Evaluation and Optimization Strategies of the Living Environment in One Resettlement Area of the South-to-North Water Diversion Project

Abstract

Taking Yunyu New Village in Nanyang City, a typical newly built resettlement area of the South-to-North Water Diversion Project of China, as an example, this paper tries to construct a health environment evaluation index system for the resettlement area and determines the priority and content of residential environment renovation in the resettlement area through residents’ health satisfaction evaluation and IPA analysis. The results revealed that six factors, namely, winter insulation, summer heat insulation, quality of domestic drinking water, indoor natural light environment, humanized design, and architectural plane function design, need to be renovated first. For the indoor environment, which is the focus of renovation, the light and heat environments were evaluated via field measurements and simulation experiments. The results show that the indoor comfort, daylighting, and energy savings of the surveyed buildings all fail to meet Chinese building design standards. Corresponding optimization strategies for indoor ventilation, thermal insulation performance of the envelope structure, and window wall ratio are proposed and verified via relevant software simulations and immigrants’ wishes. For the outdoor environment, we investigate the living habits and renovation needs of immigrants from the aspects of public space and courtyard space in the resettlement area and propose corresponding optimization strategies. The results of this research can help enhance the sense of gain and happiness of immigrants in the resettlement and provide a reference for improving the living environment of the same type of immigrant resettlement area.

1. Introduction

The South-to-North Water Diversion Project is a Chinese strategic project related to the well-being of people. Behind the brilliant achievements, nearly 180,000 residents in the water source area relocated far away. These immigrants are resettled in more than 600 immigrant resettlement areas in Henan, Hubei, and other places [1,2]. In 2021, Chinese General Secretary Xi Jinping pointed out at the symposium on the high-quality development of the follow-up projects of the South-to-North Water Diversion that “we should continue to do a good job in the follow-up assistance work for immigrant resettlement and comprehensively promote rural revitalization.” As important carriers for the lives of immigrants, resettlement areas provide the closest environmental support for improving the living environment level of immigrants and promoting their ability to participate in creating a healthy and harmonious new home. In the new era of rural revitalization, the construction of human settlements in resettlement areas will inevitably enter a new stage of high-quality and sustainable development. However, the immigrant resettlement area is initially a “top-down” construction behavior led by the government, and it inevitably does not match the “bottom-up” actual living needs of immigrants to a certain extent. In fact, the local government pays more attention to the first resettlement management and less attention to the sustainability of the later living environment. How to build a healthy living environment that adapts to the changing lifestyle of immigrants and how to optimize the allocation of resettlement area resources to meet the living needs of immigrants have become urgent problems to be solved for the high-quality and sustainable development of the resettlement areas of the South-to-North Water Diversion Project.

The living environment is the sum of the various environments surrounding living spaces [3]. Initially, researchers focused on material space environments such as the form of cities, communities, and buildings. With the development of the “people-oriented” concept, they gradually began to emphasize the importance of the needs of residents, social culture, and humanistic care [4]. Compared with China, Western countries began to advocate that residents substantially participate in community affairs earlier. Their early “Community Action Plan” added public participation in the community planning process and focused on cultivating community self-organizations [5], emphasizing that multiple subjects, such as architects, governments, and residents, jointly negotiate the planning and design of the living environment. Moreover, as China’s urbanization transitions from incremental to stock, the needs and opinions of residents are gradually receiving attention and adoption [6]. Residents have obtained relatively more right to speak through participation in public affairs, which makes planning more open and transparent, and the planning of residential areas also changes from blueprint-like planning of material space to the quality of the living environment and public participation [7]. When studying immigrants (including in urban areas, mining areas, and reservoirs), researchers pay more attention to the integration of immigrants with the local environment and local identity [8], social interaction between local residents and immigrants [9], and spatial equity [10] than to residents of general residential areas. Therefore, to evaluate the living environment of resettlement areas, scholars often start from the perspective of immigrants, obtain the subjective wishes and evaluation results of immigrants via structured questionnaires or semi-structured survey interviews, and then analyze several key factors affecting the living environment of resettlement areas [11,12,13]. Some researchers believe that measuring objective environmental standards must be based on the objective physical environment and meet the relevant local specifications. Through objective on-site observations and measurement results, they evaluate the built environment by comparing relevant evaluation systems and locally relevant specifications [14,15]. Therefore, from the existing research, the evaluation of the living environment in resettlement areas is carried out from two main aspects, namely, the subjective satisfaction evaluation of immigrants and the objective evaluation of the living environment.

“Satisfaction evaluation” is often used in subjective questionnaires. Satisfaction evaluation was first applied in fields such as psychology and sociology, and then gradually applied in the field of residential area planning. The currently widely used building environment evaluation standards worldwide, such as BEES (Building for Environmental and Economic Sustainability, Gaithersburg, MD, USA), BREEAM (Building Research Establishment Environmental Assessment Method, Watford Herts, UK), BEAT (Building Environmental Assessment Tool, Hoersholm, Denmark), LEED (Leadership in Energy and Environmental Design, Washington, US), and GBAS (Green Building Assessment Standard, Beijing, China), are applicable to the evaluation of general built environments. However, in the satisfaction evaluation of the living environment in immigrant resettlement areas, it is necessary to appropriately optimize the existing evaluation standards according to local practices and social and economic conditions. The importance–performance analysis (IPA) method is one of the methods used for satisfaction data analysis. It was proposed by Martilla and James in 1977 [16]. Later, it received the attention of scholars from different fields and was widely used in research on management decision-making, cultural heritage, and other aspects [17,18]. With increasing research, scholars have gradually realized the shortcomings of the traditional IPA method: the premise of this method is that the variables in the two dimensions of importance and satisfaction are independent of each other and are linearly related to the overall perceptions of respondents. However, in actual investigations, importance and satisfaction are difficult to use as independent variables. The quadrant distribution results also deviate greatly from the actual situation. Therefore, some scholars have made certain corrections to the IPA analysis method and have used extended importance to replace self-reported importance [19]. Deng Weizhao suggested calculating the partial correlation coefficient between individual satisfaction and overall satisfaction as the extended importance score. Since partial correlation analysis reflects only the net correlation between the specified satisfaction variable and overall satisfaction by excluding the influence of other individual satisfaction variables, it can more accurately reflect the real importance evaluation [20]. Therefore, this method is widely recognized and applied in various fields [21]. Immigrants will have certain psychological expectations for the resettlement area before relocation, and there will be different degrees of gaps between the actual living environment and their psychological expectations. The smaller the gap, the higher the satisfaction [22]. The World Bank also pointed out in the Handbook for Resettlement Planning and Implementation of Development Projects that if the design and implementation of immigrant resettlement planning cannot sensitively reflect the needs and priorities of the community, it may have an adverse impact on the social and economic development of the resettlement community and cause psychological trauma to immigrant groups [23]. From this perspective, the IPA method is suitable for evaluating the living environment in resettlement areas and can better reflect the psychological needs of immigrants and the priority of resource allocation.

