Although research on the natural ventilation of single-sided buildings is progressing, research on the natural ventilation of the Mogao Grottoes, which have special shapes and structures, is ...relatively limited. The purpose of this paper is to develop a correlation for calculating the natural ventilation rates of such grottoes. Field experiments were carried out on two typical caves to measure their meteorological parameters and natural ventilation rates to verify the validity of the proposed correlation. The results show that our correlation has good reliability and stability when predicting the natural ventilation rates of the caves. First, the new correlation has a small average deviation of 16.35%. The average deviations in the natural ventilation rates predicted by seven established correlations are as low as 17.85% and as high as 59.39%, revealing a large gap compared with the correlation proposed herein. Second, the maximum deviation in the outputs of the proposed correlation is only 7.70% between each case. Finally, a comparison between the calculated results and the values measured in Cave 328 shows that the correlation is also suitable for large-volume caves. The developed correlation provides theoretical support and a scientific method for preventive protection and a quantitative analysis method for the study of natural ventilation in caves.
Variations in temperature and moisture content in the earthen plasters of the Maijishan Grottoes can readily lead to mural deterioration. This study investigates the influence of two different ...clay/sand ratios on the hygrothermal properties of earthen plasters in the Maijishan Grottoes. Two distinct types of earthen plasters samples were created with different clay/sand ratios: one with a weight ratio of 30:70 and another with a weight ratio of 70:30. The hygrothermal properties of earthen plasters samples were examined, and the temperature and moisture content variations were evaluated based on measurement data of hygrothermal environment in three caves. The findings revealed that the influence of the clay/sand ratios on thermal properties was relatively minor compared to its effect on hygric properties. Lower clay/sand ratio resulted in decreased thermal conductivity and specific heat capacity of earthen plasters, leading to increased temperature fluctuation, but the difference is minor. Additionally, in high-humidity environments, the difference in moisture content variations between the two types is greater than in low-humidity environments as the relative humidity changes. This research holds significant implications for the preservation of murals in the Maijishan Grottoes while also providing fresh perspectives for the restoration of multi-layered mural structures.
The carbon emissions (CEs) of public buildings (PBs) in the operation stage significantly impact building life cycle assessments (LCA). Energy conservation and carbon reduction during this stage is ...necessary for China to achieve peak CEs and neutralization. Energy consumption and CEs are analyzed using energy audit data for PBs in Xi'an. CEs of PBs in the operation stage are calculated by our prediction method with an average deviation of only 4.41%. Using the logarithmic mean Divisia index (LMDI) method to analyze factors influencing CEs, we find that economic development levels impact CEs the most in the operation stage; the impact coefficient reaches 3.81. This study discusses the contribution of various driving factors of CEs via the stochastic impacts by regression on population, affluence, and technology (STIRPAT) method and simulates seven scenarios to predict change trends of the CEs of PBs in the operation stage. The rough development scenario fails to achieve the peak, the comprehensive optimization development scenario achieves the peak in 2040, and the remaining scenarios achieve the peak in 2050. The results provide practical and theoretical support for CE research and a scientific basis for predicting the CEs of PBs in the operation stage throughout China and worldwide.
•Energy consumption and carbon emissions are analyzed based on energy audit.•Set up a carbon emissions prediction method for public buildings, and evaluate the results.•The influencing factors of carbon emissions were analyzed by the logarithmic mean Divisia index method.•Discuss the contribution of various driving factors and simulate the change trend of the carbon emissions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the Mogao Grottoes in Dunhuang, China, temperature and relative humidity (RH) fluctuations are the main causes of the observed deterioration. In this paper, we experimentally and numerically ...analyze hygrothermal transfer in the cave wall of the Mogao Grottoes. A coupled heat and moisture transfer 1D model is developed to simulate the hygrothermal behavior of the cave wall of the Mogao Grottoes, which adopts the temperature and water vapor pressure as driving potentials. The model is implemented in a programming. By constructing the numerical model of the wall under boundary conditions and comparing the measured data and simulation results, we validate the numerical model and analyze the hygrothermal transfer characteristics of the wall. The temperature and moisture profiles of the cave wall are experimentally measured and numerically determined. The simulation results are compared to experimental temperature and RH values, with good agreement despite the simplifying hypotheses adopted during modeling. By analyzing the heat and moisture distributions, we find that the heat and moisture transfer process in the cave wall changes in space and time. The complicated heat and moisture transfer directions vary cyclically. Additionally, moisture transfer in the cave wall reaches the steady state more rapidly than heat transfer. Hygrothermal cycling plays an essential role in the development of mural deterioration. The developed model provides theoretical support and a scientific method for the conservation of cave sites and a quantitative analysis approach to study mural relics.
