Indoor Thermal Environment In Winter Research Articles

Winter indoor thermal environment and livability analysis of traditional residential houses in northeast Sichuan, China

With the rapid development of the national economy, increasing attention has been given to the living environment in rural areas, especially indoor thermal and wind environments. This study conducted on-site measurements and questionnaire surveys during winter in the indoor environment of five villages in northeastern Sichuan. Eighty-nine traditional residences were selected to investigate their fundamental characteristics, indoor thermal environment, humidity conditions, and comfort levels. Questionnaires and comparative experiments were also conducted with natives and locals. This combination of objective data and subjective feedback provides a comprehensive perspective for assessing the indoor thermal environment. The results showed that when expressed as neutral temperature and humidity, the temperature difference was 2.36 °C, with little humidity difference. Residents exhibited higher tolerance towards the local thermal and humidity environment than nonlocal volunteers, who showed greater sensitivity to it. In addition, residents had a Predicted Mean Vote (PMV) value of −0.69 and a heat acceptance value of −1.78, while non-local volunteers had a PMV value of −0.76 and a heat acceptance value of −1.32. A detailed evaluation and analysis of the relationship between the indoor thermal environment and human comfort of local residential houses was carried out, providing technical guidance for energy conservation and thermal insulation of local buildings.

Field Study to Compare and Evaluate Summer Thermal Comfort of School Buildings with Different Moderate Thermal Mass in Their Building Elements

Previous studies show that moderate thermal mass in school building elements can positively impact the winter indoor thermal environment in a temperate climate with mild, humid winters. Based on a field study, this research contributes new physical data of the summer indoor thermal environment of Auckland school buildings with different designs of moderate thermal mass in their building elements to add to the previous winter field-study data and demonstrates that a school building with moderate thermal mass is adequate in a temperate climate with mild, humid winters and warm, dry summers. This field study compared and evaluated the summer indoor thermal environment of classrooms with different moderate thermal mass in their building elements during the summer school term and the summer school holidays. This study found that a classroom with thermal mass in its building elements has 19% to 21% more time in summer than a classroom without any thermal mass in its building elements when indoor air temperatures are within the thermal comfort zone, which was solely impacted by the building’s thermal performance. This study established a suitable research method to analyse the field-study data and identify the differences in the indoor thermal environments of the school buildings with different designs of moderate thermal mass in their building elements.

Experimental evaluation of the cascaded energy storage radiator for constructing indoor thermal environment in winter

Clean heating technologies have been developed in past decades and numerous strategies have been adopted in improving the heat transfer performance of energy storage radiators. Nevertheless, the integrated heat storage/release effect by enhancing thermal conductivities of PCMs and the radiator has rarely been studied, and the energy utilization efficiency needed to be evaluated by considering the cascading and stratification effect. Based on these, three kinds of energy storage radiators were designed with different types and layouts of energy storage bricks, i.e. (I) magnesium–aluminum (Mg-Al) energy storage bricks without aluminum foil wrapping, (II) Mg-Al energy storage bricks wrapped by aluminum foil and (III) cascaded energy storage bricks with Mg-Al and paraffin wax-expanded graphite (PW-EG) energy storage bricks wrapped by aluminum foil. These radiators were experimentally evaluated from aspects of heat storage/release amount, heat transfer capacity and indoor thermal environment characteristics. After using aluminum foil to package energy storage bricks, the temperature rise/drop and heat storage/release rate of energy storage bricks were 21.0/56.8 °C higher and up to 95.7/119.0 W faster respectively (Radiator II vs Radiator I). While after using cascaded energy storage bricks, the heat storage/release efficiency was 11.9 %/14.6 % higher, the indoor vertical/horizontal temperature difference was 2.5/0.2 °C smaller, and the energy utilization efficiency by occupied space to total power consumption was 24.3 % higher (Radiator III vs Radiator II). Therefore, the aluminum foil packaging energy storage bricks were shown to improve the thermal conductivity, and the cascaded energy storage radiator owned higher thermal storage/release capacity and energy utilization efficiency.