After several years of practice, reservoir immigrant resettlement areas in China have changed from “blood transfusion” compensation (emphasizing immigrants and neglecting resettlement) to “hematopoietic” support for immigrants to integrate into the construction of resettlement areas. The research focus of scholars has also gradually shifted from research on compensation standards, resettlement methods, relevant policies, and working mechanisms to the evaluation of immigrant resettlement effects, post-resettlement support, and sustainable development [24]. In the past 10 years, scholars have researched long-term livelihoods and sustainable development after reservoir immigrant resettlement through methods such as follow-up investigations and factor analysis. For example, Wilmsen et al. conducted a follow-up survey of 521 households relocated from the Three Gorges Dam in China and reported that in the first five years of initial immigrant resettlement, the economic income of immigrants generally declined, and it was even difficult to meet basic living needs. However, in recent years, the income and food safety of immigrants have been taken seriously by the Chinese government, and the economic situation of immigrants has greatly improved. The Chinese government’s stimulation of the regional economy and increase in enterprise investment have paid off in immigrant resettlement areas [25]. Wang et al. took the Liujiaxia Reservoir Area on the upper reaches of the Yellow River in Gansu Province, China, as an example. On the basis of a survey of a total of 14 immigrant resettlement areas, a set of sustainable development evaluation index systems for ecological immigrant resettlement areas that integrate economic, social, and environmental aspects was constructed [26]. Another study on the livelihood resilience of three flood control project resettlement counties in the lower Yellow River of China was undertaken. An index system for guidance was constructed, and several policy suggestions have been given for the government to improve the livelihood resilience of resettled farmers [27].

This paper takes Yunyu New Village in the resettlement area of the South-to-North Water Diversion Project as the research object. First, we evaluate the overall satisfaction with their living environment, guided by the “Evaluation Standard for Healthy Buildings” [28] released in 2021 in China, an evaluation index system for the healthy environment of the resettlement area was constructed. On the basis of factor analysis, health satisfaction evaluations of the resettlement area are conducted. The IPA correction analysis method is used to extract the extended importance of indicators. Then, the priority of the transformation of the living environment in the resettlement area is determined and the renovation content is selected. For indoor environments, the evaluation of daylighting and thermal environments is carried out through on-site measurements and numerical simulations. For outdoor environments, field research and questionnaire surveys are conducted to propose practical and feasible optimization strategies, on the basis of immigrants’ willingness. The technical flowchart is shown in Figure 1.

2. Methodology

2.1. Research Subjects

Yunyu New Village is located in Taihe Town, Sheqi County, Nanyang City, Henan Province, China. The relocation task in this village was completed in 2011. It is one of the typical newly built immigrant resettlement areas of the South-to-North Water Diversion Project. There are 505 permanent immigrants. The overall shape of the village is relatively regular. The total area of homesteads in the village is approximately 31,200 square meters. The location and master plan of the village are shown in Figure 2. Most of the buildings in the resettlement area are oriented in the north-south direction. The buildings on the east side facing the highway are oriented in the east-west direction. There are several public service buildings and sites in the central area.

2.2. Importance–Performance Analysis (IPA) Method

In this method, research data are collected through questionnaire surveys. The importance and satisfaction of each evaluation indicator are scored, and the indicators are represented in a clear and intuitive IPA quadrant chart, providing a basis for evaluating the living environment of immigrants.

Owing to the use of the revised IPA method in this article, individual satisfaction and overall satisfaction of evaluation indicators were collected through a survey questionnaire, and the partial correlation between individual satisfaction and overall satisfaction was calculated as the extended importance score, replacing self-reported importance with extended importance.

In the IPA quadrant matrix, the average value of the satisfaction degree of different factors is taken as the X-axis and the extended importance is taken as the Y-axis. Taking the average value of the degree of satisfaction and the average value of extended importance as the demarcation points of the four quadrants of the IPA diagram, different factors are located in the four quadrants. The four quadrants correspond to four priorities. The priority order is as follows: the important improvement area in the second quadrant (low satisfaction, high importance) > the secondary improvement area in the third quadrant (low satisfaction, low importance) > the continuous maintenance area in the first quadrant (high satisfaction, high importance) > the overemphasis area in the fourth quadrant (high satisfaction, low importance).

2.3. Interview and Questionnaire Survey

The personnel survey in this article includes three parts: a subjective evaluation questionnaire for IPA analysis, a survey on the acceptability of indoor environment optimization strategies and a survey on the willingness to renovate outdoor environments. A combination of one-on-one and one-to-many interviews and distributed questionnaires was used. The interviews and questionnaires were conducted intermittently from 2 October to 30 November 2023; 2 April to 18 May 2024; and 1 July to 24 August 2024. Consent to use the collected information was obtained through written questionnaires and verbal interviews.

The questionnaire survey for IPA analysis was conducted using a simple random sampling method. The questionnaire is divided into three parts. The first part concerns the personal information of the immigrants, namely, their gender, age, education level, years of residence, and annual family income. The second part is the main body of the questionnaire. According to the constructed evaluation index system of the healthy environment of the resettlement area, the degree of satisfaction is scored on a 5-point-level scale. One to five points indicate “very dissatisfied”, “dissatisfied”, “generally”, “satisfied”, and “very satisfied”, respectively. The third part is the overall score of immigrants’ satisfaction with the health of the resettlement area, and uses the same 5-point-level scale. From 10 to 12 August 2024, a total of 85 questionnaires were distributed in this survey, 80 of which were valid.

To understand the degree of acceptance of the indoor environment renovation measures by immigrants, 50 immigrants were randomly selected for interviews and questionnaires via stratified random sampling. Fifty questionnaires were recovered. Among the surveyed people, those over 60 years old accounted for more than 70% of the sample. The survey content is the acceptability of various optimization measures and costs. The survey content is divided into three categories: “Nonacceptable”, “Neutral”, and “Acceptable”.

The questionnaire survey on willingness to renovate the outdoor environment is an open-ended question. Fifty immigrants were randomly selected for the interviews and questionnaires. The questions included “Your demand for public service facilities not provided in the resettlement area” and “What are your suggestions for the existing public service facilities in the resettlement area?”

2.4. On-Site Measurement

2.4.1. Test Sample

Because most buildings in the resettlement area are oriented north-south, the test sample was selected as a typical north-south-oriented apartment. The names of the rooms and the bedroom numbers in the right building plan in Figure 3 are shown. The building is a two-story brick-and-mortar structure with a wall thickness of 240 mm. The walls are plastered on both sides, and the roof is covered with cement mortar tiles. There is a single-layer iron gate and aluminum alloy sliding window as well as an iron grille on the outside. The floor-to-ceiling height is approximately 3.5 m. The ground floor of the building has a living room, a kitchen, two bedrooms, and a bathroom. The second floor has three bedrooms, a bathroom, and a balcony above the living room, and the southern side of the building has an outdoor area of approximately 70 m². There is an actual courtyard addition, with a utility room and a kitchen.

