Showing papers on "Clothing insulation published in 2017"

Passenger thermal comfort and behavior: a field investigation in commercial aircraft cabins.

Abstract: Passengers' behavioral adjustments warrant greater attention in thermal comfort research in aircraft cabins. Thus, a field investigation on 10 commercial aircrafts was conducted. Environment measurements were made and a questionnaire survey was performed. In the questionnaire, passengers were asked to evaluate their thermal comfort and record their adjustments regarding the usage of blankets and ventilation nozzles. The results indicate that behavioral adjustments in the cabin and the use of blankets or nozzle adjustments were employed by 2/3 of the passengers. However, the thermal comfort evaluations by these passengers were not as good as the evaluations by passengers who did not perform any adjustments. Possible causes such as differences in metabolic rate, clothing insulation and radiation asymmetry are discussed. The individual difference seems to be the most probable contributor, suggesting possibly that passengers who made adjustments had a narrower acceptance threshold or a higher expectancy regarding the cabin environment. Local thermal comfort was closely related to the adjustments and significantly influenced overall thermal comfort. Frequent flying was associated with lower ratings for the cabin environment.

Impact of Different Personal Protective Clothing on Wildland Firefighters' Physiological Strain

Abstract: Wildfire firefighting is an extremely demanding occupation performed under hot environment. The use of personal protective clothing (PPC) is needed to protect subjects from the thermal exposure. However, the additional use of PPC may increase the wildland firefighters’ physiological strain, and consequently limit their performance. The aim of this study was to analyze the effect of four different PPC on the physiological strain of wildland firefighters under moderate conditions (30oC and 30% RH). Eight active and healthy wildland firefighters performed a submaximal walking test wearing a traditional short sports gear and 4 different PPC. The materials combination (viscose, nomex, Kevlar, P-140 and fire resistant cotton) used during the PPC manufacturing process was different. During all tests, to simulate a real scenario subjects wore a backpack pump (20 kg). Heart rate, respiratory gas exchange, gastrointestinal temperature, blood lactate concentration, perceived exertion and temperature and humidity underneath the PPC were recorded throughout tests. Additionally, parameters of heat balance were estimated. Wearing a PPC did not cause a significant increase in the subjects’ physiological response. The gastrointestinal temperature increment, the relative humidity of the microclimate underneath the PPC, the sweat residue in PPC, the sweat efficiency, the dry heat exchange and the total clothing insulation were significantly affected according to the PPC fabric composition. These results suggest that the PPC composition affect the moisture management. This might be taken into account to increase the wildland firefighters’ protection in real situations, when they have to work close to the flames.

Study of the required thermal insulation (IREQ) of clothing using infrared imaging

Abstract: The sense of cold develops due to the increase in heat loss from a human body. Excessive cold can be a health hazard, since excessive heat loss from the body may result in hypothermia/frostbite. Decreased body temperature due to heat loss also affects the physical, manual and perceptive performance of individuals. Therefore, protective measures are taken through clothing that controls and regulates heat loss. Clothing is a protective means for thermal insulation. Clothing and garments used in cold climates should have sufficient insulation to maintain the thermal balance of the body. The required clothing insulation (IREQ) is calculated on the basis of the hypothesis concerning the heat flow by conduction, convection, radiation and evaporation. This term is well defined in standards such as BS-EN 342 and ISO 11079:2007 (E). This paper presents an experimental study of the use of state-of-the-art Infrared (IR) thermography to estimate IREQ values. However, real IREQ values are difficult to estimate, considering that parameters, such as individual metabolism, are unknown and subject to change. Therefore, relative IREQ (IREQ*) values are computed and compared. Experiments were also conducted to measure the relative IREQ of winter jackets, summer jackets, and sweaters. The infrared images were obtained using a FLIR® T1030sc camera and analyzed using FLIR® Researcher Max software. The experiments were performed under conditions of -20°C to -35°C in the cold room at UiT- The Arctic University of Norway.

