Thermal Comfort Issues Research Articles

MODERN METHODS OF THERMAL COMFORT MEASUREMENTS

The issue of thermal comfort and its subjective feelings inside a building is becoming more and more important in the modern world. It is caused by the desire to create optimal conditions in places where people stay. The article presents two methods, indirect and direct, which are typically used in the research projects. These methods enable to assess the thermal sensations of people and compare the feelings of the respondents with the value of PMV (the value of human thermal sensations) calculated using the formula from the ISO 7730 standard and the questionnaire surveys.

A Literature Review of Naturally Ventilated Public Hospital Wards in Tropical Climate Countries for Thermal Comfort and Energy Saving Improvements

The tropical climate with its high average temperatures throughout the year affects the thermal comfort of buildings, especially for naturally ventilated spaces. The government’s move to turn hospitals into green buildings is seen in line with the global commitment to conserve the environment and the country’s current policy of supporting sustainable development. To achieve this goal, energy efficiency and thermal comfort need to be given priority in the focus on hospital planning and implementation for a better quality of the indoor environment. This literature review has led to the need to improve thermal comfort in natural ventilated wards in government hospitals. Some wards are built without air conditioning to save on construction costs, reduce utility costs through low energy consumption, as well as the need for infection control and airborne infections. However, current climate change requires a special study of thermal comfort in wards that use natural ventilation. An innovative solution is proposed to solve the problem statement identified in the reviewed literature through the application of solar PV/T systems and heat pumps. This hybrid system re-uses the heat energy (cogeneration) generated from solar PV panels to be cooled by heat pumps and is then pumped into the ward for cooling purposes. The proposed system has the potential to improve thermal comfort in natural ventilation wards and increase efficiency of the solar PV system for optimal electricity generation as well as improve the overall energy performance of buildings through low-energy cooling systems. It is not only solving the thermal comfort issue but also avoid the use of extra energy for cooling by optimizing the renewable energy.

Thermal Performance of Nepalese Building- A Case Study of Dhulikhel and Biratnagar

Nepal has wide variation in altitude, so does its climate, lifestyle and housing. The building design code issued by the Government of Nepal does not address the issue of thermal comfort, which could be the reason the modern buildings built under the design code are performing poorly in terms of indoor thermal comfort. As a result, people have largely compromised in accommodation. The research includes selection of two representative buildings (at Biratnagar and Dhulikhel) followed by real time monitoring of indoor climate (temperature and Relative humidity). The logged data was used to calibrate the computer model. The model was approximated to real scenario including indoor heat loads from people, lighting, electric equipment and infiltration. Building energy modeling was done in EnergyPlus. The research work depicts the thermal performance of building by comparing the indoor climate of selected buildings of Biratnagar and Dhulikhel with the ASHARE suggested thermal comfort level for humans. The major problem found in the buildings of Biratnagar was overheating for more than 6 months period while for Dhulikhel was under heating for more than 4 months period. The author suggests further research to analyze passive techniques to improve thermal performance and reduce active energy consumption.

Performance Simulation and Analysis of Occupancy-Based Control for Office Buildings with Variable-Air-Volume Systems

Variable-air-volume (VAV) systems are used in many office buildings. The minimum airflow rate setting of VAV terminal boxes has a significant impact on both energy consumption and indoor air quality. Conventional controls usually have the terminal’s minimum airflow rate at a constant (e.g., 30% or more of the terminal design airflow rate), irrespective of the occupancy status, which may cause problems, such as excessive simultaneous heating and cooling, under ventilation, and thermal comfort issues. This paper examines the potential of energy savings from occupancy-based controls (OBCs). The sensed occupancy information, either occupant presence or people count, is used to determine the airflow rate of terminal boxes, the thermostat setpoints, and the lighting control. Using EnergyPlus, a whole-building energy modeling software, the energy savings of OBC strategies are evaluated for representative existing medium office buildings in the U.S. The simulation results show that the conventional OBC, based on occupant presence sensing, can save 8% of whole-building energy use in Miami (hot climate) for systems without air-side economizer and about 13% in both Baltimore (mixed climate) and Chicago (cold climate). Comparatively, the advanced OBC, based on people counting, can save 8% in Miami to 23% in Baltimore for systems with economizers. The outdoor-air fraction of the supply air from air-handling units significantly affects the potential energy savings from the advanced OBC strategy. In addition to energy savings, the advanced OBC satisfies the zone ventilation during all occupied hours over the whole year.

