Globe Thermometer Research Articles

Globe Temperature and Its Measurement: Requirements and Limitations.

This study addresses the measurement of the globe temperature. For this purpose, two globe thermometers with different diameters (50 and 150 mm) and a variety of thermal environmental conditions were considered. The assessments of the response times and of the influences of the globe diameter and the air velocity on the measured globe temperatures are discussed. The results of the response times clearly put in evidence that the values usually stated in the literature can be questioned and that longer measurement periods must be considered. In fact, response times >30 min were obtained in 68% of the tests performed. Moreover, differences >20ºC were obtained between the 150 and 50 mm sensors, highlighting the influence of the globe diameter. The analysis of the effect of the air velocity on the globe temperature shows mean relative differences >30% between tests in still air and with the higher air velocity considered (1.81 m s-1). On the basis of measurements carried out with the 50 mm globe, correction equations to the standard globe temperature for both natural and forced convection are proposed.

Avaliação ocupacional quantitativa das temperaturas extremas em um laboratório acadêmico: os reflexos da exposição para a saúde dos trabalhadores

<p>Every day occupational diseases incapacitate thousands of workers in a wide range of activities causing problems which vary from temporary retirements until death The diseases usually start when there is exposure to physical environmental agents above tolerance limits such as: extreme temperatures (cold and heat) present in food laboratories. In this context, this study aimed to analyze the occupational exposure to extreme temperatures in an academic milk processing laboratory of a Public Education Institution. The methodology used a descriptive, quantitative approach. Data collection used the environmental measurement instrument A recommended Thermal Stress Measure for evaluation of heat exposure Humidity Bulb Index – Globe Thermometer (IBUTG), based on the Tolerance Limits proposed by NR 15 and environmental evaluation of the cold through the ACGIH Tolerance Limit Table. The result obtained for the evaluation of the heat was of an average IBUTG of 30.075 for yoghurt production, below the tolerance limit proposed by NR 15. In order to evaluate the cold, a value of 8 ºC was obtained and the temperature range could be considered acceptable by the ACGIH for a 1 hour and 40 minutes intercalated journey.</p>

Empirical Model of Human Thermal Comfort in Subtropical Climates: A First Approach to the Brazilian Subtropical Index (BSI)

The bioclimatic well-being of individuals is associated with the environmental characteristics of where they live. Knowing the relationships between local and regional climatic variables as well as the physical characteristics of a given region and their implications on thermal comfort is important for identifying aspects of thermal sensation in the population. The aim of this study is to develop an empirical model of human thermal comfort based on subjective and individual environmental patterns observed in the city of Santa Maria, located in the state of Rio Grande do Sul, Brazil (Subtropical climate). Meteorological data were collected by means of an automatic meteorological station installed in the city center, which contained sensors measuring global solar radiation, air temperature, globe temperature (via a grey globe thermometer), relative humidity and wind speed and direction. A total of 1720 people were also interviewed using a questionnaire adapted from the model recommended by ISO 10551. Linear regressions were performed to obtain the predictive model. The observed results proposed a new empirical model for subtropical climate, the Brazilian Subtropical Index (BSI), which was verified to be more than 79% accurate, with a coefficient of determination of 0.926 and an adjusted R2 value of 0.924.

Revisiting the use of globe thermometers to estimate radiant temperature in studies of heating and ventilation

The globe thermometer has been considered a reliable instrument to quantify mean radiant temperature (MRT) since Bedford & Warner isolated its readings from air movement in their 1934 paper so that radiation could be quantified. Recent expanded use of radiant heating and cooling systems has presented new challenges for the usage of globe thermometers in the built environment by causing additional radiant asymmetries and performance expectations. Therefore, we replicate the original Bedford & Warner work to reconsider and develop a more holistic understanding of black globe performance and the determination of MRT in buildings. We recreate the MRT and air temperature separation to investigate the accuracy of globe thermometers on measuring MRTs. A radiantly heated open-plan laboratory and a radiantly cooled conference room were selected and measured with multiple globe thermometers and non-contacting infrared sensors. The globe temperature results were then corrected with air movement to produce MRTs and compared against MRTs simulated from measured surface temperatures. We demonstrate a significant impact of air speed on the MRTs obtained from globe thermometers. We also illustrate a less-investigated non-graybody emissivity variation and spatial variation of MRTs of up to 5 °C at the same height. We believe the increasing temporal and spatial resolution of digital sensors may create new challenges for using globe thermometers to measure MRTs, since fluctuating readings may camouflage potential MRT changes. Through a validation of our spatial MRT distribution with experimental results, we believe there is a need for better sensors that could spatially resolve MRTs, and recognize issues with both air speed and emissivity.