•Apply multidisciplinary method to studying mural disease in historical heritage.•Set up a hygrothermal transfer model for the cave walls, and evaluate the results.•Analyze the heat and moisture transfer properties in cave walls experimentally and numerically.•Provide a salt damage mechanism on murals relating to heat and moisture.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Fluctuation in the hygrothermal environment can facilitate the deterioration of cultural relics in the Maijishan Grottoes. The purpose of this research is to develop a hygrothermal simulation model ...of grottoes to analyze the changes in the hygrothermal environment under different influencing factors. First, the temperature and relative humidity (RH) in Cave 101 of the Maijishan Grottoes were monitored throughout the year. The results indicated that the hygrothermal environment in Cave 101 was in an annual cycle from low temperature and RH to high temperature and RH. Then, a hygrothermal simulation model of the cave was established via the coupled heat and moisture transfer method. In addition, the accuracy of the model was verified by error analysis. Finally, the influences of different factors on the hygrothermal environment in the cave were evaluated by the model. The corridor and door can effectively weaken the influence of climate change on the hygrothermal environment in the cave. With increasing size and decreasing air change per hour, the annual amplitude and diurnal change in temperature and RH in the cave decrease. However, the environment in the cave remains moist in summer. The ventilation dehumidification design could be adopted as a regulation measure. This research provides a quantitative research method for the regulation of the hygrothermal environment and promote the development of preventive environmental protection technology in the Maijishan Grottoes.
•Use the coupled heat and moisture transfer method to study the grotto environment.•Present a hygrothermal simulation model of a cave, and verify the accuracy.•Analyze the different factors influencing the hygrothermal environment in the cave.•Provide a quantitative research method for regulating the hygrothermal environment in grottoes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
As the greenhouse effect intensifies, controlling carbon emissions has become increasingly critical. China, having the world's highest carbon emissions, sees almost half of its total emissions from ...the building sector. China is confronted with the challenge of different provinces having diverse timelines for achieving carbon peak in the building sector, leading to “undesirable responses”. To address this, our study expands the research scope and introduces dynamic forecasting methods through the D-STIRPAT model. The model has produced more accurate predictions for carbon emissions in the building sector of the Central China region. The research results indicate that collaborative optimization between urban and construction industries is the most effective pathway to reduce carbon emissions. Henan Province can achieve peak emissions in the building sector relatively quickly, with most scenarios reaching their peak by 2040, with the lowest peak value reaching 415.4 MtCO2e. Hubei and Hunan provinces are likely to achieve peak emissions for most scenarios between 2050 and 2060. However, the building sector in the Central China region can achieve peak emissions between 2030 and 2045, with peak values ranging from 1.235 to 1.702 BtCO2e. In terms of carbon reduction effects, the overall strategy for achieving peak emissions in the building sector in Central China should focus primarily on optimizing urban and building sector development, supported by energy structure optimization and the promotion of building energy efficiency. Henan and Hubei provinces should prioritize urban and building sector development, while Hunan Province should emphasize both urban and building sector development and energy structure optimization concurrently. This study highlights the benefits of regional carbon emissions regulation in the building sector, provides innovative solutions for achieving dual carbon targets, and offers guidance and approaches for achieving peak emissions in the building sector through regional collaboration.
•The regional building sector has a clear advantage in terms of carbon peaking.•The STIRPAT model was applied and improved.•More building sector impact factors were considered.•Explored the dynamic relationship of influencing factors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Multi-dimensional performance optimization of buildings is crucial to achieving comfort and realizing green and sustainable development. This study developed a multi-performance collaborative ...optimization framework (MPC_BPO) to analyze modern residential retrofitting in extremely arid and hot climate zone. The parametric environmental simulation (PES) demonstrated high consistency with actual operating results (R2 > 0.92), and the multi-objective optimized artificial neural network (OPT-ANN) effectively established a high precision multi-performance prediction model (R2 > 0.96). Various multi-objective algorithms exhibited a high convergence level in the high-dimensional complex optimization process. The entropy weight and subjective weight methods ranked the Pareto frontier solution set, where the optimization scheme dominated by energy use intensity (EUI) increased daylighting index (DLI) and thermal comfort hours (TCH) by 12.32 % and 6.67 %, respectively, while reducing EUI by over 8.47 %. Applying different scenarios to other household buildings verified the generalization characteristics, showing overall high consistency despite variations in performance indicators. This research provides a scientific basis for improving residential performance in special climate zones through an appropriate framework. Using scientific methods, it analyzes the intrinsic logic between high-dimensional parameters and multiple building performances.
