Research on mathematical quantitative model of the incremental cost and income of green small towns based on the whole life cycle
Publicado en línea: 16 ago 2022
Páginas: 1013 - 1022
Recibido: 13 nov 2021
Aceptado: 15 may 2022
DOI: https://doi.org/10.2478/amns.2021.2.00211
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© 2022 Ran Zou et al., published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 International License.
China is a big country with a population of 1.3 billion people, most of whom live in the rural areas. Because of its continuous economic development, the country has made some huge strides in the field of urban construction. In 2015, the urbanisation rate of Chinese permanent residents was 56.10%, up by 1.33 percentage points from the previous year. By 2020, the rate of urbanisation reached 60% [1]. In the face of economic, resource and environmental constraints, green and low-carbon new urbanisation roads have become unavoidable in China's urbanisation process.
Several studies on greening of small towns have been conducted in recent years. Jin Hong et al. [1] investigated Sanjiang Dong Autonomous County in Liuzhou; Guangxi focused on the core green industries in small towns from the perspective of global tourism, optimised its spatial structure quantitatively and qualitatively, and conducted research and proposed appropriate optimisation strategies; Chen Jun [2] drew on his experience of the urban ecological industry system of construction in Switzerland to make recommendations for the development of green small towns in Guizhou, China; Shen Mingrui et al. [3] concentrated on the current development of ecological small towns and problems associated with green transformation, and analysed and anticipated the future development of small towns; Liu Xiaoping [4] provided a brief analysis of the importance of implementing sustainable green buildings into urban construction, as well as tips on how to develop green buildings; Yue Dan [5] proposed green small town development ideas based on the field and literature research on small towns in Anyang County, Henan Province; and Bai Tao et al. [6] created the sustainable development evaluation index system of green ecological small towns by thoroughly studying the sustainable development theory and ecological theory. According to existing research analysis, a number of research results have been achieved in green small town evaluation, green small town building technology and green small town life-cycle economics, particularly in China's green building technology and green building projects. The economy has been thoroughly studied, and a quantitative economic evaluation method and evaluation system have been developed, which are primarily used for project technical selection and optimisation. However, only general and macro countermeasures are proposed from theoretical analysis for the development strategies and suggestions for green small towns, while they are rarely analysed from the perspective of quantifying the incremental cost and benefit of green small towns throughout their life cycle.
Small towns located between urban and rural areas are given special consideration. To summarise, different disciplines can have a narrow and broad understanding of the concept of ‘small town’. In China, small towns refer to towns other than municipalities directly under the Central Government, including county towns. This concept is more in line with the legal meaning of the People's Republic of China's Urban Planning Law. A town is the political, economic, cultural and life service centre of a rural area. In China, small towns in the broad sense include market towns, while in the narrow sense it includes county towns and organic towns. A market town is an unorganised town in which the people's government of a township or ethnic township is located, which has been confirmed by the people's government at the county level and has evolved from a market to a regional economic, cultural and life service centre in the rural areas. Small towns, in general, emphasise the dynamic and rural nature of their development, which is a relatively common viewpoint in the field of small towns research in China.
Small towns are the frontier of rural development, as well as the source of material and human support for urban development. The China Urban Science Research Association's ‘Green Small Town Evaluation Criteria’ provides a clear definition of green small towns as follows: ‘Scientific planning based on local conditions, a reasonable industrial model, intensive resource and energy conservation, environmental protection, complete functions, liveable and suitable for business, and distinguishing features’, highlight the construction of material civilisation, spiritual civilisation and ecological civilisation, and realise the sustainable development of small towns [7]. The Evaluation Standard for Green Small Towns, published in March 2015, established a scientific system for the development of green small towns that is tailored to China's specific needs. It proposes a comprehensive index system for ecological planning and construction, industrial planning and construction, small town planning and construction, heritage preservation, architectural and site design, energy planning and utilisation, water-saving and water resource utilisation, solid waste treatment and resource utilisation, and management and publicity. Table 1 displays the weight indicators for nine different aspects [8].
Index weight table of evaluation standards for green small towns
| Ecological planning and construction | 0.39 |
| Industrial planning | 0.26 |
| Planning and construction of small towns | 0.27 |
| Heritage protection | 0.10 |
| Architectural design and site design | 0.39 |
| Energy planning and utilisation | 0.20 |
| Water saving and water resources utilisation | 0.14 |
| Solid waste treatment and resource utilisation | 0.13 |
| Management and publicity | 0.12 |
Gubeikou in Beijing, Daqiuzhuang in Tianjin, Haiyu in Jiangsu, Sanhe in Anhui, Guankou in Fujian, Xijiao in Guangdong and Mudong in Chongqing were the seven towns that won the national honorary title of ‘green low carbon key small towns’ in September 2011. After 3 years of construction, certain accomplishments have been achieved in town and village construction, green building, green traffic, comprehensive environmental improvement, infrastructure construction and other areas.
