Hot Summer Climate Research Articles

Advancing energy recovery ventilators with phase change materials for cooling load reduction and heat exchange efficiency improvement

Efforts to reduce building energy emissions and achieve net-zero carbon scenarios globally have increasingly focused the building sector on improving energy efficiency. Heating, ventilation, and air conditioning (HVAC) systems play a vital role in providing comfortable indoor environments but significantly contribute to energy consumption and greenhouse gas emissions. Energy recovery ventilators are efficient active systems that prevent unnecessary indoor heat loss and gain, regardless of outdoor climate, making them excellent technologies for achieving zero energy. In a hot and humid summer climate, such as in Korea, it is crucial to enhance the efficiency of energy recovery ventilators and reduce cooling energy consumption. A Green HVAC design aimed at reducing the energy consumption of active systems to near zero was proposed by applying phase change material-based modules with high heat storage performance to energy recovery ventilators. The phase change material module is stabilized with high thermal conductivity aluminum packing and is configured as a mesh-type structure to amplify heat exchange efficiency with air. Compared to the energy recovery ventilator, the application of the module demonstrated a reduction in supply air temperature by an average of 2.6 °C in high-temperature outdoor. During the effective operating period, a continuous indoor intake temperature reduction effect was observed, and the sensible heat exchange efficiency showed a 21.32 % improvement with the module using n-octadecane. Phase change material modules that can enhance ventilation and improve energy efficiency in high-temperature environments can be proposed as a technology to achieve Green HVAC.

A Multivariate Model and Correlation Study on the Impact of Typical Residential Spatial Forms in the Middle Reaches of the Hanjiang River on the Thermal Environment and Thermal Comfort

Different spatial forms affect the indoor thermal environment and human thermal comfort. A good living environment largely depends on the flexibility of spatial forms, and spatial scale and proportion are the key factors affecting these forms. We selected typical residential houses in the middle reaches of the Hanjiang River in the hot summer and cold winter climate area as an example. Through on-site measurements and questionnaire surveys, we studied the impact of residential form indicators on the thermal environment and thermal comfort. We also established a multivariate model to explore the correlation among various parameters. The results showed that the spatial-real ratio of the residential spatial form index in the middle reaches of Hanjiang River was 5–58%. The height from the ground was 2.23–6.92 m. The open-space ratio was 0.04–4.55. The explanatory power of the spatial form index to indoor air temperature was 57.5%, with a strong correlation (R2 = 0.675). The explanatory power for humidity was 38.2%, with a weak correlation (R2 = 0.525). The explanatory power of SET was 30.6–50.1%, with a weak correlation (R2 = 0.466). The explanatory power of PMV was 6.5–31.7%, and PMV1.0 was weakly correlated (R2 = 0.474). The explanatory power for PPD was 15.5%, where PPD 1.0 was close to a weak correlation (R2 = 0.508). The results of this study provide reference values for the design methods of and decision-making process for green and energy-saving regional buildings.

Analysis of the Applicability of a Phase-Change Energy Storage Wall for Public Buildings in Hot Summer and Cold Winter Climate Zones

The effects of applying a phase-change energy storage wall in office buildings in hot summer and cold winter climate zones were analyzed by comparing several factors based on numerical calculations, specifically focusing on the internal and external wall temperature, delay time, attenuation multiple, and building load. It was found that the most effective phase-change temperature was 30 °C and the optimal thickness for the phase-change layer was 30 mm. The adoption of the outer phase-change wall layout improved the heat insulation performance during the summer. This effectively enhanced the energy-saving effect of the phase-change layer thickness and layout, which aligns with the influence law of phase-change wall heat transfer.

