Indoor Thermal Comfort Conditions Research Articles

A Machine Learning approach for personal thermal comfort perception evaluation: experimental campaign under real and virtual scenarios

Personal Thermal Comfort models differ from the steady-state methods because they consider personal user feedback as target value. Today, the availability of integrated “smart” devices following the concept of the Internet of Things and Machine Learning (ML) techniques allows developing frameworks reaching optimized indoor thermal comfort conditions. The article investigates the potential of such approach through an experimental campaign in a test cell, involving 25 participants in a Real (R) and Virtual (VR) scenario, aiming at evaluating the effect of external stimuli on personal thermal perception, such as the variation of colours and images of the environment. A dataset with environmental parameters, biometric data and the perceived comfort feedbacks of the participants is defined and managed with ML algorithms in order to identify the most suitable one and the most influential variables that can be used to predict the Personal Thermal Comfort Perception (PTCP). The results identify the Extra Trees classifier as the best algorithm. In both R and VR scenario a different group of variables allows predicting PTCP with high accuracy.

A Restoration Criticism of Historical Buildings According to Thermal Comfort Conditions: Ali Gav Madrasah

Thermal comfort studies have been a subject of research since the 1930s. Thermal comfort conditions which are of great importance for human health, are also important for energy. Todays due to climate changing and a decrease in energy resources, there is a change in indoor thermal comfort conditions in historic and contemporary buildings. Thermal comfort conditions are the most important factors affecting the use of buildings. So places and spaces where thermal comfort conditions aren’t good are tried to improve to optimal. The historical buildings constitute the majority of the city's building stock in addition to their original and aesthetic architectural qualities, the value for the city. From the planning to the construction process in historical buildings it is observed architectural plan schemes are shaped by considering various environmental and climatic factors such as sun and climate thus it can be said energy uses is taken into account. It is important to use historical structures and to re-function when they are not available with their original function. With re-use, the new details and additional applications that are applied can affect the thermal comfort properties of the building positively or negatively. This study focuses on the thermal comfort properties that come with the restoration of a historic building. In this context, Ali Gav Madrasah which is located in castle borders in the historical city center of Konya in Turkey and restored with a contemporary additional feature that is considered worthy of being examined in terms of thermal comfort. Thermal analysis of the reconstructed Ali Gav Madrasah, which has undergone restoration through integration based on historical documents and excavations and has a top cover made of modern materials, was carried out in August 2018 and January 2019. According to these analyzes, today's thermal conditions are inadequate for all places in Ali Gav Madrasah of thermal comfort conditions. Comments are made on the connection of this insufficient thermal comfort with the restoration/reconstruction. From this point of view, Before the restoration procedures for historical buildings, required feasibility studies and necessary solutions about buildings thermal conditions are investigated. And then architectural details should be produced for this.

Adaptive thermal comfort and climate responsive building design strategies in dry–hot and dry–cold areas: Case study in Turpan, China

Recently, the construction of energy efficiency buildings has been one of the main objectives of sustainable development, especially for areas with extreme climate. In present study, the adaptive thermal comfort and climate responsive strategies in dry–hot and dry–cold areas were investigated with field measurement and questionnaire in the Turpan basin, China. First, the adaptive thermal comfort model was established to reveal the relationship between indoor thermal comfort conditions and outdoor climate. Then, the climate responsive strategies which helped residents adapt to harsh climate were concluded. The prototype of climate responsive dwellings is proposed. Finally, the effects of these strategies were investigated by field measurement of indoor thermal environment in two demonstration houses and evaluated by the proposed thermal comfort model. The results showed that residents in the Turpan basin exhibited better adaptability to the hot climate than the cold climate with the upper limits of 80% acceptability reaching 34 °C. The heavy structure envelope and constructional patterns based on the thermal adaptive behaviors of residents could improve indoor thermal environment. In summer, semi-basement was the most effective strategy to satisfy human thermal comfort, followed by night ventilation. The indoor air temperature in semi-basement was around 31 °C while outdoor temperature exhibited diurnal variation of 15.7 °C from 28.6 °C to 44.3 °C. In winter, passive solar heating and semi-basement were both effective. The indoor air temperature was higher in the bedroom located at the south semi-basement compared with other rooms. The study can provide new thoughts for designing climate friendly buildings in dry-hot and dry-cold areas.

