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An experimental study is carried out to examine the simultaneous cooling and heating performances of an ejector expansion CO 2 transcritical system with an adjustable ejector and a variable speed compressor under different operating conditions in detail. Experimental results show that the total capacity and the total COP of an ejector CO 2 system reach their maxima at the ejector throat diameter of 2.0 mm under extreme operating conditions. As compressor frequency decreases from 60 Hz to 35 Hz, the total COP of an ejector cycle can be increased by up to 71.4%, although the total capacity can be decreased by 21.3%. Low outdoor air temperature benefits COPs while high indoor air temperature benefit cooling and heating capacity. The empirical correlations of COPs with ejector internal geometries, compressor efficiency and operating conditions are developed, which can be used for optimization of ejector CO 2 vapor compression systems.

This study attempts to collect more comprehensive data about the indoor environmental quality in urban dwellings with schoolchildren in Beijing, China. For this purpose, indoor air temperature, relative humidity and the levels of indoor chemical and biological pollutants in 14 households were measured in 2013. Results show that, in cold winter, indoor relative humidity was often lower than the comfort limit of 30%, while indoor CO2 concentration was often higher than the acceptable level of 1000 ppm in poorly ventilated homes with high occupant load. Indoor PM2.5 pollution was very severe with the highest level of 523 µg/m3 in living room and 345 µg/m3 in children’s bedroom in winter. Compared with the recommended thresholds, the levels of indoor volatile organic compounds and carbonyl compounds in most homes were low. Cigarette smoke is an important indoor source of PM2.5, formaldehyde, acetaldehyde, acetone and benzene. Also, there are significant correlations between the concentration of total volatile organic compounds and other compounds (acetaldehyde, acetone, benzene and toluene). Furthermore, two phthalates: di (2-ethylhexyl) phthalate and di-n-butyl phthalate were frequently detected in house dust. Penicillium, Cladosporium, and Aspergillus were predominant fungi in indoor air. The fungal pollution levels in different seasons and rooms were also compared.

The relationship between the outdoor temperature and the indoor comfort temperature in naturally ventilated buildings is close to linear; this relationship is complex in heated or cooled buildings. To explore the influencing mechanism of the outdoor temperature on the indoor air temperature and thermal adaptation in winter, field studies on the thermal comfort in residential buildings with heating systems during the heating season have been conducted in three northern cities of China, with both subjective questionnaire surveys and objective on-site measurements performed simultaneously in every field survey. The results indicated that the indoor temperature is affected by the outdoor climate to some extent, even under conditions of space heating. When the outdoor temperature was below 10 °C in cold climates, the indoor temperature gradually increased with the decrease of the outdoor temperature. The outdoor temperature affected not only the adaptive behavior, but also the thermal acceptability. When the outdoor temperature experienced by the occupants in winter was lower, and the low temperature was experienced longer, the dependence on heating equipment, acceptability of a high temperature, and impatience with a low temperature environment were stronger. When the mean outdoor temperature experienced by the occupants was only slightly cold, the occupants expressed a lower thermal expectation and accepted a wider temperature range. The above climate adaptation mechanism provides a valuable reference for the design of higher efficient space heating systems.

Most hot water heating valves for apartments are constant-flow types, which limit the flow rate through an individual household for even distribution of heating water to other households. The constant-flow type is implemented by an on-off control. As a result, heating water is supplied intermittently and hence, indoor air temperature also fluctuates. Returning water temperature is also high, which reduces energy efficiency. To implement continuous feedback control, the indoor temperature dynamics was simulated to fit a measured temperature history by a state-of-the-art physical model. From the model, it was found that the most important disturbance is outdoor temperature and its effect on indoor temperature lasts about an hour. To cope with the slow response and the significant disturbance, a prediction control with proportional feedback is proposed. The control was found to be successful in implementing continuous heating water flow and improved indoor temperature control.

HISG (heat insulation solar glass) is a recently developed multi-functional glazing technology to mitigate energy consumption of buildings. HISG can generate electricity similar to conventional PV (photovoltaic) glazing products when exposed to sunlight, however it differs from them by having some extraordinary characteristic features such as thermal insulation, which is competitive with Argon filled triple glazed windows, acoustic comfort, remarkable energy saving potential and self-cleaning ability owing to TiO2 nano coating. Within the scope of this research, latest results from laboratory and in-situ testing of HISG are presented in terms of its key role in mitigating heating and cooling demand of buildings as well as clean energy generation. Lighting and thermal comfort related parameters such as shading coefficient, UV, IR and visible light intensity are also investigated through the tests conducted in real operating conditions. It is achieved from the results that instant electricity generation of HISG is 16% higher than that of standard PV glazing owing to its nano layer reflective film. Shading coefficient of HISG is only 0.136, which provides almost 80% reduction in solar heat gain compared to ordinary glazing. Indoor air temperature measured from HISG test house in summer time is very close to the ambient temperature, whereas it is found to be 14.7 °C higher in ordinary glass test house due to greenhouse effect. Annual heating and cooling demand tests indicate that HISG provides 38 and 48% energy saving in heating and cooling season, respectively. © 2016 Elsevier Ltd.

The aim of this study is the proof of concept and the validation in laboratory environment of a novel technique for in-situ measurement of indoor air temperature using IR thermography, the mock target IR thermography. The technique is based on the use of mock targets with appropriate hygrothermal properties. The physics of the examined concept are introduced by employing analytical predictions and numerical analysis, using finite elements simulations (Comsol Multiphysics). The selection of the mock target material is also justified and the optimal solutions are discussed. The laboratory validation of the proposed technique was implemented under controlled conditions in the climate chamber of the Kaunas University of Technology (Lithuania). The concept was tested under different indoor conditions and with the use of various mock targets. The measurements were also validated with the use of a compatible measurement technique (thermocouples). The prerequisites for the implementation of the technique, as well as the conditions under which the proposed technique provides reliable results are presented.

