The Experts below are selected from a list of 1413 Experts worldwide ranked by ideXlab platform
Ingvar Holmér - One of the best experts on this subject based on the ideXlab platform.
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The thermal insulation difference of Clothing Ensembles on the dry and perspiration manikins
Measurement Science and Technology, 2010Co-Authors: Zhou Xiaohong, Zheng Chunqin, Qiang Yingming, Ingvar Holmér, Chuansi Gao, Kalev KuklaneAbstract:There are about a hundred manikin users around the world. Some of them use the manikin such as 'Walter' and 'Tore' to evaluate the comfort of Clothing Ensembles according to their thermal insulation and moisture resistance. A 'Walter' manikin is made of water and waterproof breathable fabric 'skin', which simulates the characteristics of human perspiration. So evaporation, condensation or sorption and desorption are always accompanied by heat transfer. A 'Tore' manikin only has dry heat exchange by conduction, radiation and convection from the manikin through Clothing Ensembles to environments. It is an ideal apparatus to measure the thermal insulation of the Clothing Ensemble and allows evaluation of thermal comfort. This paper compares thermal insulation measured with dry 'Tore' and sweating 'Walter' manikins. Clothing Ensembles consisted of permeable and impermeable clothes. The results showed that the clothes covering the 'Walter' manikin absorbed the moisture evaporated from the manikin. When the moisture transferred through the permeable Clothing Ensembles, heat of condensation could be neglected. But it was observed that heavy condensation occurred if impermeable clothes were tested on the 'Walter' manikin. This resulted in a thermal insulation difference of Clothing Ensembles on the dry and perspiration manikins. The thermal insulation obtained from the 'Walter' manikin has to be modified when heavy condensation occurs. The modified equation is obtained in this study. © 2010 IOP Publishing Ltd.
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A Study on Evaporative Resistances of Two Skins Designed for Thermal Manikin Tore under Different Environmental Conditions
Journal of Fiber Bioengineering and Informatics, 2008Co-Authors: Faming Wang, Kalev Kuklane, Chuansi Gao, Ingvar HolmérAbstract:A cotton skin and Gore-Tex skin were designed for thermal manikin "Tore" to simulate different sweating styles (wet cotton skin inside and Gore-Tex outside to simulate sweating style of thermal manikin "Walter", and Gore-Tex skin inside with wet cotton skin outside to simulate sweating style of thermal manikins "Newton". The evaporative resistances of two skin combinations with Clothing Ensembles were compared at two different environmental conditions. In addition, the total evaporative resistance of Clothing Ensemble was calculated by both heat loss method (option 1) and mass loss method (option 2) according to ASTM F 2370. We found that the effect of different sweating mechanisms on Clothing evaporative resistance should be considered. The results showed that the total evaporative resistances obtained by option 2 were more accurate than values by option 1 under an isothermal condition. It was also found that total evaporative resistance differences between two skin combinations with Clothing Ensembles decreased with increasing Clothing Ensemble layer. In a non-isothermal condition, the total evaporative resistance calculated by option 1 was more accurate than value obtained by option 2, which was due to lower ambient temperature and condensation between each adjacent layer. (Less)
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Initial, transient and steady state evaporative resistance of impermeable protective Clothing
2006Co-Authors: Chuansi Gao, Ingvar HolmérAbstract:The measured water vapour resistances of Clothing Ensembles differ among laboratories particularly for impermeable Clothing. Due to the moisture transfer in the Clothing Ensemble, evaporative heat losses in initial, transient and steady state phases are different. The purpose of this study was to investigate moisture absorption inside underwear and outer layer as a function of time, to quantify the difference of water vapour resistance of protective Clothing (impermeable outer layer and cotton underwear) in initial, transient and steady state. Manikin Tore was used by wearing wet ‘skin’ to simulate sweating. The evaporative resistance is found to be more than two times higher in the initial phase than that in the saturation phase. The moisture content is gained exponentially in the Clothing Ensemble. On the contrary, mass loss directly from the wet skin decreases exponentially. These may partly explain the poor reproducibility while measuring the evaporative resistance of impermeable Clothing for a short period. (Less)