Indoor thermal comfort conditions in summer under subtropical climate conditions

ABSTRACTThe purpose of this study is to shade light in the field of buildings thermal comfort under subtropical environmental conditions. For this purpose, a survey and a measurement campaign of the thermal comfort conditions in 30 dwellings in Larnaca, Cyprus, was conducted. The results showed that 75% of the tenants fall within the warm and the hot thermal sensation category, whereas most of the respondents considered the thermal conditions in the investigated dwellings as neutral or close to neutral. Based on the information gathered in the field survey, interesting conclusions were drawn concerning the actual prevailing indoor conditions, but also the clothing habits of the people interviewed.

Numerical modelling of solar thermal effects on street canyon flow under calm or weak wind conditions

<p>The present study simulates the flow and temperature fields in a street canyon caused by solar heating of road and building surfaces, in either calm and weak wind conditions. Six scenarios, formed by changing the sources of heat fluxes, the wind speed (0, 1 and 3 m s^-1) and direction (±), are examined, at 12:00 solar time during June 21 in the city of Patras. A 1000-W m^-2 heat flux is considered to come out from the road surface and/or 400-W m^-2 heat flux from the left building face. These values correspond to the most intense solar radiation conditions. A computational fluid dynamics (CFD) simulation is performed and the results show that the weak winds cause increased temperatures near the building faces compared to calm conditions, due to intense vortices that entrap air masses, while moderate winds contribute to an improvement of temperatures below those for calm conditions. The entrapment of air masses may also cause increase of pollutant concentrations deteriorating both outdoor and indoor air quality and thermal comfort conditions.</p>

Passive cooling techniques

Passive cooling techniques

Experimental assessment of the impact of natural ventilation on indoor air quality and thermal comfort conditions of educational buildings in the Eastern Mediterranean region during the heating period

This paper aims to investigate the indoor comfort conditions in a typical classroom of a secondary school in Cyprus and explore the impact of natural ventilation on both thermal comfort and air quality. Natural ventilation is a significant parameter in the design of school premises as it affects human comfort conditions and thus students’ health, learning ability and performance. For the purposes of the study, indoor and outdoor environmental conditions were monitored. Various ventilation strategies and window opening patterns were examined, in order to identify the best option to exploit natural ventilation as a means to achieve optimum air quality, especially during wintertime. The in-situ measurements of temperature and relative humidity were analysed in correlation with CO2 levels. The measurements indicate values that often exceed the limits defined by standards. Moreover, the study shows that selected ventilation patterns, and window opening patterns, allow the improvement of air quality with minimum heat losses in wintertime. Conclusions present potential improvements in achieving better air quality and thermal comfort conditions. Educational buildings in Cyprus may utilize the proposed improvements, as well as other similar buildings in the Eastern Mediterranean region, with climatic conditions and building typologies as those described in the Cypriot setting.

Evaluation of vernacular and new housing indoor comfort conditions in cold climate – a field survey in eastern Turkey

PurposeThe purpose of this study is to compare vernacular and new houses in terms of indoor occupant satisfaction and thermal and visual comfort in a region with cold climatic conditions. In line with the data obtained, the contribution of passive design techniques to comfort in housing indoor will be revealed.Design/methodology/approachIn this study, the comfort conditions to be provided in a residence were determined and evaluated in Bingol with the help of questionnaires applied on vernacular and new houses. The information gathered from the occupants and the survey study was mainly designed for three purposes: (i) acquiring general information about houses; (ii) acquiring general information about occupants; and (iii) inquiring about the physical comfort satisfaction of the occupants (thermal comfort and visual comfort).FindingsAlthough the average occupant satisfaction in terms of thermal performance in vernacular houses in summer and winter is 3.91, this average is 2.01 for new houses. The average of the general visual comfort of occupants in vernacular houses is 3.59, whereas this rate is 2.63 in new houses. According to the data obtained, occupant satisfaction was higher in vernacular houses than in new houses. In general, the new settlement area is designed and positioned independently of climate and environmental conditions. This situation increases the need to use mechanical systems to provide indoor thermal comfort conditions. The increase in the need for mechanical systems leads to a significant increase in energy expenditures, as well as deterioration of health conditions in places.Research limitations/implicationsTo ensure occupant satisfaction, indoor thermal comfort conditions and healthy environments, vernacular houses should be an example for the design and building of new houses in terms of orientation, environment relations, space dimensions and space usage in accordance with the character of the region and material selection.Originality/valueThere has not been a serious research on bioclimatic, socioeconomic and cultural sustainability of the vernacular architecture of Bingol. Therefore, this region has been preferred as the study area.