Experimental Investigation of Indoor Thermal Comfort under Different Heating Conditions in Winter

Owing to historical reasons, only a few locations in the Guangdong province use heating to enhance interior thermal conditions. With the variation in climate and increase in people’s lifestyle requirements, winter heating has become increasingly necessary. However, a literature review revealed that only a few studies have investigated the heating requirements during winter in the Guangdong province. In this study, we compared the thermal comfort of radiant floor heating with wall-mounted air conditioner heating. A Guangzhou University climate chamber was used in several investigations. The findings revealed that the thermal neutral temperatures of radiant heating and air conditioner heating were 22.0 °C and 23.0 °C, respectively, about 1 °C variation in temperature. Additionally, in the research on thermal reactions and local skin temperature measurements, the impact of local thermal discomfort on the overall thermal experience was also considered. The findings showed a direct relationship between the local thermal discomfort caused by radiant heating and general thermal sensation. Thermal sensation of the subjects mainly originated from the lower extremities and was significantly affected by Va (air velocity). The relationship between the local thermal discomfort of convective heating and general thermal sensation was weak and mainly caused by the uneven thermal environment. Thus, in south China, for lowering energy usage, radiant floor heating should be used to create an improved indoor thermal environment in winter.

Winter indoor thermal environment and heating demand of low-quality centrally heated houses in cold climates

In northern China, district heating systems without terminal control typically serve thousands of end-users, thus inevitably some users suffer from insufficient warmth and others are overheated indoors due to hydraulic imbalances. This paper aimed to understand the indoor thermal conditions and the actual heating demand in low-quality centrally heated dwellings. The driving force of heating demand was analyzed based on a smartphone survey of 233 households in cold climates, and field measurements of winter indoor thermal environment and AC supplemental heating behavior were conducted in a sample of 13 cool dwellings. Logistic regression and heteroskedasticity-robust Ordinary Least Squares were adopted to assess AC usage patterns and driving forces of heating demand, respectively. New knowledge has been gathered regarding average temperatures of 17.4 ℃ and 16.8 °C in cool housing living rooms and bedrooms, respectively, outside the human thermal comfort zone. Simultaneously, intermittent and partial AC usage patterns induced by time and air temperature were observed in these cool end-users for the comfort. The average daily running time of AC devices was 2.0 h for the living room and 1.8 h for the bedroom. There were statistically significant base linking occupants' heating demands to education level, household income, tenure type, presence of children, thermal experience and heating system. However, it was not a significant factor for household size. In addition, a rebound effect of building energy efficiency improvements on the interior temperature was also noticed. The results of this study shed light on better and target-oriented residential internal temperature or heating system design for both thermal comfort requirements and energy-savings.

Solar application potential and thermal property optimization of a novel zero-carbon heating building

Building Integrated Heat Pipes (BIHP), specifically a novel passive solar house integrated with gravity heat pipes, realizes envelopes with variable thermal properties and makes effective and efficient use of solar energy to reach zero-carbon heating, and can greatly improve the indoor thermal environment in winter. In this paper, an efficient method based on particle swarm optimization for the optimization of thermal properties of the BIHP interior envelope is proposed. The key thermal properties of the heat pipe and the exterior and interior envelopes are optimized, and the solar application potential of improving indoor thermal discomfort by BIHP in five representative cities of northern China is obtained. The results show that the equivalent thermal conductivity of the heat pipe is suggested to be greater than 2 × 104 W/(m·K). The optimal BIHP should have exterior envelopes with high thermal resistance and interior envelopes with large thermal capacity. In the selected areas, the optimal BIHP improves indoor thermal discomfort by 36 %–100 % and increases the minimum indoor operative temperature by 5.1–10.5 °C compared to the reference building. BIHP is recommended in areas with the ratio of radiation to temperature difference greater than 5 W/(m2·K) and can reach zero-carbon heating in Lhasa and Yinchuan. This research provides a global matching and optimization method for the effective and efficient utilization of solar energy to reach zero-carbon heating and evaluates the application potential of BIHP.

