Solving the comfort-retrofit conundrum through post-occupancy evaluation and multi-objective optimisation

Developing appropriate building retrofit strategies is a challenging task. This case study presents a multi-criteria decision-supporting method that suggests optimal solutions and alternative design references with a range of diversity at the early exploration stage in building retrofit. This method employs a practical two-step method to identify critical comfort and energy issues and generate optimised design options with multi-objective optimisation based on a genetic algorithm. The first step is based on a post-occupancy evaluation, which cross-refers benchmarking and correlation and integrates them with non-linear satisfaction theory to extract critical comfort factors. The second step parameterises previous outputs as objectives to conduct building simulation practice. The case study is a typical post-war highly glazed open-plan office in London. The post-occupancy evaluation result identifies direct sunlight glare, indoor temperature, and noise from other occupants as critical comfort factors. The simulation and optimisation extract the optimal retrofit strategies by analysing 480 generated Pareto fronts. The proposed method provides retrofit solutions with a criteria-based filtering method and considers the trade-off between the energy and comfort objectives. The method can be transformed into a design-supporting tool to identify the key comfort factors for built environment optimisation and create sustainability in building retrofit. Practical application : This study suggested that statistical analysis could be integrated with parametric design tools and multi-objective optimisation. It directly links users’ subjective opinions to the final design solutions, suggesting a new method for data-driven generative design. As a quantitative process, the proposed framework could be automated with a program, reducing the human effort in the optimisation process and reducing the reliance on human experience in the design question defining and analysis process. It might also avoid human mistakes, e.g. overlooking some critical factors. During the multi-objective optimisation process, large numbers of design options are generated, and many of them are optimised at the Pareto front. Exploring these options could be a less human effort-intensive process than designing completely new options, especially in the early design exploration phase. Overall, this might be a potential direction for future study in generative design, which greatly reduce the technical obstacle of sustainable design for high building performance.</p

STRESS AND DEFORMATION ANALYSIS OF A U-SHAPED THIN AQUEDUCT BASED ON SHELL ELEMENT

In order to study the stress and deformation characteristics of Jigongzui U-shaped thin shell aqueduct structure, shell element in ANSYS is proposed to establish the three-dimensional finite element model of the aqueduct for numerical calculation, and the relevant mechanical parameters are obtained by detecting the depth of concrete carbonization. The simulated results show that: (1) The concrete carbonization depth of Jigongzui aqueduct reached 20mm, accounting for about 20% of the total thickness of the channel wall; (2) With the increase of aqueduct water level, the deformation and stress of the aqueduct body gradually increase. The maximum deflection in the middle of the span is 6.98mm, which is less than the limit value of the specification, but the tension in some areas at the bottom of the middle of the span is obvious, exceeding the allowable tensile strength. It is suggested to strengthen the aqueduct body by pasting high-performance fiber materials to improve the stress distribution of the aqueduct body; (3) Shell&nbsp; element has fast calculation speed and high efficiency when simulating similar U-shaped thin shell aqueduct, which can be popularized in simulating similar thin shell structures

Structural, Surface Morphology and Optical Properties of ZnS Films by Chemical Bath Deposition at Various Zn/S Molar Ratios

In this study, ZnS thin films were prepared on glass substrates by chemical bath deposition at various Zn/S molar ratios from 1/50 to 1/150. The effects of Zn/S molar ratio in precursor on the characteristics of ZnS films were demonstrated by X-ray diffraction, scanning electron microscopy, optical transmittance, X-ray photoelectron spectroscopy, and Fourier transform infrared spectrometry. It was found that more voids were formed in the ZnS film prepared using the precursor with Zn/S molar ratio of 1/50, and the other ZnS films showed the denser structure as the molar ratio was decreased from 1/75 to 1/150. From the analyses of chemical bonding states, the ZnS phase was indeed formed in these films. Moreover, the ZnO and Zn(OH)2 also appeared due to the water absorption on film surface during deposition. This would be helpful to the junction in cell device. With changing the Zn/S molar ratio from 1/75 to 1/150, the ZnS films demonstrate high transmittance of 75–88% in the visible region, indicating the films are potentially useful in photovoltaic applications

Geostatistical mapping and quantitative source apportionment of potentially toxic elements in top- and sub-soils: A case of suburban area in Beijing, China

Abstract The risk assessment and source identification for potentially toxic elements (PTEs) in soils, particularly agricultural soils from megacities, are significant for environmental protection and pollution control. In this study, an intensive sampling (4127 topsoil samples and 994 subsoil samples) was conducted in the Shunyi District, Beijing, which is a suburban area with extensive cropland cover and has been impacted by the megacity over several decades. Concentrations and distributions of 8 PTEs, including V, Cr, Ni, As, Cd, Zn, Pb and Hg, were determined, and their possible sources were quantitatively assessed by principal component analysis (PCA), redundancy analysis (RDA), positive matrix factorization (PMF) analysis, and anthropogenic contribution ratio method. Among 8 PTEs, Zn, V and Cr exhibited significantly high concentrations in soils, with means of 68.29, 68.19 and 52.13 mg/kg, respectively, followed by Pb (23.84 mg/kg), Ni (22.91 mg/kg), As (8.30 mg/kg), Cd (0.15 mg/kg) and Hg (0.05 mg/kg). RDA and PCA demonstrated that the rock weathering was a significant source of V, Cr, Ni and As, and the local emissions and atmospheric deposition respectively contributed most of Cd, Zn and Pb, and of Hg in soils. This source category was confirmed the spatial variations of anthropogenic contribution ratios to individual PTEs. PMF results showed that the local emissions contributed 96.3% of Cd, 44.4% of Zn and 32.0% of Pb in soils, and the atmospheric source carrying urban pollutants amounted to 78.7–80.2% of Hg. In this case, several effective analysis methods have been successfully applied to quantify the impact of a megacity to PTEs in suburban soils. These results improve understanding of the contamination status of PTEs in suburban soils from Beijing megacity, and provide basis for policymaker regarding environmental protection and pollution control

Cu–Zn Cation Disorder in Kesterite Cu2ZnSn(SxSe1–x)4 Solar Cells

Cu–Zn cation disorder plays a vital and controversial role in kesterite CuZnSn(S1–xSex)4 solar cells. We demonstrate using density functional theory and nonadiabatic molecular dynamics simulations that the Cu–Zn disorder across different planes (i.e., Cu–Sn and Cu–Zn planes) is significantly more detrimental to device performance than the case when disorder is confined only to the Cu–Zn planes. The main reason is that different plane disorder induces a significant elongation of Sn–S/Se bond lengths, leading to a downshift of the conduction band minimum, decreasing the band gap, and reducing the optical absorption. Moreover, Cu–Zn disorder across different planes accelerates nonradiative electron–hole recombination and decreases charge carrier lifetime due to the reduction of the band gap and enhanced electron-vibrational interaction. Our results provide a theoretical explanation for the influence of Cu–Zn disorder on material performance and offer valuable insight into the design of more efficient solar cells