2.4.2. Test Time and Content

The test time of the indoor and outdoor hot and wet environments was from 18:30, 20 January to 8:00, 22 January 2024. The temperature and humidity data from 00:00 to 23:59 on January 21 were selected, and the test period was sunny. The investigation revealed that the resettlement area has seriously hollowed out, with the permanent resident population of each household ranging from 1–2 people and the aged population being the main population. Apart from sometimes using the second floor to dry grain, their activities are mainly on the first floor. Therefore, in this study, the air temperature and relative humidity of the courtyard, living room, bedroom 1, and bedroom 2 on the first floor of the building were investigated and tested. The measurement point height was 1.5 m away from the ground. The measuring instrument was a USB-type COS-04-0 automatic temperature and humidity recorder, and the monitoring data interval is 5 min. In addition, to make the measurement results more accurate and convenient for comparison with the software simulation results, the author’s team used a handheld FY-11 embedded temperature and humidity recorder on 1 January 21 (sunny) to record the air temperature and humidity at the same location in the living room and bedroom of the survey building.

The test time for the surface temperature of the building walls was 10:00–18:00 on 21 January 2024. The measurements were taken every two hours, three points were averaged for each measurement, and the corresponding internal and external test points were measured within 10 min. The measurement object was the external wall of the survey building. The measurement points are shown in Figure 4. The measurement instrument used was a TM902C thermocouple electronic thermometer.

The indoor light environment test time of the resettlement house was 9:00–18:00 on 17 September 2023. It was sunny during the test period. Measurements were taken every hour. The test objects are the main rooms on the first floor, namely, the living room, bedroom 1, and bedroom 2. In accordance with the “Day-lighting measurement method” GB/T5699-2017 [29], the measurement height is 750 mm away from the ground, and the specific point layout is shown in Figure 5.

All test instruments used and their parameters are shown in

Table 1. Technical parameters of the test instrument.

Instrument	Test Content	Measurement Range	Accuracy
USB model COS-04-0 automatic temperature and humidity recorder	Air temperature	−20~60 °C	±0.3 °C
	Relative humidity	0~100%	±2%
Handheld FY-11 embedded temperature and humidity recorder	Air temperature	−50~70 °C	±1 °C
	Relative humidity	10~99%	±1%
TM902C thermocouple electronic thermometer	Surface temperature	−50~1300 °C	±0.1 °C
Biaozhi GM1020 illumination meter	Illumination meter	0~200,000 LX	±0.1 LX

.

2.5. Software Simulation

(1)

Energy consumption simulation

We use EnergyPlus software (V9-0-1) to simulate building energy consumption. The thermal conductivity, specific heat capacity, and dry density of the main building materials are determined in combination with the physical performance calculation parameters of the building materials given in the Code for Thermal Design of Civil Buildings of China (GB50176-2016) [30], as shown in

Table 2. Investigated thermal properties of all the building materials.

Material	Dry Density (kg/m3)	Thermal Conductivity (W/m·K)	Specific Heat Capacity (J/kg·K)
Lime mortar	1600	0.81	1.05
Cement mortar	1800	0.93	1.05
Clay brick masonry	1800	0.81	1.05
Steel reinforced concrete	2500	1.74	0.92
Cement mortar hanging tile	2300	0.93	1.05
Flat glass	1800	0.52	1.26

. The wall is composed of lime mortar, brick walls, and lime mortar; the floor is composed of floor tile, polymer cement mortar, and a cast-in-place reinforced concrete floor; and the roof is composed of cement mortar hanging tile, a reinforced concrete roof panel, and lime mortar. The construction material layers of the building envelope are shown in Figure 6. According to the actual situation and living habits of the resettlement area, the personnel included two people, an elderly man and a young man. The young man has farm work or temporary work from 08:00 to 12:00 and from 14:00 to 19:00. The old man performs simple housework in the living room from 08:00 to 19:00, walks from 19:00 to 20:00, and rests from 20:00 to 08:00 in the bedroom. The heating and cooling room is set as the first-floor living room and two bedrooms. Other parameters, such as the floor plan, building height, and window-to-wall ratio, are set according to the actual situation. The summer design day is 21 July, and the winter design day is 21 January.

(2)

Indoor natural ventilation simulation

For indoor ventilation, the Gbsware software VENT 2022 is used. The simulated ventilation time was set as summer. Considering the shielding of the surrounding buildings to the sample buildings, the overall resettlement area is modeled and simulated according to the actual situation. The arc division accuracy is 0.24 m, the initial grid size is 0.8 m, the minimum and maximum subdivision series are 1, the minimum iteration number is 200, and the number of grids is 223,855. According to the Design Code for Heating Ventilation and Air Adjustment of Civil Buildings (GB50736-2012), the average outdoor wind speed in Nanyang is 2.7 m/s, the wind direction is 22.5° (ENE), and the rough ground index is 0.16. The calculation domain of the summer conditions is 349.5 m, the width is 305.4 m, and the height is 108 m. The main building environment around the survey building is shown in Figure 7, where H is the maximum building height.

(3)

Daylighting simulation

The daylighting simulation is performed using the Gbsware software DALI 2022. Apart from the 3D form set as the energy consumption model, the initial conditions for daylighting are set as follows: the grid size is 500 mm; the wall offset is 250 mm; the ceiling, wall, and outer surface are lime mortar; the reflection ratio is 0.75; the ground is white porcelain glazed brick; and the reflection ratio is set at 0.8.

3. Selection of Renovation Content

3.1. Construction of the Index System

This study refers to the “Evaluation Standard for Healthy Buildings” (T/ASC 02/2021) [28]. First, six criterion levels are determined, namely, air, water, comfort, fitness, humanistic care, and service. Second, combined with relevant research on living environments, 20 more detailed secondary indicators are further summarized. See

Table 3. Selection of health environment evaluation indicators in the resettlement area.

Main Categories	Detailed Indicators
Air	Air quality, outdoor air quality, toilet and kitchen exhaust
Water	Quality of drinking water, toilet and kitchen drainage
Comfort	Internal and external noise, indoor natural light environment, summer heat insulation, winter thermal insulation
Fitness	Outdoor fitness venues, children’s playground, the elderly activity venues
Humanistic care	Building plane function design, barrier-free design, outdoor communication site, public space quality, humanized design of the building
Service	Repair of existing buildings, safety management, and garbage cleaning

for details.