Modeling of thermal performance of multilayer protective clothing exposed to radiant heat

Studies presented in this paper concern wide issue of thermal comfort of protective clothing. The Computer Aided Design (CAD) software tools to analyze thermal insulation of multilayer textile assembly used in thermal protective clothing were applied. First, 3D geometry and morphology of a real textile assembly was modeled. In the designed model different scales of resolution were used for individual layers, ranging from a homogenized nonwoven fabrics model to mapping the geometry of yarns in woven fabrics model. Next, the finite volume method to estimate thermal insulation properties of this assembly, when exposed to heat radiation, was used. Finally, the simulation results were verified experimentally using method described in EN ISO 6942. On the basis of both simulation and experimental results obtained for the multilayer textile assembly, protective clothing parameters directly affecting the ability to protect against heat, were determined. Correlating simulated and experimental values of these parameters were obtained, which may indicate that applied software can be an effective tool in analyzing thermal properties of newly designed multilayer functional clothing.

Verification of the Fanger Model in Real Conditions

This study presents the issue of thermal comfort based on the Fanger model. The research was conducted in 5 rooms in the autumn-winter period. The research consisted of measurement of thermal environment parameters, air temperature and flow rate, relative air humidity, globe temperature sensor and light intensity. During the research, the students filled in questionnaires concerning thermal sensation. This allowed them to express their assessment of thermal comfort (predicted mean vote PMV and predicted percentage of dissatisfied PPD), as well as their preferences concerning the prevailing room conditions. Differences between the actual average predicted rating index and the Fanger model were shown. It can be noted that Fanger’s model does not reflect the results of the respondents.

Passive cooling techniques

Passive cooling techniques

Learning from the past: Temporary housing criteria in conflict areas with reference to thermal comfort

Emergency shelter is usually provided in natural or man-made disaster situations. In the case of long sheltering periods, it may be called temporary housing. This study aims to investigate this notion with reference to the Gaza Strip experience. A survey was first carried out with local specialists in the field to discuss the policies and solutions that have been implemented to shelter displaced people in Gaza. Based on the output of this survey, design criteria were implemented for a proposed conceptual design of temporary housing units based on the reuse and adaptation of shipping containers. The criteria established include the issue of thermal comfort, which was a main point of weakness, to a dangerous level, in previous sheltering solutions implemented in Gaza. Thus, a parametric numerical assessment of thermal comfort conditions in the proposed temporary housing unit was carried out. The assessment examined the effect of three design measures to improve thermal comfort as follows: reducing solar absorption, grouping of units, and using thermal insulation in walls and roofs. The study results show that it is very difficult to achieve thermal comfort and ensure the safety of displaced people in the examined temporary housing units, considering the hot climate of Gaza, without the use of well-designed thermal insulation.

The Study of Footwear Thermal Insulation Using Thermography and the Finite Volume Method

The paper concerned the issue of ergonomics and thermal comfort of footwear. The presented work was an attempt to apply selected modeling CAD software and the finite volume method for analysis of heat transfer through footwear between the shoes’ user and his surroundings. Based on the actual two selected sport shoes, three-dimensional models have been designed, taking into account their different geometry and raw material composition. The models used simplifications related to the internal construction (in microscale) of the specific parts of the footwear (sole, insole, shank, lining and tongue). The main purpose of the work was to determine the influence of the simplifications used on the accuracy of simulation as a tool to predict thermal insulation of real shoes determined by means of thermal imaging camera. The simulations results were in correlation with the experiment and showed that applied software can be an effective tool in studying the thermophysiological properties of footwear.

Comparison of microclimate measurements and perceptions as part of a global evaluation of environmental quality at neighbourhood scale

The EUREQUA project raises the issue of the definition and evaluation of the environmental quality of neighbourhoods. The approach consists of integrating and cross-referencing observable data characterising the physical environment and people’s perception of their quality of life. The study area is a neighbourhood in Toulouse (France) with high social and typo-morphological diversity, subject to noise and air pollution nuisances. Three 3-day field campaigns were organised in January, April, and June 2014. Instrumented and commented walks took place three times per day. For each one, measurements of physical environmental parameters and surveys were performed simultaneously at six locations in the neighbourhood. The study focuses on microclimate and thermal comfort issues. It aims to compare in situ meteorological data of air temperature, humidity, wind speed, and mean radiant temperature, with quantitative results rating human perception of heat, humidity, wind, and thermal comfort. The variability in perception and measurements is mainly driven by seasonal effects, especially for heat and humidity, and, to a lesser extent, for wind. Wind perception and measurement also vary spatially, thus highlighting site effects. Linear models indicate a positive link between heat perception and mean radiant temperature, as well as between wind perception and mean and standard deviation of wind speed (with a higher sensitivity of people to wind under winter climate conditions). Finally, it is found that perception of thermal comfort is only slightly linked to the different microclimate dimensions, and is rather driven by other appreciation factors and emotional criteria related to the general environmental quality of the study area.

