• Energy Research
• 11. Sustainability close
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With the continuous deepening of China's rural construction and development, people's living conditions are improved day by day, while accompanied by energy and environment crisis issues. This paper mainly analyzes the energy consumption pattern and the indoor environment of rural households in China and discusses the energy-saving optimization strategies for improving the thermal environment of buildings. Questionnaire surveys and field surveys were conducted in three villages in Guanghan, China. The measurement results show that the annual indoor temperature range of the region in the summer is 15–31 °C and the relative humidity range is 34%-96%. The average indoor temperatures in summer and winter are 28 °C and 16 °C respectively. The indoor thermal environment of rural buildings is usually poor and cannot meet the requirements of Chinese standards. At the same time, the architectural design and energy consumption pattern of rural households are different from those in urban areas as countryside has unique characteristics. Finally, we put forward certain energy-saving improvement measures at the end of the article.

Renewable paper reusing plays a significant role in the sustainable environment under the background of the shortage in forest resources and the pollution from the paper industry. The conventional reusing stream of waste office paper appears to have low reusing rates while consuming massive amounts of energy in intermediate steps. In this study, we developed a novel portable renewable desktop paper reusing system based on font area detection and greyscale sensor. The proposed system consists of two main parts, namely, a greyscale sensor and font area detection model and a polishing mechanism. Acting as an ink mark detector for waste desktop paper, the greyscale sensor and font area detection model can detect the font in the waste desktop paper using an adaptive dynamic compensation schematic. The polishing mechanism will grind the font area of the wasted desktop paper, and this paper reusing processing is non-chemical, energy saving and environmentally friendly. The proposed system is demonstrated through simulations and experimental results, which show that the proposed renewable desktop paper reusing system is portable and is effective for reusing waste office paper in the office. An accuracy of 99.78% is demonstrated in the greyscale sensor and font area detection model, and the average reuse rate of one piece of paper is 2.52 times, verifying that the proposed portable system is effective and practical in renewable desktop paper reusing applications.

This study focuses on the development and analysis of a real-time updated operations strategy of a distributed energy system (DES). Owing to the relevant Chinese policy of electrical transmission and distribution, combined cooling, heating, and power system (CCHP) and photovoltaic (PV) systems are not currently allowed. However, with the Chinese supply-side power grid reform, the permissions for connections between DESs and utilities are gradually evolving. By performing building simulation and using mixed integer linear programming (MILP), a real-time updated operation strategy of a DES is established. Then, considering the DES from Tianjin Eco-city as a case study, a comparative analysis between this updated strategy and the current operation strategy is performed by evaluating three factors: economic efficiency, energy consumption, and CO2 emission. The results show that the updated strategy can reduce 29.12% of electricity time-of-use cost, 10.11% of total fuel consumption, and 18.40% of CO2 emission during the cooling season. Besides, a method of “rolling load forecasting” for DES by using Support vector regression machine (SVR) is proposed and discussed. The testing shows that the Mean Absolute Percentage Error (MAPE) is below 7.5%. And when the training sample is large, the particle swarm optimization algorithm can be used to shorten the modeling time of the air conditioning load forecasting model.

The use of phase change materials (PCMs) in building enclosures is an efficient way to reduce the heat gain and/or loss in summer and winter. It was evident that the thermal performance of buildings with PCMs was affected by the outdoor air temperature significantly. However, the influence of humidity, which was serious in the humid subtropical climate was unclear. To explore the effect of PCMs under a humid subtropical climate, the thermal performance of a lightweight building outfitted with PCMs with a melting temperature of 25 °C was investigated. The actual outdoor air temperature with a humidity of 40–90 RH% and wind velocity of 2–6 m/s blowing from the east, west, south, and north was assumed for the performance assessment. A simulated model was developed using EnergyPlus and verified against experimental data. The energy savings by using PCMs was reduced from 3.9% to 2.6% when the outdoor humidity increased from 40 to 90 RH% in summer. However, the savings was not obvious in winter. Annual energy savings decreased from 1.64% to 1.32% with humidity increasing from 40 to 90 RH%. For annual condition, the average energy savings was reduced from 1.43% to 0.92% when the wind speed increased from 2 m/s to 6 m/s. From an economic point of view, the investment payback period was less than 10 years when the PCM price was lower than 18.0 Yuan/kg.