3.2. Descriptive Analysis of Survey Results

The personal information statistics of the respondents are shown in Figure 8. The gender composition of the respondents is basically balanced, among which women (57.5%) are more common than men (42.5%); those over 60 years of age account for 61.3%, and those over 45 years of age account for 87.5%, indicating that the resettlement area has a serious aging problem; middle school and below account for 66.3%, and only 10% are above college, indicating that the interviewed immigrants have a low education level; those who have lived for 10 years or more account for 88.8%, indicating that most of the respondents are permanent residents of the resettlement area; and the annual average income of the respondents’ family members is less than 50,000 yuan, of which those below 30,000 yuan account for 73.8%, indicating that the immigrants in the resettlement area have a low income. According to the survey interviews, most immigrants have no direct source of income. Most young people leave to work, and those left behind are more often older. This finding also shows that the currently surveyed resettlement area is in decline.

The ranking of individual satisfaction is shown in

Table 4. Satisfaction ranking of each performance index in the resettlement area.

Evaluation Item	Av. Value	Ranking
Security administration	4.425	1
Outdoor air quality	4.263	2
Outdoor fitness venues	4.163	3
Garbage cleaning	4.150	4
Internal and external noise	4.013	5
Toilet and kitchen drainage	3.750	6
Toilet and kitchen exhaust air	3.363	7
Air quality in the living space	3.350	8
Public space quality	3.113	9
Outdoor communication venue	3.113	10
Activity venues for the elderly	2.963	11
Humanized design of the building	2.575	12
Indoor natural light environment	2.550	13
Children’s playground	2.500	14
Barrier-free design	2.388	15
Building plane function design	2.113	16
Winter insulation	1.575	17
Quality of domestic and drinking water	1.550	18
Summer heat insulation	1.500	19
Repair of resettlement houses	1.475	20

. In general, more than half of the performance factor satisfaction exceeds 3. The factors associated with high satisfaction are concentrated in the services of the resettlement area, such as safety management and garbage cleaning, and the outdoor environment, such as outdoor air quality and outdoor fitness venues. The factors associated with low satisfaction are concentrated on the physical performance of resettlement houses, such as summer heat insulation, winter heat preservation, and the quality of domestic drinking water. The satisfaction level of resettlement house repair is the lowest, at 1.475. According to the survey, the resettlement house has been repaired once, but most immigrants are not satisfied with this repair and believe that it does not solve the actual problem of resettlement houses. The difference between the satisfaction rankings of No. 1 and No. 20 is relatively large, indicating that the advantages and disadvantages of the resettlement area are both prominent.

The average overall satisfaction value of immigrants in the resettlement area is 3.138. It can be considered that immigrants are generally neutral with respect to the resettlement area. Necessary improvement is expected to reach a level of general satisfaction (4.0) or high satisfaction (5.0).

3.3. Factor Analysis

SPSS software was used to analyze the satisfaction of each performance index in the resettlement area. Principal component analysis was used to select principal components with eigenvalues greater than 1 as common factors. According to the results of the Kaiser–Meyer–Olkin (KMO) and Bartlett tests, the suitability of KMO sampling is 0.751 (greater than 0.7), and the significance is <0.001, indicating that it is suitable for factor analysis.

According to the rotating component matrix, as shown in Figure 9, the secondary factors are re-integrated on the basis of load values (if a secondary factor has load values in two components, the larger the load value is taken, as the larger the value is, the higher the correlation with the corresponding component). Six new categories as suggested components are then summarized: A–F. Category A has the highest contribution rate of variance (27.503%). More results of the factor analysis are shown in

Table 5. Factor analysis results for each category.

Category	Characteristic Value	Contribution Rate of Variance %
A	5.501	27.503
B	2.154	10.772
C	1.698	8.492
D	1.592	7.958
E	1.273	6.366
F	1.078	5.392

.

3.4. Modified IPA Analysis

The partial correlation between each individual’s level of satisfaction and overall satisfaction was analyzed, and the partial correlation coefficient was used as the extended significance score. The specific results are shown in

Table 6. Satisfaction mean value and extended significance of each factor.

Category	Factor	Av, Value of Satisfaction	Extended Importance Degree	Weight
A	Winter insulation	1.575	0.259	0.911
	Summer heat insulation	1.500	0.312	0.900
	Quality of domestic and drinking water	1.550	0.353	0.696
	Indoor natural light environment	2.550	0.407	0.516
B	Humanized design of the building	2.575	0.265	0.774
	Public space quality	3.113	0.164	0.724
	Barrier-free design	2.388	0.135	0.631
C	Internal and external noise	4.013	0.105	0.750
	Outdoor air quality	4.263	0.060	0.505
	Toilet and kitchen drainage	3.750	0.196	0.798
	Toilet and kitchen exhaust air	3.363	0.224	0.695
D	Outdoor fitness venues	4.163	0.007	0.681
	Children’s playground	2.500	0.013	0.661
	Activity venues for the elderly	2.963	0.131	0.658
	Outdoor communication venue	3.113	0.274	0.562
E	Security administration	4.425	0.058	0.819
	Garbage cleaning	4.150	0.030	0.817
F	Air quality in the living space	3.350	0.103	0.646
	Repair of houses	1.475	0.178	0.548
	Building plane function design	2.113	0.256	0.425

. The load coefficient is taken as the weight, and the satisfaction score and ranking of the primary factors are obtained from the weighted average of the secondary factors. The results are shown in

Table 7. Order of each category’s satisfaction and extended importance.

Category	Satisfaction	Ranking	Extended Importance Degree	Ranking
A	1.713	6	0.382	1
B	2.702	4	0.235	3
C	3.818	2	0.189	4
D	3.195	3	0.144	5
E	4.288	1	0.049	6
F	2.390	5	0.237	2

. Comfort is the primary factor with the lowest degree of satisfaction and the highest degree of importance.

3.5. Analysis of Renovation Priority

The IPA analysis diagram is shown in Figure 10. The secondary factors in the second quadrant (important improvement area) include winter insulation, summer heat insulation, drinking water quality, indoor natural light environment, humanized design, and building functional layout. Therefore, these factors are the focus of improving the living environment in the resettlement area and need to be prioritized for renovation.

The current situation of winter insulation, summer heat insulation, and the natural lighting environment needs to be further verified through on-site measurements to obtain sufficient data for research and future renovation strategies. Humanized design requires sufficient research on the willingness of immigrants. Owing to the need to coordinate with relevant departments, such as the government and water companies, to improve the quality of drinking water, and because the government and immigrants temporarily do not afford large-scale renovation of buildings, the “quality of domestic and drinking water” and “building plane function design” are not included in the discussion of this paper. The research framework is shown in Figure 11.