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Moisture absorption, mass loss and evaporative resistance of permeable Clothing in a transient condition
Journal of Donghua University, 2006Co-Authors: Chuansi Gao, Ingvar HolmérAbstract:The water vapour resistance of Clothing Ensembles is not as commonly determined as dry thermal insulation. The measurement techniques are more complicated and the measurement values differ among laboratories. Due to complicated moisture transfer process through Clothing Ensemble, the moisture absorbed and evaporated varies in transient and steady state phases depending on properties, thickness of Clothing, and environmental conditions. The purpose of this study was to measure moisture absorption inside hygroscopic underwear, hydrophobic and permeable outer wear as a function of time, to investigate mass loss from “skin” as well as from manikin, to quantify evaporative heat loss and total heat loss from manikin, to determine evaporative resistance of Clothing. Manikin Tore was used by wearing wet “skin” to simulate sweating. Moisture content gain of the inner garment shows an exponential relation against time. Moisture in the outer permeable garment shows very small gain. On the contrary, mass loss directly from the wet skin decreases exponentially. The mass loss from the manikin is relatively stable throughout three test phases. The evaporative heat loss is about two thirds of the total heat loss from the sweating manikin. One hour measurement time is sufficient to get stable results while measuring the evaporative resistance of Clothing Ensembles with hygroscopic inner garment and permeable outer garment. The variation between the 1st hour and the 3rd hour is less than 5%. The length of transient period and measurement time requirement is dependent on the permeability, thickness of Clothing Ensembles and environmental conditions. (Less)
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The comparison of thermal properties of protective Clothing using dry and sweating manikins
2006Co-Authors: Chuansi Gao, Ingvar Holmér, Jintu Fan, Xianfu Wan, George HavenithAbstract:The thermal insulation of Clothing is commonly determined by dry thermal manikins either made of plastic or metal. For the determination of evaporative resistance of Clothing Ensemble, there exist three types of manikin methods: pre-wetted underwear or “skin” covered on dry manikins, the manikin with regulated constant water supply to the “skin” surface and the sweating fabric manikin based on a water filled body covered with waterproof but vapour permeable fabrics. The purpose of this study was to compare thermal insulation and moisture evaporative resistance of a set of protective Clothing measured using different type of manikins. The total thermal insulation of seven EU project Ensembles (Subzero A and B, Permeable (PERM), Impermeable (IMP), Nomex coverall (with two types of underwear) and Cotton coverall) were measured using the manikin Tore in Sweden, the sweating fabric manikin Walter in Hong Kong, and the manikin Newton in the UK. The results showed that total thermal insulation is reproducible for the seven Clothing Ensembles measured on the manikins Walter and Tore. The coefficient of variance is less than 8%. Nomex coverall with cotton underwear has 8-16% higher total insulation than that with polypropylene underwear. The apparent evaporative resistance of the impermeable coverall with cotton underwear measured on Newton was 44.5% lower than the evaporative resistance measured on Walter. The effect of condensation and conduction at room temperature environment and measuring time allowing full accumulation of moisture in Clothing Ensembles might be two important factors affecting the evaporative resistance.
Richard R. Gonzalez - One of the best experts on this subject based on the ideXlab platform.