Modelling of radiation-based thermal stress indicators for urban numerical weather prediction

Two widely used radiation-based thermal stress indices, the Wet-Bulb Globe Temperature (WBGT) and the Universal Thermal Climate Index (UTCI), are implemented into the Canadian urbanized version of the GEM Numerical Weather Prediction (NWP) model in order to improve heat-health meteorological products in urban areas. Predictions with 250-m grid spacing over the Greater Toronto Area (GTA), Canada, reveal that spatial distribution of both WBGT and UTCI are similarly sensitive to mesoscale features such as the lake-breeze flows. Accurate prediction of WBGT and its indicators is found as evaluated with measurements during clear-sky and cloudy condition cases. In particular in clear-sky conditions the scattering index of solar radiation from the atmospheric model is found to be more realistic than fixed values. Links between intermediate important variables representing thermal load on a body, the mean radiant temperature (TMR), and a synthetic variable equivalent to the globe temperature (TG) as measured with a globe thermometer sensor are closely analyzed. Results show that the use of distinct TMRWBGT and TMRUTCI leads to differences of up to 50% due to a different energy partitioning and that TMR and TG are linked through a hysteresis cycle.

Subjective Human Perception of Open Urban Spaces in the Brazilian Subtropical Climate: A First Approach

This research concerns a first approach to adapt the thermal comfort bands of the Physiological Equivalent Temperature (PET), New Standard Effective Temperature (SET), and Predicted Mean Vote (PMV) indices to Santa Maria’s population, Rio Grande do Sul, Brazil, on the basis of the application of perception/sensation questionnaires to inhabitants while, at the same time, recording meteorological attribute data. Meteorological and thermal sensation data were collected from an automatic weather station installed on paved ground in the downtown area, which contained the following sensors: a scale gauge; a global radiation sensor; a temperature and humidity sensor; a speed and wind direction sensor; a gray globe thermometer. First of all, air temperature, gray globe temperature, relative air humidity, wind speed, wind gust, global solar radiation and precipitation were collected. People were interviewed using a questionnaire adapted from the model established by ISO 10551. The results demonstrated the efficiency of the linear regression model and the adequacy of the interpretive indexes, presenting results different from those analyzed by other authors in different climatic zones. These differences meet the analyzed literature and attest to the effectiveness of the calibration method of the PET, SET, and PMV indices for the Brazilian subtropical climate. After calibration, the PET index hit rate increased from 32.8% to 69.3%. The SET index, which had an initial hit rate of 34.6% before calibration, reached a hit-rate of 64.9%, while the PMV index increased from 35.9% to 58.7%.

The thermal environment effect on the comfort of electronic factory worker

In this paper, thermal comfort issues of the operators working on one of the electronics companies in the evaporator area are observed. The objective of this study is to reduce Percentage of Dissatisfied (PD) of operators in an effort to improve the work productivity. PD is predicted using CBE Thermal Comfort Tool by measuring the thermal variables around the evaporator area and by calculating the Heat Stress Index (HSI). The operator productivity is analyzed by Wet Bulb Globe Thermometer (WBGT) Work-Rest Chart. The PD of operators before and after improvement is compared. The results showed that the average temperature around the operators area at evaporator station is high with average WBGT of 33,6°C. HSI value is 51.95 indicating that the effect of 8-h exposure is severe strain with work impact is health threat for unit operators and acclimatization is necessary. The PD value is 96% indicating that almost all operators feel uncomfortable at work. These indicate that the thermal environment should be improved. The proposed improvement is by installing water cooled and sprayed into the evaporator area. This installation is able to reduce HSI and PD by more 70% and more 60%, respectively. These findings indicate that improving the thermal environment will be able to improve working comfort which will further affect the level of work productivity.