4. Indoor Environmental Evaluation and Optimization Strategies

4.1. Evaluation of the Indoor Environment

4.1.1. Thermal Environment Evaluation

According to the “Energy-saving Design Standard for Rural Residential Buildings” (GB/T 50824-2013), in hot summer and cold winter areas, the indoor calculation temperature of the main functional rooms such as bedrooms and living rooms of rural residential buildings should be 8 °C in winter and 30 °C in summer without any heating or air conditioning measures [31]. The temperatures of the living room and two bedrooms of the surveyed building are 5–6 °C on a typical winter day, and the temperatures of the living room and bedrooms of the surveyed building are 32–33 °C on a typical summer day, which do not reach the calculated temperature of the energy-saving design standard.

On the typical winter day measured, the outdoor temperature reached a maximum value of 10.9 °C at approximately 15:00 and a minimum value of −1.2 °C at 6:00, with a temperature difference of nearly 12 °C, whereas the temperature difference between the living room and the two bedrooms was relatively small, within 1 °C. For relative humidity, the outdoor humidity reached a maximum value of 93.4% at approximately 8:00 and a minimum value of 74.4% at approximately 15:00, with a difference of nearly 20%, whereas the humidity difference during the day in the living room and the two bedrooms was relatively small, within 5%. Although the outdoor temperature and humidity fluctuate greatly, the indoor temperature and humidity can maintain a relatively stable state. See Figure 12.

This is because although the living room and bedrooms have doors and windows facing outdoors, owing to the immigrants’ need for heat preservation in winter, the doors and windows are often closed tightly. There is almost no wind near the doors and windows at the entrances of the measured living room or bedrooms, which also shows that the air-tightness of the doors and windows is good and that the heat loss from ventilation in winter is small. At 14:00, when the solar radiation is strong, there is no obvious change in the temperature of the living room or bedrooms. The living room is shaded by trees in the courtyard, bedroom 1 is shaded by an additional building in the courtyard, and bedroom 2 is north-facing and has no direct sunlight all day. Therefore, the surveyed building has less direct solar radiation heat gain in winter.

Combined with the wall surface temperature, although the outer wall temperature is constantly changing, the inner wall temperature can basically maintain a relatively stable state. Figure 13 shows that the thermal insulation performance of the building envelope is good. However, the inner wall temperature is 1–2 °C lower than the indoor air temperature, indicating that heat is continuously output from the indoors to the wall in winter.

4.1.2. Daylighting Environment Evaluation

According to the Chinese General Code for Building Environment (GB55016-2021), the average lighting coefficient of side lighting of residential buildings should not be less than 2%, and the average lighting coefficient of indoor natural lighting should not be less than 300 lx [32]. As shown in

Table 8. Distribution of indoor natural illumination (working conditions on sunny days, lx).

Test Room	Max. Illumination	Min. Illumination	Av. Illumination
Living room	2370	12	333
Bedroom 1	337	3	128
Bedroom 2	100	1	30
Kitchen	62	2	25

, except the living room, whose average illumination is 333 lx, none of the other rooms meet the standard.

Although bedroom 1 is in southern China and the window is large, the added building (utility room, as shown in Figure 3) in the courtyard severely blocks bedroom 1, resulting in poor indoor lighting. Because the window is small and high, the indoor illumination is insufficient, the average illumination is 30 lx, the gap from the standard is large, and the indoor area has been in a dark state for a long period of time. Field photos are shown in Figure 14.

4.1.3. Comfort Evaluation

According to the calculation of the estimated average thermal sensation index (PMV, Predicted Mean Vote) in the Chinese national standard “Requirements and Evaluation Methods for Indoor Human Thermal Comfort Environment”(GB/T 33658-2017) [33], the metabolic rate is set as 1.0, because the indoor activities of immigrants are mainly sitting and chatting. In winter, for thick warm cotton clothes, cotton pants, etc., the heat resistance value is 1.09 clo; in summer, for a T-shirt, short coat, etc., the heat resistance value is 0.3 clo. EnergyPlus (V9-0-1) is used for data simulation.

• The winter temperature and humidity data are input into the calculation formula as defined in Ref. [33], and the calculation results of PMV-PPD are shown in

  Table 9. Winter PMV-PPD calculation results for the main used rooms.

  	Living Room	Bedroom 1	Bedroom 2
  Air dry ball temperature (°C)	5.1	5.1	5.2
  Mean radiation temperature (°C)	4.6	4.6	4.7
  Wind speed (m/s)	0	0	0
  Relative air humidity of air (%)	71	72.2	72.1
  Metabolic rate (met)	1	1	1
  Clothing thermal resistance (clo)	1.09	1.09	1.09
  PMV	−4.51	−4.51	−4.48
  PPD	100%	100%	100%

  .
• The summer temperature and humidity data are input into the calculation formula, and the calculation results of the PMV-PPD are shown in

  Table 10. Summer PMV-PPD calculation results for the main used rooms.

  	Living Room	Bedroom 1	Bedroom 2
  Air dry ball temperature (°C)	32.1	32.2	31.8
  Mean radiation temperature (°C)	30.1	29.9	29.3
  Wind speed (m/s)	0.049	0.037	0.023
  Relative air humidity of air (%)	64.7	65.3	67
  Metabolic rate (met)	1	1	1
  Clothing thermal resistance (clo)	0.3	0.3	0.3
  PMV	1.99	1.98	1.79
  PPD	76%	76%	66%

  .

The control specification mentioned that “the indoor environment PMV should be within the scope of (−1, +1), namely, the indoor environment of expected dissatisfaction (PPD, Predicted Percentage of Dissatisfied) should not be more than 25%”. Table 9 and Table 10 indicate that the PMV and PPD of the rooms do not meet the specifications and that, with no air conditioning equipment, immigrants do not feel comfortable either in summer or in winter.

According to the above analysis of the indoor thermal environment, the surveyed farm house in summer and winter not only failed to meet the energy-saving design standards of rural residential buildings in summer and winter, but also did not meet the national standard of indoor human thermal comfort environment requirements. An analysis of the indoor light environment revealed that the indoor illumination of the main rooms was seriously insufficient. This finding is consistent with the results of the subjective satisfaction evaluation of immigrants mentioned above. Given the requirements of Zone A in hot summers and cold winters in the Code for Thermal Design of Civil Buildings (GB50176-2016) [30], the design strategy for the indoor thermal environment in the resettlement area should ensure indoor lighting, summer heat insulation, and winter insulation and pay attention to natural ventilation and shading design.

In this work, which combines subjective satisfaction evaluation and objective experimental measurement results, the indoor thermal environment (including the natural light environment, building thermal insulation, building plane function, etc.) and the outdoor environment (including the humanized design and building plane function, etc.) are the focus of the resettlement area transformation. The strategies for these two aspects are described below.

4.2. Indoor Environment Optimization Strategies

4.2.1. Validation of Simulation

The measured room temperatures of the living room and two bedrooms on a typical winter day, January 21, were compared with the room temperatures simulated by EnergyPlus software (V9-0-1). See Figure 15. The deviation is as follows: the measured average room temperature in the living room on that day is 5.3 °C, the average room temperature simulated by the software is 5.1 °C, and the deviation is 3.9%; the measured average room temperature in bedroom 1 on that day is 5.3 °C, and the evaluated room temperature simulated by the software is 5.1 °C, with a deviation of 3.9%; the measured average room temperature in bedroom 2 on that day is 5.4 °C, and the evaluated room temperature simulated by the software is 5.2 °C, with a deviation of 3.8%.