The Quality Living; A Main Rating Category for Sustainable New Construction in Egypt

This paper is made to describe the Quality Living category which is one of the main categories of the proposed sustainable rating & certification system for new construction in Egypt presented by the accredited Ph.D. research made for the purpose of promoting the sustainable building practices and embracing the potential of green buildings in Egypt. The terms Quality Living, Indoor Environmental Quality, and Health & Wellbeing, as some of these terms are stated in different international sustainable rating systems, are all focusing to encourage the promotion of occupants’ productivity, comfort, and well-being by prioritizing the social and environmental sustainable parameters within the building design to offer a better quality of life rather than keeping the economical concern as the only prevailing priority for new construction in Egypt. The Quality Living category, as described below, is having an assembly of mandatory and scoring credits based on the sustainability three bottom lines; environmental, social, and economical aspects which can promote the quality living issues in new construction including the health comfort, air comfort, thermal comfort, visual comfort, nuisance management, and safety management issues.

Relationship of Wind Movement to Thermal Comfort at the Fencing House in Samarinda

In fulfilling the thermal comfort level in the room can be carried out efforts to control the effect of climate on the building. In this case of wind and thermal comfort issues, passive control efforts, such as examples of the potential for air movement for ventilation and air exchange, are possible. The room of air movement is necessary because it plays an important role in achieving comfort in the room. While the temperature or humidity of the air inside the room is high, but there is sufficient air movement then the thermal comfort of the space can be achieved. The movement of air outside the building into space can also serve to cool the space. In addition, the movement of air can release heat from the surface of the skin through evaporative cooling (evaporative cooling). The greater the speed of air movement, the more heat that can be removed from the surface of the Human body. The purpose of this study is to examine the relation of wind movement to thermal comfort by connecting wind movement to thermal comfort in the fencing room to find out the cause and to produce good and convenient design concepts applied to fencing building in Samarinda. Quantitative data from the observation and measurement in the form of field data comparable with the theory, to obtain a thermal comfort findings at fencing in Samarinda.

Hybrid system of an indirect evaporative air cooler and HDH desalination system assisted by solar energy for remote areas

This paper presents an experimental investigation of a hybrid system of indirect evaporative air cooler and HDH desalination system assisted by solar energy for remote areas. Due to the unavailability of fresh water sources and as a result of rising ambient air temperature in most remote areas, the proposed system is a good option for these remote areas. In order to achieve this goal in remote areas, the practical apparatus proposed in this study consists of two sub-systems: (i) indirect evaporative air cooler with baffles, which can use to human thermal comfort issues, (ii) HDH desalination system assisted by the solar energy, which can use to produce the freshwater. The results of the experimental study showed that the cooling load was ranged between 253.26 and 417.4 W, accumulated distillate water productivity was 38.65 l/day, and the coefficient of performance ranged between 0.214 and 3.49 at the air flow rate of 70 m3/h during the period 8:00 am–6:00 pm. Also, as the secondary air flow rate increases from 60 to 90 m3/h, accumulated distillate water productivity increases from 35.78 to 47.21 l/day, and average daily coefficient of performance increases from 1.78 to 2.256. The proposed system in this study represents an effective and good selection in remote areas.

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.

Objective and subjective evaluation of thermal comfort in the Loccioni Leaf Lab

Thermostatically controlled loads in commercial buildings are usually ruled by set points indicated by well-established international standards like EN 15251. These thresholds set the acceptable comfort ranges based on several parameters such as activity level, climatic conditions and building orientation. However, there are so many aspects which can affect the occupant perception of comfort ranging from physical and mental aspects to cultural aspects while only few of them are clearly measurable.This paper presents a methodology for the simultaneous subjective and objective evaluation of thermal comfort in commercial buildings. The methodology is based on the intermediate protocol level for the evaluation of thermal comfort as suggested by ASHRAE’s Performance Measurement Protocols for Commercial Buildings. It is applied in the office spaces of the Loccioni Leaf Lab, located in the province of Ancona, Italy, during the summer period. The study is utilized for the identification of serious thermal comfort issues but also for the determination of the preferred comfort conditions in the Leaf Lab office spaces.