The Environment Canada Pan and Parapan American Science Showcase Project

AbstractThe Pan and Parapan American Games (PA15) are the third largest sporting event in the world and were held in Toronto in the summer of 2015 (10–26 July and 7–15 August). This was used as an opportunity to coordinate and showcase existing innovative research and development activities related to weather, air quality (AQ), and health at Environment and Climate Change Canada. New observational technologies included weather stations based on compact sensors that were augmented with black globe thermometers, two Doppler lidars, two wave buoys, a 3D lightning mapping array, two new AQ stations, and low-cost AQ and ultraviolet sensors. These were supplemented by observations from other agencies, four mobile vehicles, two mobile AQ laboratories, and two supersites with enhanced vertical profiling. High-resolution modeling for weather (250 m and 1 km), AQ (2.5 km), lake circulation (2 km), and wave models (250-m, 1-km, and 2.5-km ensembles) were run. The focus of the science, which guided the design of the observation network, was to characterize and investigate the lake breeze, which affects thunderstorm initiation, air pollutant transport, and heat stress. Experimental forecasts and nowcasts were provided by research support desks. Web portals provided access to the experimental products for other government departments, public health authorities, and PA15 decision-makers. The data have been released through the government of Canada’s Open Data Portal and as a World Meteorological Organization’s Global Atmospheric Watch Urban Research Meteorology and Environment dataset.

Tear osmolarity is sensitive to exercise-induced fluid loss but is not associated with common hydration measures in a field setting

ABSTRACTThis investigation (i) examined changes in tear osmolarity in response to fluid loss that occurs with exercise in a field setting, and (ii) compared tear osmolarity with common field and laboratory hydration measures. Sixty-three participants [age 27.8 ± 8.4 years, body mass 72.15 ± 10.61 kg] completed a self-paced 10 km run outside on a predetermined course. Body mass, tear fluid, venous blood and urine samples were collected immediately before and after exercise. Significant (p < 0.001) reductions in body mass (1.71 ± 0.44%) and increases in tear osmolarity (8 ± 15 mOsm.L−1), plasma osmolality (7 ± 8 mOsm.kg−1), and urine specific gravity (0.0014 ± 0.0042 g.mL−1; p = 0.008) were observed following exercise. Pre- to post-exercise change in tear osmolarity was not significantly correlated (all p > 0.05) with plasma osmolality (rs = 0.24), urine osmolality (rs = 0.14), urine specific gravity (rs = 0.13) or relative body mass loss (r = 0.20). Tear osmolarity is responsive to exercise-induced fluid loss but does not correlate with the changes observed using other common measures of hydration status in the field setting. Practitioners shouldn’t directly compare or replace other common hydration measures with tear osmolarity in the field.Abbreviations: BML: Body Mass Loss; CV: Coefficient of Variation; Posm: Plasma osmolality; SD: Standard Deviation; Tosm: Tear Osmolarity; Uosm: Urine Osmolality; USG: Urine Specific Gravity; WBGT: Wet bulb globe thermometer

Infrared thermography as a method for evaluating the heat tolerance in dairy cows