Increasing roof reflectance reduces absorption of solar radiation, roof surface temperature and heat ingress into the building. This leads to an increase in indoor comfort and reduction in room air temperature that in turn results in energy saving by reducing AC demand. To assess this impact of cool roofs on buildings in rural and peri-urban areas of India, a study was performed on two un-conditioned school buildings in Hyderabad (ZPH School) and Nagpur (VNHM School). Two classrooms of same size, function, and occupancy from both the school buildings were monitored for a period of ten weeks starting from March 2014 till May 2014. The data from the experiments and their analyses showed promising results. The average reduction and peak reduction in indoor air, roof underdeck and roof overdeck surface temperatures are 2.1 °C, 5.0 °C and 12.3 °C and 4.3 °C, 10.0 °C and 26.3 °C respectively for the room with white roof as opposed to grey roof in ZPH School and 1.5 °C, 4.0 °C and 9.5 °C, and 3.3 °C, 4.2 °C, and 25.2 °C respectively in VNHM School. The results from the experiment prove that white roof has a significant effect in reducing the indoor air temperatures in buildings due to reduction in outdoor and indoor roof surface temperature.

Previous studies have shown that poorly ventilated classrooms can have negative impact on the health of children and school staff. In most cases, schools in Serbia are ventilated naturally. Considering their high occupancy, classroom air quality test determines the level of air pollution, after which it is possible to implement corrective measures. The research presented in this study was conducted in four schools which are located in different areas and have different architecture designs. Measurements in these schools have been performed during the winter (heating season) and spring (non-heating season) and the following results were presented: indoor air temperature, relative humidity and carbon dioxide concentration. These results show that the classroom average concentration of carbon dioxide often exceeds the value of 1500 ppm, during its full occupancy, which indicates inadequate ventilation. Measurement campaigns show that carbon dioxide concentration increased significantly from non-heating to heating season in three of the four schools. Analysis of measurements also determined high correlation between relative humidity and carbon dioxide concentration in all schools in winter season. This fact may constitute a solid basis for the fresh air supply strategy. [Projekat Ministarstva nauke Republike Srbije, br. III42008: SINPHONIE - Schools Indoor Pollution and Health: Observatory Network in Europe]

Current increasing of costs for the acquisition of buildings causes effort to efficiently use all the space in these construction projects. The aim is therefore to make maximum use of under-roof space, both in new buildings and in buildings already standing. Because of the trend of construction with light wooden structures wrapped in thermal isolation, it is not easy to avoid summer overheating in under-roof spaces. For this reason, we’ve focused on optimizing building structures in terms of overheating in summer, so that additional costs for air conditioning were negligible or, ideally, non-existent. It is well known from our previous experience that there is smaller rise and fluctuation of indoor air temperature in rooms with heavy mass constructions (e.g. reinforced concrete, bricks, etc.) compared to rooms with light structures.

The experimental work was held in commercial broiler house at Babil village, Menofia Governorate, latitude and longitude angles are 30.67°N and 30.98°E, respectively) during winter season of 2015in order to evaluate the performance of manufactured heating system and its effect on indoor air temperature and energy requirements. The indoor air temperature above the floor surface, indoor air relative humidity, fuel consumption, heat energy addition and specific heating power for every cubic meter of house volume were measured and specific fuel consumption also. Broilers performance evaluation was also determined in terms of live body mass. The obtained results showed that using manufactured heater in heating broiler house the weekly average indoor air temperature ranged between 31.61 to 23.26 oC at first and fifth week respectively. Whereas, the indoor relative humidity ranged between 26.15 to 52.48% at the same ages. The average heat energy addition to the house was 63.28 kW throughout the bird's life and specific heating power was 148.4 W/m 3 at the first week and reduced to be 37.07 W/m 3 at fifth week. Heating energy requirements decreased from 422.59 kJ/h.kg at the first week of age until reached to 19.45 kJ/h.kg at fifth week of age where the average broilers body mass was 2.2 kg.

The variety of occupant behaviors in buildings have led to a significant mismatch between simulated building energy performance and measured one. It is crucial to collect real occupant behaviors in buildings to achieve accurate simulation purpose, although there exists a great challenge due to the cost of monitoring devices and privacy concerns. This study proposed an inexpensive and minimally intrusive method, to recognize behavior information from environment parameters by data mining approach. To validate this method, experiments were conducted in three bedrooms. Two types of classification algorithms were developed to recognize AC operations from the experiment data of indoor air temperature and relative humidity. Two types of recognition rules were generated from algorithm training in one dataset, and tested in the other datasets. Based on the testing results, the performance of the two algorithms were evaluated and compared. The results indicated that the C4.5 decision tree algorithm was not suitable for mining AC operations, while the curve description algorithm had good performance in processing the time-series curves of air temperature and relative humidity. Through this experiment, it is confirmed that AC operations can be recognized from indoor air temperature and relative humidity by data mining approach. The main contribution of this study is that a promising approach was developed, which is inexpensive and minimally intrusive on gathering and interpreting information about occupants’ daily behaviors.

The use of evaporative cooling in industrial buildings is becoming increasingly popular nowadays. However, there is a lack of detailed and sufficient evaluation in the literature of simple evaporative cooling systems used in this type of buildings, particularly in the climate of Central and Eastern Europe. Therefore, this article evaluates evaporative cooling (EC) systems for an assumed industrial building located in Poland using the TRNSYS 17 software. The analysis of six systems located in four Polish cities (Koszalin, Lublin, Suwalki and Wroclaw) was carried out. Simple EC systems using both direct and indirect evaporative cooling were assessed. The systems were evaluated in terms of the number of hours that each system does not reach the room air temperature setpoint (TTF), electricity and water consumption and the seasonal coefficient of performance (SCOP). The results have shown that the largest number of the TTF hours is for systems located in Lublin and the smallest in Koszalin. Depending on the analysed system, the number of the TTF hours is for Koszalin and Lublin from 178 h to 611 h and from 429 h to 1194 h, respectively. By generalizing the results, EC systems have the potential to save energy in the climate of Poland. Out of the analysed systems, the S5 system, which uses both direct and indirect evaporative cooling and only outside air for humidifying, has the greatest potential for use. It was also found that systems using outside air for humidifying instead of exhaust air reach higher energy efficiency and lower indoor air temperature more.