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u s military use of thermal manikins in protective Clothing research
2002Co-Authors: Thomas L. Endrusick, Leander A. Stroschein, Richard R. GonzalezAbstract:Abstract : The U.S. military has utilized thermal manikins in protective Clothing research for nearly 60 years. Prior to their development, the evaluation of textile thermal insulation was limited to one-dimensional, guard-ring flat plates. During WW II, thermal manikins were instrumental in obtaining knowledge of combat Clothing Ensemble insulation during simulated adverse environmental conditions. Additionally, reports from the various combat theaters regarding the inadequacies of certain Clothing components prompted numerous thermal manikin studies resulting in rapid improvement of many combat Clothing components before the war's end. During the immediate post-war years, thermal manikin data was used to develop detailed tables of military cold weather Clothing insulation and the corresponding climatic zones of issue. During the 1960's, thermal manikin research began to focus on the thermal burden imposed by protective Clothing in hot environments. Research using a 'sweating' thermal manikin allowed for the measurement of the maximum evaporative heat transfer obtainable by the wearer of a given Clothing Ensemble. In the 1970's, thermal manikin studies in combination with human wear trials provided the necessary parameters to develop the first reliable equations for predicting core temperature, skin temperature, and heart rate while wearing various military Clothing Ensembles. From the early 1980's to the present day, extensive research within the U.S. military using thermal manikins has resulted in a vast improvement of all major protective Clothing systems for land, sea, and air based personnel. Thermal manikin data also constitutes vital input to several predictive models assessing the amount of thermal stress soldiers will experience during a wide range of environmental conditions and occupational settings. Today, sophisticated thermal manikins are used worldwide in a large number of NATO military and commercial Clothing research programs.
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Benefit of heat acclimation is limited by the evaporative potential when wearing chemical protective Clothing
Ergonomics, 1999Co-Authors: Stephen K Chang, Richard R. GonzalezAbstract:Heat acclimation-induced sweating responses have the potential of reducing heat strain for chemical protective garment wearers. However, this potential benefit is strongly affected by the properties of the garment. If the Clothing Ensemble permits sufficient evaporative heat dissipation, then heat acclimation becomes helpful in reducing heat strain. On the other hand, if the garment creates an impenetrable barrier to moisture, no benefit can be gained from heat acclimation as the additional sweating cannot be evaporated. Ten subjects were studied exercising on a treadmill while wearing two different chemical protective Ensembles. Skin heat flux, skin temperature, core temperature, metabolic heat production and heart rate were measured. It was found that the benefit of heat acclimation is strongly dependent on the ability of the body to dissipate an adequate amount of heat evaporatively. The evaporative potential (EP), a measure of thermal insulation modified by moisture permeability, of the Clothing ensem...
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Benefit of heat acclimation is limited by the evaporative potential when wearing chemical protective Clothing.
Ergonomics, 1999Co-Authors: Stephen K Chang, Richard R. GonzalezAbstract:Heat acclimation-induced sweating responses have the potential of reducing heat strain for chemical protective garment wearers. However, this potential benefit is strongly affected by the properties of the garment. If the Clothing Ensemble permits sufficient evaporative heat dissipation, then heat acclimation becomes helpful in reducing heat strain. On the other hand, if the garment creates an impenetrable barrier to moisture, no benefit can be gained from heat acclimation as the additional sweating cannot be evaporated. Ten subjects were studied exercising on a treadmill while wearing two different chemical protective Ensembles. Skin heat flux, skin temperature, core temperature, metabolic heat production and heart rate were measured. It was found that the benefit of heat acclimation is strongly dependent on the ability of the body to dissipate an adequate amount of heat evaporatively. The evaporative potential (EP), a measure of thermal insulation modified by moisture permeability, of the Clothing Ensemble offers a quantitative index useful to determine, a priori, whether heat acclimation would be helpful when wearing protective Clothing system. The data show that when EP is < 15%, heat acclimation affords no benefit. An evaporative potential graph is created to aid in this determination.