The objective of this study was to determine whether infrared thermography is a useful tool for the recognition of dairy cows in a state of thermal heat stress, as well as to identify the best region of the animal to be evaluated for this recognition. Physiological variables, including rectal temperature, respiratory frequency, cardiac frequency, and panting score were recorded in 38 lactating cows. For the assessment of environmental parameters, a digital black globe thermometer (TGD-200 model) was used. Thermographic photographs of different regions of the body of cows were taken using an infrared camera (FLIR® System T300) and indicated respective superficial temperature. Physiological variables and superficial body temperature in different regions varied between genetic groups (Girolando: ½ Holstein × ½ Gir and ¾ Holstein × ¼ Gir; purebred Holstein). The environmental temperature ranged from 20.7 to 37.9 °C with a relative humidity reaching 95%. The mean rectal temperature (40.84 °C), respiratory frequency (111.36 breaths/min), and cardiac frequency (99.22 beats/min) were higher for pure Holstein than for Girolando cows. Positive correlations were found between the physiological parameters and thermographic measures. The highest positive correlation (0.74) was found between the temperature in the lateral region of the udder and rectal temperature. Thermography is a good indicator of thermal comfort. The best region to identify heat stress in cows using thermography is the lateral region of the udder.

Risk of exposure to heatstroke in sugarcane workers in São Paulo State, Brazil

Environmental heat is an aggravating factor for sugarcane workers, and manual cane cutting is one of the heavy work activities that favor the generation of metabolic heat. This can combine with other precarious working conditions to produce heatstroke, potentially leading to serious complications and even death. The study aimed to quantify the risk of overheating in sugarcane cutters in São Paulo, Brazil. Drawing on a specific methodology, the study used four years of data to estimate the Globe Thermometer Wet Bulb Index based on light, moderate, and heavy activities. The results showed that the legal limit was exceeded for continuous activity in periods from 1 to 8 hours, which requires control measures in order to continue working. The principal observation was the risk of heatstroke in the three types of activity: light, moderate, and heavy. The limits were exceeded throughout the work shift on 7% of the days for heavy activity and on 3% of the days for moderate activity. In addition, the areas with the highest risk of heatstroke coincide with predominant cane-growing.

A Low-Cost Environmental Monitoring System: How to Prevent Systematic Errors in the Design Phase through the Combined Use of Additive Manufacturing and Thermographic Techniques

nEMoS (nano Environmental Monitoring System) is a 3D-printed device built following the Do-It-Yourself (DIY) approach. It can be connected to the web and it can be used to assess indoor environmental quality (IEQ). It is built using some low-cost sensors connected to an Arduino microcontroller board. The device is assembled in a small-sized case and both thermohygrometric sensors used to measure the air temperature and relative humidity, and the globe thermometer used to measure the radiant temperature, can be subject to thermal effects due to overheating of some nearby components. A thermographic analysis was made to rule out this possibility. The paper shows how the pervasive technique of additive manufacturing can be combined with the more traditional thermographic techniques to redesign the case and to verify the accuracy of the optimized system in order to prevent instrumental systematic errors in terms of the difference between experimental and actual values of the above-mentioned environmental parameters.

Calibration of Heat Stress Monitor and its Measurement Uncertainty

Wet-bulb globe temperature (WBGT) equation is a heat stress index that gives information for the workers in the industrial areas. WBGT equation is described in ISO Standard 7243 (ISO 7243 in Hot environments—estimation of the heat stress on working man, based on the WBGT index, ISO, Geneva, 1982). WBGT is the result of the combined quantitative effects of the natural wet-bulb temperature, dry-bulb temperature, and air temperature. WBGT is a calculated parameter. WBGT uses input estimates, and heat stress monitor measures these quantities. In this study, the calibration method of a heat stress monitor is described, and the model function for measurement uncertainty is given. Sensitivity coefficients were derived according to GUM. Two-pressure humidity generators were used to generate a controlled environment. Heat stress monitor was calibrated inside of the generator. Two-pressure humidity generator, which is located in Turkish Standard Institution, was used as the reference device. This device is traceable to national standards. Two-pressure humidity generator includes reference temperature Pt-100 sensors. The reference sensor was sheltered with a wet wick for the calibration of natural wet-bulb thermometer. The reference sensor was centred into a black globe that has got 150 mm diameter for the calibration of the black globe thermometer.

