Top PDF Analysis of the thermal comfort and energy performance of a thermal chair for open plan office

Analysis of the thermal comfort and energy performance of a thermal chair for open plan office

Analysis of the thermal comfort and energy performance of a thermal chair for open plan office

offices/buildings with thermal chairs. A recent study by Veselý et al. [47] numerically investigated the energy performance of a personalised heating systems in a medium sized office in relation to the building fabric characteristics and climatic conditions. The study used a combination of two tools to carry out the numerical analysis: Energyplus to simulate the building energy consumption and Predicted Mean Vote (PMV) and Matlab to predict the energy saving potential of the personalised heating systems. The Matlab model uses data from an earlier experimental study [48] carried out in a climatic chamber, which provides the relationships between thermal sensation gains and the corresponding energy use. The results showed up to 73 kWh/m 2 y energy saving can be achieved by reducing the setpoint from 21 °C to 18 °C. The present work will address the gaps in the literature by carrying out field experiments and Building Energy Simulations. The field experiment will be carried out in an actual office environment which will focus on how the users adjust the thermal chair temperature settings, the thermal preference and satisfaction before and after using the device. Unlike previous works, the thermal chair units will be integrated into the multi zone building energy simulation model to predict the energy consumption of the building with and without the device. The approach allows the investigation of the temperature and comfort level in various locations, for example, how would a thermal chair perform in the middle of the room as compared to a thermal chair near the window. Furthermore, the present study will also investigate the effect of adjusting the set point from 22 to 20 °C, 18 and 16 °C.
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Computational and field test analysis of thermal comfort performance of user controlled thermal chair in an open plan office

Computational and field test analysis of thermal comfort performance of user controlled thermal chair in an open plan office

In this study, a thermal chair prototype was developed that allowed personal control over the temperature settings of the back-rest and the seat. Limited research focuses on different methods to provide individual user control over the thermal environment. This is particularly difficult to achieve in an open plan office setting, where changing the temperature in one area directly influences the comfort and satisfaction of other occupants seated nearby. In this study, the application of the thermal chair was analysed using Computational Fluid Dynamics (CFD) and field-test analysis in an open plan office in Leeds, UK during winter. The results of the CFD model indicated an improvement in the local thermal comfort of the user. The CFD analysis provided detailed analysis of the thermal distribution around a siting manikin and was used to design and construct the thermal chair. The results of the field data survey indicated a great improvement in users’ comfort (20%) and satisfaction (35%). This study concludes that local thermal control of the occupant improves their overall thermal comfort. It recommends further work to optimise the design of the thermal chair and to improve the modelling for better predictions.
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A user controlled thermal chair for an open plan workplace: CFD and field studies of thermal comfort performance

A user-controlled thermal chair for an open plan workplace : CFD and field studies of thermal comfort performance

In order to address these changes, this study investigated the application of an advanced thermal control system in an open plan setting that allowed users to set their immediate thermal environment according to their requirements. and remain comfortable over a wider range of ambient temperatures. Previous works [9] have shown that allowing the indoor ambient temperature to be lowered by a few degrees can result in large energy savings because the space is heated less intensely and less often. The work will utilise Computational Fluid Dynamic (CFD) and field testing to assess the thermal comfort performance of a thermal chair which allows users to control heating that is provided directly through the surfaces of seat and backrest. Initially, Computational Fluid Dynamic (CFD) analysis will be used to simulate the thermal distribution around a manikin seated on the thermal chair. The CFD code FLUENT will be used with the Finite Volume Method (FVM) approach and the Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) velocity-pressure coupling algorithm with the second order upwind discretisation. Thermal comfort levels will be calculated using the ASHRAE PMV method. The CFD results will inform the design, construction and field testing of a prototype and optimise performance. The purpose of the field experiment is to assess the effectiveness of the thermal chair at providing comfort in a realistic office environment. For this purpose, a thermal chair prototype equipped with thermal control over the seat and the back will be produced and examined in an open plan office in Leeds, UK during the winter season. The field study will examine the comfort and satisfaction of the users before and after the use of the thermal chair.
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Neutral thermal sensation or dynamic thermal comfort? Numerical and field test analysis of a thermal chair

Neutral thermal sensation or dynamic thermal comfort? Numerical and field test analysis of a thermal chair