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Limited effectiveness of heat acclimation to soldiers wearing US Army and US Air Force chemical protective Clothing. Technical report
1995Co-Authors: Stephen K Chang, Richard R. GonzalezAbstract:Heat acclilmation-induced sweating responses have the potential of reducing heat strain for soldiers wearing chemical protective garment. However, this potential benefit is strongly affected by the properties of the garment. If the Clothing Ensemble permits sufficient evaporative heat dissipation, then heat acclimation becomes helpful in reducing heat strain. On the other hand, if the garment creates an impenetrable barrier to moisture, no benefit can be gained from heat acclimation as the additional sweating cannot be evaporated. We studied 10 subjects exercising on a treadmill while wearing two different U.S. military chemical protective Ensembles. Skin heat flux, skin temperature, core temperature, metabolic heat production, and heart rate were measured. We found that the benefit of heat acclimation is strongly dependent on an unimpeded ability of evaporative heat loss from skin areas. The evaporative potential (EP), a measure of thermal insulation modified by moisture permeability, of the Clothing Ensemble offers a quantitative index useful to determine whether heat acclimation is helpful while protective Clothing system. Our data show that when EP is less than 15%, heat acclimation affords no benefit. An evaporative potential graph is created to aid in this determination.
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Limited Effectiveness of Heat Acclimation to Soldiers Wearing U.S. Army and U.S. Air Force Chemical Protective Clothing.
1995Co-Authors: Stephen K Chang, Richard R. GonzalezAbstract:Abstract : Heat acclilmation-induced sweating responses have the potential of reducing heat strain for soldiers wearing chemical protective garment. However, this potential benefit is strongly affected by the properties of the garment. If the Clothing Ensemble permits sufficient evaporative heat dissipation, then heat acclimation becomes helpful in reducing heat strain. On the other hand, if the garment creates an impenetrable barrier to moisture, no benefit can be gained from heat acclimation as the additional sweating cannot be evaporated. We studied 10 subjects exercising on a treadmill while wearing two different U.S. military chemical protective Ensembles. Skin heat flux, skin temperature, core temperature, metabolic heat production, and heart rate were measured. We found that the benefit of heat acclimation is strongly dependent on an unimpeded ability of evaporative heat loss from skin areas. The evaporative potential (EP), a measure of thermal insulation modified by moisture permeability, of the Clothing Ensemble offers a quantitative index useful to determine whether heat acclimation is helpful while protective Clothing system. Our data show that when EP is less than 15%, heat acclimation affords no benefit. An evaporative potential graph is created to aid in this determination.
Divo A Quintela - One of the best experts on this subject based on the ideXlab platform.
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occupational exposure to cold thermal environments a field study in portugal
European Journal of Applied Physiology, 2008Co-Authors: Virgilio A M Oliveira, Adélio Rodrigues Gaspar, Divo A QuintelaAbstract:The present work is essentially dedicated to the study of cold thermal environments. The analysis includes 32 industrial units from 6 activity sectors and the measurements were carried out in 101 workplaces. Different environmental conditions were identified and a clear relationship with the different types of workplaces was established. The work environments were thus allocated to three typical exposure categories corresponding to freezing and refrigerating cold stores and free-running or controlled air temperature manufacturing workplaces. In order to characterize the level of cold exposure, the method proposed by ISO/TR 11079, Technical Report, 1st edn, International Organization for Standardization, Geneva (1993) was adopted. The results for each activity sector demonstrate that a significant percentage of workers are repeatedly exposed to extreme conditions with insufficient Clothing insulation. A value between 20 and 40% corresponds to the most critical situation, where the selected Clothing Ensemble does not provide adequate insulation (I clr < IREQ min). The ideal scenario, represented by I clr values between IREQ min and IREQ neutral, shows the lowest percentages with an overall result of only 10%. When all the sectors are considered together, from a total of 3,667 workers, about one-third (1,151) are exposed to the cold. Among the workplaces under analysis, 14 are characterized by a continuous exposure greater than the DLE neutral. Those who work under such conditions, on average, have a time shift 60 min longer than the calculated DLE value.