The measured room temperatures of the living room and two bedrooms on a typical summer day, July 21, are also compared with the simulation by EnergyPlus. See Figure 15. The deviation is as follows: the measured average room temperature in the living room on that day is 32.6 °C, the average room temperature simulated by the software is 32.1 °C, and the deviation is 1.5%; the measured average room temperature in bedroom 1 on that day is 32.7 °C, and the evaluated room temperature simulated by the software is 32.2 °C, with a deviation of 1.6%; the measured average room temperature in bedroom 2 on that day is 32.6 °C, and the evaluated room temperature simulated by the software is 31.8 °C, with a deviation of 2.5%. Thus, the deviations between the measured and simulated values of the main rooms on a typical winter day and summer day are within 5%, and the simulated data can accurately reflect the indoor thermal environment of the building.

4.2.2. Optimization of Indoor Ventilation and Lighting

Natural ventilation has an important effect on healthy indoor environments, especially in terms of cooling in the summer. Through the setting of window positions and the ratio of appropriate windows to walls, draughts will be formed as much as possible, which will have a positive effect on heat prevention in summer. The main problems of the existing plane are as follows: (1) the added building in the courtyard blocks bedroom 1; (2) the original window is a sliding window, and the ventilation area is only half of the window opening; (3) because of the privacy considerations of north bedroom 2 and the kitchen facing the street, small and high windows are set, so the rooms have poor indoor lighting and ventilation. In this work, the indoor and courtyard air environments of the first floor are simulated. The ventilation effect of the current situation is shown in Figure 16a. Poor ventilation in bedroom 1 can be found.

On the basis of the above current problems, simulations of single measures and combination measures are needed to verify the ventilation effect. In Case 1, only the added building in the courtyard is demolished to improve the ventilation and lighting conditions of bedroom 1. The ventilation effect is shown in Figure 16b. In Case 2, the sliding windows of the main rooms on the first floor are changed into case windows, which can be opened fully, and the ventilation effect is shown in Figure 16c. In Case 3, the north window areas of bedroom 2 and the kitchen (still the sliding window) are increased. Considering the privacy of the north street facing, the window height is set at more than 1500 mm. Combined with the limit of a 0.4 northbound window wall ratio for residential buildings in hot summers and cold winters [34], the northbound window wall ratio is increased to approximately 0.3, and the window sizes of bedroom 2 and the kitchen are increased from 1500 mm × 500 mm to 1500 mm × 1800 mm. The ventilation effect is shown in Figure 16d. Case 4: The combined measures of the above three cases and the ventilation effect are shown in Figure 16e. To facilitate a quantitative comparison,

Table 11. Average indoor wind speed (m/s).

	Living Room	Bedroom 1	Bedroom 2
Current situation	0.049	0.037	0.023
Case 1: Demolishing the added utility room	0.039	0.072	0.041
Case 2: Changing sliding window into casement window	0.087	0.039	0.032
Case 3: Expanding the north window area	0.049	0.035	0.028
Case 4: Combination of Case 1,2,3	0.067	0.102	0.034
Case 5: Combination of Case 1,2, and adding a staircase window	0.084	0.118	0.027

summarizes the average wind speed of the room under each condition. Case 1 has a certain impact on the ventilation of bedroom 1. Case 2 has a significant impact on the ventilation of the living room. Case 3 has little impact on the ventilation of the three main rooms. Case 4 (combined measures) has a great impact on the ventilation of the living room and bedroom 1, but does not form draught. On the basis of the ventilation analysis of the above cases, we add Case 5, that is, combining Cases 1 and 2, and add a stairwell window (1000 mm × 1500 mm, windows 900 mm high); the ventilation effect is shown in Figure 16f. The ventilation of the living room and bedroom 1 has significantly improved, and the ventilation from the living room door to the stairwell window and the kitchen and bedroom 2 have also improved to some extent. After a comprehensive analysis, the final ventilation optimization choice is determined to be Case 5.

To explore whether there is an impact on indoor lighting while improving indoor ventilation, the GBware software DALI 2022 is used to simulate the indoor lighting of the current situation and case 5. The simulation results of the lighting coefficient values are shown in Figure 17. The indoor lighting effect of bedroom 1 has significantly improved.

4.2.3. Optimization of the Thermal Insulation of the Envelope Structure

(1)

Wall

The above analysis reveals that although the insulation performance of the outer wall of the building is good and does not require excessive treatment, the temperature of the inner wall in winter is lower than the indoor temperature. A common measure is to add an insulation layer to the inner wall to improve the insulation performance of the wall. Although the internal insulation and external insulation of the wall in hot summer and cold winter areas can be used, and the insulation effect of external insulation is better than that of internal insulation, considering the economy and beauty of the wall, priority should be given to the use of paste EPS boards (expanded polystyrene boards) for interior insulation and light-color heat insulation coatings for indoor surfaces. Taking bedroom 1 as an example, the simulation results are shown in Figure 18. The addition of EPS boards has an obvious insulating effect in winter. The temperature difference before and after the transformation is approximately 2.3 °C, the heat insulation effect in summer is not obvious, and the temperature difference between the front and back is approximately 0.6 °C. The average daily temperature in summer is approximately 31.5 °C; the average temperature in winter is approximately 7.6 °C, which is close to the calculated temperature of 8 °C.

(2)

Roof and floor slab

According to the current simulation results, the average room temperature of each room on the second floor is approximately 5 °C higher than that on the first floor, the temperature fluctuation is obvious, and the southward closed balcony on the second floor is as high as 41 °C at 16 p.m. Due to the serious hollowing out of the resettlement area, more young and middle-aged people go out to work, the number of resettlement houses is mostly 1–3 people, the living room on the first floor and two bedrooms are used, and the rooms on the second floor are mostly idle. In addition, there is a lack of grain drying area in the resettlement area, and the second-floor room is mostly used for drying grains.

Therefore, considering the replacement of the actual use function of the second floor of the resettlement house, it is of little significance to adopt thermal insulation measures on the roof. Heat insulation measures should be adopted for the floor corresponding to the main rooms on the first floor to reduce the impact of the temperature on the second floor. The current structure of the second floor from top to bottom is a 10 mm floor tile + 15 mm polymer cement mortar + 100 mm cast-in-place reinforced concrete floor (the parameters of each material are shown in Table 7), with a general heat transfer coefficient of 4.360 W/m²·K. A single layer of 8 mm reinforced composite wood floor (with a thermal conductivity of 0.170 W/(m²·K)) should be added, and the general heat transfer coefficient of the renovated floor slab is K = 3.618 W/m²·K. Glass sliding doors can be added to the first-floor stairwell to reduce the air convection of the first and second floors through the open stairwell.