Shahzad uses thermal decision, which is a combination of thermal sensation and thermal preference [8]. Thermal decision shows that in case a respondent felt neutral (thermal sensation) but wanted a change in the thermal environment to slightly warmer (thermal preference), their thermal decision is the combination of the two, which is slightly warm. Therefore, although the respondent had a neutral thermal sensation, because they wanted to feel slightly warmer, overall they want to feel slightly warm (thermal decision) [8]. Thermal decision was used in this research as well as thermal sensation, thermal preference, comfort and, satisfaction. This study examined the accuracy of the application of neutral thermal sensation in thermal comfort research. Occupants’ views of thermal comfort were investigated in the context of an open plan office when a thermal chair was provided. The separate temperature controls on the back and the seat of the chair allowed respondents to adjust the temperature according to their requirements to find their own comfort condition. The study investigated whether this comfort condition is in agreement with thermal neutrality or not.
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Neutral thermal sensation or dynamic thermal comfort? Numerical and field test analysis of a thermal chair

Neutral thermal sensation or dynamic thermal comfort? Numerical and field test analysis of a thermal chair

This study investigated the accuracy of neutral thermal sensation as the measure of thermal comfort through the application of a thermal chair. The prototype of an office chair equipped with heat pads on the seat and the back of the chair with separate temperature controls was designed [23], as illustrated in Figure 2. The application of this thermal chair was examined through field studies of thermal comfort in an open plan office in the University of Leeds in the winter of 2014, where 44 occupants with mainly sedentary activities participated in the research. This was the real context of the office and participants continued with their normal everyday activities during the study. Respondents were mainly in their twenties and thirties and they included 15 females and 19 males. Their views of comfort, satisfaction and thermal comfort (presented in Table 1) were recorded before and after an hour of using the thermal chair, as presented in Figure 2. As explained separate manual control systems were provided for the seat and the back of the chair and occupants were briefed on using them. The temperature settings of the chair for every participant were recorded and the satisfaction of the respondents regarding the use of the thermal chair was investigated. A good practice example of the workplace with a good quality of thermal environment was selected for this study to limit the impact of the thermal environment on occupants’ thermal decision. For this reason, the thermal environment was measured (dry bulb temperature, humidity and mean radiant temperature). Accordingly, the PMV was calculated and it was compared against the ASHRAE Standard 55-2013, which was satisfactory.
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Visual thermal landscaping (VTL) model : a qualitative thermal comfort approach based on the context to balance energy and comfort

Visual thermal landscaping (VTL) model : a qualitative thermal comfort approach based on the context to balance energy and comfort

This research follows the grounded theory , where several hypothesis are considered and during the journey of the study the theory emerges [22]. This is in line with the application of a qualitative method and particularly the use of visual analysis. Graphical visual analysis is recently used by many researchers, such as economists, biologists and mathematicians [32]. In thermal comfort field, visualising the data in the context provides a platform to derive meanings, connections between the data and patterns according to the meaning and context. It allows a fresh view of the field using a holistic approach (i.e. analysing all aspects and their connections in one go), which can be used to question the existing theories and their assumptions (e.g. thermoneutrality) and to introduce new hypotheses. This study investigated the application of an innovative qualitative Visual Thermal Landscaping (VTL) model to holistically analyse the collected data. Environmental, personal and contextual information are monitored, such as environmental measurements (e.g. dry bulb temperature, relative humidity and mean radiant temperature), occupants’ views (e.g. overall comfort, satisfaction, thermal sensation and preference ASHRAE seven-point scale [33]) and contextual information (e.g. seating arrangements, teamwork and work performance criteria). The data collection was repeated three times a day: morning (09.00-12.00), noon (12.00-14.00) and afternoon (14.00-16.00). The study was applied in an open plan office in the UK in July. The building was naturally ventilated and very energy efficient (BREEAM excellence). Twelve occupants participated in the study, including seven males and five females. The collected data was visualized and analysed using the proposed VTL model, as presented in Fig 1.
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Energy And Thermal Comfort Analysis For Air Conditioning And Ventilation System In Laboratory

Energy And Thermal Comfort Analysis For Air Conditioning And Ventilation System In Laboratory