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Occupational exposure to cold thermal environments: a field study in Portugal
European Journal of Applied Physiology, 2008Co-Authors: A. Virgílio M. Oliveira, Adélio R. Gaspar, Divo A QuintelaAbstract:The present work is essentially dedicated to the study of cold thermal environments. The analysis includes 32 industrial units from 6 activity sectors and the measurements were carried out in 101 workplaces. Different environmental conditions were identified and a clear relationship with the different types of workplaces was established. The work environments were thus allocated to three typical exposure categories corresponding to freezing and refrigerating cold stores and free-running or controlled air temperature manufacturing workplaces. In order to characterize the level of cold exposure, the method proposed by ISO/TR 11079, Technical Report, 1st edn, International Organization for Standardization, Geneva ( 1993 ) was adopted. The results for each activity sector demonstrate that a significant percentage of workers are repeatedly exposed to extreme conditions with insufficient Clothing insulation. A value between 20 and 40% corresponds to the most critical situation, where the selected Clothing Ensemble does not provide adequate insulation ( I _clr
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MEASURING THERMAL INSULATION OF Clothing WITH DIFFERENT MANIKIN CONTROL METHODS. COMPARATIVE ANALYSIS OF THE CALCULATION METHODS
2008Co-Authors: A. V. M. Oliveira, V. J. Branco, Adélio Rodrigues Gaspar, Divo A QuintelaAbstract:Summary: The main objective of the present study is the assessment of Clothing thermal insulation values obtained with the three thermal insulation calculation methods, using experimental data from different manikin regulation modes in each body part. A summer Ensemble, a typical business suit and a cold protective Clothing Ensemble were considered for analysis. The measurements were carried out in a climate chamber with a thermal manikin with 16 body parts. The tests were performed according to ISO 9920 (2007) specifications. 1 Abstract The present experimental work is dedicated to the analysis of the thermal insulation of Clothing when the measurements are carried out with different manikin regulation modes in the body parts. The three thermal insulation calculation methods - the serial, the global and the parallel - are also considered and the results are discussed and presented for the total (IT), the basic (Icl) and the effective (Icle) Clothing insulations. A comparative study is performed with different Clothing Ensembles, namely a summer Ensemble, a typical business suit and a cold protective Ensemble. Despite of the manikin regulation mode, the results obtained with the serial method are always the highest. On the other hand, the thermal comfort regulation mode shows a tendency for presenting the higher values while the constant heat flux regulation mode presents the lower ones. Considering the results for the total thermal insulation and for the thermal comfort equation regulation mode, the values of the relative differences between the serial and global methods were 23,1% for the cold protective Ensemble, 9,0% for the business suit and 7,0% for the summer Ensemble. The corresponding values for the global and parallel methods were -2,8%, -2,4% and -2,8%, respectively. In addition, the higher differences between the calculation methods are obtained, in the majority of the cases, with the constant skin temperature regulation mode.
Adam W. Potter - One of the best experts on this subject based on the ideXlab platform.
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Heat Strain Decision Aid (HSDA) accurately predicts individual-based core body temperature rise while wearing chemical protective Clothing.
Computers in Biology and Medicine, 2019Co-Authors: Adam W. Potter, Andrew P. Hunt, Bruce S. Cadarette, Alison L. Fogarty, Shankar Srinivasan, William R. Santee, Laurie A. Blanchard, David P. LooneyAbstract:Abstract Purpose We examined the accuracy of the Heat Strain Decision Aid (HSDA) as a predictor of core body temperature in healthy individuals wearing chemical protective Clothing during laboratory and field exercises in hot and humid conditions. Methods The laboratory experiment examined three chemical protective Clothing Ensembles in eight male volunteers (age 24 ± 6 years; height 178 ± 5 cm; body mass 76.6 ± 8.4 kg) during intermittent treadmill marching in an environmental chamber (air temperature 29.3 ± 0.1 °C; relative humidity 56 ± 1%; wind speed 0.4 ± 0.1 m s−1). The field experiment examined four different chemical protective Clothing Ensembles in twenty activity military volunteers (26 ± 5 years; 175 ± 8 cm; 80.2 ± 12.1 kg) during a prolonged road march (26.0 ± 0.5 °C; 55 ± 3%; 4.3 ± 0.7 m s−1). Predictive accuracy and precision were evaluated by the bias, mean absolute error (MAE), and root mean square error (RMSE). Additionally, accuracy was evaluated using a prediction bias of ±0.27 °C as an acceptable limit and by comparing predictions to observations within the standard deviation (SD) of the observed data. Results Core body temperature predictions were accurate for each chemical protective Clothing Ensemble in laboratory (Bias −0.10 ± 0.36 °C; MAE 0.28 ± 0.24 °C; RMSE 0.37 ± 0.24 °C) and field experiments (Bias 0.23 ± 0.32 °C; MAE 0.30 ± 0.25 °C; RMSE 0.40 ± 0.25 °C). From all modeled data, 72% of all predictions were within one standard deviation of the observed data including 92% of predictions for the laboratory experiment (SD ± 0.64 °C) and 67% for the field experiment (SD ± 0.38 °C). Individual-based predictions showed modest errors outside the SD range with 98% of predictions falling Conclusion The HSDA acceptably predicts core body temperature when wearing chemical protective Clothing during laboratory and field exercises in hot and humid conditions.
