Page Not Found
Page not found. Your pixels are in another canvas.
Sitemap
A list of all the posts and pages found on the site. For you robots out there is an XML version available for digesting as well.
Pages
About me
About me
Page not in menu
This is a page not in th emain menu
Posts
Future Blog Post
Published:
This post will show up by default. To disable scheduling of future posts, edit config.yml and set future: false.
Blog Post number 4
Published:
This is a sample blog post. Lorem ipsum I can’t remember the rest of lorem ipsum and don’t have an internet connection right now. Testing testing testing this blog post. Blog posts are cool.
Blog Post number 3
Published:
This is a sample blog post. Lorem ipsum I can’t remember the rest of lorem ipsum and don’t have an internet connection right now. Testing testing testing this blog post. Blog posts are cool.
Blog Post number 2
Published:
This is a sample blog post. Lorem ipsum I can’t remember the rest of lorem ipsum and don’t have an internet connection right now. Testing testing testing this blog post. Blog posts are cool.
Blog Post number 1
Published:
This is a sample blog post. Lorem ipsum I can’t remember the rest of lorem ipsum and don’t have an internet connection right now. Testing testing testing this blog post. Blog posts are cool.
portfolio
Portfolio item number 1
Short description of portfolio item number 1
Portfolio item number 2
Short description of portfolio item number 2
publications
Impacts of uncertainty in building envelope thermal transmittance on heating/cooling demand in the urban context
Published in Energy and Buildings, 2022
Urban building energy modeling (UBEM) is a promising tool to evaluate building energy consumption at high temporal-spatial resolution at urban scale. However, state-of-the-art UBEMs use identical building envelope thermal transmittance according to design specifications in model characterization, which neglects the uncertainty in U-values of the building stock. To evaluate the impacts of uncertainty in U-values on heating/cooling demand at the urban scale, this study proposes a physics-based model of building envelope thermal transmittance to generate the U-value distributions of building stocks. Diversified U-values were assigned to buildings according to the building age, while identical initial U-values in the design served as a baseline. The impact of uncertainty in building envelope U-values was assessed by comparing the heating/cooling demand simulated under different U-value distributions, taking 33,222 residential buildings in Beijing as a case study. The results showed that, considering uncertain physical factors, thermal transmittance followed a right-skewed distribution, which led to an increase in the heating/cooling demand of the building stock. The annual total heating/cooling demand increased by 26% and 13%, respectively. The diversity in the heating/cooling demand intensity of the building stock was enhanced when more causes of uncertainty were considered, which was more evident in the building stock with a small range of building age or heating demand intensity. Therefore, it is advisable to consider the uncertainty in the building envelope thermal transmittance in UBEM simulations for energy evaluation and planning at the district or urban scale.
Recommended citation: Liu, Z., Zhou, X., Tian, W., Liu, X., & Yan, D. (2022). Impacts of uncertainty in building envelope thermal transmittance on heating/cooling demand in the urban context. Energy and Buildings, 273, 112363. https://www.sciencedirect.com/science/article/pii/S0378778822005345
Integrated physical approach to assessing urban-scale building photovoltaic potential at high spatiotemporal resolution
Published in Journal of Cleaner Production, 2023
Assessing the urban-scale building photovoltaic (PV) potential is important for designing urban environments, retrofitting existing structures, or integrating PVs with grids. However, few studies have considered high-temporal-resolution simulations, the facade PV potential, and a comprehensive PV model simultaneously; thus, the overall accuracy of the estimation of PV potential may be limited. Therefore, this study developed an integrated framework to assess the urban-scale PV potential of rooftops and facades at high spatiotemporal resolution. The proposed approach integrates an anisotropic sky diffuse model, a vector-based shading calculation method, and a temperature-related PV performance model. The annual PV potential and spatial/temporal characteristics were analyzed in a case study of over 170,000 buildings in Beijing. The results showed that the estimated rooftop PV power generation was 7.55 TWh/y, whereas the facade PV power generation was 18.07 TWh/y, which was 239% of the rooftop PV yield. The integrated model estimated PV yield with higher accuracy than the simplified models by depicting more details. The proposed approach can be applied to the large-scale assessment of future energy systems with increasing penetration of PVs, and the results can support effective policies for the integration of PVs into the built environment in dense cities.
