| 21. |
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| 22. |
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| 23. |
- Bouskill, Lisa M., et al.
(författare)
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The relationship between ventilation index and thermal insulation
- 1998
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Ingår i: Proceedings / ICCE8 the 8th International Conference on Environmental Ergonomics, 18-23 October 1998, San Diego, California, USA. - : International Conference on Environmental Ergonomics. - 0966695305
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Konferensbidrag (refereegranskat)
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| 24. |
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| 25. |
- Broede, Peter, et al.
(författare)
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The Universal Thermal Climate Index UTCI Compared to Ergonomics Standards for Assessing the Thermal Environment
- 2013
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Ingår i: Industrial Health. - 1880-8026. ; 51:1, s. 16-24
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Forskningsöversikt (refereegranskat)abstract
- The growing need for valid assessment procedures of the outdoor thermal environment in the fields of public weather services, public health systems, urban planning, tourism & recreation and climate impact research raised the idea to develop the Universal Thermal Climate Index UTCI based on the most recent scientific progress both in thermo-physiology and in heat exchange theory. Following extensive validation of accessible models of human thermoregulation, the advanced multi-node 'Fiala' model was selected to form the basis of UTCI. This model was coupled with an adaptive clothing model which considers clothing habits by the general urban population and behavioral changes in clothing insulation related to actual environmental temperature. UTCI was developed conceptually as an equivalent temperature. Thus, for any combination of air temperature, wind, radiation, and humidity, UTCI is defined as the air temperature in the reference condition which would elicit the same dynamic response of the physiological model. This review analyses the sensitivity of UTCI to humidity and radiation in the heat and to wind in the cold and compares the results with observational studies and internationally standardized assessment procedures. The capabilities, restrictions and potential future extensions of UTCI are discussed.
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| 26. |
- Bröde, Peter, et al.
(författare)
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Deriving the operational procedure for the Universal Thermal Climate Index (UTCI)
- 2012
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Ingår i: International Journal of Biometeorology. - : Springer Science and Business Media LLC. - 1432-1254 .- 0020-7128. ; 56:3, s. 481-494
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Tidskriftsartikel (refereegranskat)abstract
- The Universal Thermal Climate Index (UTCI) aimed for a one-dimensional quantity adequately reflecting the human physiological reaction to the multi-dimensionally defined actual outdoor thermal environment. The human reaction was simulated by the UTCI-Fiala multi-node model of human thermoregulation, which was integrated with an adaptive clothing model. Following the concept of an equivalent temperature, UTCI for a given combination of wind speed, radiation, humidity and air temperature was defined as the air temperature of the reference environment, which according to the model produces an equivalent dynamic physiological response. Operationalising this concept involved (1) the definition of a reference environment with 50% relative humidity (but vapour pressure capped at 20 hPa), with calm air and radiant temperature equalling air temperature and (2) the development of a one-dimensional representation of the multivariate model output at different exposure times. The latter was achieved by principal component analyses showing that the linear combination of 7 parameters of thermophysiological strain (core, mean and facial skin temperatures, sweat production, skin wettedness, skin blood flow, shivering) after 30 and 120 min exposure time accounted for two-thirds of the total variation in the multi-dimensional dynamic physiological response. The operational procedure was completed by a scale categorising UTCI equivalent temperature values in terms of thermal stress, and by providing simplified routines for fast but sufficiently accurate calculation, which included look-up tables of pre-calculated UTCI values for a grid of all relevant combinations of climate parameters and polynomial regression equations predicting UTCI over the same grid. The analyses of the sensitivity of UTCI to humidity, radiation and wind speed showed plausible reactions in the heat as well as in the cold, and indicate that UTCI may in this regard be universally useable in the major areas of research and application in human biometeorology.
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| 27. |
- Bröde, Peter, et al.