Predicting the Impact of Climate Change on Thermal Comfort in A Building Category: The Case of Linear-type Social Housing Stock in Southern Spain

The Climate Change scenario projected by the IPCC for the year 2050 predicts noticeable increases in temperature. In severe summer climates, such as the Mediterranean area, this would have very negative effects on thermal comfort in the existing housing stock, given the current high percentage of dwellings which are obsolete in energy terms and house a population at serious risk of energy poverty. The main aim of this paper is to generate a predictive model in order to assess the impact of this future climate scenario on thermal comfort conditions in an entire building category. To do so, calibrated models representing linear-type social multi-family buildings, dating from the post-war period and located in southern Spain, will be simulated extensively using transient energy analyses performed by EnergyPlus. In addition, a sensitivity analysis will be performed to identify the most influential parameters on thermal discomfort. The main results predict a generalized deterioration in indoor thermal comfort conditions due to global warming, increasing the average percentage of discomfort hours during the summer by more than 35%. This characterization of the future thermal behaviour of the residential stock in southern Spain could be a trustworthy tool for decision-making in energy retrofitting projects which are so badly needed. To do so, further work is required on some limitations of this model so that different user profiles and typologies can be represented in detail and an economic assessment can be included.

Numerical investigation of the influence of heat emitters on the local thermal comfort in a room

In this paper a numerical analysis of the effect of heat emitter characteristics on the local indoor thermal comfort condition in a room is presented. A dynamic model, able to evaluate the 3D distribution of the mean radiant temperature in the whole volume of a thermal zone is developed. The model allows a fast evaluation, in terms of computational time, of the view factors associated to the inner points of a room thanks to the use of the MATLAB Contour Double Integral Formula (CDIF) routine. The new tool has been used in order to obtain, by means of a series of dynamic yearly simulations, a comparison among different heat emitters (i.e. in-slab radiant floor, in-slab radiant ceiling, lightweight radiant ceiling, radiator, radiant vertical wall and all-air systems) in terms of 3D distribution of the local operative temperature in a room. The knowledge of the 3D distribution of the operative temperature enables the local analysis of the indoor thermal comfort conditions established in the room during the year. The local Predicted Mean Vote (PMV) distribution within the room is calculated for each considered configuration. The results allow to quantify how the reduction of the maximum surface temperature of the emitters, which can be experienced when the envelope thermal insulation is increased, can create more uniform indoor thermal conditions by reducing the differences existing among the heat emitters.

Thermal comfort prediction in a building category: Artificial neural network generation from calibrated models for a social housing stock in southern Europe

A significant part of the housing stock in southern Europe is obsolete and in need of extensive retrofitting to improve its energy performance and thermal comfort. However, before adequate retrofit measures can be proposed for this housing stock, the characterization of current building performance is fundamental. Although the simulation tools frequently used and widely accepted by the scientific community ensure accurate results, these require high computational times. The main aim of this paper is the development of a surrogate model to speed up the thermal comfort prediction for any member of a building category, ensuring high reliability by testing the entire simulation process with real data measured in-situ. To this end, an artificial neural network (ANN) is generated under MATLAB® environment using the data obtained from EnergyPlus simulations for linear-type social housing multi-family buildings in southern Spain, which were constructed in the post-war period. The developed ANN provides a regression coefficient between simulation targets and ANN outputs of 0.96, with a relative error between monitored and simulated data below 9%. A further result is that the building category characterization shows a general lack of suitable indoor thermal comfort conditions, thereby showing the great need for effective retrofit strategies.

The potential for domestic thermal insulation retrofits on the South African Highveld

The South African Highveld is a portion on the inland plateau characterized by low winter ambient temperatures. Studies done in several climatic regions around the world have found a positive relationship between inadequate housing and low indoor temperatures during the winter season. Prolonged exposure to low indoor temperature is a threat to human physical health. This study characterizes indoor human thermal comfort conditions in typical low-income residential dwellings during the winter season. Mapping indoor human thermal comfort can assist in exploring the potential for domestic thermal insulation retrofits interventions. In-situ temperature measurements were done in 2014, 2016 and 2017 across three Highveld settlements of kwaZamokuhle, kwaDela, and Jouberton. The sample included a mixture of old (pre-1994), post 1994 Reconstruction and Development Programme (RDP) as well as non-RDP structures. Findings were that 88% of sampled dwellings in Jouberton 2016, 86% in Jouberton 2017, 62% in kwaDela and 58% in kwaZamokuhle had daily mean temperatures below the WHO guideline of 18°C. These low indoor temperatures indicate poor insulation in these sampled dwellings. Across all settlements, insulated dwellings had higher daily mean indoor temperatures than non-insulated dwellings. These findings indicate the potential to use thermal insulation retrofits in improving indoor thermal conditions as the majority of dwellings are non-insulated thereby exposing occupants to low indoor temperatures.