Effect of the envelope structure on the indoor thermal environment of low-energy residential building in humid subtropical climate: In case of brick–timber vernacular dwelling in China

The brick–timber structure plays a crucial role in creating a comfort indoor thermal environment for low-energy vernacular dwellings. Herein, the thermal environment of the dwelling was studied by DesignBuilder software and evaluated using Adaptive Predicted Mean Vote (APMV) index. These results revealed that the indoor damp and cold feelings intensified in winter, and the mountain as a natural wind barrier weakened the attack of the prevailing wind in winter. These results leaded that the wind speed of the tested room was lower than 0.1 m/s. The thermal comfort satisfactory days in a year accounts for 56.2%, and the overall level of indoor thermal environment was low in the rest of the year, especially in winter. The simple structure of the exterior envelope and the single material were the main reasons for the poor indoor thermal environment of naturally ventilated buildings. Therefore, optimization strategies such as increasing the insulation materials of the envelope and adopting insulating glass windows were proposed. Compared to that before the retrofitting, the overall thermal environment grade of the vernacular dwelling has been improved by 4.7% (grade I), -0.3% (grade II) and -4.3% (grade III), respectively. The poor thermal performance and airtightness of the envelope easily lead to the negative effect of outdoor cold, heat and water vapor entering the house, which affects the thermal environment grade. These conclusions provided a reference for the optimization of the thermal environment of existing low-energy vernacular dwellings in subtropical humid climate areas. • Poor indoor thermal environment in winter in low-energy buildings. • Building airtightness is as important as the thermal performance of the envelope. • Buildings in humid subtropical climates should be well protected from moisture. • The height of surrounding buildings influences wind speed and shading

Thermal Environment Analysis and Thermal Comfort Evaluation of Huizhou Folk Dwelling Houses Guided by Auxiliary Interior Space Layout

The Huizhou folk dwelling houses are important carriers of the traditional Huizhou cultural and architectural heritage in China. However, such dwelling houses have obvious shortcomings such as damp, dark, insufficient lighting, and inability to cope with cold weather. Existing studies on Huizhou folk dwelling houses haven’t considered factors such high humidity or low temperature that can lead to poor indoor thermal environment in winter, and few have concerned about the theoretical analysis on the formation mechanism of the indoor thermal environment. Therefore, to fill in this research blank, this paper aims to give thermal environment analysis and thermal comfort evaluation on the Huizhou folk dwelling houses under the guidance of auxiliary interior space layout. At first, this paper took the first courtyard of the typical “series-courtyard” structure of the Huizhou folk dwelling houses as the subject, and analyzed the thermal environment of the second courtyard, including the outer wall, door, roof, patio, and ground, and the amount of heat transfer, the amount of radiant heat, and the amount of heat exchange of ventilation were tested. Then, based on the location selection, layout, and architectural morphology of the Huizhou folk dwelling houses, this paper studied the relationship between the thermal comfort of Huizhou folk dwelling houses and the wind and heat environment in winter, the specific test items were indoor temperature, comfort degree, wall temperature, and air tightness, and the test results could provide basis and direction for the renovation of indoor thermal environment of Huizhou folk dwelling houses. At last, this paper gave the analysis results of an actual example, and verified the effectiveness of the analysis and evaluation methods in this paper.

Improving the indoor thermal environment in lightweight buildings in winter by passive solar heating: An experimental study

Traditional lightweight building envelopes with constant thermal properties are of small heat capacity and large thermal resistance. Lightweight building envelopes with variable thermal conductivity and variable equivalent specific heat capacity can promote passive solar heat gain for clean heating and improve the indoor thermal environment in winter. In this paper, a real-scale lightweight solar house integrated with flat gravity-assisted heat pipes and PCM (phase change material) was built up, and the indoor heating effects of four forms of the solar house were experimentally studied. The results showed that (1) the heat pipes efficiently transferred solar heat absorbed by the exterior surface of the south envelope into the indoor environment during the day and increased the average daytime indoor air temperature by 3.8°C, but this benefit was not proportional to the area of heat pipes. (2) The PCM effectively stored solar energy during the day and released heat to the indoor environment at night, and the daily range of indoor air temperature was reduced by 8.7°C, with only 81% mass and 33% volume of concrete block, respectively. (3) The solar house increased the effective proportion of solar energy for indoor heating from 8.7% to 57.5% in the form of DHP + PCM house.

Thermal Performance of School Buildings: Impacts beyond Thermal Comfort.

