The effect of PCM wall is affected by many factors. To achieve full potential of phase change material used with structural insulated panel, the present paper investigates the impacts of PCM location and thickness on dynamic thermal characteristics of external wall of residential buildings, based on numerical simulation method. First, full implicit scheme of specific heat mathematical model of phase change wall is established by using finite difference method. Then, the boundary conditions in summer and winter are obtained based on a standard residential room under free running in Xi’an through typical meteorological year data. Finally, the thermal characteristics such as internal surface temperature, decrement factor and hourly heat flux are gained for each position and certain PCM thickness under the same boundary conditions. The results show that the optimal location is the PCM layer inside of SIP external wall and the optimum thickness is 0.04 m for SIP with heat transfer coefficient of 0.45 W m−1 °C−2. The results could provide reference for engineering applications of phase change wall. The present work is a part of DeST3.0, which first introduces PCM module into DeST. © 2020, Springer Nature Singapore Pte Ltd.

Phase change material (PCM) combined with building envelopes is an effective approach to establish a comfortable indoor thermal environment in summer. Thermal storage performance of PCM wallboard relies on the outdoor climatic conditions with suitable temperature. In the present paper, the thermal performance of PCM wallboard under different climate conditions is experimental investigated in artificial controlled conditions. The experimental conditions are based on typical meteorological year data of five cities in Northwest China. Two valuation indexes are proposed to quantitatively describe the climate characteristics. The experimental results highlight that the PCM wallboard thermal performance is significantly affected by temperature characteristics. In the climate condition of Xi’an, the PCM wallboard can reduce 88.9% temperature accumulation value. This work could provide reference for the applicability analysis and thermal design of PCM envelopes in different climate conditions. © 2020, Springer Nature Singapore Pte Ltd.

In this paper, the total daily global solar radiation is tested at 18 locations with different morphological characteristics in Xi'an University of Architecture and Technology. PTgui is used to convert the panoramic pictures from Baidu Street Map to fisheye images. Sky view factor (SVF) and tree view factor (TVF) are calculated by Rayman model with fisheye images. SVF is used to calculate the total daily global solar radiation at the 18 locations with two different methods and TVF is used to classify the locations. The calculations and testing results are compared and combined the morphological characteristics. Then it is found that using suitable methods on different locations is necessary to obtain more accurate results whether the TVF (tree view factor) is more than 0.3 or less. To obtain solar radiation at different locations in the urban area, the calculating methods should be carefully chosen based on the morphology characteristics of the location.
© 2019 The Authors, published by EDP Sciences.

Solar radiation is a major factor in promoting the sustainable development of urban settlements. To understand the distribution of solar radiation in urban settlements, this paper develops the sky view factor (SVF) algorithm based on the parameterization platform to simplify the calculation of solar radiation. In this paper, the test of total solar radiation is carried out in 18 different locations in Xi'an University of Architecture and Technology. The total solar radiation of 18 points is calculated using the SVF-based calculation model. Comparing the calculated results with the measured results, it is found that the calculated values are consistent with the measured values. The results show that the algorithm is consistent with the measured data. It shows the effectiveness and high precision of the proposed algorithm. The algorithm can calculate the total solar radiation more quickly, and provide technical support for urban preliminary design schemes in urban microclimate. © 2019 The Authors, published by EDP Sciences.

Urbanization seriously affects the urban climate and the quality of human settlement. Based on Landsat8 remote sensing and building vector data, local climate zone (LCZ) method is employed to study the influences of urban form on land surface temperature (LST) of Xi'an. The results confirmed that the LST of the built-up LCZ is higher than the land cover LCZ. In built-up LCZ, LST is increasing with the increasing of building density. In land cover LCZ, the LST of bare land is the highest. Surface urban heat island (SUHI) of 14 samples in LCZ also been calculated. Highest SUHI intensity is found in low-rise buildings with high density area. LST intensity of water body and forest are lower than others in land cover LCZ.
© 2019 The Authors, published by EDP Sciences.

Improving the thermal transfer performance of phase change material (PCM) component has attracted more and more attention in building the energy-saving field. This paper presented an optimized PCM component which is encapsulated in a metal container, to promote the thermal performance of the wall. Thermal transfer of PCM component is optimized by adding internal fin through numerical simulation software COMSOL Multiphsics. The simulation model was verified by data from publicly available published literature. The temperature difference of PCM component in front and back heating surface (ΔT s) was employed to obtain the optimal geometric parameters including spacing (S fin) and length (L fin) of the fin. Thermal performance of the wall with the optimized and non-optimized PCM component was compared under the summer typical climate. The wall with optimized PCM component has the best capacity for heat storage and release. The interior surface temperature reduction of the wall with optimized PCM component is lower by 2.1 °C than reference wall. © Published under licence by IOP Publishing Ltd.