Thermal sensations and comfort investigations in transient conditions in tropical office

A review of occupancy-based building energy and IEQ controls and its future post-COVID

Occupancy schedules and density can have a substantial influence on building plug, lighting, and air conditioning energy usage. In recent years, the study related to occupancy and its impact on building energy consumption has gained momentum and is also promoted by ASHRAE as it has created a multi-disciplinary group to encourage a comprehensive study of occupant behaviour in buildings. Past studies suggest that building systems do not consume the same energy and provide similar Indoor Environmental Quality (IEQ) to their designed specifications due to inaccurate assumptions of occupants and their behaviour. Supplying ASHRAE 62.1 specified minimum required ventilation based on accurate occupancy may lead to significant air-conditioning energy savings. However, the same strategy is not suitable in the current time since minimum required ventilation may not be sufficient to mitigate the SARS-CoV-2 virus spread in confined spaces. High-temperature cooling augmented with elevated air movement across an acceptable range of velocity can maintain the health and comfort of occupants by providing higher ventilation and without an energy penalty. The analysis of the literature highlights strengths, weaknesses, and key observations about the existing occupancy monitoring and occupancy-based building system control methods to help in the direction of future occupancy-based research.

Design of sports clothing for hot environments

The clothing design based on sweat distribution pattern is called as body mapping clothing. Comparisons of three designs of body mapped and one conventional design of T-shirt was done in a wearer testing at a controlled chamber of 33 °C and 60% relativity humidity in a treadmill at 12 km/h for 40 min followed by 10 min resting. It is concluded that with the full body mapped T-shirt the increase in skin temperature is reduced in the chest area, shoulder, the body back by 47%,44% and 55% respectively; the increase in skin micro climate relative humidity is reduced in the chest area, shoulder, the body back by 54%,39.2% and 53% respectively; the increase in heart beat rate is reduced by 5.1%; the subjective perceptions of skin temperature, skin moisture and comfort are better; the wearer will be able to improve the running performance due better comfort level in terms lesser increase skin temperature, skin micro climate relative humidity and heart beat rate.

Field study of thermal comfort in non-air-conditioned buildings in a tropical island climate

The unique geographical location of Hainan makes its climate characteristics different from inland areas in China. The thermal comfort of Hainan also owes its uniqueness to its tropical island climate. In the past decades, there have been very few studies on thermal comfort of the residents in tropical island areas in China. A thermal environment test for different types of buildings in Hainan and a thermal comfort field investigation of 1944 subjects were conducted over a period of about two months. The results of the survey data show that a high humidity environment did not have a significant impact on human comfort. The neutral temperature for the residents in tropical island areas was 26.1 °C, and the acceptable temperature range of thermal comfort was from 23.1 °C to 29.1 °C. Residents living in tropical island areas showed higher heat resistance capacity, but lower cold tolerance than predicted. The neutral temperature for females (26.3 °C) was higher than for males (25.8 °C). Additionally, females were more sensitive to air temperature than males. The research conclusions can play a guiding role in the thermal environment design of green buildings in Hainan Province.

Certain personal and environmental factors as predictors of thermal sensation perceived by a population of students in a university setting from Timisoara, Romania: a case study

Background

The aim of the performed study was to investigate personal and environmental factors as predictors of thermal sensation perceived by a population of students in a university setting.

Methods

The study consisted of two samples, a winter sample (154 students: 44.2% males and 55.8% females, aged 19–30 years) and a spring sample (147 students: 52.4% males and 47.6% females, aged 19–30 years), randomly selected from the same population of students. The method was an observational inquiry (case study) with a standardized questionnaire (11 items, 3 items for thermal sensation assessing through 3 scales with 3, 5 and 7 steps, alpha Cronbach’s index 0.854) applied and establishing 3 microclimate factors (air temperature, relative humidity and wind velocity), with calculation of normal effective temperature. The survey was performed over four successive days, during two seasons (winter—February and spring—May).

Results

The performed study demonstrated a tendency of students to perceive the comfortably cold more frequently than comfortably warm throughout the 4 days of the survey during the winter, except Monday. Thermal sensation of discomfort was more frequently perceived as warm than cold throughout the spring time of the survey and winter, except Tuesday. Predictors of thermal sensation perceived by students in the amphitheatre were as follows: nationality (−2loglikelihood change or chi square = 42.12, Sig. 0.000), relative humidity (chi square = 10.65, Sig. 0.005) and gender during the winter, and wind velocity (change in −2loglikelihood = 11.96, Sig. 0.001) and nationality during the spring.

Conclusions

Certain personal and environmental factors were suggested as predictors for thermal sensation perceived by a population of students in a study setting.

Integrating a human thermoregulatory model with a clothing model to predict core and skin temperatures

This paper aims to integrate a human thermoregulatory model with a clothing model to predict core and skin temperatures. The human thermoregulatory model, consisting of an active system and a passive system, was used to determine the thermoregulation and heat exchanges within the body. The clothing model simulated heat and moisture transfer from the human skin to the environment through the microenvironment and fabric. In this clothing model, the air gap between skin and clothing, as well as clothing properties such as thickness, thermal conductivity, density, porosity, and tortuosity were taken into consideration. The simulated core and mean skin temperatures were compared to the published experimental results of subject tests at three levels of ambient temperatures of 20 °C, 30 °C, and 40 °C. Although lower signal-to-noise-ratio was observed, the developed model demonstrated positive performance at predicting core temperatures with a maximum difference between the simulations and measurements of no more than 0.43 °C. Generally, the current model predicted the mean skin temperatures with reasonable accuracy. It could be applied to predict human physiological responses and assess thermal comfort and heat stress.