•A novel multi-performance collaborative optimization framework(MPC_BPO).•Coupled simulation of high-dimensional parameters and multi-performance.•Optimization results generalization validation analysis.•A case of building retrofitting in extremely arid and hot climate zone.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the Mogao Grottoes, hygrothermal cycling is the main cause for the observed mural deterioration development. A coupled heat and mass transfer (HMT) model in cave walls is constructed; it describes ...the hygrothermal behavior in porous wall construction and materials. This model allows us to evaluate their abilities to regulate microclimate conditions in caves and ensure a suitable protective environment. In this paper, finite variation effects in boundary conditions and material characteristics on the HMT model response are investigated. To determine the most influential hygrothermal parameters, further uncertainties in the parameters (density, heat capacity, thermal conductivity, adsorption isotherm and vapor permeability) and boundary conditions of the model are discussed. Additionally, both quantitative local sensitivity analysis (LSA) and global sensitivity analysis (GSA) was conducted to analyze the input parameters of the numerical model to identify the primary input parameters influencing the model's results. The results show that density and heat capacity do not significantly influence the simulated results when these properties are changed to values 2.5 times greater than those of the reference case. A lower vapor permeability or thermal conductivity and an improved adsorption isotherm are better for maintaining a stable humidity environment and reducing the mural salt disease risk. Note that the boundary conditions significantly affect the simulated results, especially reducing the average air relative humidity value; the amplitude air temperature value seems more beneficial for suppressing the salt damage risk to mural paintings.
•Apply multidisciplinary method to studying mural disease in historical heritage.•The heat and mass transfer model was applied and improved.•Analyze the finite variation effects on the heat and mass transfer model response.•Provide an analysis approach on environmental regulation of mural conservation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•The CO2 concentration of cave in Mogao Grottoes has been 1500ppm.•A system of mechanical ventilation of one cave was designed and be tested.•The air exchange rate was increased by the system of ...mechanical ventilation.•The air turbulence wasn’t changed obviously in this system.
During the peak tourist season, the CO2 concentration in some caves in Mogao Grottoes often exceeds 1500ppm. A mechanical ventilation system for Cave 328 of Mogao Grottoes is thereby designed and the experiment is conducted in January and February of 2015. The results indicate that the air exchange rate has improved from 3.2h−1 in the case of natural ventilation to 6h−1 in mechanical ventilation, while the air turbulence merely increases from 0 to 0.05m/s in the body of the cave and 0.15–0.2m/s in the aisle in natural ventilation to 0–0.1m/s in the body of the cave and 0.2–0.3m/s in the aisle in mechanical ventilation. It is thus concluded that the mechanical ventilation system effectively increases the air exchange rate without causing noticeable disturbance of the air in the cave, and the protective environment of the cave is sustained. A theoretical reference can be hopefully provided in the design and implementation of the mechanical ventilation system in Mogao Grottoes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Murals in Mogao Grottoes consist of three parts: support layer, earthen plasters and paint layer. The earthen plasters play a key role in the preservation of murals. It is a mixture of Dengban soil, ...sand, and plant fiber. Two different natural fibers, hemp fiber and cotton fiber, were
reinforced to earthen plasters in the same percentage to evaluate the influence on hygrothermal performance. The two types of earthen plasters were studied: one containing hemp fiber in the fine plaster (HFP) and the other containing cotton fiber in the fine plaster (CFP). Specific heat capacity,
dry thermal conductivity, water vapor permeability, and sorption iso-therms were investigated. The results showed that the difference between two natural fibers has much more impact on the hygric properties (water vapor permeability and sorption isotherms) of earthen plasters than on their
thermal performance (specific heat capacity and dry thermal conductivity). The CFP with higher density has higher thermal conductivity than the HFP with lower density. But no significant differences of specific heat capacity were observed. Compared with HFP, CFP used in murals can reduce the
rate of water transfer and prevent salt from transferring water to the mural surface. The overall findings highlight that all these features of CFP are beneficial to the long-term preservation of murals. The study of the earthen plasters in Mogao Grottoes is of general significance, and the
measured properties can be used to obtain coupled heat and moisture analysis of the earthen plasters and to dissect the degradation mechanism of murals.
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