2.1. Sample Selection Method
Neighborhoods constitute fundamental entities within urban ecosystems, and issues encountered at the citywide level often result from the cumulative effects of inadequate planning at the community level [
21]. Decisions made on a community scale are intricately intertwined with overall quality of life. As a result, we undertook a comprehensive examination of the residential neighborhood layout characteristics in Wuhan, drawing upon existing research within the literature and widely adopted computational tools, such as Google Earth, Baidu Street View, and Geographic Information Systems (GISs). This analysis synthesizes empirical observations from the physical world with satellite imagery. Furthermore, we evaluated the architectural configurations within the residential built-up areas under investigation.
Based on the framework of six fundamental urban forms proposed by Rode et al., we abstracted and selected two distinct layout classifications for 30 residential districts located in the Jianghan, Jiang’an, and Wuchang districts of Wuhan [
22]. These classifications include the ‘Parallel Row Layout (PRL1)’, with buildings oriented in both east–west and north–south directions, as well as the ‘Staggered Row Layout (SRL2),’ characterized by east–west alignment but staggered in both east–west and west–north spacing, with a 1/2 building offset. Moreover, in terms of the overall statistical distribution, these two layout forms constitute 50% and 33% of the recorded layout forms, respectively, signifying their prevalence in Wuhan. As outlined in
Table 1, drawing upon the statistical findings from our study, we established two typical residential building layouts for simulating and calculating building energy consumption and carbon emissions.
Each single building within the layout types was numbered in order from south to north and from west to east, and the building numbers are displayed in the diagram presented in
Table 1. This method was employed to analyze the energy consumption characteristics of each individual building and to explore the impact of different residential cluster layout forms on the energy consumption of single buildings.
2.2. Research Tools and Methods
The spatial configuration of a neighborhood exerts influence on the energy consumption of buildings by interfacing with climatic factors. This interaction encompasses various aspects, such as the shading effects resulting from inter-building positioning, the direct impact of solar heat, and the wind environment on building surfaces, as well as the indirect influence stemming from the microclimate environment shaped by the collective building mass [
23]. Presently, prevailing research methodologies primarily involve statistical analyses grounded in empirical data, simulation-based investigations employing computational tools, and hybrid approaches combining statistical and simulation techniques. In this study, our initial approach involves employing a statistical research method to analyze the layout of residential buildings in Wuhan using empirical data. Subsequently, building upon this foundation, we construct an idealized model of these residential structures. Leveraging the VirVil-HTB2 tool, we then engage in simulation-based research to assess both energy consumption and solar radiation patterns within these buildings.
In this investigation, a two-step approach was taken. Firstly, using actual investigation and research methods, residential clusters in Wuhan city situated in the hot summer and cold winter climatic region were categorized and organized, and the typical layout forms of residential clusters were summarized. Secondly, based on the climatic conditions of the region, a sensitivity analysis was conducted utilizing VirVil-HTB2 17 energy consumption simulation software to examine the correlation between the solar radiation reception of buildings and building energy consumption and carbon emissions under different residential cluster layout forms. The purpose of this analysis was to observe changes in the role of solar radiation as a crucial factor in the influence of various building cluster forms on building energy consumption (
Figure 1). The HTB2 10 software, developed by the Welsh School of Architecture, Cardiff University, UK, is a comprehensive energy simulation software that includes the VirVil-HTB2 dynamic energy simulation plugin that operates on the commonly used SketchUp platform, capable of performing building energy simulations on an urban scale [
24,
25,
26]. The accuracy and reliability of the simulation results were verified by experts in the field, including Alexander and others [
27].
The energy consumption intensity of buildings is influenced by a combination of factors, including the layout of building groups, the architectural design of individual buildings, the spatial configuration of the group, and the presence of greenery, road planning, and building equipment, among others. In this particular study, we aim to isolate the building group layout as the sole variable of investigation. Consequently, we will exclude the impact of factors such as plant greening, road planning, and building equipment. Additionally, we will standardize parameters like building density, floor area ratio, and the architectural typology of individual buildings to maintain consistency, enabling us to conduct simulations of building energy consumption using an idealized model.
