A CAD-BEM geometry transformation method for face-based primary geometric input based on closed contour recognition

Performance analysis during the early design stage can significantly reduce building energy consumption.However,it is difficult to transform computer-aided design(CAD)models into building energy models(BEM)to optimize building performance.The model structures for CAD and BEM are divergent.In this study,geometry transformation methods was implemented in BES tools for the early design stage,including auto space generation(ASG)method based on closed contour recognition(CCR)and space boundary topology calculation method.The program is developed based on modeling tools SketchUp to support the CAD format(like*.stl,*.dwg,*.ifc,etc.).It transforms face-based geometric information into a zone-based tree structure model that meets the geometric requirements of a single-zone BES combined with the other thermal parameter inputs of the elements.In addition,this study provided a space topology calculation method based on a single-zone BEM output.The program was developed based on the SketchUp modeling tool to support additional CAD formats(such as*.stl,*.dwg,*.ifc),which can then be imported and transformed into*.obj.Compared to current methods mostly focused on BIM-BEM transformation,this method can ensure more modeling flexibility.The method was integrated into a performance analysis tool termed MOOSAS and compared with the current version of the transformation program.They were tested on a dataset comprising 36 conceptual models without partitions and six real cases with detailed partitions.It ensures a transformation rate of two times in any bad model condition and costs only 1/5 of the time required to calculate each room compared to the previous version.

Prediction and validation of diffusive uptake rates for indoor volatile organic compounds in axial passive samplers

The diffusive uptake rate is essential for using passive samplers to measure indoor volatile organic compounds(VOCs).The traditional theoretical model of passive samplers requires available regression formulas of uptake rates and physicochemical properties of adsorbents to predict the uptake rate.However,it is difficult to obtain the uptake rates of different VOCs under different sampling periods,and it is also difficult to obtain the physical parameters of adsorbents accurately and effectively.This study provides a reliable numerical prediction method of diffusive uptake rates of VOCs.The modeling was based on the standard automated thermal desorption(ATD)tubes packed with Tenax TA and the mass transfer process during adsorption.The experimental determinations of toluene uptake rate are carried out to verify the prediction model.Diffusive uptake rates of typical indoor VOCs are obtained from the literature to calibrate the key apparent parameters in the model by statistical regression fitting.The predicted model can provide the VOC diffusive uptake rates under different sampling duration with an average deviation of less than 5%.This study can provide the basis for fast and accurate prediction of diffusive uptake rates for various VOC pollutants in built environments.

Flexibility potential of Cs_(2)BX_(6)(B=Hf,Sn,Pt,Zr,Ti;X=I,Br,Cl)with application in photovoltaic devices and radiation detectors

As interest in double perovskites is growing,especially in applications like photovoltaic devices,understanding their mechanical properties is vital for device durability.Despite extensive exploration of structure and optical properties,research on mechanical aspects is limited.This article builds a vacancyordered double perovskite model,employing first-principles calculations to analyze mechanical,bonding,electronic,and optical properties.Results show Cs_(2)Hfl_(6),Cs_(2)SnBr_(6),Cs_(2)SnI_(6),and Cs_(2)PtBr_(6)have Young's moduli below 13 GPa,indicating flexibility.Geometric parameters explain flexibility variations with the changes of B and X site composition.Bonding characteristic exploration reveals the influence of B and X site electronegativity on mechanical strength.Cs_(2)SnBr_(6)and Cs_(2)PtBr_(6)are suitable for solar cells,while Cs_(2)HfI_(6)and Cs_(2)TiCl_(6)show potential for semi-transparent solar cells.Optical property calculations highlight the high light absorption coefficients of up to 3.5×10^(5) cm^(-1)for Cs_(2)HfI_(6)and Cs_(2)TiCl_(6).Solar cell simulation shows Cs_(2)PtBr_(6)achieves 22.4%of conversion effciency.Cs_(2)ZrCl_(6)holds promise for ionizing radiation detection with its 3.68 eV bandgap and high absorption coefficient.Vacancy-ordered double perovskites offer superior flexibility,providing valuable insights for designing stable and flexible devices.This understanding enhances the development of functional devices based on these perovskites,especially for applications requiring high stability and flexibility.

中国被动式住宅围护结构的气候适应性热特性研究

被动房由于其高保温和高气密性特征,具有巨大的节能潜力。近年来,中国开展了大规模被动房建设。然而,调研显示被动房之间存在显著的能源性能差异,尤其是在不同气候区。因此,本研究基于建筑仿真模型对被动房能耗进行比较分析,以探究被动房在不同气候区的节能潜力。由于气候差异主要影响建筑物的供冷采暖负荷,本文以被动房屋供暖、通风和空调系统的能耗为研究对象,并与传统房屋能耗对比。为进一步提高被动房气候适应性,本文对建筑围护结构的热参数进行敏感性分析,定量探究了外墙和窗户保温以及气密性对不同气候区供冷采暖能耗。此外,还计算了不同内热源强度下供冷采暖能耗变化,综合分析围护结构热特性对建筑能耗的影响。结果表明,外墙保温减弱会导致能耗大幅增长,尤其是对于中国严寒地区被动房。然而,保温需求会随着内热源强度的变化而变化,例如对于夏热冬冷地区的被动房,当内热源密度增加到20 W/m^(2)时,最佳保温强度将从0.4 W/(m^(2)·K)(标准值)降低至1.0 W/(m^(2)·K),从而每年可节省4.65 kW·h/(m^(2)·a)供冷采暖能耗。

Green building research from design to operation in the past 20 years: A perspective

dented levels during the past centuries.Along with the rapid urbanization crossing the world,serious environmental and energy issues have become global challenges.To address these challenges,the promotion of green building is critical because the construction industry consumes about 40%of the total energy and accounts for 30%of the total greenhouse gas emissions.The goals of green buildings is twofold:1)enhancing indoor environmental quality(IEQ),promoting human health and productivity;2)conserving energy,limiting pollutants and carbon dioxide emissions.