Recommended citation: Liu, Z., Liu, X., Zhang, H., & Yan, D. (2023). Integrated physical approach to assessing urban-scale building photovoltaic potential at high spatiotemporal resolution. Journal of Cleaner Production, 135979. https://www.sciencedirect.com/science/article/abs/pii/S0959652623001373
Exploring the impacts of heterogeneity and stochasticity in air-conditioning behavior on urban building energy models
Published in Sustainable Cities and Society, 2024
Heterogeneity and stochasticity, two main aspects of uncertainty in occupant behavior (OB), at the urban scale are not featured in most current urban building energy modeling (UBEM) platforms, and their respective impacts on urban-scale building energy consumption remain unclear. We aimed to introduce OB uncertainty into the UBEM workflow and assess the differences in the impacts of heterogeneity and stochasticity on cooling demand. Different OB models were integrated into the cooling demand simulation of residential building stocks, considering the heterogeneity and stochasticity in both occupancy and energy-use behavior. The impacts of heterogeneity and stochasticity on urban-scale cooling demand and its applications for different purposes in UBEM are discussed. We found that stochasticity in occupancy decreased the peak cooling demand by 54%, whereas the uncertainty in air-conditioning (AC) behavior had little effect. Heterogeneity is the main reason for the diversity in cooling demand, whereas stochasticity better reflects the dynamics of cooling demand. Occupancy and AC behavior models with higher fidelity are required to obtain results with higher spatial or temporal resolution, which should be selected according to the UBEM applications. The proposed approach will contribute to the development of appropriate urban-scale occupant behavior models and bridge urban mobility with occupant-centric UBEMs.
Recommended citation: Liu, Z., Dou, Z., Chen, H., Zhang, C., Wang, S., Wu, Y., ... & Yan, D. (2024). Exploring the impacts of heterogeneity and stochasticity in air-conditioning behavior on urban building energy models. Sustainable Cities and Society, 105285. https://www.sciencedirect.com/science/article/pii/S2210670724001136
A novel acceleration approach to shadow calculation based on sunlight channel for urban building energy modeling
Published in Energy and Buildings, 2024
Shadow effect among buildings has great impacts on the building energy consumption and the performance of building photovoltaic, and calculating shadows on building surfaces in urban building energy modeling (UBEM) faces challenges of inefficiency, especially for dense urban areas. In this study, a novel shadow calculation approach based on sunlight channel is proposed that can streamline the surrounding environment and accelerate the shadow calculation process. The sunlight-channel algorithm can further accelerate the shadow calculation process by dynamically predetermining the shading surfaces according to the actual solar position. In a real urban context, the proposed approach can accelerate the computation process by over 10 times over the baseline and over 34 times over the non-accelerated method, with a mean absolute percentage error (MAPE) of 1.13% for the total solar radiation. The proposed approach copes well with both large-scale urban models and the complexity of building structures, particularly for urban models with complex changes in building heights. This approach can significantly enhance the computational efficiency in complex urban environments, facilitating an accurate and rapid analysis of the energy consumption and solar potential of buildings in dense cities.
Recommended citation: Liu, Z., Zhou, X., Shen, X., Sun, H., & Yan, D. (2024). A novel acceleration approach to shadow calculation based on sunlight channel for urban building energy modeling. Energy and Buildings, 114244. https://www.sciencedirect.com/science/article/pii/S0378778824003608
talks
Talk 1 on Relevant Topic in Your Field
Published:
This is a description of your talk, which is a markdown files that can be all markdown-ified like any other post. Yay markdown!
Conference Proceeding talk 3 on Relevant Topic in Your Field
Published:
This is a description of your conference proceedings talk, note the different field in type. You can put anything in this field.
teaching
Teaching experience 1
Undergraduate course, University 1, Department, 2014
This is a description of a teaching experience. You can use markdown like any other post.
Teaching experience 2
Workshop, University 1, Department, 2015
This is a description of a teaching experience. You can use markdown like any other post.