HTB2 software represents a comprehensive energy simulation tool meticulously crafted by the Welsh School of Architecture at Cardiff University, United Kingdom. Its primary purpose lies in conducting dynamic simulations to assess the thermal performance of buildings. Conversely, VirVil-HTB2 stands as a dynamic energy simulation plugin ingeniously built upon the widely utilized design tool SketchUp. This innovative plugin facilitates an intuitive approach to energy prediction and analysis during the conceptual phases of design. HTB2 seamlessly interfaces with SketchUp through the VirVil Plugin, treating buildings as simplified geometric constructs primarily to facilitate energy simulations at the planning scale [
15,
24]. VirVil-HTB2 utilizes direct, diffuse, and direct normal solar radiation data to compute solar radiation incidents on exterior surfaces. When integrated with SketchUp 2018 software, it offers precise simulations and calculations for the solar radiation received on each façade of a building [
28]. In the context of this study, where we exclusively examine the complex layout of buildings as the singular variable, disregarding the influence of factors such as greenery, roads, and building equipment, the primary determinant impacting solar radiation reception is mutual shading among the buildings. This metric serves as an indicator of mutual shading within building clusters, with higher solar radiation reception values indicating reduced shielding by neighboring structures. Initially, climate data specific to the Wuhan region were acquired from the Energy Plus website. Subsequently, these data were imported into the VirVil-HTB2 software to establish the model’s geographic location and account for climate factors.
VirVil-HTB2 is a simulation and computational software that builds upon the foundation of HTB2 and SketchUp, centering its attention on energy simulations at the planning level while offering the flexibility of selecting varying simulation cycles. Within these simulations, local geographic coordinates and climate parameters were incorporated into the software. A year-long simulation cycle was chosen, enabling the software to model energy consumption throughout different months in accordance with local climatic conditions. The necessary material parameters were then programmatically supplied to the model. Building upon these parameters, energy simulations of the building cluster were conducted. As can be seen in
Table 2, the simulated solar radiation and energy consumption levels have been categorized into four distinct color codes, each reflecting their respective intensities. In this context, the red hue signifies the highest values, the yellow hue indicates values of greater magnitude, the blue hue represents lower values, and the white hue designates the lowest values.
In recent years, the utilization of linear regression analysis has significantly advanced in studies pertaining to building energy consumption analysis. To comprehensively assess the impact of building cluster shading on energy consumption and internal distribution patterns, it is imperative to quantify and analyze these effects [
29]. Consequently, in this study, we employ the linear regression analysis method to precisely quantify research data. Using SPSS software, we conducted correlation and multiple linear regression analyses on the simulated data. Initially, we sought to establish whether a correlation exists between solar radiation values, representing the mutual shading conditions among building clusters, and building energy consumption. Subsequently, based on this preliminary analysis, we conducted a linear regression analysis to quantify the causal relationship.
2.3. Parameter Setting
In this study, monolithic buildings with identical basal areas conforming to the scale of residential buildings were utilized for the purpose of data comparison and variable control. The parameters required for the model were established in accordance with various relevant regulations, such as the Design Standard for Energy Efficiency of Residential Buildings in Hot Summer and Cold Winter Zones (JGJ134-2010) [
30], Design Standard for Residential Buildings of Low Energy Consumption (DB42/T559-2022) [
31], Code for Thermal Design of Civil Buildings (GB 50176-2016) [
32], and Standard for Urban Residential Area Planning and Design (GB 50180-2018) [
33], to ensure consistency in building density, volume ratio, and body shape coefficient. Specifically, the base area was set to 40 m × 10 m, and the number of building floors and floor height were set to 10 and 3 m, respectively. Energy consumption and carbon emission data were simulated for different spatial layouts of the residential area by changing the layout of the residential spaces, with the parameters of roof, walls, and windows outlined in
Table 3.
Based on the climatic data acquired from the official website of Energy Plus, the VirVil-HTB2 was used to compute the building energy consumption and carbon emissions for four types of typical settlement models. In the VirVil-HTB2 data, the energy consumption for the purpose of heating in hot summer and cold winter areas of China was calculated for five months, namely January, February, March, November, and December, and the energy consumption for the purpose of heating was calculated for nine months, namely March, April, May, June, July, August, September, October, and November. The average operational energy consumption data were determined by averaging the sum of energy consumption for cooling, heating, and other energy consumption purposes. Subsequently, the energy consumption and carbon emission data of hot summer and cold winter areas were observed and discussed [
28].