The above two measures are simulated using EnergyPlus. The additional wood floor in the living room and two bedrooms reduces the typical daily room temperature by 1.2 °C, and the winter room temperature increases by 0.5 °C, which has a certain effect on improving indoor thermal comfort, as shown in Figure 19. The glass sliding door in the stairwell does not significantly increase the room temperature in summer and winter; the average room temperature change in summer is only 0.3 °C, and the winter room temperature increases by 0.4 °C, as shown in Figure 20. Therefore, it is suggested that users with better conditions consider adding a composite wood floor on the second floor.

(3)

Doors, windows, and shading

According to the relevant provisions of the Code for Thermal Design of Civil Buildings (GB50176-2016) [33], the heat transfer coefficient limit of outer doors and windows in hot summers and cold winters region zone A is 3.5 W/(m²·K). The current outer window material is a 3 mm single-layer transparent glass and aluminum alloy window frame, and the heat transfer coefficient of the whole window is 6.6 W/(m²·K); the outer door of the living room is a single-layer iron door, and the heat transfer coefficient is 6.5 W/(m²·K), all of which exceed the limit. The outer window material should be changed to 6 mm transparent glass + 12 mm air + 6 mm transparent glass with a plastic window frame with a heat transfer coefficient of 2.8 W/(m²·K), and the single-layer iron gate should be changed to a double iron door with a heat transfer coefficient of 1.6 W/(m²·K). The simulation results in Figure 21 show that when the window material was changed, the temperature of the main rooms improved. Taking bedroom 1 as an example, the typical daily average daily air temperature in summer decreased by 0.7 °C, and that in winter increased by 0.5 °C. The replacement of the outer door did not or hardly change the typical average daily temperature in the living room either in winter or in summer.

The iron grille is set on the outside of the existing window, which has a certain anti-theft function and can be retained. A window net-screen is installed on the inside to block the insects. At the same time, priority is given to installing movable louver shading facilities on the outside. If fixed shading is used, it may not meet the needs when a large amount of sunlight is needed in winter and natural ventilation is needed in summer. The movable louver can be flexibly switched according to the needs at different times. Judging from the current situation, only movable sunshades need to be installed on the southern side of the living room.

4.3. Indoor Environment Renovation and Strategy Adjustment

4.3.1. Immigrant Acceptance of Indoor Environment Renovation Strategies

The results of the acceptance degree of each optimization strategy are shown in Figure 22. Approximately 60% of immigrants cannot accept the demolition of added buildings in the courtyard because this leads to the open-air placement of electric vehicles, farm tools, and firewood. However, if it is replaced by a canopy, 80% of immigrants are acceptable; more than 90% of immigrants believe that if natural ventilation indoors in summer can be improved, the new windows on the north side of the stairwell can be accepted, but anti-theft measures need to be taken; more than 80% of immigrants believe that if electricity bills can be saved, they can accept internal insulation of the wall, adding movable sunshades on the outside of the living room, and changing the window materials and forms; for adding laminate flooring on the second floor, more than 50% of immigrants think it is unacceptable and believe that there is no need to add wooden flooring because, in summer, they are used to wetting the floor on the second floor, opening the second-floor windows to increase ventilation and reduce the floor temperature through water evaporation; some immigrants also think that general wooden flooring with lower cost can be installed.

4.3.2. Adjustment of Indoor Environment Optimization Strategies

Through the above analysis, the optimization strategies for the light and heat environment of the surveyed building can be adjusted and summarized as follows:

(1)

Demolish the added utility room building in the courtyard, but a new space with at least a canopy is needed for parking electric vehicles, farm tools, and sundries;

(2)

Add a new 1000 mm × 1500 mm window on the north side of the stairwell to enhance summer ventilation;

(3)

Paste EPS board internal insulation in the main use rooms on the first floor, and simultaneously use light-colored thermal insulation coating for finishing;

(4)

Change the external window material to insulating glass of 6 mm transparent glass + 12 mm air + 6 mm transparent glass, a plastic window frame, and a casement window;

(5)

Add movable sunshades on the outside to the south of the living room;

(6)

Replace the second-floor floor slab corresponding to the main rooms with a single-layer ordinary wooden flooring (the cost is 25 yuan/square meter).

5. Outdoor Environment Optimization Strategies

The above text determined the renovation content as the indoor lighting and thermal environment and humanized design of the building through subjective satisfaction evaluation and objective on-site measurement, and proposed practical and feasible renovation strategies through software simulation. The strategies were finally adjusted and determined on the basis of the willingness of the immigrants. However, the outdoor environment in the resettlement area is also a part of the living environment, and in the IPA analysis of Section 3, the two outdoor environmental factors “Barrier-free design” and “Children’s playground” are in the secondary improvement zone (third quadrant). Therefore, this chapter explores the optimization strategies for the outdoor environment in the resettlement area.

5.1. Investigation of Immigrants’ Willingness

5.1.1. Public Space

Photographs of the village collective public space surveyed at the site are shown in Figure 23.

Table 12. The number of questionnaires in which various public space elements are mentioned in need.

Category	Outdoor Drying Site	Day-Care Facilities for the Elderly	Restaurant	Kindergarten	Shop	Quantity and Type of Fitness Equipment
Number of questionnaires that make the proposal	21	12	10	8	5	2

shows the number of questionnaires in which various public elements were mentioned in the field survey. “Your demand for public service facilities not provided in the resettlement area” is an open-ended question. Approximately 32 of the recovered questionnaires answered this question. The top three in terms of questionnaire quantity are “outdoor drying ground”, “daytime care facilities for the elderly”, and “restaurant”. More than half of the respondents thought that outdoor drying grounds should be set up. Although the living environment of immigrants has changed, their living habits have not changed. They are accustomed to growing grains and vegetables. Therefore, during the harvest season, grains need to be dried outdoors, and they often occupy public roads or squares, affecting normal traffic and public activities. Owing to the serious aging problem in resettlement areas as well as the existence of some disabled or semi-disabled elderly people, daytime care facilities for the elderly are also options with high demand in the resettlement area.

“What are your suggestions for the existing public service facilities in the resettlement area?” is also an open-ended question, and 24 people answered this question. The most frequently reflected issue is that the usage frequency of “sports venue” and “party-mass service center” is relatively low. The public sports venue in the surveyed resettlement area is a stage + basketball court. Owing to the prominent phenomenon of people going out to work, the traditional cultural customs of villagers have obviously disappeared. The red stage for performance has been idle for many years, and the basketball court is used only by a small number of pupils, lacking more abundant cultural facilities. The party–mass service center is normally an important indoor communication and activity place for villagers. However, owing to insufficient facilities and short opening hours, the service center in this village has been in a semi-neglected state for a long period of time.