Effects of solar energy absorbed by south wall on carbon emission from space heating in hot summer-cold winter region

Carbon emission caused by space heating (CEH) in hot summer and cold winter climate zone has increased dramatically. Taking advantage of the solar energy absorbed by south wall (SEASW) can effectively reduce CEH, however, the accurate quantification of its impact remains a challenge. The study investigates the potential of SEASW in mitigating CEH. Key parameters affecting CEH, such as sunny day ratio, insulation form, and outer surface heat transfer coefficient of south wall (h), were analyzed. Results show the reduction in carbon emissions caused by the solar energy absorbed by each unit area of the south-facing wall (ΔCreduction) can be as high as 18.61 kgCO2⋅m−2 for the wall employing internal insulation and smaller h. A prediction model of ΔCreduction was further developed by using multivariate nonlinear regression, which can estimate the reduction in CEH for different fuels as heating source by a south wall in different sizes. Besides, the potential of SEASW on the reduction of carbon emission per unit floor area can reach 12.2 %. This study underscores the importance of SEASW as a carbon-neutral heating strategy, particularly for regions characterized by short winter heating periods and lower heating loads compared to colder climates. It provides valuable insights for sustainable energy practices and policy formulation.

Experimental study of a novel Radiative cooling-Dual phase change material roof under hot summer and warm winter climate

In hot summer and warm winter climates, phase change materials (PCMs), with their ability to absorb and store thermal energy, can effectively reduce indoor temperature fluctuations and lower cooling loads when applied to roofs. Therefore, this study proposes a novel Radiative cooling-Dual phase change material (RC-DPCM) roof and conducts experimental research on its regulation of indoor and outdoor thermal environments. This energy-efficient roof integrates radiative sky cooling with PCM latent heat storage technologies within a compact building envelope. The innovative dual-PCM configuration can store heat from both indoor sources and outdoor solar radiation during the day through integrated PCM layers. At night, radiative cooling materials emit heat to the deep universe, helping the PCM layers complete solidification. The thermal performance of the RC-DPCM roof was tested in hot summer and warm winter climates compared to other roof designs: a single layer of aluminum (AL) roof, the Aluminum-Thermal insulation (AL-TH) roof, the Radiative cooling (RC) roof, the Radiative cooling-Outside phase change materials (RC-OPCM) roof, and the Radiative cooling-Inside phase change materials (RC-IPCM) roof. Results showed that the RC-DPCM roof significantly improved indoor thermal comfort and efficiency. Compared with the AL roof, the RC-DPCM roof reduced the average indoor temperature by 1.13 °C (or 2.49 °C during working hours) and continuously dissipated heat from the indoor environment to the ambient environment, reducing the cooling load. Additionally, the RC-DPCM roof achieved a 172.9 % average cooling load reduction during working hours, outperforming other roofs, thus demonstrating its potential as an innovative solution for sustainable and energy-efficient buildings. The RC-DPCM roof effectively reduced peak indoor temperatures and cooling load, demonstrating its potential as an innovative solution for sustainable and energy-efficient buildings.

Field measurement study of indoor thermal environment of badminton halls in a hot summer and cold winter region in different seasons in China

The indoor thermal environment has a direct impact on human thermal comfort and health. In order to assess the status of the indoor thermal environment of typical sports buildings in hot summer and cold winter climate zones in China, 14 badminton halls in 10 cities in Hubei Province (including 5 venues in Wuhan) in this climate zone are chosen as research objects for field testing of indoor thermal environment parameters in 4 seasons. All the tested stadiums are naturally ventilated in non-event conditions. The results reveal that the average indoor temperature of badminton halls in summer is excessively high (i.e., 31.89 °C), which is higher than the regulation specified in JGJ31-2003 or GB-T18883-2022 on the reference interval of the indoor air temperature of venues in summer, (i.e., (26–28 °C) or (22–28 °C), respectively). The average indoor temperature of badminton halls in winter is too low (i.e., 12.95 °C), and it is lower than the recommendations of JGJ31-2003 or GB-T18883-2022 on the reference interval of the indoor air temperature of venues in winter (i.e., (16–18 °C) or (16–24 °C), respectively), relative humidity and air velocity are in the thermal comfort interval for all seasons, and the indoor thermal environment factors of badminton courts in spring and autumn meet the comfort requirements. The indoor and outdoor temperatures and the relative humidity of badminton courts are highly correlated. The indoor temperature and relative humidity vary according to changes in those factors outdoors, whereas the air velocity is not affected by outdoor changes. In the hot summer and cold winter climate zones, some discrepancies in the indoor temperature variation patterns of badminton halls at various altitudes are detectable. The results of this study aim to provide a solid basis for the development of indoor thermal-comfort standards for sports stadiums in China.