Performance evaluation of a solar energy assisted hybrid desiccant air conditioner integrated with HDH desalination system

In this study, the performances of a solar energy assisted hybrid desiccant air conditioning system integrated with humidification–dehumidification (HDH) desalination system are numerically investigated. The aim of this study is to benefit from the temperature rise of the regeneration air outside of the desiccant conditioning system as well as the water vapor content in this regeneration air by feeding it to the humidification-dehumidification water desalination unit to produce distillate water. The distillate water productivity, human thermal comfort issues, and energy saving represent the main objective of the present numerical study. The simulated results developed for subsystems are validated with the published experimental results. The effects of regeneration air temperature and flow rate on supply cooled air temperature, distillate water productivity, the cooling coefficient of performance and overall daily coefficient of performance of the proposed system are investigated. The results show that (i) the distillate water productivity increases from 3.175 to 5.011L/h and overall daily coefficient of performance decreases from 4.392 to 3.636 with increasing the regeneration air temperature from 75 to 95 as (ii) the increase in the regeneration air flow rate from 70 to 130 m3/h, increases the distillate water productivity from 2.988 to 4.78L/h and decrease the overall daily coefficient of performance from 4.66 to 3.386. The study demonstrates that the proposed system represents the best options in hot and humid regions.

The issue of thermal comfort of medical clothing in the operating room

La ropa médica tiene la función principal de protección. Sin embargo, esta función debe estar correlacionada con una buena experiencia de comodidad para el usuario. La comodidad es un tema muy importante, ya que los profesionales están expuestos a situaciones de estrés que pueden influir, negativamente, en su desempeño laboral. Más específico, el confort térmico juega un papel crucial para el mejor rendimiento de la ropa médica usado en la sala de operaciones, que implica la regulación del calor y la transferencia de masa entre un cuerpo vestido y el medio ambiente, una vez que la ropa es la interfaz entre el cuerpo y el medio ambiente. El objetivo de este trabajo fue estudiar el comportamiento de propiedades térmicas de batas quirúrgicos y trajes de aire limpio usados en la sala de operaciones. Se realizó una comparación entre estos dos tipos de prendas con equipos Alambeta, para propiedades térmicas estacionarias y un Maniquí Térmico, para propriedades dinâmicas, como el flujo de calor y el aislamiento térmico. Se encontró que el aislamiento térmico de las prendas es estadísticamente diferente, mostrando que la diferencia entre los trajes puede ser percibida por el usuario.

Influence of sinusoidal airflow and airflow distance on human thermal response to a personalized ventilation system

Since the concept of personalized ventilation was introduced in the late 1990s, many studies on thermal comfort have been conducted and a number of parameters identified. In this research, the influence of three parameters, the airflow speed, airflow fluctuating period and a parameter which has drawn less attention in previous studies – the airflow distance between the human subject and the nozzle of the personalized ventilation device on air movement perception, thermal sensation and thermal comfort – are studied. The combinations of fluctuating period and airflow amplitude were selected based on the Power Spectrum Density method. Then 25 human subjects participated in the thermal comfort experiment, each of them underwent 54 tests of different experimental conditions and expressed their thermal feelings by completing the survey questionnaire. Our findings showed that a longer airflow distance could lead to cooler thermal sensation, but not cause any difference in thermal comfort. Changing the fluctuating period of the sinusoidal airflow from 10 s to 60 s did not cause an influence on thermal sensation, but a shorter fluctuating period could result in a higher air movement perception. When dealing with thermal comfort issues, a joint effect with airflow speed and fluctuating period occurs and this should also be considered.

The study of knitted fabric thermal insulation using thermography and finite volume method

The article concerns the widespread issue of thermal comfort; investigations into textiles and thermal insulation problems are presented. Materials that were tested include double-layer knitted fabrics with potential application in multi-layer garments addressed to a specific group of users. The investigated materials were constructed with the following raw materials: cotton, polypropylene, polyester, polyamide, bamboo, and viscose. The textiles with a comparable geometric structure and different composition were tested for their thermal insulation. In the experimental section the temperature gradients in specific constant ambient conditions using a thermal imaging camera were obtained. In the simulation section three-dimensional models of actual textiles were designed and the temperature gradients on the basis of performed simulations were calculated. Both measurements and simulations yielded comparable results and showed that the comparatively thick knitted fabrics’ thermal insulation strongly depends on the raw materials from which they were made and less on the parameters of the yarn.

Urban sustainability in the Arabian Gulf: Air conditioning and its alternatives

This paper examines shifting approaches to urban sustainability in the Arabian Gulf by focusing on the issue of air conditioning and thermal comfort. It considers the recent foregrounding of tradition and heritage within the arena of mega-project development in Qatar, using the Msheireb Downtown Doha Project as an example of a wider regional trend around urban sustainability. Through its focus on air conditioning, the paper draws on Appadurai’s recent critique of design singularity to examine built environment sustainability in relation to the indoor comfort norms and practices, for both bodies and objects, which are now well established across the Gulf region.