Thermal Comfort Study and Ventilation Evaluation of an Office” by Daghigh (2012). The study is about finding relating to thermal comfort parameters, air exchange rate, age of air values and air exchange effectiveness in main office of Mechanical and Manufacturing Engineering Department of University Putra (UPM) Malaysia for air conditioned office. Thermal condition in study office rooms has to be considered carefully mainly because of the high occupant compactness in these areas and because of the negative influences that an unacceptable thermal environment has on learning and performance. Other is “Potential Design Parameters for Enhancing Thermal Comfort in Tropical Terrace House: a Case Study in Kuala Lumpur” (Sadafi et al, 2007). The design, modification of the house and adaption of the occupants the reasons for thermal comfort conditions in residential buildings vary.
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Passive Strategies and Low-Carbon Technologies: Evaluating the Energy Performance and Thermal Comfort of a Passive House Design

Passive Strategies and Low-Carbon Technologies: Evaluating the Energy Performance and Thermal Comfort of a Passive House Design

From the energy consumption analysis related to construction type and thickness, it was determined that the lowest amount of energy consumption is achieved with 400mm hempcrete insulation. In terms of shading devices, louvers are used and they are closed during summer days when the incident radiation is greater than 400W/m 2 and closed during winter nights to minimize heat losses through the windows. In order to prevent overheating in summer, the macroflow formula and profile are arranged. The windows should be left open when:

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Energy performance and thermal comfort of courtyard/atrium dwellings in the Netherlands in the light of climate change

Energy performance and thermal comfort of courtyard/atrium dwellings in the Netherlands in the light of climate change

With increased global concerns on climate change, the need for innovative spaces which can provide thermal comfort and energy efficiency is also increasing. This paper analyses the effects of transitional spaces on energy performance and indoor thermal comfort of low-rise dwellings in the Netherlands, at present and projected in 2050. For this analysis the four climate scenarios for 2050 from the Royal Dutch Meteorological Institute (KNMI) were used. Including a courtyard within a Dutch terraced dwelling on the one hand showed an increase in annual heating energy demand but on the other hand a decrease in the number of summer discomfort hours. An atrium integrated into a Dutch terraced dwelling reduced the heating demand but increased the number of discomfort hours in summer. Analysing the monthly energy performance, comfort hours and the climate scenarios indicated that using an open courtyard May through October and an atrium, i.e. a covered courtyard, in the rest of the year establishes an optimum balance between energy use and summer comfort for the severest climate scenario.
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The impact of refurbishment on thermal comfort in post-war office buildings

The impact of refurbishment on thermal comfort in post-war office buildings

The first task was to form the exemplars which are representative of post-war office buildings. The typical characteristics which formed the parameters of the base case models were derived from surveys [6], regulations of the era [7], data analysis [8], previous studies [3, 9]. However, the literature data for non-domestic buildings is limited and relatively out of date. To increase the accuracy of the models, sensitivity analysis was carried out to identify the inputs with the most significant effect on the outputs of interest, namely energy demand and thermal comfort. As part of this process, the results were compared with national survey averages [6] and benchmarks [10], in order to ensure results were realistic. The base case results were also compared with the results of work [8] on the energy consumption of 2,600 buildings derived from their Energy Performance Certificates (EPCs). The built form of non-domestic buildings varies significantly and strongly affects the energy demand. Despite this diversity, detailed work by Steadman et al [11] suggests that six built forms adequately represent UK office buildings according to the layout of the space and the main lighting method (artificial or daylight). For the present study, the most common type, “cellular daylit 4 storeys”, which is of 34% of non-domestic UK buildings and 63.8% of the offices in 1994, was chosen as shown in Fig. 1(a). Supporting information was derived from the office benchmarks [10] which include a specific cellular daylit case. Room widths of 7 m separated by a 2 m corridor were used in the exemplar design, in line with the daylighting requirements described in [11]. As shown in Fig. 1(b), two office zones and a circulation zone were defined on each of the 32 m by16 m floors.
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Energy efficiency and thermal comfort upgrades for higher education buildings

Energy efficiency and thermal comfort upgrades for higher education buildings

Several field studies cited in the ref. (Brager & De Dear 1998) corroborated the unreliability of the PMV model for naturally ventilated buildings by comparing the static model of comfort (PMV-PPD) with the adaptive comfort model. The results showed that the PMV-PPD predictions agreed with the observed thermal sensations for buildings with HVAC systems, but this scenario was completely different in naturally ventilated buildings because the PMV model failed to predict the thermal sensations. In this case the occupants found a wider range of temperatures more comfortable than temperatures suggested by the PMV. This finding was also supported by Brager et al. (2004) who studied the effect of personal control on operable windows via surveys and physical monitoring. Their results showed that the greater the adaptive opportunity, i.e. the level of control that the occupant has on their local environment, such as the presence of operable windows, led to a greater tolerance of the temperature range. Wong and Khoo (2003) conducted a study on thermal comfort in Singapore’s naturally ventilated classrooms through objective and subjective measurements. Their results indicated that the conventional thermal comfort criteria failed to predict the occupants’ thermal comfort because temperatures beyond the conventional thermal comfort range, as stated by ASHRAE Standard 55-92, were indicated as comfortable by the occupants.
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Does a neutral thermal sensation determine thermal comfort?