Based on field study data regarding the winter indoor thermal environment of three classrooms with different building envelopes, this study compared and evaluated these environments, not only related to students’ thermal comfort but also to their health. The inadequacy of the conventional New Zealand school building for maintaining a comfortable and healthy winter indoor thermal environment has been identified. A classroom with thermal mass had 31%, 34% and 9% more time than a classroom without thermal mass when indoor temperatures met 16 °C 18 °C and 20 °C respectively and has 21.4% more time than the classroom without thermal mass when indoor relative humidity was in the optimal range of 40% to 60%, in a temperate climate with a mild and humid winter. Adding thermal mass to school building envelopes should be considered as a strategy to improve the winter indoor thermal environment in future school design and development. Adding thermal mass to a school building with sufficient insulation can not only increase winter indoor mean air temperature but can also reduce the fluctuation of indoor air temperatures. This can significantly reduce the incidence of very low indoor temperature and very high indoor relative humidity, and significantly improve the indoor thermal environment.

Design optimization of rural building in dry-hot and dry-cold area using a back propagation (BP) neural network

This study describes the numerical analyses of the indoor air temperature of the earth building located in dry-hot and dry-cold area in order to evaluate the effects of the passive design parameters on the indoor environment and then determine the optimal values of the design parameters. Firstly, a short-term monitoring was performed in an existing earth building, aiming to validate the numerical building model developed by using an advanced simulation software EnergyPlus. Then a series of regional studies on the effect of building parameters on indoor environment of the earth building were investigated and the simulated results indicated that four design parameters, i.e. building orientation, window to wall area ratio, projection factor of window shading and external wall thickness, exhibit the distinctly impacts on the indoor thermal environment in winter and summer. Next, a back propagation (BP) neural network model with ten neurons in the hidden layer was established using Matlab R2016a to predict the indoor environment, and the degree discomfort hours (DDH) in winter and summer were calculated as the output data. Finally, the itemized intensive scanning technique was used to successively select the values of the passive parameters in their range and the predicted results indicated that the optimal passive parameters are 6°east of south, 18.20 %, 0.66 and 643 mm, respectively.

Climate Adaptation and Indoor Comfort Improvement Strategies for Buildings in High-Cold Regions: Empirical Study from Ganzi Region, China

The improvement of building and living conditions in high-cold areas has always been an issue worthy of attention, but there is currently no research using field survey data for evaluation. The Ganzi region, based in the western plateau of China, is a typical example for such a study. Restricted by factors such as natural conditions and economic level, the winter indoor thermal environment of western plateau houses is generally poor. Taking the new residential houses in the Ganzi region as a case study, the authors of this paper conducted field research and analyses. First, the authors analyzed the construction technology and functional layout of the building through thermal environment testing and investigation; second, the authors analyzed the user’s activity path according to the production and lifestyle; thirdly, the authors comprehensively evaluated the indoor thermal comfort through questionnaires and a predicated mean vote (PMV)-predicted percentage dissatisfied (PPD) evaluation model. The research results showed that: (1) the construction technology, functional layout, and temperature distribution of the new residential building were consistent with the user’s activity path, which could effectively improve thermal insulation ability and thermal comfort; (2) compared to the developed eastern regions, the users in the building showed a stronger tolerance and wider acceptable temperature range in the extreme climate environment; and (3) under certain cooperative work conditions, an indoor temperature of 10–14 °C could meet basic thermal environment requirements and thus lower the limits of the standards. The author’s method was proven to be more resilient than current standards in dealing with climate change. Therefore, this research can provide a practical reference for the improvement of peoples’ living conditions and sustainable development in cold regions and other harsh areas.

Study on Indoor Thermal Environment of Traditional Dwellings in the Watery Town in Suzhou in Winter

Traditional dwellings have their own characteristics and values in the construction of indoor thermal environment. In order to analyze the current situation of thermal environment of dwellings in Southern Region of the Yangze River. This paper takes traditional dwellings in the watery town in Suzhou as the research object, and studies the indoor thermal environment in winter through field measurement of indoor and outdoor temperature and relative humidity of dwellings in winter, questionnaire survey and PMV-PPD thermal evaluation system. The results show that the average indoor temperature is 7.5°C, humidity of residential is 72%, the average predicted thermal sensation vote is -2.79, the predicted dissatisfaction is over 90%, and the indoor thermal environment dissatisfaction in public questionnaire survey is 20.83%, which is far from the predicted dissatisfaction PPD. It shows that the vote of hot feeling underestimates the residents' tolerance for the environment, and corrects the deviation of PMV value through adaptive coefficient. The revised aPMV value is greater than PMV value, but the thermal and humidity environment level is still Class III, which does not meet the living conditions. Water source heat pump can be used as a heating method in winter to improve the thermal environment, which can provide reference for improving indoor thermal environment of residential buildings in water towns.