Indoor thermal comfort is dynamic because of complex interactions between occupants, season-specific climatic parameters, and region-specific socio-cultural setup. A thermally comfortable environment is a key requirement for obtaining good classroom performance. Providing adequate thermal comfort is considered to be the greatest challenge in naturally ventilated (NV) conditions in tropical cities during the summer season. Present study is focused on assessing student's thermal perceptions and behavioural adjustment in NV university classrooms within the tropical-wet climatic zone in Bangladesh. Field surveys consisting of 24 observations were made during the peak summer in 2017, and 579 data sets were collected and analyzed. The mean indoor air temperature, relative humidity, and wind velocity were observed at 30.9 °C, 78.4% and 0.8 m/s. We used a linear regression model to estimate the neutral temperature, but Griffiths predicted mean comfort temperature (27.8 °C) was found to be more relevant to the classroom environment and the sample size. About 43.7% of Students voted within two central comfort bands (0 and + 1) on the ASHRAE thermal sensation scale having a temperature range of 27.5–33.8 °C. Hence, we compared student comfort temperatures (Tcomf) obtained from Griffiths method with the existing thermal comfort models. About 87.7% and 81% of students Tcomf was observed within 80% and 90% acceptability zone of ASHRAE standard 55 respectively. Moreover, about 89.3% and 95.9% of the students' Tcomf was found within Category II and Category III comfort bands of CEN (EN 15251), respectively. Results indicate that students are comfortably adapted to the extreme weather during summer.

The refrigerant-heated radiator (RHR) has been proved to be an efficient refrigerant-heated terminal of the air-source heat pump (ASHP) for space heating. The evaluation and analysis of the RHR heat transfer performance are of importance to the design and operation analysis of the heating system. In this paper, to investigate the heat transfer performances of the RHR, the detailed mathematical model considering the heat transfer and pressure drop of the RHR was established. Meanwhile, the experimental RHR heating system are conduct to verify the superiority of the system COP and validate the proposed mathematical model. The results showed that the simulation errors of radiator outlet temperature, pressure drop and heat transfer capacity ranged from −2.3 °Cto 2.5 °C, −11.1% to 13.5% and −4.35% to 3.43%, respectively. Based on the RHR model, the characteristics of the RHR and the parametric analysis of the radiator heat transfer performances were investigated. The results indicated that the proportion of radiation heat transfer of the RHR is increased by 80–100% in comparison with other radiant-convective terminals. And the refrigerant flow rate, condensation temperature and indoor air temperature were the three main parameters affecting the heat transfer performance of the RHR.

Heating, ventilation and air-conditioning systems (HVAC), at demand side, have been regarded increasingly as promising candidates to provide frequency regulation service to smart power grids. To assess the performance of the frequency regulation service provided by the demand side, dedicated frequency regulation test signals have been proposed that are relatively demanding and critical to power grids considering the quality of the service provided by the demand side. However, other practical signals might be demanding and critical to buildings at the demand side considering the impact of the service on indoor environment control. In this study, a set of criteria is proposed to assess the demanding level of frequency regulation signals to power grids and buildings at demand side, respectively. The impacts of providing frequency regulation service (to power grids) on indoor environment control are quantified when HVAC systems are following practical signals with different demanding levels to buildings. The results show that indoor air temperature can have a relatively large offset when HVAC systems are following frequency regulation signals demanding to buildings. In addition, the indoor air temperature offset will increase when regulation capacity provided increases. Two dedicated test signals for buildings are therefore recommended to verify the environment control performance of buildings when providing frequency regulation service to power grids.

Building retrofitting plays a critical role in achieving sustainable development and is an efficient way to improve the indoor air quality (IAQ) of existing spaces. The IAQ in classrooms has a significant impact on the health and academic achievement of students. However, improving the IAQ of existing classrooms is challenging if minimum architectural modifications are allowed. Different natural ventilation retrofitting techniques were proposed to improve the IAQ in existing classrooms at Jordan University of Science and Technology, which is located in a hot arid region. Computer simulations were used to analyze the ventilation rate, indoor operative temperature, relative humidity, and CO2 concentration in the base Case classroom and after the implementation of the proposed retrofitting techniques. Simulation results were compared with those obtained in the base case to determine the most efficient natural ventilation retrofitting technique. The best results were obtained by using a solar chimney to assist a wind tower, which resulted in an increase in the comfort hours during the occupation time, an improvement in the average monthly ventilation rate range, a decrease in the CO2 concentration, and an improvement in the relative humidity ratio. An energy-saving of 39% would be achieved compared with the use of split unit air condition systems. Economic assessment of the proposed system using net present value indicates positive economic viability., Civil engineering; Energy; Environmental science; Energy conservation; Energy use in building; Air quality; Environmental assessment; Green engineering; Architecture; Natural ventilation; Retrofit techniques; Indoor air quality; Indoor air temperature; Energy consumption.

The radiant cooling system has a substantial energy-saving effect and can be widely applied in different kinds of low-energy buildings. This article reports the experimental study of the design strategy of the radiant cooling system in low-energy buildings from the perspective of thermal response characteristics of an indoor environment. Two types of a modular radiant cooling system, namely, the copper tube radiant cooling (CTRC) and the capillary radiant cooling (CRC) systems, were investigated. The experiments were conducted in two office rooms characterized by low energy consumption. In total, 16 cases (eight for CTRC and eight for CRC) were analyzed, covering supply water temperature with a range of 12–19 °C. The experimental results show that the supply water temperature has a more substantial effect on the temperature distribution of the envelope for CTRC, than that of CRC. The indoor air temperature stratification is acceptable in the active area of the occupant with a modular radiant cooling system. Moreover, the thermal response of the envelope is highly sensitive to the lower supply water temperature (below 16 °C) using CTRC and to the higher supply water temperature (above 15 °C) using CRC. The low supply water temperature (below 15 °C) can improve the thermal stability speed of indoor air to a greater degree using CTRC, than that of CRC. The supply water temperature for CTRC with 15–16 °C, and 18–19 °C for CRC in low-energy buildings can exert an optimal cooling benefit.

Over the last decade, the influences of vertical greenery systems (VGSs) and green roofs (GRs) on indoor air temperature, surface temperature of walls, and energy consumption have been widely investigated. There is little information on how VGSs and GRs influence the indoor operative temperature of an air-conditioned space, even though it is a measure of human thermal comfort. This study experimentally investigates the effects of VGS and GR on indoor operative temperatures. Two experimental rooms, one equipped with VGS and GR and the other without, are constructed in Xiangtan, China, which is located in the hot summer and cold winter climate zone. The rooms are controlled using identical indoor air temperature set-points. During the experiments in summer 2018, the indoor and outdoor thermal environmental parameters were measured and recorded automatically. The results indicate that the operative temperature of the room with VGS and GR was reduced by 0.4 °C on average and a maximum of 2.1 °C compared to the room without VGS and GR. The impact of VGS and GR on the operative temperature in the daytime is greater than at night. In addition, the VGS and GR also decrease the oscillation of the operative temperature, and a more stable thermal environment can be achieved with VGS and GR. A computer program was developed using EnergyPlus, and the results were validated using experimental data. By performing computer simulations during the whole cooling season (from June 1 to September 30), it was found that the operative temperature of the room with VGS and GR was reduced by 0.59–0.65 °C during the daytime (7:00 a.m.–7:00 p.m.) and remained almost unchanged at night. Further, the set-point temperature of the room with VGS and GR can be 0.76–0.84 °C higher than that of the room without VGS and GR in the daytime to maintain the same level of thermal comfort. An energy saving correction from 7% to 8% on the daytime energy consumption is proposed with this increased set-point temperature.