(författare)
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Heat gain from thermal radiation through protective clothing with different insulation, reflectivity and vapour permeability
- 2010
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Ingår i: International Journal of Occupational Safety and Ergonomics. - 2376-9130. ; 16:2, s. 231-244
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Tidskriftsartikel (refereegranskat)abstract
- The heat transferred through protective clothing under long wave radiation compared to a reference condition without radiant stress was determined in thermal manikin experiments. The influence of clothing insulation and reflectivity, and the interaction with wind and wet underclothing were considered. Garments with different outer materials and colours and additionally an aluminised reflective suit were combined with different number and types of dry and pre-wetted underwear layers. Under radiant stress, whole body heat loss decreased, i.e., heat gain occurred compared to the reference. This heat gain increased with radiation intensity, and decreased with air velocity and clothing insulation. Except for the reflective outer layer that showed only minimal heat gain over the whole range of radiation intensities, the influence of the outer garments’ material and colour was small with dry clothing. Wetting the underclothing for simulating sweat accumulation, however, caused differing effects with higher heat gain in less permeable garments.
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| 28. |
- Bröde, Peter, et al.
(författare)
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Heat transfer through protective clothing under symmetric and asymmetric long wave thermal radiation
- 2008
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Ingår i: Zeitschrift für Arbeitswissenschaft. - 0340-2444. ; 62:4, s. 267-276
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Tidskriftsartikel (refereegranskat)abstract
- This report considers results of an ED funded research on thermal properties ofprotective clothing and their use in the assessment of the thermal strain at work. In order to study the effects of the asymmetry oflong wave thermal radiation on the heat transfer through protective clothing, the heat loss under all-side and unilaterally applied radiation with the same incident radiant power of 279 W/m2 was measured with a thermal manikin and compared to a reference condition where mean radiant temperature was equal to air temperature. With exposure to radiation a lowered heat loss, i.e. heat gain for the whole covered body area was observed, which did not depend on radiant asymmetry for the dry as well as for the combined dry and evaporative heat loss, and which was attenuated when wearing a more insulating underwear. However, under one-sided radiation a more inhomogeneous spatial distribution occurred with higher heat gains and higher surface temperatures at the irradiated body parts. Practical Relevance The direction ofthermal radiation in the horizontal plane may be neglected when assessing the physiological heat strain in protective clothing by heat budget models. In contrast to this, it may be advisable to consider radiant asymmetries with respect to thermal comfort with low intensity radiation, and the most intense radiant source when assessing the risk of skin burns.
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| 29. |
- Bröde, Peter, et al.
(författare)
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Infrared radiation effects on heat loss measured by a thermal manikin wearing protective clothing
- 2005
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Ingår i: Environmental ergonomics XI : proceedings of the 11th International Conference, 22-26 May, 2005, Ystad, Sweden - proceedings of the 11th International Conference, 22-26 May, 2005, Ystad, Sweden. - 1650-9773. - 9163170620 ; , s. 74-77
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Konferensbidrag (refereegranskat)
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| 30. |
- Bröde, Peter, et al.
(författare)
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Non-evaporative effects of a wet mid layer on heat transfer through protective clothing
- 2008
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6327 .- 1439-6319. ; 104:2, s. 341-349
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Tidskriftsartikel (refereegranskat)abstract
- In order to assess the non-evaporative components of the reduced thermal insulation of wet clothing, experiments were performed with a manikin and with human subjects in which two layers of underwear separated by an impermeable barrier were worn under an impermeable overgarment at 20 °C, 80% RH and 0.5 ms-1 air velocity. By comparing manikin measurements with dry and wetted mid underwear layer, the increase in heat loss caused by a wet layer kept away from the skin was determined, which turned out to be small (5-6 Wm-2), irrespective of the inner underwear layer being dry or wetted, and was only one third of the evaporative heat loss calculated from weight change, i.e. evaporative cooling efficiency was far below unity. In the experiments with 8 males, each subject participated in two sessions with the mid underwear layer either dry or wetted, where they stood still for the first 30 minutes and then performed treadmill work for 60 minutes. Reduced heat strain due to lower insulation with the wetted mid layer was observed with decreased microclimate and skin temperatures, lowered sweat loss and cardiac strain. Accordingly, total clothing insulation calculated over the walking period from heat balance equations was reduced by 0.02 m2 °C W-1 (16%), while for the standing period the same decrease in insulation, representing 9% reduction only showed up after allowing for the lower evaporative cooling efficiency in the calculations. As evaporation to the environment and inside the clothing was restricted, the observed small alterations may be attributed to the wet mid layer’s increased conductivity, which, however, appears to be of minor importance compared to the evaporative effects in the assessment of the thermal properties of wet clothing.
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