Inferring Clothing Insulation Levels Using Mechanisms of Heat Transfer

Abstract: To maintain productivity and alertness, individuals must be thermally comfortable in the space they occupy (whether it is a cubicle, a room, a car, etc) However, it is often difficult to non-intrusively assess an occupant’s “thermal comfort,” and hence most HVAC engineers adopt fixed temperature settings to “err on the safe side” These set temperatures can be too hot or too cold for individuals wearing different clothing, and as a result lead to feelings of discomfort as well as wastage of energy Since humans dress to target a comfortable thermal sensation, it is reasonable to assume that clothing is an important measure of current thermal sensation To this end, we develop SiCILIA, a platform that extracts physical and personal variables of an occupant’s thermal environment to infer the amount of clothing insulation without human intervention The proposed inference algorithm builds upon theories of body heat transfer and is corroborated by empirical data SiCILIA was tested in a vehicle with a passenger-controlled HVAC system Experimental results show that the algorithm is capable of accurately predicting an occupant’s thermal insulation with a mean prediction error of 007clo

Evaluation of two cooling devices for construction workers by a thermal manikin

Abstract: Two kinds of wearable cooling devices were evaluated for their cooling effect by a thermal manikin. All measurements were conducted in a climatic chamber. The cooling fans worked almost 3 h. Their cooling effect was large at the head and had little effects on other parts of the manikin. They decreased the insulation of a typical clothing ensemble of outdoor workers in construction industries from 0.75 clo to 0.48 clo. The cooling vest for heat protective clothing mainly worked on the trunk. It did not have enough effect nor had steady cooling effect. But the vest worked as direct cooling device for the trunk. The effect of the fans to Standard Effective Temperature (SET) is evaluated by simulation. The difference of SETs between the case of the typical ensemble and the case with the cooling fans at 35 °C of the surrounding environment is 2.6 °C. The lower the surrounding temperature is, the larger the difference between SETs of different clothing insulation value is.

Thermal clothing to reduce heart failure morbidity during winter: a randomised controlled trial.

Abstract: Objective To examine whether providing thermal clothing improved the health of patients with heart failure during winter. Design Parallel group randomised controlled trial. Setting Large public hospital in Brisbane during winter 2016. Participants 91 patients with systolic or diastolic heart failure who were over 50 years old. Intervention 47 patients were randomised to receive thermal clothes (socks, top and hat) and 44 received usual care. Patients could not be blinded to their randomised group. All patients’ data were available for the primary outcome which was collected blind to randomised group. Main outcome measures The primary outcome was the mean number of days in hospital during winter. Secondary outcomes included quality of life and sleep, and blood tests were collected for cardiovascular risk factors. Participants completed clothing diaries in midwinter which were used to estimate their overall clothing insulation using the ‘clo’. Monitors inside the participants’ homes recorded indoor temperatures throughout winter. Results The mean number of days in hospital during winter was 4.2 in the usual care group and 3.0 in the thermal clothing group (mean difference –1.2 days, 95% CI –4.8 to 2.5 days). Most participants (85%) in the thermal clothing group reported using the thermals. There was an increase in overall clothing insulation at night in the thermal clothing group (mean difference 0.13 clo, 95% CI 0.03 to 0.23). Most participants in both groups did not wear sufficient clothing (defined as a clo below 1) and regularly experienced indoor temperatures below 18°C during midwinter. Conclusions There was no clear statistical improvement in health in the thermal clothing group. Efforts to improve health during winter may need to focus on passive interventions such as home insulation rather than interventions that target behaviour change.

Variations of PMV based Thermal Comfort and Cooling/Heating Load according to MET

Abstract: Purpose: Korean government originally established the target of greenhouse gas emission reduction by 30% by the year of 2020, but adjusted the target to 37% reduction by 2030, recently. The efficient indoor environmental control is an essential factor for the achievement of the goal. However, most of the indoor environment control is based on the dry-bulb air temperature, which is one of the most simplified control methods having limitation to truly represent thermal comfort of individual occupants. A variety of factors affect the thermal comfort such as dry-bulb air temperature, humidity, air movement, radiation, clothing insulation and metabolic activity level. Method: In this circumstance, this study investigated the effects of MET (metabolic rate) on thermal load and PMV, which is the thermal comfort index considering all the comfort factors listed above. Four cased were simulated using EnergyPlus: Case1: 0.7 (Sleeping), Case2: 1.0 (Seated, quiet), Case3: 2.0 (Walking), Case4: 2.3 (Fast walking, Dish washing). Result: It turned out that indoor air temperature in MET 0.7 Case can be even 10℃ higher than that in MET 2.3 Case to accomplish the same PMV in the summer period and that MET has dominant effects on heating and cooling load in residential buildings.