Does a neutral thermal sensation determine thermal comfort?

When thermal sensation and thermal preference were combined (thermal decision), 36% of the respondents did not want to feel neutral. 25 occupants (i.e. 8%) felt neutral but preferred to feel thermal sensations other than neutral. 77 respondents (i.e. 25%) already felt neutral but the thermal changes they wanted would not add up to a thermoneutral sensation. 13 respondents (i.e. 3%) wanted to feel beyond the range of slightly cool, neutral and cool, as they preferred to feel warm, hot, cool or cold. In the follow up interviews, 70% of the participants acknowledged individual differences in perceiving the thermal environment. When asked what thermal sensation they would prefer to feel when working, 40% of them wanted ‘slightly cool’ and ‘cool’ to feel fresh and not sleepy, and 30% preferred feeling ‘slightly warm’ to ‘warm’, due to the lack of movement and the sedentary nature of the work. Only 30% of them wanted a ‘neutral thermal sensation’ when working. Most members of this group considered thermoneutrality the ‘obvious’ choice.
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Dimension analysis of subjective thermal comfort metrics based on ASHRAE Global Thermal Comfort Database using machine learning

Dimension analysis of subjective thermal comfort metrics based on ASHRAE Global Thermal Comfort Database using machine learning

Shifting our control goal from physical parameters to subjective responses might be a solution to improve thermal comfort without necessarily increasing energy consumption. For example, the occupancy responsive control that takes occupants’ subjective response into the control loop has attracted the interests of researchers, device manufactories, and building operators. Compared with the conventional way to maintain the indoor temperature and humidity within a fixed pre-set range regulated or suggested by building standards, the occupancy responsive control collect occupants’ real-time responses on the thermal environment and then adjust the control target settings accordingly. Integrating occupants’ thermal responses, such as hot/cold complaints [11], online thermal votes [12] and etc., has demonstrated the potential to enhance thermal comfort while save energy as much as 20% - 40% in office settings [13], [14].
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Thermal Comfort in Built Form

Thermal Comfort in Built Form

Abstract – Thermal comfort is the condition of mind that expresses satisfaction with the thermal environment, simply put our body feels at harmony with the climatic condition surrounding us. Our daily life comprises states of activity, fatigue and recovery, and thus it is essential that the mind and body recovers through recreation, rest and sleep to counter balance the mental and physical fatigue and for that we need to have place where we can minimize or eliminate unfavourable factors. The need to achieve thermal comfort in our housing is one of the main factors in a design process and consequences of not achieving it through design increases the cost of using such a building.
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Thermal comfort of colonial office building, 
		Semarang using EnergyPlus 
		simulation

Thermal comfort of colonial office building, Semarang using EnergyPlus simulation

which can achieve the savings of 11.3% on electric consumption. In Singapore, Wong (2003) studied the effects of shading devices on temperature. His study showed that horizontal shading devices reduce indoor temperature by 0.61 o C to 0.88 °C. The vertical shading device can reduce the temperature by 0.98°C in another study by Yang and Hwang (1995). They also investigated the influences of external shading on energy savings in a Taiwanese building. The direct air conditioning, power consumption readings indicate an average savings of 25% if external shading is properly installed. Contradictory, Tzempelikos (2010) and Gratia and Herde (2007) reported that shading devices can lead to big energy savings when they are applied in combination with the appropriate glass type, enabling them to modify the thermal effect of windows to a great extent.
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An analysis of thermal comfort in primary schools in Vietnam

An analysis of thermal comfort in primary schools in Vietnam

In this work, the authors have evaluated the thermal environment in naturally ventilated classrooms and the occupants’ perception of comfort in three primary schools in Ho Chi Minh City, Vietnam. Quantitative and qualitative approaches were used in the study. This study is a part of a larger research project developing environmental design standards for primary school in Ho Chi Minh City, Vietnam. The larger study includes other environmental conditions such as daylighting, indoor air quality and noise but these are outside the scope of this article.
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Thermal comfort and occupant behaviour in office buildings in south-east China