Enhancing energy efficiency of PCM wall in winter with novel PCM-DLCB coupling design

In order to enhance the thermal performance of the phase change material (PCM) wall during winter, a novel PCM and double-layer capillary bundles (PCM-DLCB) coupling wall is proposed. The PCM-DLCB wall utilizes the capillary bundle near the outer surface to capture solar energy during sunny winter days. The heat is then transferred to the capillary bundle near the inner surface through a circulating pump, promoting the melting of the PCM. Optimization and long-term operation comparison research were conducted using numerical simulation to investigate the potential of the PCM-DLCB wall to improve energy efficiency during winter. Five structural parameters, including the type of PCM, the position of the capillary bundle, the position and thickness of the PCM layer, the spacing of the capillary bundles, and the flow velocity in the capillary bundle, were selected as variables for structural and operation optimization. The optimization target was the accumulated heat gain from the inner surface of the wall. The research results indicate that: (1) The most suitable PCM is RT-18HC; (2) Placing the PCM layer between the double-layer capillary bundle yields better results compared to other arrangements; (3) Optimal energy saving is achieved when the outer capillary bundle is positioned 6 mm away from the outer surface and the inner capillary bundle is positioned 8 mm away from the inner surface; (4) The optimal thickness of the PCM layer is 10 mm; (5) The optimal flow velocity in the capillary bundle is approximately 0.04 m/s. Furthermore, long-term operation results based on a typical hot summer and cold winter climate zone reveal that the optimized PCM-DLCB wall provides a 7.80 % increase in indoor heat gain compared to an ordinary PCM wall during winter, and an 18.4 % increase compared to a wall without PCM.

The Future Sustainability of the São Francisco River Basin in Brazil: A Case Study

The viewpoint and reaction of a country towards climate change are shaped by its political, cultural, and scientific backgrounds, in addition to the distinct characteristics of its evolving climate and the anticipated and actual consequences of the phenomenon in the times ahead. A region’s climate has a significant impact on how water is managed and used, mostly in the primary sector, and both the distribution of ecosystem types and the amount and spreading of species on Earth. As a result, the environment and agricultural practices are affected by climate, so evaluating both distribution and evolution is extremely pertinent. Towards this aim, the climate distribution and evolution in the São Francisco River basin (SFRB) is assessed in three periods (1970–2000, 1981–2022) in the past and 2041–2060 in the future from an ensemble of GCMs under two SSPs (Shared Socioeconomic Pathways), SSP2-4.5 and SSP5-8.5. The Köppen-Geiger (KG) climate classification system is analyzed, and climate change impacts are inferred for this watershed located in central-eastern Brazil, covering an area equivalent to 8% of the country. Results predict the disappearance of the hot summer (Csa) and warm summer (Csb) Mediterranean climates, and a reduction/increase in the tropical savanna with dry winter (Aw)/dry summer (As). A striking increase in the semi-arid hot (BSh-steppe) climate is predicted with a higher percentage (10%) under SSP5-8.5. The source and the mouth of SFRB are projected to endure the major impacts of climate change that are followed by a predicted increase/decrease in temperature/precipitation. Future freshwater resource availability and quality for human use will all be impacted. Consequences on ecosystems, agricultural, and socioeconomic sectors within the SFRB might deepen the current contrasts between regions, urban and rural areas, and even between population groups, thus translating, to a greater extent, the inequality that still characterizes Brazilian society. Maps depicting land use and cover changes in SFRB from 1985 to 2022 highlight tendencies such as urbanization, agricultural expansion, deforestation, and changes in shrubland and water bodies. Urban areas fluctuated slightly, while cropland significantly increased from 33.57% to 45.45% and forest areas decreased from 3.88% to 3.50%. Socioeconomic data reveals disparities among municipalities: 74.46% with medium Human Development Index (HDI), 0.59% with very high HDI, and 9.11% with low HDI. Most municipalities have a Gross Domestic Product (GDP) per capita below US$6000. Population distribution maps show a predominance of small to medium-sized urban and rural communities, reflecting the basin’s dispersed demographic and economic profile. To achieve sustainable adaptation and mitigation of climate change impacts in SFRB, it is imperative that integrated measures be conducted with the cooperation of stakeholders, the local population, and decision-makers.