Clothing design parameters that affect estimation of clothing insulation change due to posture and motion

Abstract: Clothing insulation is one of the basic parameters that affects human heat exchange with the environment. There are available standard methods to measure individual clothing items and combinations’ insulation (EN 15831), and standards that present databases and allow summing individual items insulation (ISO 9920). The latter does not account for many effects that occur when dressing the clothing ensemble, e.g. tucking shirt into pants or not, compression of layers, clothing design features. An aim of this study was to study and evaluate textile and clothing design parameters that may affect clothing combinations’ insulation while using data from available clothing studies. Such an overview would support preparations for improving the summation method, and motion and wind corrections. This would allow more accurate risk assessment and selection of appropriate protective, functional clothing for work tasks in any environments, thus, diminishing the thermal stress. The methods included a revision of available clothing databases where more or less detailed data on clothing items and combination parameters was available. According to earlier results, 67 % of summation results were over 10 % different and 24 % were 20 % or more different from ensemble measurement results. A variety of parameters that were of interest for the summation method or wind and motion effect correction were defined, and if possible, measured, e.g. number of layers, their thickness etc. Draping, stiffness of layers and compressibility could be of interest but were not covered in this preliminary work. The present evaluation did show that in addition to basic factors defined in ISO 9920 for correcting for wind and motion – total clothing insulation, air velocity and walking speed, also posture, number of layers, their thickness (possible relation to draping and stiffness of layers) and looseness of lower body layers around hips had significant influence on predictions. About 20 % of all total resultant clothing insulation predictions, while considering the listed parameters still exceeded 10 % difference with measured values compared to 43 % of corresponding ISO 9920 corrections. More detailed information on clothing components design and use may allow improved insulation estimations. A calculation error of less than 10 % could be acceptable, while less than 5 % would be preferable for physiological modelling purposes. (Less)

Indoor Environmental Quality: Thermal Comfort

Abstract: The fundamental principles for achieving thermal comfort for occupants are well-established. This article presents these basic theories and uses these to address the new challenge of achieving thermal comfort sustainably, especially with changes in the future climate. Long-established methods including the predicted mean vote and predicted percentage dissatisfied are presented in detail, and opportunities of increasing the comfort range by means of adaptation through changes in clothing and activities as well as the psychological effect of providing of individual thermal control are described. Ways for reducing energy consumption in building design will also be considered, and the limit for which these measures will work in reducing energy consumption whilst preserving adequate levels of thermal comfort with climate change is investigated.

Validation of a Clothing Heat Transfer Model in Nonisothermal Test Conditions

Abstract: Heat transfer through clothing systems can mean the difference between life and death for first responders, such as firefighters, who perform intense physical activity in extreme environmental conditions. Total heat loss (THL) is a fabric level test method required by the National Fire Protection Association (NFPA) to assess the thermal burden imposed by materials in the construction of turnout clothing. This methodology, however, does not account for garment fit, construction, or air layers that develop within the clothing. Instead, thermal manikins may be used to measure the THL of entire clothing systems according to ASTM test methods. Environmental test conditions between the two standard methods (fabric versus manikin) differ, creating the need for an adapted heat transfer model for manikin THL comparisons in similar environmental conditions. Therefore, the purpose of this research was to validate the assumptions of a heat transfer model originally developed and published by Ross, Barker, and Deaton (2012) for its accuracy in predicting manikin THL in nonisothermal test conditions. Three protective clothing systems with varying levels of clothing insulation were tested for THL in both isothermal and nonisothermal conditions as well as on the sweating guarded hot plate. Predictive calculations using Ross’s heat transfer model, adapted from the original THL hot plate calculation in ASTM F1868, Standard Test Method for Thermal and Evaporative Resistance of Clothing Materials Using a Sweating Hot Plate, were correlated to the actual manikin measurements taken in isothermal conditions to determine if there is any bias present in the current model.