Design and performance of a novel miniaturized electrostatic sampler for efficient airborne particulate matter sampling

Considering that people spend more than 80%of their time indoors,ambient particulate matter(PM)in the built environment could pose severe environmental health risks to public health.PM sampling,a technique for the enrichment of PM in the air,is essential for ambient PM composition analysis to understand its environmental and health effect.The filtering method that is widely used features a complex post-processing and carries the risk of pore clogging.It is a great challenge to sample airborne PM efficiently for subsequent analysis.Here,we proposed a novel miniaturized electrostatic sampler based on corona discharge and a modified vertically focused electric field for efficient PM sampling.Four intercoupling physical fields in the developed sampler were analyzed,including corona discharge,airflow,particle charging and particle deposition.The collection efficiencies for particles with various sizes(0.01–10μm)were conducted by simulation and the lowest efficiency occurs at about 0.3–0.5μm.With an increase in discharging voltage from−6 kV to−9 kV,the lowest efficiency rises from 88.2%to 96.6%.An electrostatic sampler entity was manufactured to test the collection efficiency of PM and the results are in good agreement with the simulation.The induced ring plate can significantly improve the total collection efficiency from 35%to 90%under−6 kV discharging voltage in the experiment.The novel electrostatic sampler exhibits potential and enlightenment for efficient and convenient PM sampling.

建筑全生命周期碳排放——内涵、计算和减量

The life-cycle assessment method,which originates from general products and services,has gradually come to be applied to investigations of the life-cycle carbon emissions(LCCE)of buildings.A literature review was conducted to clarify LCCE implications,calculations,and reductions in the context of buildings.A total of 826 global building carbon emission calculation cases were obtained from 161 studies based on the framework of the building life-cycle stage division stipulated by ISO 21930 and the basic principles of the emission factor(EF)approach.The carbon emission calculation methods and results are discussed herein,based on the modules of production,construction,use,end-of-life,and supplementary benefits.According to the hotspot distribution of a building’s carbon emissions,carbon reduction strategies are classified into six groups for technical content and benefits analysis,including reducing the activity data pertaining to building materials and energy,reducing the carbon EFs of the building materials and energy,and exploiting the advantages of supplementary benefits.The research gaps and challenges in current building LCCE studies are summarized in terms of research goals and ideas,calculation methods,basic parameters,and carbon reduction strategies;development suggestions are also proposed.

An effective method to determine bedding system insulation based on measured data

The thermal environment is an essential factor that affects sleep quality.In many circumstances,the bed microenvironment is more important than the ambient environment because of the large covered area of the human body and the close contact between the bedding system and the human body.The main objective of this research is to establish an effective method to determine bedding system insulation.A thermal manikin was used in the measurement of bedding system insulation.Three different types of quilts,which were filled with cotton,polyester and duvet respectively,were chosen to be tested.In total ten different quilts with different materials and weights were involved in the test.Four regular arrangements of covers were chosen with coverage rates of 94.1%,85.9%,70.6%,and 54.4%to test.A total of 64 bedding systems were tested to build an effective method to determine the bedding system insulation.On the basis of test data,the change of bedding system insulation with coverage was found to be nonlinear.Exponential fitting was applied to establish an insulation evaluation method for bedding system insulation.In addition,the effects of quilt cover and sleepwear on bedding system insulation were discussed and thermal insulation increment caused by quilt cover and sleepwear were estimated.The relationships between neutral indoor temperature and weight per unit area of the quilt for different coverage rates have been quantified based on existing subject experiments.This research provides an effective method to determine bedding system insulation,which can be widely used in thermal comfort research and HVAC system design.

Extraction method of typical IEQ spatial distributions based on low-rank sparse representation and multi-step clustering

Indoor environment quality(IEQ)is one of the most concerned building performances during the operation stage.The non-uniform spatial distribution of various IEQ parameters in large-scale public buildings has been demonstrated to be an essential factor affecting occupant comfort and building energy consumption.Currently,IEQ sensors have been widely employed in buildings to monitor thermal,visual,acoustic and air quality.However,there is a lack of effective methods for exploring the typical spatial distribution of indoor environmental quality parameters,which is crucial for assessing and controlling non-uniform indoor environments.In this study,a novel clustering method for extracting IEQ spatial distribution patterns is proposed.Firstly,representation vectors reflecting IEQ distributions in the concerned space are generated based on the low-rank sparse representation.Secondly,a multi-step clustering method,which addressed the problems of the“curse of dimensionality”,is designed to obtain typical IEQ distribution patterns of the entire indoor space.The proposed method was applied to the analysis of indoor thermal environment in Beijing Daxing international airport terminal.As a result,four typical temperature spatial distribution patterns of the terminal were extracted from a four-month monitoring,which had been validated for their good representativeness.These typical patterns revealed typical environmental issues in the terminal,such as long-term localized overheating and temperature increases due to a sudden influx of people.The extracted typical IEQ spatial distribution patterns could assist building operators in effectively assessing the uneven distribution of IEQ space under current environmental conditions,facilitating targeted environmental improvements,optimization of thermal comfort levels,and application of energy-saving measures.