Study on Winter Indoor Thermal Environment of Temporary Shelters Built in Nepal After Massive Earthquake 2015

Natural disasters and wars are main reasons that force people to leave their homes and consequently require urgent needs including temporary shelters. After massive earthquake 2015, thousands of Nepalese who lost their home were doomed to live in temporary shelters, mostly self-built by using zinc/tarpaulin sheets which can hardly provide sufficient thermal comfort. We need to analyze the thermal characteristics of the temporary shelters for creating a better environment for their own sake. Thus, this study tries to evaluate the winter indoor thermal environment of different types of local materials used for insulation in these investigated shelters. The indoor and outdoor thermal environment was measured by digital data loggers at the 10-minute intervals for winter in thirteen different shaped shelters in main three earthquake affected districts: Gorkha, Sindhupalchowk and Lalitpur. The mean indoor and mean outdoor air temperatures were found 12.3°C and 10.1°C. The total heat loss coefficient estimated in thirteen shelters ranges from 74.8 to 325.9 W/K and their specific values with respect to the ranges from 8.1 to 20.4 W/ (m2.K). These values are very large in comparison to those in ordinary houses; this is the major reason of low indoor air temperature especially during nighttime. This suggests that some insulating materials need to be added or replaced with the materials used for the improvement for better indoor thermal environment.

A field investigation on the winter thermal comfort of residents in rural houses at different latitudes of northeast severe cold regions, China

The severely cold regions of Northeast have a colder climate and large latitude span in China. Scholars should pay more attention to the creation of a comfortable indoor thermal environment in winter. In order to understand indoor thermal environments and residents’ thermal comfort statuses in areas at different latitudes, a field survey was conducted in three areas: Harbin (45°N), Changchun (43°N) and Shenyang (41°N). On-site environmental parameter measurements and a subjective questionnaire were conducted simultaneously. Then, the relation between operative temperature and building energy consumption was explored. The results showed that the neutral operative temperature is the highest in Harbin (16.8 °C), followed by Changchun (16.4 °C) and Shenyang (16.0 °C), which are all higher than the measured temperatures. For these regions, 90% of the acceptable temperature ranges are 14.6–19.1 °C, 14.4–18.6 °C and 13.9–18.2 °C, respectively. The expected operative temperatures are 18.6 °C, 17.8 °C and 17.3 °C higher than the neutral temperature, respectively. This reveals that as the latitude increases, the neutral temperature, the upper and lower limits of the acceptable range and the expected temperature are all increased. For different ages, the youth have a higher requirement in terms of thermal comfort, followed by the middle-aged and elderly groups. Compare to males, females feel colder under the same operative temperature. Due to the independent heating system in rural houses, adjusting the heat supply, instead of clothing, is the main adaptive behavior. Regarding building energy consumption, as the latitude declines, the influence of changes in operative temperature increases. If both the regional neutral temperature and zoning heating mode are adopted, energy consumption further decreases. These findings provide a reference for the development of an evaluation standard for indoor thermal environments and an energy-saving design for rural houses in the northeast severe cold regions of China.

Thermal comfort of motion and stationary states for recreational spaces of colleges and universities in the cold regions of China

This study examined a representative college activity centre in China’s cold regions and conducted a field measurement study and questionnaire analysis on the indoor thermal environment in winter. Data fitting and comparative analysis were performed on the predicted mean vote (PMV) calculated from measured environmental parameters and the seven-point vote value actual mean vote (AMV) based on the questionnaire. According to the least square method, the corresponding human adaptive coefficient λm in the motion state and λs in the stationary state were obtained. Based on the research, the thermal comfort survey results were reported for the two states for recreational spaces of colleges and universities. These results suggest that the AMV and PMV do not coincide in the two states. The actual thermal sensation is less sensitive than predicted through the sensitivity analysis for the two states. The respondents’ actual thermal sensation is less sensitive when exercising than stationary state. Moreover, both PMV and AMV in motion state are higher than those in stationary state, illustrating that the state of motion has a greater influence on thermal sensation. This research provides a theoretical basis and data reference for the low energy design of recreational spaces of colleges and universities.