Bed microclimate can directly affect the thermal comfort of the human body. A study combining experiments and field measurements was conducted to determine the effects of bedding insulation and indoor air temperature on bedding temperature and thermal comfort. The experiments involved varying indoor air temperatures (14, 18, 22, and 26°C) and bedding system insulations (3.1, 3.7, and 4.4 clo). Six male college students participated in the experiments, and three of these also participated in the field study along with a further three to give a total of six participants in the field study. Six participants each completed 4 experiments of 3 hours duration for the experimental part of the study. The two-week field study was conducted in students’ respective dormitories, where measurements of bedding temperature and feedback on thermal perceptions were obtained. The experimental results indicated that the higher the bedding insulation and indoor air temperature were, the warmer the participants felt. Linear relationships were found between air temperature and bedding temperature, air temperature and skin temperature, and bedding temperature and thermal sensation vote. Different body parts, except for the head, shared similar sensitivities to the bedding temperature but have varying thermal requirements. The thermal neutral bedding temperature in the experiments was 31.1°C whereas that in the field study was 32.1°C. This difference could have arisen due to metabolic rates, anticipated control, and self-adaptive behaviors. Based on measured data, a comfort zone for bedding insulation and air temperature was developed to further investigate the sleeping environment and its impact on daily life.

The Lumped Parameter technique is a simplified thermal modelling method, which can be informed by measured operational data whilst allowing for physical interpretation of components and processes. The application of Lumped Parameter methods to the residential sector has been limited, primarily due to the lack of availability of operational data and the complex nature of real-world factors, such as variable occupant behaviours. This work investigates the potential of using the Lumped Parameter technique for modelling the performance of existing houses using high resolution in-situ measurements. Lumped Parameter models are created based on building surveys of eleven existing domestic buildings in the UK. The models are shown to have an average Root Mean Square Error (RMSE) of 1.35°C when compared to measured values of internal air temperature. A parametric analysis of model parameters showed wall thermal resistance, window area, boiler efficiency and infiltration rate as the most significant factors affecting the indoor air temperature calculated values. Model calibration improved the average RMSE to 1.03°C (a 23.7% decrease from initial fit). In conclusion, the Lumped Parameter models were able to realistically represent the majority of the houses, highlighting the technique's potential in informing strategic retrofit decision making across the housing stock.

Sudden changes in outdoor air temperature within the time scale of several days can affect human thermal comfort demand. Although the influence of short-term thermal experience on the thermal sensation (STEI) in one season (e.g., in summer) has been focused on, the differences of this effect in different seasons have rarely been studied. In this study, to investigate the regularity of the difference, a follow-up field survey was conducted from July 2019 to January 2020 in Chongqing, China. The results show that when outdoor air temperature suddenly rises, the STEI is higher in summer than that in autumn (approximately 0.14 scales) when the indoor air temperature is 28–30 °C. When the indoor air temperature is 24–27 °C, no significant difference was observed. In addition, the STEI is higher in autumn than that in summer (approximately 0.09 scales) when the outdoor air temperature suddenly decreases, and when the STD is −1 °C, the impact of short-term thermal experience on the body in autumn is less than that in winter, by approximately 0.04 scales. The effect can cause a variation of approximately 0.28–0.84 °C in the body's neutral temperature, with a maximum of 1.3 °C based on Griffiths method (G = 0.356/K).

There is a need to improve the understanding and the knowledge of energy efficiency measures for residential buildings in sub-Arctic climate regions. This paper presents an investigation of two identical multi-family residential buildings in the sub-Arctic climate of northern Sweden, before and after renovation. During the renovation, additional insulation of the external walls and new windows were installed in one building, while the other building retained its original envelope. The energy usage data for the past four heating seasons were collected, including data from before and after the renovation. Detailed thermal indoor climate data were gathered for specific months. The data from the two separate buildings showed that the renovation did not result in a significant improvement in energy usage. Prior to the renovation, the energy usage data showed a difference of 2–3% in the heat supply between the two buildings, and this difference persisted after the renovation. On the other hand, the indoor air temperature was raised. The renovated building had an indoor air temperature which was 2 °C higher than the not yet renovated building. IDA ICE models were constructed and validated with the measured data to investigate how a lower indoor air temperature would affect the energy usage and indoor thermal climate. The models showed that with a reduction in the indoor air temperature by 2 °C after the renovation, the thermal climate would maintain an acceptable level according to PMV/PPD standards, and would result in a 13–14% reduction of the heat supply during the cold months. With an annual reduction of 15%, the heat supply could be reduced by 270 MWh per year for the whole area where the buildings are located. This clearly demonstrates the importance of adjusting the heating system after an energy efficiency measure has been performed.

With hospitals in megacities becoming larger, the hospital-street layout has an increasingly larger impact on the efficiency and stability of a hospital. In this study, the indoor-environment quality of a semi-closed hospital street and the adjacent outpatient waiting areas were investigated using objective on-site measurements and subjective questionnaire-based surveys. The results revealed that the hospital street had an over-heated and over-humid environment, with a humidity ratio of 17.7–18.6 g/kg. Consequently, the occupant-dissatisfaction rate in terms of the thermal environment exceeded 50%. The blending of air from the hospital street with that from the outpatient waiting areas led to an indoor air temperature of 27–29 °C in the latter, which exceeds the standard threshold of 26 °C. The indoor air quality (in terms of CO2, total volatile organic compounds (TVOC), and PM2.5 concentration) of the hospital street was good, ensuring compliance with existing Chinese standards. However, spot glare through the transparent ethylene-tetra-fluoro-ethylene (ETFE) membrane roof and uneven illumination in the hospital street caused visual discomfort. Vibration of the ETFE membrane roof during rainfall led to noise levels of 79.5 dB(A) in the hospital street and 70 dB(A) in the outpatient waiting rooms, severely reducing acoustic comfort and resulting in an occupant-dissatisfaction rate of 60%. Thus, this study provides data, both objective and subjective, of the indoor-environment quality in both hospital streets and outpatient waiting areas.