The Annual Effect of Landscapes on the Indoor Thermal Environment in Residential Areas—A Case Study in Southern Hunan

Landscape elements are crucial to the quality of the built environment. Thermal comfort is one of the important paths through which landscape elements affect the quality of the built environment. Most studies investigate the impacts of the landscape on the outdoor thermal environment, while ignoring the impacts on the indoor environment. A residential area in Chenzhou, a typical city having a hot summer and cold winter climate, was taken as an example to reveal the effect on the indoor thermal environment of landscapes. The annual distribution of the indoor thermal environment was analyzed with the “Envi-met+IDW” model, which was created to evaluate the annual thermal impact. Analytical results show that, from the perspective of the annual cycle, the camphor tree has the best performance in regulating the indoor thermal environment, followed by water and the palm. Manila grass has a very weak impact on indoor thermal comfort throughout the year. Camphor trees, water, and palm extend the “acceptable temperature” by 523 h, 416 h, and 388 h respectively. However, the camphor tree also has the strongest cooling effect on indoor environments during winter, increasing the “heating demand temperature” by 289 h.

Experimental study of a PV-PCM window under hot summer and warm winter climate

An energy-efficient PV-PCM (Photovoltaic-Phase change material) window is proposed in this study. During the day, a portion of the incident solar radiation is converted into electricity, while excessive heat from internal sources and solar radiation is stored within the PCM infill. At night, the stored heat can be released from the PCM. Unlike existing PV windows with PCM infill, the PCM is sealed in separate modules, allowing for easy adjustment or removal to better adapt to different weather conditions. In this study, the light, thermal and electrical performance of the PV-PCM window was tested in comparison with common clear glazing window, PV window and PCM-infill window under hot summer and warm winter climate.The experiment results demonstrated the ability of PV-PCM window in delaying and reducing the peak indoor temperature in hot summer. Compared with common clear glazing window, the peak temperature reduced by 8.67, 5.35 and 10.70 °C in the three days. Correspondingly, the indoor heat gains were reduced by 364.97, 265.96 and 301.10 kJ. SHGC of the proposed PV-PCM window was reduced to <0.30, whereas the U-value was reduced to <2.50 W/(m2·K). Compared with the PV window, more power generation were observed by PV-PCM window because of the cooling effect brought by the PCM module nearby. Whilst balancing thermal regulation, the daily power generations of the 0.36 m2 semi-transparent CdTe PV-PCM window were 548.33, 316.55 and 58.85 kJ.

Building energy saving of a rotatable radiative cooling-photovoltaic system by alternate utilization of solar energy and radiative cooling

Building-integrated photovoltaic (BIPV) and Building-integrated radiative cooling (BIRC) are recognized as efficient renewable utilization technologies that can promote building energy savings and reduce carbon dioxide emissions. An innovative rotatable radiative cooling-photovoltaic (RRC-PV) system is proposed, which has multi-functions of photovoltaic power generation, radiative cooling power utilization, and overhang shading. The nonstop alternate utilization of solar energy and free cooling energy from the outer space can be realized. The system breaks the constraint of limited building surface areas and has significant meaning for the renewable energy exploit in high-density cities.In this study, the model of the RRC-PV module is developed and validated with experimental data. Rhino and Grasshopper platform are used, and the radiative cooling power is calculated with a self-developed GH_Cpython program. The RRC-PV system is applied to a typical office in Shenzhen with hot summer and warm winter climate. By applying the RRC-PV modules with total area of 1.68 m2, the daytime PV power generation is 361.9 kWh throughout the year, and the nocturnal radiative cooling power utilization is 246.9 kWh. The building energy usage intensity was reduced from 89.7 kWh/(year·m2) to 83.7 kWh/(year·m2), resulting in payback period of less than 6 years.