A generalized model of human body radiative heat exchanges for optimal design of indoor thermal comfort conditions

Human thermal sensation depends heavily on radiative exchanges between the human body and the surrounding environment. Because these exchanges play a crucial role in the thermal balance of the human body, about 35% of the process, human thermal sensation should draw the attention of planners when designing both indoor environments and equipment.The present study aims to contribute to this field by proposing a procedure for delineating the optimal comfort conditions for occupants in most of the articulate and realistic configurations of actual indoor environments. Specifically, this procedure enables accurate assessment of the radiant field surrounding a subject in a given indoor realistic environment and considers its variability with space and time along with the presence of high-intensity radiant sources. The proposed simulation tool contains a set of algorithms in which the degree of complexity depends on the level of accuracy for modelling the radiative heat transfer between the occupants and surrounding environment.The feasibility of these algorithms for designers and researchers has also been checked for a single room characterised by the presence of windows in two different exposures. This configuration implies a complex pattern of the sun entering the room, which in turn determines relevant spatial modifications of the indoor comfort thermal conditions. Such complex situations are effectively interpreted by the proposed model.This analysis provides useful indications for suitable design of layouts of the confined space and the size of an effective heating, ventilating, and air conditioning system to limit the discomfort felt inside the room.

An innovative PCM system for thermal comfort improvement and energy demand reduction in building under different climate conditions

In recent years, applying phase change materials (PCMs) has attracted growing attention due to its potential to energy conservation with thermal comfort in the buildings. The proper use of PCM in a building can reduce the energy demand considerably, keeping the indoor temperature within the comfort range. One of the major issues associated with the use of PCM is the dependency of its performance on the climate conditions, such as the ambient temperature in which it is used. This study introduces an innovative double layer PCM system aim to improve thermal comfort conditions and minimize energy demand. In the scope of PCM performance improvement under different climates during hot and cold months, a constructive solution is the incorporation of two PCM types with different properties, such as melting temperature and enthalpy in room envelopes. The behavior of such a system under five different climatic regions with emphasis on dry and semi-arid climates as dominant climates of Iran was numerically investigated. The study of this new system is conducted by a room with one exterior and some interior boundary conditions in hot and cold months. In this work, The Fanger comfort model has been used for a comprehensive evaluation of new system’s impact on thermal comfort conditions. The results showed that the double layer PCM system improves percentage of time in which the indoor thermal comfort conditions are met from 73% to 93% in dry climate, and from 63% to 75% in semi-arid climate in winter. Furthermore, the heating energy consumption is reduced by 17.5% in dry climate, and by 10.4% in semi-arid climate in the country of Iran.

Energetic investigation of solar assisted heat pump underfloor heating systems with and without phase change materials

The application of phase change materials (PCMs) in the building envelope can improve the thermal performance and the indoor thermal comfort conditions because they allow the proper storage or release of energy. In this work, three different solar assisted heat pump underfloor heating systems with and without the use of phase change material are designed, simulated and evaluated energetically for a building of 100 m2 floor area. Different kinds of solar collectors (flat plate, photovoltaic, thermal photovoltaic) are coupled to a storage tank which feeds a heat pump for space heating purposes. The PCM is used on the underfloor heating system in order to increase the storage capacity and to avoid the operation of the heat pump during the peak electricity demand period. Furthermore, this work presents and compares the coefficient of performance, the electricity consumption, the solar coverage and the indoor temperature distribution of a building in Athens (Greece), with and without a PCM layer on the floor. More specifically, the PCM is placed on the underfloor heating system and different cases are examined by changing the collecting area, the collector type and the thickness of the insulation layer in the floor. The results prove that the use of the PCM layer on the underfloor heating system reduces the heating load by about 40%. The electricity consumption can be reduced between 42% and 67% using the solar-driven systems. It is also found that the system with the thermal PV consumes the lowest grid electricity. Moreover, the lowest simple payback period is found to be 9.61 years for the system with flat plate collectors without PCM. The simulation is conducted with TRNSYS for all the winter period.

