corresponds to the position of an infant in a stroller, was significantly higher than the reflected

radiation from the ground, which correspond to the chest and head of the guardian adult.

Therefore, infants are thus exposed to a more extreme thermal environment than that felt by

an adult.

The body of an infant characteristically gets heat easily in hot environments and loses heat

easily in cold environments [2]. Also, the thickness of an infant’s skin is thin that of an adult [3],

and the infant is easy to make its temperature higher [4]. Consequently, it can be said that the

thermal sense of adults may increase the risk of heat stroke in infants.

The seat of a stroller is subject to heat transfer by convection from the air around the stroller,

by shortwave solar radiation from the sun, and by thermal radiation from the ground surface.

This heat is mainly then transferred to the infant’s body by heat conduction on the body surface

area in contact with the seat and by thermal radiation from the seat. Therefore, the stroller itself

can be treated as part of the infant’s clothing.

The following studies have examined the human factors relating to an infant’s clothing: clothing

area factor by Fukazawa et al. [5], Kurazumi et al. [6] and Golden et al. [7], clothing thermal

insulation by Fukazawa et al. [5], Tourula et al. [8] and Kurazumi et al. [9], and stroller clothing

area factor and clothing thermal insulation by Kurazumi et al. [10]. Tourula et al. [8] clarified

that the clothing thermal insulation in a stroller is higher than without the stroller. It was

reported that the clothing thermal insulation increased with each air layer of the clothing

ensemble. However, the clothing area factors and the clothing thermal insulations including the

stroller were not measured. The mentioned above, there are individual factors, but there is no

combined factor with a stroller. Therefore, the human factors of the infant in a stroller for

evaluating the thermal environment are insufficient at all. In other words, it is indispensable

that the clothing area factors and the clothing thermal insulations including the stroller should

be measure.

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European Journal of Applied Sciences (EJAS) Vol. 11, Issue 1, January-2023

Services for Science and Education – United Kingdom

Kurazumi et al. [10] studied the heat transfer area of a naked infant body in a stroller. The

clothing area factor of a naked infant body in a stroller with a reclining angle of 150° is 3.21.

Also, in a study by Tsuchikawa et al. [11] on the projection area factor of a naked infant body in

a stroller, the clothing area factor was estimated to be 3.76, based on the projected area of the

naked infant [10], which matches the azimuth and reclining angle of 130°. The results are

mostly consistent with this study. Therefore, the clothing area factor for infants in strollers,

even from the viewpoint of the heat transfer area, is understood to significantly affect the body

heat balance between the infant and the environment.

In the body heat balance based on the naked, the heat transfer area in the clothed state is

obtained by multiplying the heat transfer area for the naked body by a coefficient value. This

coefficient value is proposed as clothing area factors for typical clothed combinations in the

ASHRAE Fundamentals Handbook [12], for example. These values are a comprehensive list of

previous research results.

The clothing area factor is calculated by using of an empirical formula expressed as a linear

equation in which the thermal insulation of clothing is an explanatory variable, as in the work

of Sprague and Munson [13], Olesen et al. [14], McCullough et al. [15], IOS 15831:2004 [16], and

ISO 9920:2007 [17]. The formula [18], expressed as a linear formula in which the air volume of

the under-clothing climate related to the degree of clothing slack is an explanatory variable, is

also used to determine the clothing area factor.

In the previous formula, the clothing area factor fcl is calculated as an experience value. The

clothing area factor fcl as the empirical values are the measured values up to the range of about

1.5. However, Tsuchikawa et al. [11] and Kurazumi et al. [10] stated that the stroller’s clothing

area factor fcl exceeds 3.0. In addition, the clothing that is conventionally measured is clothing

that covers the body. However, compared to the normal measured clothing, the stroller seat

covers only the back of the body. Therefore, considering the heat transfer area of a naked infant

body in a stroller, as revealed by Tuchikawa et al. [11] and Kurazumi et al. [10], the

abovementioned calculation method cannot accurately express the clothing area factor of an

infant in a stroller. That is, it is difficult to consider the clothing thermal insulation of an infant

in a stroller.

The mentioned above that the amount of heat exchange between the infant and the surrounding

environment can be calculated for each conduction, convection, and radiation path, and the

stroller itself can be treated as part of the infant’s clothing. Although the clothing thermal

insulation for individual clothing ensembles and strollers has been examined, the clothing

thermal insulation for the combination of them has not been examined at all. This purpose of

this study is to examine the heretofore unknown target values for the clothing area factor and

clothing thermal insulation of clothing ensembles with a stroller. In order to evaluate the

infant's thermal environment, the typical target values are thought to be significant.

MEASUREMENTS

Measurement Plan of Clothing Area Factor

It is difficult to take measurements using an infant in thermal environmental experiments. For

this purpose, Kurazumi et al. [9, 10] made an infant body model similar to the subject [19].

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European Journal of Applied Sciences (EJAS) Vol. 11, Issue 1, January-2023

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Figure 1. Seasonal clothing ensembles.

Standards for the stroller [21, 22, 23, 24] are stipulated for safe assembly; however, only

CPSA001 [22] was standardized for the stroller reclining angle. The CPSA001 [22] for an A-type

stroller states that, for infants between 1 and 4 months old (who cannot yet hold their head up)

or sleeping infants, the stroller must have a reclining angle of 150°. For infants between 4 and

48 months, the stroller must have a reclining angle of over 130°. Therefore, similar to Kurazumi

et al. [10], this study utilized a backrest angle of 150° with the infant in a reclined seated

position.

Measurements of the clothing area factor were made using the photographic method in Olesen

et al. [14], which was improved by Yamato et al. [25, 26] and Kurazumi et al. [27]. In the infant's

posture in a stroller, a large part of the body extends in the sagittal direction and is asymmetric

in the coronal and median planes.

In this configuration, it is necessary to measure the clothing area factor for all azimuth angles

and at different elevation angles [25-27]. Figure 2 shows the measurement coordinate system.

The origin of the measurement coordinates is the center of the infant body, 0.05 m behind the

navel. Measurements were taken for 48 combinations of azimuth and elevation angles.

Elevation directions were at 0° and 60° from the coordinate origin. Due to the asymmetric

position of the infant body model, the azimuth angles for measurement were set at 15° intervals

around the median plane of the infant body model.