At the moment, the main technologies used in the construction of green small towns in China include four aspects: ecological planning and land-intensive use; energy-saving and renewable energy use; water-saving and water resource utilisation; solid waste treatment; and resource utilisation. According to the current state of affairs in China, energy conservation and emission reduction are the most pressing tasks they face. Energy conservation is an important part of creating a resource-saving society, and it is the energy-using field with the greatest potential for energy conservation, so it has become the focus of energy conservation efforts. At the same time, China's total freshwater resources are relatively small, accounting for only 6% of the global total, and placing it among the 13 water-scarce countries. The per capita water resources is only 2,200 m2, accounting for one-quarter of the world's per capita water resources, with an extremely uneven spatial and temporal distribution. The scarcity of water resources and the worsening of water pollution have become major factors affecting China's long-term development. The Chinese energy-saving technology needs to focus on developing energy-saving and renewable energy use as well as water-saving and water resource use in green cities and towns, so this is an important aspect for the development of Chinese energy-saving technology.
With the incremental cost and incremental income of green small towns clarified, and developing the whole life cost-benefit quantitative model of green small towns using the Xiuyuanhe Green Ecological City in Zhangqiu, Shandong Province and the Lujiayao immigration project in Hongsibao, Ningxia Province as examples, this article calculates the economic performance of the whole life period, and the evaluation structure is used for green small town policy research.
The incremental cost of building technology in green small towns refers to the additional investment costs incurred in project planning, design, construction and transportation, replacement and maintenance, operation and management, and other aspects to achieve specific green goals and adopt building technology measures [9].
It is divided into two parts based on the different payment times: the initial investment cost and the later investment cost.
First, we consider the initial investment. The use of energy-saving and renewable energy utilisation technologies, water-saving, and water resource utilisation technologies will raise the project's initial investment cost, primarily due to the increased initial investment in the building envelope energy-saving, solar hot water system, reclaimed water system and rainwater system. For green small towns, the most effective way to improve the energy-saving performance of the building enclosure is to increase the thickness of the enclosure insulation layer and use the entire window heat transfer coefficient of less than 2.8 W/m2·K outer window to achieve energy savings of 65% for residential buildings and 50% for public buildings. The initial investment cost of energy conservation of the building enclosure is the increased insulation thickness and the use of high-performance doors and windows. Because traditional small towns do not have a small town solar hot water system, reclaimed water system or rainwater system, the one-time investment in the equipment and pipelines of the said systems becomes the increased initial investment cost.
The second factor is the investment cost at a later stage. This primarily includes the costs of operation, maintenance, repair and replacement. To make the building envelope energy efficient, the solar hot water system, reclaimed water system and rainwater system in normal operation during the building's 50-year use period, the system requires daily costs of operation, maintenance and repair. As systems and equipment may not last for more than 50 years, this also means that the project's replacement costs will rise.
As a result, the incremental cost of small towns over their entire life cycle is calculated as follows: =
The economic, environmental and social benefits of green building technology are referred to as the ‘incremental benefits of green small town building technology’. Economic income is direct, whereas social and environmental income is indirect. That is the beneficial impact of green small towns on society and the environment, other than the owners. The incremental income of green small town construction technology includes economic income during operation, environmental income from a reduction in air pollution, health benefit to residents and social income saved by municipal facilities, which is as follows:
The economic income generated by the resources and energy saved after the completion and operation of green small
As China primarily relies on thermal power plants that use coal as a fuel source for power generation, the operation of green small towns saves a significant amount of electricity. It can also reduce the consumption of fossil fuels, which means that CO2, SO2, NO
In China, pollution can cause a variety of diseases. Green small towns use less energy on a daily basis and therefore PM10 and PM2.5 emissions are correspondingly reduced. Furthermore, as the incidence of respiratory diseases decreases, so do the medical expenses of the people. As a result, this paper considers the economic benefits of PM10 and PM2. 5 reducing emissions in green small towns as a means of providing health and social benefits,
The construction cost of municipal sewage facilities is reduced as a result of green small towns’ outstanding performance in saving water and energy. It enables to avoid social losses, save a significant amount of electricity, reduce the country's power investment and avoid economic losses caused by a lack of electricity. As a result, municipal facility investment scale reduction is caused by water and electricity savings as its social benefits of municipal facility saving,
The cost-effectiveness ratio is the ratio of project cost to benefit, which can reflect the project's rate of return on investment. The cost-effectiveness index was used in this paper to assess the economics of green small town buildings over their entire life cycle. To further refine the economics of the various return methods, the following formula is used to calculate the cost-effect ratio of direct and indirect returns:
The Ningxia Ecological Migration Project was launched by the state to improve the quality of life of the people in the ancient area of Xihai in Ningxia. Wuzhong City's Hongsibao District is a national key ecological resettlement project that has relocated and resettled nearly 200,000 poor people.