Building community-driven vertical greening systems for people living on less than £1 a day: A case study in Nigeria

This paper reports and evaluates the process involved in designing and building affordable community-driven vertical greening systems (VGS) prototypes in a low-income neighbourhood of Lagos, Nigeria. Prototypes are intended to fulfil the dual function of improving indoor thermal comfort conditions and providing substrate to grow edible and medicinal plants. Besides that, the research aims to identify entrepreneurial competences and relationships in the community to transform the prototypes into commercially viable local products. ‘Qualitative fieldwork’ is used as a methodological approach and a product development roadmap is proposed that reports: design and construction development; performance evaluation of thermal impact and plant growth; costing; and community acceptability of the four different prototypes built in two different phases: rainy season 2014 and dry season 2016. The prototypes reduced internal air temperatures by an average of 2.3 °C, moving internal comfort conditions to the comfort zone for around 90%–100% of the time. Besides that, they provided around 16 crops of edible and medicinal plants per year. For two variants of prototypes (bamboo and prefabricated timber), the study reports a range of revenues from the sales of crops, and the estimated payback period (PBP) and internal rate of return (IRR) of the investment.

Mathematical modeling and performance evaluation of a desiccant coated fin-tube heat exchanger

A solid-desiccant system that utilizes low grade heat is potentially a viable add-on to conventional HVAC systems since it can help reduce power consumption significantly, for achieving indoor thermal comfort conditions. In contrast to desiccant wheels which carry out adiabatic dehumidification, isothermal dehumidification process that may be realized by a cross-flow heat exchanger is much more efficient. In this paper, a novel mathematical model is developed to simulate heat and mass exchange phenomena of a desiccant coated fin tube heat exchanger (DCFTHX). This model takes solid side mass transfer resistance as well as fin efficiency into consideration. The model is validated using experimental results in the literature. It is also compared against simplified models to establish its utility. A parametric study is then conducted to investigate the effects of geometrical parameters as well as mass flow rate of water and air velocity on dehumidification and adsorption heat removal performance of the DCFTHX as well as the performance of the augmented air-conditioning system under warm and humid ambient conditions. Under the range of parameters and conditions simulated, if low grade waste heat (50 °C hot water) is available for regeneration, integration of DCFTHX sub-system with a conventional air conditioning system can yield as high as 31% energy savings (even when the additional power consumed by pumps and blower fans is accounted for).

Improving indoor air quality and thermal comfort in office building by using combination filters

Poor indoor air quality and thermal comfort condition in the workspace affected the occupants’ health and work productivity, especially when adapting the recirculation of air in heating ventilation and air-conditioning (HVAC) system. The recirculation of air was implemented in this study by mixing the circulated returned indoor air with the outdoor fresh air. The aims of this study are to assess the indoor thermal comfort and indoor air quality (IAQ) in the office buildings, equipped with combination filters. The air filtration technique consisting minimum efficiency reporting value (MERV) filter and activated carbon fiber (ACF) filter, located before the fan coil units. The findings of the study show that the technique of mixing recirculation air with the fresh air through the combination filters met the recommended thermal comfort condition in the workspace. Furthermore, the result of the post-occupancy evaluation (POE) and the environmental measurements comply with the ASHRAE 55 standard. In addition, the level of CO2 concentration continued to decrease during the period of the measurement.

An evaluation methodology proposal for building envelopes containing phase change materials: the case of a flat roof in Turkey’s climate zones

ABSTRACTPhase change materials (PCMs) can be used to enhance the thermal energy storage capacity of a building element to improve indoor thermal comfort conditions and decrease energy usage, yet these effects need to be carefully analysed to achieve the desired benefits. This paper proposes an evaluation methodology for building envelopes: first, a numerical computational fluid dynamics model is validated by experimental work; then, time-dependent simulations are used to analyse monthly energy requirements and heat flux. A sample flat roof is evaluated in terms of required cooling load with and without PCM in Turkey’s climate zones. Graphical phase change representations and heat flux results were used to evaluate the cooling load reduction in addition to the effects of PCM type and PCM amount and the necessity for night cooling. In conclusion, the methodology is flexible and can be utilized to evaluate the building element for various parameters.

A numerical prediction of the passive cooling effects on thermal comfort for a historical building in Rome

In recent times, numerical simulations are increasingly gaining ground for the energy saving and thermal comfort evaluation of historical buildings.In the present paper a transient 2D model of the Pavilion 2B of the Ex-Mattatoio (Past abattoir) in Rome is presented, created by Computational Fluid Dynamics (CFD) software based on the finite element method (FEM). The simulations take into account time variations and interactions between indoor and outdoor thermal conditions, with the aim of evaluating different usage profiles and of estimating passive cooling effects in presence of natural ventilation and high thermal masses.The main goal of this work is to show the CFD numerical models potential in quantifying the cooling effects and the indoor thermal comfort conditions, in order to enhance passive and hybrid strategies based on natural ventilation and nocturnal thermal masses precooling.