In recent years, a huge research effort aimed at developing adaptive materials for improving building indoor thermal comfort has been detected. Yet, only a few analytic and dynamic approaches have been implemented to predict building materials thermal performance. In this study, an analytic model is elaborated to evaluate the thermal performance of a well insulated case study prototype building equipped with a thermochromic envelope, and bench-mark it against cool-only and dark-only applications. Therefore, the effect of the selected thermochromic solutions on the indoor environment of the building in terms of surface and indoor air temperature is evaluated both in summer and winter conditions. Results show that the application of the thermochromic membrane and wall paint represents a win-to-win solution combining the well-established passive cooling effect of high reflectance materials in summer with desirable solar gains produced by dark surfaces in winter. Average indoor air temperature reductions up to 0.2 and 0.5 K were found in summer, while a 0.5 and 0.6 K increase was registered in winter, for the low and high insulation configuration, respectively, when compared to more common dark and cool solution.

Combining phase-change materials (PCM) into building envelopes can improve indoor environmental comfort and reduce energy consumption. To adapt to seasonal changes (e.g., hot summer and cold winter), a novel type of hybrid PCM-containing wallboard (including three different PCMs) was fabricated. The hybrid PCM wallboard has a wide phase-change temperature range and can work under different climates for indoor thermal comfort and energy saving. Reduce-scale test cells, two hybrid PCM wallboard integrated test boxes (including Mode 1 PCM wallboard and Mode 2 PCM wallboard) and another equipped with gypsum wallboards, were compared to study the thermal performance of the PCM contained wallboard in both passive and active systems. The results indicate that the hybrid PCM system can narrow indoor air temperature fluctuations and maintain indoor thermal comfort at any time of the entire year. Mode 2 PCM wallboards were found to be more suitable for regulating the indoor thermal environment , as they exhibited more heat release to the indoors during the daytime and less heat loss at nighttime during winter. Under stimulations of different temperature fluctuations, three different layers of the PCMs worked to respond to the temperature fluctuations. Two indices ( I and E) were put forward to evaluate the thermal performance of the PCM wallboards. The I index showed that Mode 1 PCM wallboard is suitable for reducing fluctuations of indoor temperature in winter and transition season scenarios. According to the E index, throughout one year, Mode 2 PCM wallboard has higher utilization efficiency than that of Mode 1. Finally, a comparative test was performed with the active system to evaluate the energy saving potential of the two hybrid PCM wallboards. The results show that energy consumption in the hybrid PCM wallboard box is nearly 30% less than that of gypsum wallboard.

Active chilled beams support high temperature cooling which enables the opportunities of direct ground-coupling and self-regulation. Direct ground-coupling implies cooling through a ground heat exchanger without use of a chiller and self-regulation refers to the elimination of individual room control systems. This paper presents the operation and indoor air temperatures in such an office building located in Stockholm, Sweden, and the analysis includes the unprecedented hot summer of 2018. The results show that the system is capable of supplying the building with enough cooling to not exceed desired indoor air temperature levels. It is also concluded that the self-regulation kept the indoor air temperature satisfactory uniform. The difference between the highest and lowest temperature is 1.9 K on average and below 2.4 K during 90% of the time. Regarding stability, the least stable temperature recorded has a standard deviation of 0.8 K while the average standard deviation is less than 0.5 K. The indoor air temperature during summer is about 2 K lower than suggested by standards. This calls for conducting a thermal comfort survey and may be remedied by increasing the chilled water temperature. To increase the performance of the system, the ground is cooled during winter by preheating the supply air. During 2018, slightly more cooling was extracted in the summer than recharged during winter.

The thermal sensations of people differ from each other, even if they are in the same thermal conditions. The research was carried out in a didactic teaching room located in the building of the Faculty of Civil and Environmental Engineering in Poland. Tests on the temperature were carried out simultaneously with questionnaire surveys. The purpose of the survey was to define sensations regarding the thermal comfort of people in the same room, in different conditions of internal and external temperatures. In total 333 questionnaires were analyzed. After the discriminant and neural analyses it was found that it is not possible to forecast the thermal comfort assessment in the room based on the analyzed variables: gender, indoor air temperature, external wall radiant temperature, and outdoor air temperature. The thermal comfort assessments of men and women were similar and overlapped. The results of this study confirm that under the same thermal conditions about 85% of respondents assess thermal comfort as good, and about 15% of respondents assess thermal comfort as bad. The test results presented in this article are similar to the results of tests carried out by other authors in other climatic conditions.

Indoor thermal environments in residential buildings vary due to differences in the outdoor climates, the envelope thermal properties of the buildings, the types of heating and cooling systems, and adaptive behaviors such as the operation of air conditioners and windows by dwellers. This study comprehensively investigated the thermal environments in 46 apartments in nine cities across five climate zones in China via on-site monitoring of the indoor air temperature, the relative humidity, and the air conditioner and window use for one year. The results demonstrate large variations in the thermal environments among the cities. During the heating period, the interior air in Urumqi and Shenyang was overheated (>24 °C) 43% and 59% of the time, respectively, while the indoor air temperature in Chongqing can be lower than 10 °C. As the outdoor climate became warmer, the temperature difference between indoors and outdoors decreased due to the increased window-opening duration. In summer, the indoor humidity ratio was higher than 12 g/kg for a long time in all cities except Urumqi. A clear linear positive correlation between the indoor and outdoor humidity ratios was identified until the indoor humidity reached 18 g/kg, which was due to the increased use of air conditioners. The results of this study provide an updated overall picture of the thermal environments in Chinese residential buildings.