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Biophysical Assessment and Predicted Thermophysiologic Effects of Body Armor
PLOS ONE, 2015Co-Authors: Adam W. Potter, Julio A. Gonzalez, Anthony J. Karis, Xiaojiang XuAbstract:Introduction Military personnel are often required to wear ballistic protection in order to defend against enemies. However, this added protection increases mass carried and imposes additional thermal burden on the individual. Body armor (BA) is known to reduce combat casualties, but the effects of BA mass and insulation on the physical performance of soldiers are less well documented. Until recently, the emphasis has been increasing personal protection, with little consideration of the adverse impacts on human performance. Objective The purpose of this work was to use sweating thermal manikin and mathematical modeling techniques to quantify the tradeoff between increased BA protection, the accompanying mass, and thermal effects on human performance. Methods Using a sweating thermal manikin, total insulation (IT, clo) and vapor permeability indexes (im) were measured for a baseline Clothing Ensemble with and without one of seven increasingly protective U.S. Army BA configurations. Using mathematical modeling, predictions were made of thermal impact on humans wearing each configuration while working in hot/dry (desert), hot/humid (jungle), and temperate environmental conditions. Results In nearly still air (0.4 m/s), IT ranged from 1.57 to 1.63 clo and im from 0.35 to 0.42 for the seven BA conditions, compared to IT and im values of 1.37 clo and 0.45 respectively, for the baseline condition (no BA). Conclusion Biophysical assessments and predictive modeling show a quantifiable relationship exists among increased protection and increased thermal burden and decreased work capacity. This approach enables quantitative analysis of the tradeoffs between ballistic protection, thermal-work strain, and physical work performance.
Simon Hodder - One of the best experts on this subject based on the ideXlab platform.