5.1.2. Courtyard Space

During the investigation and interviews, it was found that old immigrants had the habit of raising poultry and livestock. However, in today’s resettlement area, owing to the narrow courtyard space and hygiene and odor issues, none of the households in the surveyed resettlement area raise poultry and livestock in the courtyard. However, immigrants have a relatively strong willingness in this regard.

More than 90% of the immigrants in the whole village have added a one-story bungalow in the courtyard space. The bungalow consists of two rooms. One is a utility room for parking agricultural machinery and sundries, and the other is a kitchen. Compared with urban residents, immigrants are more accustomed to using stoves to light fires and cook. Stoves can make better use of agricultural waste and are more economical than induction cookers. Adding a stove to the kitchen in the original building plan results in a smoke exhaust problem, so the original planned kitchen on the north side is usually idle. However, the added bungalow leads to insufficient ventilation and lighting in bedroom 1.

In addition, there is a row of east-west-oriented houses on the east side of the resettlement area (as shown in Figure 24). Because the main rooms (living room and second-floor bedroom) face west, the interior of the courtyard is relatively narrow, there are no trees to block it, and there are no sunshade measures for the building. There is a strong problem of overheating from the west sun in summer.

5.2. Design Strategies Based on Immigrants’ Willingness

5.2.1. Public Space Renovation Strategies

To fully meet the needs of immigrants, idle open spaces in the resettlement area should be used, and outdoor venues that conform to the production and living habits of immigrants, such as outdoor drying venues and outdoor communication venues, should be established. Moreover, multiple functions should be achieved in a composite way. For example, it is a drying venue during busy farming seasons and an outdoor communication venue during slack farming seasons. “One outdoor venue with multiple complex functions” is an effective way to solve the current problems of “single function, large land occupation, and difficult maintenance” in the resettlement area. The addition of necessary facilities for immigrants of different age groups to achieve equality in the configuration of public service facilities, such as daytime care facilities for elderly people and restaurants, is needed for the resettlement area.

5.2.2. Courtyard Space Renovation Strategies

To address the two issues of the inability to raise poultry and add buildings in courtyards, this article proposes the following optimization strategies.

First, owing to the need to raise poultry, the existing courtyard space is narrow and cannot meet this need in the courtyard. A centralized poultry-raising location for every five households in the resettlement area can be set up, and sanitary cleaning can be conducted in a timely manner.

Second, for courtyard additions. Combined with the above light and heat environment renovation strategy, the added kitchen in the courtyard can be retained, while the added utility room should be demolished and rebuilt on the west side of the courtyard gate. This approach is more convenient for placing agricultural machinery tools and vehicles without affecting dining and moving flows in the kitchen. The distance between the added building and the main building is changed from the original 280 mm to 3790 mm, which allows more lighting and ventilation for bedroom 1 without changing the living habits of the immigrants. As shown in Figure 25.

In addition, to address the problem of excessive west–west-oriented house types on the east side of the resettlement area, considering the narrow courtyard and the unsuitability of planting trees for shading, the installation of fixed or movable sunshades on the west side of the rooms can be considered.

6. Discussion

This paper proposes renovation strategies in combination with local immigrants’ wishes and spatial environment characteristics, which are helpful for local government public space renovations and spontaneous building environment renovations, help improve immigrants’ sense of gain and happiness, realize the optimal allocation of resources in the resettlement area, and provide a reference for the formulation of relevant policies for the follow-up support work of the South-to-North Water Diversion Project.

However, owing to professional and space limitations, the following limitations remain:

(1)

This article focuses only on the physical environment of buildings in resettlement areas, with insufficient attention given to other issues in immigrant resettlement areas.

(2)

With respect to the humanized design of the resettlement area, the research focuses on mixed age groups, and little attention has been given to the living needs of the elderly and children.

(3)

With respect to the outdoor environment of the resettlement area, renovation strategies were only proposed on the basis of the willingness of immigrants to renovate, without conducting indoor measurements and software simulations, such as indoor environments, to more objectively propose renovation strategies.

(4)

The selection of optimization strategies is based on local conventional materials, and no comparison of multiple material selections has been conducted.

Future work directions can be as follows:

(1)

The problems of the immigrant resettlement areas are diverse and complex, and relevant scholars should supplement the investigation and evaluation of social, economic, and political environments and propose relevant optimization suggestions to promote the healthy and sustainable development of resettlement areas.

(2)

Due to the large proportion of elderly individuals and children in the resettlement area, special research on elderly individuals and children should be conducted in the future.

(3)

Long-term monitoring of the outdoor environment in the resettlement area and evaluation of the comfort level of outdoor public spaces are needed to propose more practical and feasible outdoor environment renovation strategies.

(4)

In the future, various renovation strategies and material choices can be provided on the basis of the economic conditions and wishes of immigrants’ families.

7. Conclusions

This paper takes Yunyu New Village, a typical resettlement area of the Chinese South-to-North Water Diversion Project, as an example and evaluates the living environment of the resettlement area using IPA indicator analysis, on-site measurements, numerical simulations, and questionnaire surveys. According to the evaluation results, corresponding optimization strategies are proposed for both indoor and outdoor physical environments. The main findings are as follows:

(1)

Subjective satisfaction evaluation and IPA results revealed that winter heat preservation, summer heat insulation, the quality of domestic drinking water, the indoor natural light environment, humanized design, and building plan functions are factors in priority renovation areas and are the focus of the renovation of the living environment in the resettlement area.

(2)

On the basis of objective measured data and software simulation data and relevant specifications, the light and heat environments of the main use rooms of resettlement houses on typical days in winter and summer do not meet the energy-saving design standards for rural residential buildings in China, nor do they meet the indoor human thermal comfort environment requirements stipulated by the national standard.

(3)

Ventilation simulation reveals that demolishing the added utility room in the courtyard, changing sliding windows to casement windows, and adding a window in the staircase has a positive effect on the ventilation of the main used rooms on the first floor. It can form a cross breeze in the house. Moreover, the indoor light environment of the main bedroom also improved to a certain extent.

(4)

By comparing each strategy with the indoor thermal environment before and after renovation and the immigrants’ acceptance of the renovation strategy, the specific renovation strategy can be determined as follows: demolishing the added utility room, adding EPS boards for internal insulation of the main rooms, changing the window frame material and opening method, adding movable sunshades, and laying wooden flooring in some spaces on the second floor.

(5)

In terms of the outdoor space environment, after fully investigating the immigrants’ wishes, the determined renovation strategy is as follows: in public spaces, idle open spaces in the resettlement area are used to achieve multiple functions and realize the equalization of the configuration of public service facilities; in courtyard spaces, the utility room is moved to the west side of the gate, and livestock raising sites in the resettlement area are set up to meet the requirements of immigrants.