Compared with all-air system, the cooling load dynamics for integration operation of radiant ceiling panel (RCP) and dedicated outdoor air system (DOAS) is more complex, and there is a lack of practical cooling load calculation method in current standards and guidebooks. This study aims to explore their cooling load dynamics and develop a simplified calculation method for such integrated system. A heat balance based model to calculate the cooling load for the integrated system was established. The results showed that RCP with DOAS removed more room heat gain than all-air system at the same indoor air temperature set-point, and the peak cooling load of RCP with DOAS is 16% larger. It was also found that ignoring DOAS in cooling load calculation could make the results 6% larger than DOAS integrated. In addition, there is a condensation risk if RCP alone was used to maintain air set-point temperature. To help the application of the integrated system at design stage, we proposed cooling load correction coefficient rrad as the cooling load difference between radiant and all-air system, and the cooling load split fraction rDOAS for DOAS. Through orthogonal screening, 6 significant factors on rrad and rDOAS were selected. Simplified models for rrad and rDOAS calculation in both continuous and intermittent operation modes were established using simulation data, and a revised design process for the integrated system was proposed.

There is increasing evidence of adverse health impact of solid biomass fuel, and its use may hinder thermal comfort, which may lead to lower quality of life. Hence, current study aims to assess the thermal comfort at a rural location of Punjab, India. The indoor air temperature and relative humidity in rural households during winter varied from 11.9–25.2 °C and 63.4–90.5% respectively, during pre-summer it ranged between 21.3 and 27.4 °C and 48.4–78.4% while during summer it ranged between 28.4 and 37.8 °C and 13.7–63.8% respectively. The PMV of the households ranged between −0.85 to 0.69 (winter), −0.32 to 0.4 (pre-summer) and 0.53 to 1.25 (summer) for American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) 55-2017 and −0.56 to 1.11 (winter), 0.04 to 0.99 (pre-summer) and 1.21–2.36 (summer) for European Committee for Standardization (CEN) European standard EN15251 while the Predicted Percentage of Dissatisfied ranged between 5 and 20% (winter), 5–8% (pre-summer) and 11–38% (summer) for ASHRAE 55-2017 and 5–31% (winter), 5–26% (pre-summer) and 36–90% (summer) for EN15251 guidelines. On the other hand, Adaptive thermal comfort (ATC) during winter and pre-summer was comfortable for 80 and 90% acceptable limits (ASHRAE-2017) and ranged between too cool to comfortable for EN15251 (Class I, II and III) while during summer thermal comfort for occupants was comfortable for ASHRAE 2017 and EN15251 (Class I, II, III) but did not comply with EN guidelines in some households using either clean fuel or chullah. Thermal comfort sensation was observed to be slightly cool to neutral during winter, neutral during pre-summer and slightly warm during summer according to Predicted Mean Vote method. The results were also compared using a thermal comfort and household survey and found to be similar with the model results. Climate change is leading to changes in temperature which may have an impact on the built environment. Hence, the current study suggests formulating policies on the uses of household fuel and design of kitchen with proper ventilation to increase thermal comfort which in turn will also reduce air pollutants. Keywords: Thermal comfort, PMV, PPD, Household air pollution, Climate change, Adaptation strategies

In recent years, the indoor air temperature in residential buildings for space heating rose gradually in the severe cold area of China. Would people feel comfortable in a warmer environment? This paper focuses on the appropriate indoor air temperature in winter. Two field investigations were conducted on the indoor thermal environment and human adaptation in residential buildings with district heating in Harbin during two winter seasons from 2011 to 2014. Ten apartments and their residents were chosen as samples in each investigation. The investigations included measurements of physical environmental parameters as well as subjective questionnaires. The results show that when the indoor air temperature was higher than 24 °C, people would have a sensitive response and preferred a lower temperature. An ordinal logistic regression model was used to examine the result of the linear regression model. The neutral temperature derived from the logistic model is 0.5 °C higher than that from the linear model and the adjusted neutral temperature is 0.8 °C higher than the linear model. Detecting whether people felt “cool” or not and “warm” or not is relatively accurate with the logistic model. It is not sensitive to judge whether people felt “neutral” in low air temperatures. Thermal neutral temperature is not a suitable set-point of indoor air temperature. In the severe cold area of China, the indoor air temperature of 20 °C is suggested as the standard for space heating in residential buildings in terms of comfort and energy saving.

In this paper, the optimum thermal insulation configuration in buildings with earth-air heat exchanger has been calculated based on time lag and decrement factor theory. In previous studies which all focused on buildings with conventional air-conditioning systems, the indoor air temperature has been assumed constant, while it is not valid for buildings conditioned by earth-air heat exchanger. Thereby, optimal insulation configuration in these buildings seems to be different from what previously reported. In this study, transient heat conduction equation is solved numerically for different multilayered wall configurations. Results showed that three-layer insulation, which is the optimal layout for buildings with conventional air-conditioning systems, is not desirable for buildings with earth-air heat exchanger. In such buildings, a wall with single-layer insulation at the outside and a wall with two layers of insulation (middle and outside) have the best performance, respectively. In these configurations, the decrement factor is 35% smaller, and the time lag is an hour longer than those of three-layer layout. Furthermore, results indicated that the optimum insulation configuration is independent of the system design characteristics and building wall materials.

The indoor environment of a mechanically ventilated hospital building controls infection rates as well as influences patients’ healing processes and overall medical outcomes. This review covers the scientific research that has assessed patients’ medical outcomes concerning at least one indoor environmental parameter related to building heating, ventilation, and air conditioning (HVAC) systems, such as indoor air temperature, relative humidity, and indoor air ventilation parameters. Research related to the naturally ventilated hospital buildings was outside the scope of this review article. After 1998, a total of 899 papers were identified that fit the inclusion criteria of this study. Of these, 176 papers have been included in this review to understand the relationship between the health outcomes of a patient and the indoor environment of a mechanically ventilated hospital building. The purpose of this literature review was to summarize how indoor environmental parameters related to mechanical ventilation systems of a hospital building are impacting patients. This review suggests that there is a need for future interdisciplinary collaborative research to quantify the optimum range for HVAC parameters considering airborne exposures and patients’ positive medical outcomes.

Synergic effect of the individual components of the indoor environment is considered to be a significant determinant of the quality of the indoor environment. The quality of the indoor environment affects not only the user's comfort but also the health of the users of the buildings. The main objective of the paper is to confirm or exclude a statistically significant impact of hygro-thermal conditions on the indoor air quality (IAQ). Hygrothermal conditions and indoor air quality are the essential components of the indoor environment. The indoor air temperature [°C], the relative humidity [%] and the indoor air quality are monitored in the apartment of the prefabricated residential building (Ostrava, Czech Republic) during several months. The measuring MEMS MOS gas sensor AS-MLV-P2 contains a metal oxide semiconductor based gas sensor detecting differences the concentration of harmful substances such as alcohols, aldehydes, ketones, organic acids, amines, and aliphatic and aromatic hydrocarbons. The measured gas concentration is calculated with an algorithm into a CO(2) equivalent [ppm]. The observed values are subjected to correlation analysis.