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Updated Database of Clothing Thermal Insulation and Vapor Permeability Values of Western Ensembles for Use in ASHRAE Standard 55, ISO 7730 and ISO 9920; Results of ASHRAE RP-1760
2021Co-Authors: James Smallcombe, Kalev Kuklane, Simon Hodder, Dennis Loveday, Magdalena Mlynarczyk, Amitava Halder, Jakob Petersson, George HavenithAbstract:ASHRAE RP-1760 aimed to update the database of western Clothing as used in ANSI/ASHRAE Standard 55-2013, Thermal Environmental Conditions for Human Occupancy (ASHRAE 2013a), ISO Standard 7730-2005, Ergonomics of the Thermal Environment—Analytical Determination and Interpretation of Thermal Comfort Using Calculation of the PMV and PPD Indices and Local Thermal Comfort Criteria (ISO 2005), and ISO Standard 9920-2009, Ergonomics of the Thermal Environment— Estimation of Thermal Insulation and Water Vapor Resistance of a Clothing Ensemble (ISO 2009). The previous database, established in the 1970’s and 1980’s, relied mostly on single zone manikins and did not provide detail on air and body movement effects on insulation. Insulation values of up to 70 Clothing Ensembles (31 male, 39 female) were measured in a static standing posture at 0.2, 0.4 and 1 m.s-1 (0.66, 1.31, 3.28 ft.s-1) air speed, walking in 0.2 and 1.0 m.s-1 air speed , and in a sitting posture in 0.2 m.s-1 air speed. Measurements were conducted in three laboratories on three manikins with up to 34 individually controlled zones. In addition, vapor resistance was determined in 31 Ensembles. This new database provides total, intrinsic and air insulation values, vapor resistance and Clothing area factors as well as correction factors to estimate the wind and movement effect on Clothing insulation. Furthermore, the model to estimate the Clothing area factor from insulation values of the Ensembles was updated reflecting changes in commonly worn Clothing styles
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Sweat-induced skin wetness perception can be significantly manipulated independently of the level of physical skin wetness [Abstract]
The FASEB Journal, 2015Co-Authors: Davide Filingeri, Damien Fournet, Simon Hodder, George HavenithAbstract:Skin wetness perception is driven by inputs from cold and mechano sensitive skin afferents. We hypothesized that in the absence of skin cooling, sweat induced wetness perception can be manipulated by altering the mechanical interaction between skin, sweat and Clothing. Ten males (22±2years) performed an incremental walking protocol (5Km/h; gradient: 2 to 16%) during two trials designed to produce the same level of physical skin wetness but to induce lower (TIGHT-FIT) and higher (LOOSE-FIT) wetness perception. In the TIGHT-FIT, a tight fitting Clothing Ensemble was worn to reduce the mechanical interaction between skin, sweat and Clothing. In the LOOSE-FIT, a loose fitting Ensemble augmented this interaction. To limit sweat evaporation and skin cooling, a vapour impermeable Ensemble was also worn during the trials. Heart rate, rectal temperature, mean skin temperature, skin conductance (SC), whole body skin wetness (wbody) and wetness perception were recorded. Exercise induced sweat production and physical skin wetness increased significantly (SC: 3.1±0.3 to 18.8±1.3µS, p 0.05). However, the reduced mechanical interaction generated by the TIGHT-FIT Ensemble lowered significantly wetness perception (p
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displacement ventilation environments with chilled ceilings thermal comfort design within the context of the bs en iso7730 versus adaptive debate
Energy and Buildings, 2002Co-Authors: Dennis L Loveday, Ken Parsons, A H Taki, Simon HodderAbstract:Abstract The current design standard BS EN ISO7730 [Moderate thermal environments—determination of the PMV and PPD indices and specification of the conditions for thermal comfort, International Standards Organisation (1995)] is based upon the work of Fanger, and essentially comprises a steady-state human heat balance model that leads to a prediction of the sensation of human thermal comfort for a given set of thermal conditions. The model was derived from laboratory-based measurements conducted in the mid-1960s in relatively ‘conventional’ environments. However, a chilled ceiling operated in combination with displacement ventilation represents a more sophisticated environment as compared with the original conditions in which the Fanger model was derived. This raised a question about the applicability of the current standard when designing for thermal comfort in offices equipped with chilled ceiling/displacement ventilation systems. This paper presents findings from an EPSRC-funded study that sought to answer the above question. Human test subjects (184 in total) carried out sedentary office-type work in a well-controlled environmental test room that simulated an office fitted with the above system. Measurements of environmental variables were taken at a number of locations near the subjects, each of whom wore a typical office Clothing Ensemble. The reported thermal comfort sensations were compared with values predicted from BS EN ISO7730 over a range of system operating conditions. It was shown that the current standard BS EN ISO7730 may be used, without modification, when designing for the thermal comfort of sedentary workers in offices equipped with chilled ceiling/displacement ventilation systems. These findings are interpreted within the context of a proposed modification to thermal comfort design standards that includes adaptive effects, and the influence of BS EN ISO7730 on the development of other radiant surface/displacement ventilation configurations is discussed.