Evaluation of cooling energy saving and ventilation renovations in office buildings by combining bioclimatic design strategies with CFD-BEM coupled simulation

Bioclimatic design knowledge and measures, including passive techniques and natural ventilation cooling, are urgently for building renovation to mitigate global warming. The performance of indoor airflow, energy, economic, and environmental aspects has been researched separately. However, developing a comprehensive framework to investigate bioclimatic strategies under the impact of climate change is challenging. This study aims to integrate bioclimatic design strategies with a coupled simulation approach using Fluent and EnergyPlus to evaluate retrofitting techniques for a single-room office in a university building in a hot summer and cold winter climate. A bioclimatic analysis was conducted to recommend cost-effective passive cooling strategies, including natural ventilation and window shading systems. Two passive measures, changing window types and furniture layouts, were included in renovation packages. Results indicated that the empty model is not valid compared to the fully furnished model when calculating room air change per hour (ACH). Natural ventilation was the most cost-effective strategy to mitigate climate change, with a net present value (NPV) ranging from USD 135.09 to 402.81 over 30 years. However, a higher ACH did not ensure a longer natural ventilation period. By changing the top-hung window to a vertical sash and implementing a movable furniture layout, can achieve better ventilation efficiency. The installation of window vertical shadings had the highest annual emission savings by 2080, while it performed negative economic viability in both the present and the 2050 climates. This research demonstrated how combining bioclimatic measures with a co-simulation approach can offer a thorough evaluation of building energy retrofitting. The results could support architectural and engineering design by integrating bioclimate measures to identify the most effective strategies.

Energy and economic performance optimization of a window with variable transparency shape-stabilized PCM in hot summer and cold winter climate zone

Improving the thermal performance of windows is important for building energy efficiency. Filling windows with variable transparency shape-stabilized phase change materials (VTSS-PCM) improves the thermal inertia of windows while avoiding the leakage of PCM. In this paper, a new type of VTSS-PCM window was proposed, tested, simulated and optimized in hot summer and cold winter climate zone. A numerical model of the VTSS-PCM window was built, and the model was validated using experimental tests. On this basis, three key parameters of VTSS-PCM were investigated and optimized. Finally, the energy and economic performance of the optimized VTSS-PCM window were compared with a typical hollow glass window. The results showed that the total annual unfavourable heat transfer (TAHT) and the annual investment cost (AIC) of the VTSS-PCM window obtained from the optimization were 118.16 kWh/m2 and 8.53 CNY/m2, respectively. Compared with the hollow glass window, the VTSS-PCM window reduced the TAHT by 30.14% and the total annual cost by 28.39%. The VTSS-PCM window produced a better development potential in terms of energy performance and economic performance. This study provided a reference for the application of the VTSS-PCM window in hot summer and cold winter regions of China.

Effect of adding natural and synthetic antioxidants to broiler drinking water as antistressor on productivity, antioxidant statues and hematological traits under heat stress

This study was conducted to explore the benefit of adding synthetic and natural antioxidants nutritional additives in drinking water to increase broiler resistance to heat stress in the hot summer climate on productive performance, and physiological status. A total of 600 chicks of broiler (Ross-308) were distributed into ten treatments, each treatment with three replicates of 20 chicks. The treatments of study are: T0: (Positive control: drinking water without adding-DW)- without heat stress, treatments exposed to heat stress: [T1: (Negative control: drinking water without adding-DW, but exposed to heat stress), T2: (100 mg BHT/1 L DW) (BHT – butylhydroxytoluene: synthetic antioxidant), T3: (100 mg vit E/1 L DW) (synthetic antioxidant), T4: (200 mg saffron/1 L DW) (natural antioxidant, T5: (200 mg curcumin/1 L DW), T6: (100 mg saffron+ 50 mg BHT/1 L DW), T7: (100 mg saffron+50 mg vit E/1 L DW), T8: (100 mg curcumin+ 50 mg BHT/1 L DW), T9: (100 mg curcumin+ 50 mg vit E/1 L DW)]. Data of the study analyses and display that the synthetic and natural antioxidants nutritional additives had significantly decreases in the temperature of body parts surface (head, back, under wings, cloaca), general body temperature, mortality%, Malondialdehyde (MDA), heat shock proteins (HSP-40 and HSP -70), Corticosterone hormone concentration in the blood serum and heterophiles: lymphocytes (H/L) ratio. However, body weight, body weight gain, Production index (PI), feasibility (economic profit), water intake (WI), Glutathione Peroxidase (GSH-Px), super oxide dismutase (SOD), total antioxidant capacity (TAC), Newcastle (ND), Infectious bursal (IBD) diseases and Infection bronchitis virus (IB), so feed conversion ratio (FCR) had significantly improved in the all treatments of water additive in the treatments of positive control T0 compared with the negative control T1. Whereas, feed intake had non-significant differences among all treatments of the study. In all traits of the study natural antioxidant additives: saffron and curcumin additives seen superiorly