Previous studies have demonstrated a potential reduction in cooling load and improvement in comfort from the implementation of night ventilation. This paper describes the performance, in terms of indoor environmental conditions, of three buildings from both the U.S. and India that use night ventilation as their primary cooling method. The research methods used the following approach: (1) Assess the cooling strategy in relation to the adaptive comfort model; (2) Develop a hybrid model, using both first principle equations and the collected data, to predict the instantaneous air and mass temperatures within each building and use the model to assess performance of the cooling strategy; (3) Determine an optimized ventilation control strategy for each building to minimize energy and maintain comfortable temperatures. (4) Develop a statistical model using collected data to predict the window opening pattern for occupants of a building using natural night ventilation. The study yielded the following results: (1) The buildings in the mild climate are successfully keeping the indoor temperature low, but also tend to be overcooling; (2) The night ventilation strategy has very little impact on indoor conditions of the buildings in the mild climate; (3) The impact of night ventilation is less significant when there is low internal loads and heavy mass; (4) The building in the hot and humid climate is keeping the indoor temperature within the comfort bounds for 88% of the year; (5) The night ventilation strategy has advantageous impact on indoor conditons of the building in the hot and humid climate, but not enough to cool the space on its own; (6) Model predictive control has the potential to further improve the performance of night ventilation. (7) Window opening behavior for the building using natural night ventilation is most heavily dependent on indoor air temperature and mass temperature.

On account of radiant time factors method, this article presents a computed way of floor radiant cooling loads using radiant time factor procedure program to compute floor radiant time factors and to get floor radiant heat gains by test data collected within 24 h, then dynamic floor radiant cooling loads could be acquired by matrix operations. Five experimental conditions are selected to validate the calculated results. The experimental results indicate that the crest value errors between room-cooling loads and separating cooling loads about each condition are among the range −3.2% to 4.7%, and the mean value errors are less than 6.1%. The floor radiant cooling loads decrease and delay according to the changes of floor radiant heat gains. Crest value errors between measurement cooling loads and calculation cooling loads are among the range −1.8% to 2.3%, and the mean value errors are not more than 3.2%. Taking radiant time factor procedure program to compute corresponding building room floor radiant time factors with three types of building envelope, floor radiant cooling loads’ characteristics would be obtained under two conditions such as different radiant time factors and different radiant heat gains. So the room floor radiant time factors are calculated by radiant time factor procedure program, and building room floor radiant cooling loads can be computed.

The increase in global temperature in recent years (which is likely to continue) has the power to affect the temperatures of indoor workplaces. This increase may in turn, be reflected in human performance. The present article analyzes the relationship between air temperature, blood pressure and heart rate variation in students in a learning environment through Video Display Terminals (VDT), located in northeastern Brazil. The thermal conditions were analyzed during three consecutive days, according to ISO 7726: 1998; in the group of students who underwent changes in indoor air temperature, their blood pressure and heart rate were also measured. When the air temperature was of 20ºC, 24% of the subjects’ heart rate exceeded 100bpm, while for 30 °C this number reached 51%. The results revealed changes in diastolic blood pressure and heart rate when air temperature increases.

Numerous field studies conducted in different locations have found that peoples’ thermal comfort varies with local climate. However, little is understood about the effect of moving from one climate to another. Literature suggests that people would be able to adapt to the typical indoor climate in a new location, though estimated timescales for this process differ. This paper uses data from a 6-month field study to investigate the process of thermal adaptation to a new climate. The field study consisted of a series of four thermal comfort surveys conducted with 48 occupants of single occupancy residential accommodation units, which helped to estimate their preferred temperatures. The surveys were carried out between October 2015 and April 2016 in Southampton, UK, with high resolution indoor air temperature data collected for the periods between the surveys.Study participants were grouped into three categories: long term residents of the UK (Category A), recently moved to the UK from cold climates (Category An) and recently moved to the UK from warm climates (Category B). The higher indoor temperatures of participants from cool climates (Category An) indicates the influence of indoor thermal history in determining thermal comfort conditions in a new location. This is highlighted by the fact that 94% of Category An participants reported having heating in their previous residence compared to 17% of Category B participants. Analysis of comfort temperatures over the first 6 months of occupancy shows no indication that occupants from Category An or B are adapting their indoor preferences to match that of long term UK residents, given the choice to create their preferred environment. Finally, comparison of indoor air temperature and comfort temperature found a higher correlation in Category A participants which supports the key principles of adaptive comfort theory. Category An demonstrated fairly close correlation though air temperatures were higher than comfort temperatures which may be due to embedded heater use behaviour patterns. Category B demonstrated no correlation between comfort temperature and air temperature which may be due to unfamiliarity to indoor heating systems.

For the purpose of evaluating passive cooling effects in summer, a thermal investigation of traditional houses was conducted in the sub-tropical region of Nepal. The results were as follows: (1) daytime indoor air temperature is 4.6 K less than outdoor air temperature. (2) The daytime surface temperature of the thatched roof is lower than the clay tile and cement tile roof. The results indicate that passive cooling and moisture control effects are found in traditional houses with earthen floors, thatched roof, mud and brick walls and mud vessels which are effective in producing thermal comfort for residents.