Offering a model for estimating black globe temperature according to meteorological measurements

ABSTRACTBlack globe temperature (Tg) is one of the most common measurement variables used for assessing heat stress; however, it is usually not reported in meteorological data. This study developed a model to estimate Tg based on meteorological measurements, in order to calculate the occupational heat stress index in outdoor workplaces. This descriptive and analytical study was conducted from May to September 2013 in Qom, Iran. Environmental variables such as natural wet‐bulb temperature (Tnw), dry‐bulb temperature (Ta), solar radiation (SR) and relative humidity (RH) were measured by meteorological instruments in weather stations and Tg was measured by a globe thermometer in the same situations at different times. Data were analysed using IBM SPSS16. Independent variables including Tnw, Ta, SR and RH and the dependent variable Tg were introduced to the software, and several regression models were obtained. Finally, a model that had the most appropriate correlation with a significance level of 0.05 was chosen as the best model. The correlation co‐efficients between Tg and Tnw, Ta, SR and RH were obtained as 0.84, 0.63, 0.75 and −0.75, respectively. The results showed that Ta, SR and RH can justify about 90% of the variation in Tg. There was a significant relationship between Tg and Ta, SR and RH (p &lt; 0.05). The correlation co‐efficient between actual and estimated data was 0.95 (p &lt; 0.001). The model obtained can be trusted to estimate the black globe temperature in a hot and dry environment and can be useful in assessing occupational heat stress in outdoor workplaces.

Impact of glazing to wall ratio in various climatic regions: A case study

It is architecturally accepted that glazing system is considered as the most fragile part of buildings in terms of energy indoor performance. It is the only part of the building which has direct solar gain due to the transparent materials. Consequently, this part of building envelope should reap high consideration by architects and engineers, particularly in regions where solar radiation is high. The research aims to investigate the influence of glazing to wall ratio in different microclimate regions in Saudi Arabia which has been introduced by the author hot dry, hot humid and moderate climates. The research has studied the most possible glazing ration in the region based on previous work 5%, 10%, 20%, 30% and 40% out of the external wall. The paper used computer modelling TAS EDSL which has been validated using field monitoring study. Moreover, globe thermometer be used in order to investigate the impact of student’s position with respect to glazing system. Finally, questionnaire will be utilised to obtain actual thermal comfort from students in the selected regions with maintaining the same PSBD. The study reveals that south and east directions are the worst in terms of gaining the maximum amount of heat in all the locations. The research suggest that glazing to wall ratio is recommended to be 10% in both climate conditions hot and dry and hot and humid.

Identifying potential effects from anthropometric variables on outdoor thermal comfort

In this study, we carried out outdoor thermal comfort surveys with pedestrians during warm periods of the year throughout 2012 to 2015 in downtown Rio de Janeiro, Brazil. Monitoring points were defined in respect of urban geometry attributes. For the measurements, a light-weight weather station was used, to which a gray globe thermometer was attached. The ‘Universal Thermal Climate Index’ (UTCI) and the derived ‘Dynamic Thermal Sensation’ (DTS) units were used as baseline for comparisons with reported thermal sensation votes from 985 respondents. The survey questionnaire included questions as regards thermal perception as well as personal, self-reported characteristics of the respondents. We analyze results in terms of influencing aspects on reported thermal sensation due to anthropometric characteristics of the sample, including gender, age, body mass and skin colour. Results point to the statistical significance of body mass as well as skin colour in moderating the effect of thermal conditions on users' thermal judgement. Gender effects were found to be insignificant whereas age impacts can be a matter of concern in climate-sensitive urban design. In the multivariate regression equation obtained from raw data, along with the meteorological data only skin colour was found to be a good predictor, slightly improving its predictive power.