Thermal comfort and occupant behaviour in office buildings in south-east China

It is found from many field studies that there is a gap between the results from the field measurement and the PMV (Busch, 1992., De Dear and Fountain, 1994., Humphreys, 1994., Goto et al, 2007). Kwok and Chung (2003) took a field measurement in Japan in both an air- conditioned classroom and a naturally-ventilated classroom. The results showed that, in the air-conditioned classroom, the measured indoor environmental factors were in ASHRAE‘s comfort zone, but students felt too cold to be comfortable. Another finding was that, although the average indoor air temperature in the naturally-ventilated classroom was 3°C higher than in the air-conditioned classroom, the result of the thermal sensation vote shows the naturally-ventilated classroom is more comfortable than the air-conditioned classroom. Moujalled et al (2008) agreed with this finding. They carried out field studies in five naturally- ventilated office-buildings in the south east of France during both the hot and the cold seasons. The results showed that the occupant thermal sensation was related to operative temperature in the hot season, and the occupant was less sensitive to the temperature increasing in the naturally ventilated office building. In addition, they found that, in naturally-ventilated buildings, the PMV model was not reliable to predict occupant thermal comfort either in hot or cold seasons and the model would result in more heating/cooling time. In can be seen from the field study that occupants can actually accept a higher temperature than predicted by the PMV model in summer and a lower temperature in winter. Similar results of a discrepancy between the field measurement and PMV were also proved by other researchers (Schiller, 1990., Bush, 1992., de Dear and Fountain, 1994., Humphreys, 1994., Wong and Khoo, 2003., Liang et al, 2012). It seems that the PMV model may not be an ideal assessment model for the actual environment.
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Does a neutral thermal sensation determine thermal comfort?

Does a neutral thermal sensation determine thermal comfort?

Neutral thermal sensation is commonly used as the measure of thermal comfort [1-3], and the ASHRAE seven-point thermal sensation scale (based on thermal-neutrality and presented in Table 1) is the most widely used measure of thermal comfort [4]. ASHRAE also introduces thermal preference, comfort and satisfaction scales (shown in Table 1), but most studies only consider thermal sensation in assessing thermal comfort [4] and they are focused on this measure [5,6]. This goes so far as some researchers define thermal comfort as an ‘intermediate point, when neither cold nor hot’ [7]. Many researchers, such as Fanger, investigated the comfort temperature, in which the occupant feels neutral [3]. These findings directly influenced the creation of standards, such as the thermal comfort zone in thermal comfort standards (e.g. ASHRAE Standard 55 [8]). They try to define the thermal conditions, in which over 80% of the occupants are likely to feel neutral and therefore comfortable [9].
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Performance Analysis from the Energy Audit Of A Thermal Power Plant

Performance Analysis from the Energy Audit Of A Thermal Power Plant

Indirect method is also called as heat loss method. The effi- ciency can be arrived at, by subtracting the heat loss fractions from 100. The standards do not include blow down loss in the efficiency determination process. A detailed procedure for calculating boiler efficiency by indirect method is given be- low. However, it may be noted that the practicing energy mangers in industries prefer simpler calculation procedures. The data required for calculation of boiler efficiency using indirect method are:

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Energy Efficient Landscape for Thermal Comfort in Buildings and Built-up Areas

Energy Efficient Landscape for Thermal Comfort in Buildings and Built-up Areas

and ground-level ozone as indicated by [26].Water is an architectural element that has been used extensively in our ancient buildings and gardens not only because of the aesthetic factors but by realising its efficiency in regulating the micro climate. These properties of water can be utilised in modern buildings for energy conservation (Fig. 7). Water has the potential to improve the physical comfort by evaporative process. Evaporation of water absorbs a significant amount of heat. A fine spray of water fountain further reduces the air temperature due to maximum surface contact between air and water. The rate of heat loss depends upon the relative velocity of water and air during contact, the difference between wet bulb temperature of air and initial temperature of water and the time of contact between air and water. Water bodies were used as an integral part of building complex in built up spaces of several archeologically important cities. The large water feature planned all along the facade on the side of prevailing wind direction can contribute directly to bring immediate micro climatic change in the environment.
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