In recent years, slatted floors made of materials like fiber composite and plastic have been introduced in animal housing systems. These modern floor types are claimed to have low heat conductivity and hence be “better” for the sheep than expanded metal, but the actual preference in sheep has not yet been tested. The aim of this study was to investigate the preference of ewes for different floor materials at low ambient temperatures. The experiment was performed in a non-insulated building and the indoor air temperature varied from -11.8 to + 3 °C. Each experimental pen measured 3.0 x 2.0 m (total 6.0 m2) and were divided into two equal sections (A and B). A total of 30 non-pregnant ewes were sheared and allocated to one of ten stable groups with three animals per group. Five different floor types - expanded metal, slatted floor made of fiber composite, slatted floor made of plastic, solid floor made of wood and solid floor consisting of a rubber mat, were installed in section A and B in the experimental pens. Groups were habituated to all floor material combinations and systematically rotated through the ten pens. Behaviors were scored from 20 hour video recordings using instantaneous sampling at 10 minute intervals. In addition, heat conductivity properties of the five different floor materials were tested. On days with low temperatures, the ewes were standing or walking more, resting less, eating or drinking more and resting more in physical contact than on days with higher temperatures. When given the choice, ewes showed clear preferences for standing/walking and resting on solid floor materials than on slatted floors. This is consistent with earlier preference tests on sheared sheep. Ewes did not seem to show a clear preference for one slatted floor material over another for resting. The proportion of time spent standing/walking in the pen was steadily reduced as air temperature in the barn increased. The present experiment suggests that none of the floor combinations had thermal properties that adversely affect resting and other general behaviors of the animals. The heat conductivity properties were similar among the slatted floors. In conclusion, the claimed favorable thermal properties of plastic slatted floors and fiber composite were not confirmed. There must be other properties of the floor than heat conductivity that influences the preference in ewes.

There is a global concern about energy in buildings generally for two major reasons. The first one is to minimise the energy consumption in buildings, while the other is to provide thermally comfortable buildings with minimum energy usage. Most of the work carried out in buildings was in office as well as domestic sector. However, the limited publication was done in educational buildings generally. The significance of this research is to take into consideration the energy pattern in a school building in the Kingdom of Saudi Arabia. The research is going to use TAS EDSL computer modelling with its validation. TAS is one of the most commonly used software globally to predict energy building performance. In addition to that, the school will be visited for monitoring. Several types of advanced tools will be used to measure indoor air temperature, relative humidity and much more. This investigation shows that the utilisation of natural ventilation has a major impact on internal temperatures. It has lowered the minimum by 6°C and also lowered the maximum by 3°C. In addition to that, there is a noticeable influence on the top classroom which has its roof exposed to the outdoors. Such outcomes can serve the new vision of Saudi Arabia 2030 and aid to improve the reliance of its buildings on energy.

Firewood consumption and air temperature were investigated in winter and summer in traditional houses in the Banke, Bhaktapur, Dhading, Kaski, and Solukhumbu districts of Nepal. The firewood consumption rate was 235–1130 kg/capita/year. The results showed that the households in the temperate climate used less firewood than those in the subtropical climate. The indoor and outdoor temperature difference (7.8 °C), the vertical temperature difference (7.1 °C), and the maximum indoor air temperature (42 °C) were most significant in the kitchen. The results demonstrated a waste of energy in winter and an uncomfortable thermal environment in summer. If thermal storage on the wall were introduced in winter as well as airtight openings and improvements in fireplaces, we could reduce the usage of firewood, and the thermal and air environment would be improved.

The bioclimatic architecture considers the local climatic conditions in order to reconcile maximally the comfort condition of the occupants. Through the several simulations effectuated by the TRNSYS software, this paper shows that the new architecture produced in the south of Algeria following the northern cities tendency is not fully adapted to the hot dry climate of the southern regions, such as the city of Biskra. In these regions, the passive techniques design influence strongly on the thermal architectural space performance. In this regard, diverse of the vertical shading devices size were proposed to evaluate the impact of this passive technique on the thermal performance of the promotional apartments situated in the city of Biskra. The comparative analysis between the simulation results says that the effectiveness of the vertical shading devices on the thermal performance spaces is reducing the indoor air temperature during the summer period. In addition, this analysis shows that promotional apartments are unsuitable for the desert climate.The bioclimatic architecture considers the local climatic conditions in order to reconcile maximally the comfort condition of the occupants. Through the several simulations effectuated by the TRNSYS software, this paper shows that the new architecture produced in the south of Algeria following the northern cities tendency is not fully adapted to the hot dry climate of the southern regions, such as the city of Biskra. In these regions, the passive techniques design influence strongly on the thermal architectural space performance. In this regard, diverse of the vertical shading devices size were proposed to evaluate the impact of this passive technique on the thermal performance of the promotional apartments situated in the city of Biskra. The comparative analysis between the simulation results says that the effectiveness of the vertical shading devices on the thermal performance spaces is reducing the indoor air temperature during the summer period. In addition, this analysis shows that promotional apartm...

The aim of this study was to investigate the variation in air quality on days with low outdoor air temperatures in Norwegian horse stables. A total of 19 insulated, mechanically-ventilated stables with horses kept inside during the night were included in the study. In almost all of the stables (n=18) ventilation fans were operated during the night. In eleven of the stables the exhaust fans had a manual step by step regulation whereas in the remaining eight stables the exhaust fans were regulated by a temperature-setpoint thermostat. Fresh air inlets however, were highly variable in design and management leading to potential for ineffectiveness of ventilation functions. In four of the stables there were no specific air inlet systems, in five stables the exit door was used as the only air inlet. Mean outside air temperature was 0.0 ± 0.8 °C and mean indoor air temperature was 7.5 ± 0.5 °C. Mean level of CO2 was 1800 ppm and only in one stable CO2 exceeded 3000 ppm. Mean inside ammonia (NH3) was 1.3 ppm and only in one stable the level of NH3 exceeded 5 ppm. The total dust concentration was 0.69 ± 0.19 mg/m3 and in two stables the dust concentration exceeded 1.0 mg/m3. Half of the stables visited had a lower calculated air exchange rate than recommended. Still, the majority of the stables maintained acceptable air quality, with ammonia and dust levels within recommended levels.

A good ventilation is important to improve indoor air in buildings. In Sub-Saharan Africa regions and other countries, both health and productivity are indeed elements depending on indoor comfort. The purpose of this research is to suggest a new thermal comfort approach based on subjective responses of occupants and mathematical models. There is a lack of data about indoor comfort in residential buildings in the tropical islands of Indian Ocean and the aim of the research is to propose guidelines for more comfortable constructions in Madagascar and other countries of the Indian Ocean. Experimental and subjective data were collected in 67 traditional habitats and 25 public and private schools, located in 25 districts of urban communes in the Northern Madagascar. Mathematical modelling was based on Rohles approach. At total of 992 questionnaires were collected and analysed during rainy and dry seasons. The results showed that traditional buildings were more comfortable than schools. Comfort temperature varied from 24.6 to 28.4 °C during both seasons in residences and schools. When the indoor air temperature varied in the 24.5–27.5 °C range, more than 80% of peoples were satisfied.