The research on the influence of building air tightness to energy consumption of residential building in a hot summer and cold winter zone in China

The hot summer and cold winter zone in China belong to the non-central heating area. In recent years, with the improvement of people’s living standards, more and more residential building have begun to adopt various heating methods. However, many existing buildings have poor air tightness level, and the indoor thermal environment is in a bad condition, which also causes a great waste of energy. Based on the actual measurement of the airtightness of a demonstration building, this paper studies the effects of residential airtightness on heating and air conditioning energy consumption and indoor thermal environment in winter. The simulation results show that in the hot summer and cold winter zone, the level of air tightness also influence the heating and air conditioning energy consumption, but the impact on heating energy consumption is more obvious. In addition, when selecting energy-saving measures, the relationship between the level of air tightness and the level of insulation should be weighed. We should not reduce energy consumption only by improving the airtightness level. Otherwise, the investment is large and the energy saving effect is very poor.

Performance evaluation and comparison between rural new and traditional house in severe cold regions of China

With the development of urban-rural integration, the number of newly built houses is increasing. Due to the influence of climatic characteristics, traditional technology, economy etc, the phenomenon of large heating energy consumption and low indoor thermal comfort in winter is common in rural houses. In order to explore the energy-saving design methods for rural houses in severe cold regions and create a low-carbon and comfortable indoor thermal environment in winter, this paper selects the new house and traditional house of Zhalantun, Inner Mongolia as research objects, applying the methods of testing and calculation to comprehensive comparison of the differences between two types of housing from the aspects of building energy consumption, indoor thermal environment and thermal performance of building envelop. Results show that through the reasonable thermal environment zoning, performance optimization of building envelop and improvement of heating mode etc., the indoor thermal environment can be effectively improved, so as to achieve the purpose of comfort and energy saving.

Study on winter indoor thermal environment of temporary shelters built in Nepal after massive earthquake 2015

After massive earthquake 2015, thousands of Nepalese who lost their permanent houses by the hardest hits were forced to live in makeshift temporary shelters. The people residing in these shelters are facing extreme coldness that causes various health-related problems in winter. The field measurement on indoor thermal environment was conducted in one of the district hit by massive earthquake, Lalitpur. The indoor and outdoor air temperatures of five shelters were measured by a set of thermometers with digital data loggers at the ten minute intervals in winter. The mean indoor and mean outdoor air temperatures during the measured night-time were found to be from 10.3°C and 7.6°C; they were lower than lower limit value of acceptable indoor temperature at 11°C found from our previous research. We analyzed the thermal characteristics of those shelters measured for seeking whether the improvement is possible or not and also how much of it is affordable. Thus, in this study, we evaluated the indoor thermal environment by estimating the heat-transmission characteristics of the used materials in these investigated shelters. The total heat loss coefficient estimated in five shelters per respective floor areas ranged from 11.2 to 15.4 W/(m2·K). These values obtained are very large due to low thermal insulation materials used. The paper ends with important lesson that reduce the total heat loss coefficient needs to reduce down to 2∼7 W/(m2·K) for realising the need to indoor air temperature above at 11°C could be 70% of nighttime hours. Such reduction of heat loss was found to be realized by adding affordable materials, i.e. cellular polyethylene foam and clothes for respective walls and roof.

Study on indoor thermal environment of rural dwellings in Northwest China in winter

In order to study the status of the indoor thermal environment of the northwest rural dwellings in winter, the thermal performance and the residents’ adaptability are investigated and the indoor and outdoor thermal environment parameters are measured in Zhongwei region of Ningxia, the indoor thermal environment is analyzed and evaluated by the operating temperature. The results show that the northwest rural residents have strong adaptability to the cold indoor thermal environment in winter. In this area, the cold and daily temperature difference in winter is large, but the solar energy is rich, and it has the geographical advantage of developing passive solar building. The thermal performance of existing rural dwellings is poor and the indoor thermal environment is not ideal. It is necessary to enhance the thermal performance of building’s heat collection, thermal storage and enclosure structure.