Research on the window operating behavior of offices is of great significance for reducing building energy consumption and improving indoor comfort. The open-plan office is a common office form that involves a large number of people and a complex staff composition. The window operating behaviors in open-plan offices are also random and various. This study took three open-plan offices with different situations (area, office type, staff composition, etc.) as an example, which provides a new perspective on how people behave differently when opening or closing windows. The window operating behaviors in two typical seasons (summer and transition seasons) were recorded and analyzed. The occupants’ schedules and influencing factors of window operating behavior were investigated by questionnaire surveys. In addition, the indoor environmental parameters, occupancy situation, and on-off statuses of windows and air conditioning were acquired through field measurements. Furthermore, the differences in window operating behaviors in the three open-plan offices were compared from the perspectives of influencing factors, duration of the window on-off statuses, and cause of window control actions, among others. In addition, Spearman Correlation Coefficient was used to analyze the ranks of the candidate motivations for window operating behaviors. The preliminary results show that influenced by the personnel composition, type of air conditioner and adjustable degree of windows, the window operating behaviors of different office buildings have larger discrepancies than that in the same building. However, there were some common characteristics in the window regulation behaviors of the three open-plan offices: they were generally influenced by the coupling of environmental factors, schedule factors, and equipment factors. This study reveals that when expand the research object from a single building to multiple buildings, more difficulties and challenges would be involved into behavior research.

With the development of social economy, heating in the south of China has been concerned widely. As one of the energy sources of decentralized heating, natural gas (NG) has been used more and more popularly. This paper aimed to study the impact of residential building heating on NG consumption, and took Wuhan city, the representative city needing heating in winter of the south of China due to its location and climate, as an example. Firstly, a typical residential building model was established through DeST software. The heating load was simulated, and the corresponding NG consumption index was calculated. Secondly, appropriate methods were used to forecast the basic data of Wuhan city in 2020, including households and per capita gross national product (GDP), etc. Thirdly, the NG consumption of residential buildings with and without heating were predicted. Finally, the impact of residential building heating on NG consumption was analyzed. The results showed that the average annual household heating consumption of residential building in Wuhan city in 2020 was 2100 kWh/ household, and the NG consumption using for residential building heating was 295 Nm3/household. In addition, the NG consumption of residential building generated by space heating with 100% heating rate was 2.82 times the NG consumption generated by the stove and water heater, showing that residential building heating had a large impact on NG consumption. This study can contribute to choosing appropriate heating method in the southern cities of China, and further planning the gas pipe network in these cities.

This paper focused on the impact of window shades’ physical characteristics and opening modes on annual air conditioning energy consumption of residential buildings in China. Three building models with different window layouts were proposed initially, and then validated by the dimensionless indicator annual energy performance (AEP) to determine the final building model adopted in this study. Harbin, Beijing, Guangzhou, Changsha and Kunming were selected to represent five different climate zones in China. The shading model has taken six physical characteristics of window shades, viz. outer emissivity, inner emissivity, solar transmittance, solar reflectance, thermal infrared transmittance, conductivity and two opening modes, viz. up & down mode as well as left & right mode, into consideration. Besides, the window shades operation schedule was summarized through 949 valid questionnaires. The annual air conditioning energy consumption was calculated via EnergyPlus software, and then the impact of the above different opening modes and parameters on energy use were investigated. The analysis results indicated that the top & bottom opening mode is better than the left & right mode when used in Harbin, and the effect of two different modes in air conditioning energy consumption in Kunming is similar. But in the other three cities, the left and right mode is preferred. Besides, the analysis results of the impact of different physical characteristics on air conditioning energy use in different climate zones could help improve the energy performance of window shades.

The transportation buildings alongside the expressways (TBE) have comprehensive characteristics, providing shopping and accommodations for drivers and passengers. However, the indoor thermal environment and energy consumption of such service buildings was not covered in most studies. To this end, based on some typical TBEs, this study investigated the thermal environment and energy consumption characteristics for TBEs. And the mentioned TBEs are located in Xiong'an New Area, a national special zone with requirements of low carbon and low energy consumption in China's cold region. The thermal environment study included questionnaire survey and on-site investigation by adopting dynamic thermal comfort evaluation index (i.e., Relative Warmth Index (RWI) and Heat Deficit Rate (HDR)). Then, the TBE energy consumption was investigated with the main influencing factor analyses. Finally, numerical simulations were conducted to analyze the energy efficiency approaches in TBE. The results showed that RWI and HDR were able to evaluate the thermal comfort of personnel in transitional environment of TBE in winter. Meanwhile, when the room temperature was set as 16 °C, it was still able to maintain the thermal environment for the indoor staff. The main energy influencing factors of TBEs are building scale, system equipment and usage characteristics. Besides, it was practicable to adopt the heat pump system to replace conventional space heating and cooling system, of which the total energy consumption of geothermal heat pump reduced by 38.1%.