Responses of air-conditioning loads to climate change and its impact on carbon emissions in the hot summer and warm winter climate

Energy consumption of air-conditioning in wet and hot climates is not only for cooling but, to a large extent, for dehumidification. Taking urban agglomeration in the Pearl River Delta region as a case study, this study analysed the cooling and dehumidification loads during the past 20 years. In addition, the impacts of cooling and dehumidification loads on carbon emissions were determined. The results showed that there was large spatial heterogeneity in the variations of the cooling and dehumidification loads. The cooling design loads in 1991–2020 was increased 1.83% to 5.56% compared to those in 1971–2000, while the loads for dehumidification was decreased 0.92% to 5.5%. Carbon emissions from cooling were increased, exceeding the carbon reduction from dehumidification, which leads to a weak increase in total carbon emissions. This study revealed that air-conditioning design should fully consider climate change impact by separating cooling and dehumidification loads, increasing the cooling load to avoid insufficient air-conditioning output but reducing the dehumidification load to promote energy efficiency of the air-conditioning system and to reduce carbon emissions. More importantly, an assessment of design loads with climate change in city or small scales should be made before determining summer air-conditioning system design capacity.

Morphology Optimization of Residential Communities towards Maximizing Energy Self-Sufficiency in the Hot Summer Cold Winter Climate Zone of China

Further research is needed on the capability of residential communities to achieve energy self-sufficiency under the constraints of current standards of land use, in particular for the Hot Summer and Cold Winter climate zone (HSCW) of China, where the majority of communities are dominated by high floor-area ratios, thus high-rise dwellings, namely less solar potential per unit floor area, while most residents adopt a “part-time, part-space” pattern of intermittent energy use behavior, thus using relatively low energy per unit floor area. This study examines 150 communities in Changsha to identify morphological indicators and develop a prototype model utilizing the Grasshopper platform. Community morphology is simulated and optimized by taking building location, orientation, and number of floors as independent variables and building energy consumption, solar PV generation, and energy self-sufficiency rate as dependent variables. The results reveal that the morphology optimization can achieve a 4.26% decrease in building energy consumption, a 45% increase in PV generation, and a 13.2% enhancement in energy self-sufficiency, with the optimal being 39%. It highlights that energy self-sufficiency cannot be achieved solely through morphology improvements. Moreover, the study underscores the crucial role of community orientation in maximizing energy self-sufficiency, with the south–north orientation identified as the most beneficial. Additionally, a layout characterized by a horizontally closed and staggered pattern and a vertically scattered arrangement emerges as favorable for enhancing energy self-sufficiency. These findings underscore the importance of considering morphological factors, particularly community orientation, in striving towards energy-self-sufficient high-rise residential communities within the HSCW climate zone of China.