Assessing the accuracy of globe thermometer method in predicting outdoor mean radiant temperature under Malaysia tropical microclimate

Assessing outdoor human thermal comfort and urban climate quality require experimental investigation of microclimatic conditions and their variations in open urban spaces. For this, it is essential to provide quantitative information on air temperature, humidity, wind velocity and mean radiant temperature. These parameters can be quantified directly except mean radiant temperature (Tmrt). The most accurate method to quantify Tmrt is integral radiation measurements (3-D shortwave and long-wave) which require using expensive radiometer instruments. To overcome this limitation the well-known globe thermometer method was suggested to calculate Tmrt. The aim of this study was to assess the possibility of using indoor globe thermometer method in predicting outdoor mean radiant temperature under Malaysia tropical microclimate. Globe thermometer method using small and large sizes of black-painted copper globes (50mm, 150mm) were used to estimate Tmrt and compare it with the reference Tmrt estimated by integral radiation method. The results revealed that the globe thermometer method considerably overestimated Tmrt during the middle of the day and slightly underestimated it in the morning and late evening. The difference between the two methods was obvious when the amount of incoming solar radiation was high. The results also showed that the effect of globe size on the estimated Tmrt is mostly small. Though, the estimated Tmrt by the small globe showed a relatively large amount of scattering caused by rapid changes in radiation and wind speed.

The globe thermometer in comfort and environmental studies in buildings

The reasons for the inferior performance of many existing buildings and associated energy systems are diverse, but an important part-cause is insufficient attention to the influence of occupant behaviour. In smart buildings it is necessary to allow for the integration of human behaviour in the HVAC system. In addition, many researchers are limited in their investigation by not having low cost tools that can provide information for their studies. This article is a review of the present state of art about the globe thermometer. It describes how to build your own globe temperature sensor and describes experiments that illustrate the feasibility of using a black globe thermometer with 40 mm diameter.

Analysis of Thermal Comfort in Flat in New High Residential Building

This paper focuses on the analysis of thermal comfort in a flat in the new high residential building. Providing the optimal parameters of thermal comfort in each room of the flat is the basic prerequisite for the satisfaction with housing. Incorrect position and size of heating elements, incorrect positioning of the furniture and incorrect use of residential interiors may significantly disturb the thermal comfort. Residential areas in the new residential buildings are much more intensively used as in the other types of buildings. Surface of new flats is the most optimized. Experimental measurements were carried out in the winter season in 2016 in the residential rooms of the large flat in the new high residential building. Device Testo 480 with temperature and humidity sensor, globe thermometer and turbulence sensor was used for the measurements. Obtained values of air temperature, air relative humidity, air velocity, globe temperature and indexes PMV, PPD are presented in the graphs. Heating system of the flat and the possibility of its regulation, positioning and size of the heating elements in the individual rooms, positioning of the furniture and the utilization of rooms were evaluated on the basis of parameters of thermal comfort. In the conclusion of the paper, there are principles on the architectural design of the residential interiors and their heating in the new residential buildings.

Validation of Environmental Stress Index by Measuring Infrared Radiation as a Substitute for Solar Radiation in Indoor Workplaces

Background: The exposure of individuals to heat at different jobs warrants the use of heat stress evaluation indices. Objectives: The aim of this study was to validate environmental stress index using an infrared radiation (IR) measurement instrument as a substitute for pyranometer in indoor workplaces. Methods: This study was conducted on 2303 indoor workstations in different industries in Isfahan, Iran, during July, August, and September in 2012. The intensity of the Infrared Radiation (IR) (w/m2) was measured at five-centimeter distances in six different directions, above, opposite, right, left, behind and below the globe thermometer. Then, the dry globe temperature (Ta), wet globe temperature (Tnw), globe temperature (Tg) and relative humidity (RH) were also simultaneously measured. The data were analyzed using correlation and regression by the SPSS18 software. Results: The study results indicate that a high correlation (r = 0.96) exists between the environmental stress index (ESI) and the values of wet bulb globe temperature (P < 0.01). According to the following equation, WBGT = 1.086 × ESI - 1.846, the environmental stress index is able to explain 91% (R2 = 0.91) of the WBGT index variations (P < 0.01). Conclusions: Based on the results, to study heat stress in indoor workplaces when the WBGT measurement instrument is not available and also in short-term exposures (shorter than 30 minutes) when measuring the wet bulb globe temperature shows a considerable error, it is possible to calculate the environmental stress index and accordingly to the WBGT index, by measuring the parameters of dry bulb temperature (Ta), relative humidity (RH), and infrared radiation intensity that can be easily measured in a short time.