An empirical study of indoor air quality in badminton stadiums in hot summer and cold winter regions of China during spring and fall seasons

The indoor air quality has a direct impact on human health. In order to obtain the current status of indoor air quality in typical sports buildings in hot summer and cold winter climate zones in China, indoor badminton courts in 10 cities in Hubei Province in this climate zone were selected as research objects for field testing of indoor environmental parameters in spring and autumn, and predict air quality parameters for non-testing times. All the tested stadiums are naturally ventilated in non-event conditions, and the average daily indoor CO2 concentration was 526.78 ppm in spring and 527.63 ppm in autumn, and the average daily PM2.5 concentration was 0.035 mg/m3 in spring and 0.024 mg/m3 in autumn, all of which met the requirements of GB/T 18883-2022, the average concentration of CO2 ≤ 1000 ppm and PM2.5 ≤ 0.05 mg/m3. The indoor CO2 concentration and PM2.5 concentration of the tested badminton halls under natural ventilation gradually increased with the accumulation of exercise time, making the indoor air quality of the badminton halls decrease, which would negatively affect the health of the people exercising in this environment.

The role of green fertilizers for soil fertility and increasing the yield of agricultural crops

The article discusses the prospects for the introduction of crop sideral crops - white mustard, white clover, spring barley, Rowan-leaved phacelia, oilseed radish on irrigated arable land in the Central part of the Chui valley of Kyrgyzstan after harvesting winter wheat, which corresponds to the basics of organic management of irrigated agriculture. In the arid, hot summer climate of the Chui valley, the cultivation of crop siderates is accompanied by the use of regular irrigation using sprinklers. The issues of accumulation of aboveground and root mass of sideral crops - white mustard, white clover, spring barley, Rowan-leaved phacelia, oilseed radish and their influence on increasing potato yield are studied. The article considers the advantage of joint mineralization of hard - to-decompose forms of plant residues of the previous crop-winter wheat and green phytomass of crop siderates to replenish the organic matter of the soil and to obtain environmentally friendly crop production. The materials of the research work allow us to recommend crop sideral crops on the irrigated arable lands of the Central part of the Chui valley of the KYRGYZ Republic: white mustard, white clover, spring barley, Rowan-leaved phacelia, oilseed radish as green fertilizers.

Analysis of 2D heat transfer of shear wall thermal bridges influencing on the exterior wall

ABSTRACT Frame-shear wall structures are widely used in high-rise buildings, and their thermal bridges account for a large portion of the entire exterior wall area. The purpose of this study was to investigate heat transfer of shear wall thermal bridge (SWTB) that influences the exterior wall of a building. A typical 3D COMSOL model of the SWTB junction was built, and indices were used to quantify its thermal characteristics of the SWTB junction. The results showed that the peak values and peak width of the heat flux at the interface of the exterior wall and thermal bridge increased with an increase in the thermal resistance of the SWTB. When the thermal resistance of the SWTB (R tb ) is greater than or equal to the thermal resistance of the exterior wall (R w ), the influencing area A i n f no longer increases. In addition, the maximum error of replacing K 2D with K 1D discussed in this paper was 3.56%, which can be neglected in engineering applications in hot summer and cold winter climate zones. Finally, strategies to reduce the heat loss of the SWTB were proposed. The results of this study provide valuable data for engineers to evaluate the thermal characteristics of SWTB in building designs.

Experimental study of RRC-PV modules under hot summer and cold winter climate

Building-integrated photovoltaic (BIPV) and building-integrated radiative cooling (BIRC) technologies are popular methods for utilizing renewable energy to address the energy crisis. However, limited facade areas of buildings restrict the amount of renewable energy that can be harvested. The design of reversible radiative cooling-photovoltaic (RRC-PV) module was introduced to address this issue. During the day, the PV side converts part of the incident solar radiation into electricity. At night, the module can be flipped and the RC side emits infrared radiation to the cold outer space, allowing for the free cooling energy exploitation.The performance of RRC-PV modules was tested in Shenzhen with hot summer and cold winter climate, by applying them as rooftop awnings and overhang shadings. Solar power generations were similar for both experiments, with daily electrical efficiencies in the range of 11.4–13.0 %. Meanwhile, the radiative cooling performance was better in the rooftop awning experiment, with an average nocturnal cooling power of 33.7–34.5 W/m2. In contrast, the average nocturnal cooling power reduced to 4.8–4.9 W/m2 in the overhang shading experiment. The results highlighted the importance of evaluating the radiative cooling potential by assessing the sky exposure of building facades.