The Lujiayao Project in Hongsibao District, Ningxia, has a total of 2,194 households, a total land area of 2.15 km2 and a residential construction area of 118,800 m2. The residential building unit is a two-family, single-sloping roof with a slope of 23° with a 108 m2 floor-area and a 54 m2 household area [13,14,15,16]. The project's energy saving and solar energy-utilisation technologies primarily include enclosure energy-saving and solar domestic hot water systems. The details of its technical design are given below [17,18,19,20,21].
The exterior wall is made of 240-mm thick porous brick, with external insulation made of 50-mm thick XPS insulation board and a heat transfer coefficient of 0.611 W/m2·K. Each of the two walls has a total insulation area of 120.2 m2. Furthermore, the roof surface is reinforced concrete tile, with external insulation of 90-mm thick XPS insulation board and a heat transfer coefficient of 0.464 W/m2·K. Each of the two roofs has a total insulation area of 121.6 m2. The outer window is a PVC-framed hollow glass window with a heat transfer coefficient of 2.7 W/m2·K and a surface area of 17.72 m2 per two outdoor windows.
Solar energy will be used in the project to provide domestic hot water for residential buildings. Their system is made up of a vacuum pipe collector, a hot water storage tank, a hot water pipe and an auxiliary heat source. Water consumption for four people is 120 L/d. As a result, the system's average daily water consumption
Table 2 shows the incremental cost and income of energy saving and solar energy utilisation technology.
Incremental cost and income of energy saving and solar energy utilisation technology of Ningxia Project (Unit: 10,000 yuan)
| Energy saving of enclosure structure | 2.43 × 103 | 2.36 × 104 | 9.25 × 103 | 1.43 × 104 |
| Solar photothermal system | 1.27 × 103 | 4.44 × 103 | 1.56 × 103 | 2.88 × 103 |
| Energy-saving and solar energy utilisation technology | 3.70 × 103 | 2.80 × 104 | 1.08 × 104 | 1.72 × 104 |
Table 3 shows the incremental cost-benefit analysis of energy conservation and solar energy utilisation technologies.
Incremental cost-benefit evaluation of Energy Saving and Solar Energy Utilisation of Ningxia Project
| Building envelope energy saving | 9.71 | 3.81 | 5.88 |
| Solar hot water system | 3.50 | 1.23 | 2.27 |
| Energy-saving and solar energy utilisation technology | 7.57 | 2.92 | 4.65 |
Zhangqiu Shuyuan River Green Ecological City was designated as a Shandong Provincial Green Ecological Demonstration City in 2015, with a total urban area of 23.75 km2 and a starting area of 3.04 km2. Special planning for the architecture, transportation, energy and municipal administration of the Xiuyuan River green eco-city area in Zhangqiu City was carried out under the guidance of the overall positioning of ‘a wealthy, harmonious, and happy new Zhangqiu under the framework of Jinan's big city’, combined with the planning and design strategies of the eco-city area. Design, and then accomplish the ecologicalisation and greening of the entire urban area. The surface water in the area comes from the Bayan River's Embroidery Source section, of which Mingshui Lake is 125 ha. The water resource utilisation technology used in the green ecological urban area of Zhangqiu Shuyuan River aims to regulate storage and reduce emissions. They also use non-traditional water sources like rainwater and reclaimed water to increase the utilisation rate of non-traditional water resources. The daily water consumption and reclaimed water treatment facilities of the entire urban residential building shall be reasonably planned in accordance with the project's goal of a water utilisation rate greater than 30%. Figure 1 depicts the specific planning. Given the safety of indoor water in residential buildings and people's acceptance of reclaimed water, reclaimed water is primarily used in residential communities for greening water, road square flushing, landscape water replenishment and car flushing, but not for building toilet flushing. The project will use a reclaimed water station with a contact oxidation treatment process and a daily reclaimed water treatment capacity as
Fig. 1
Schematic diagram of the distribution of water treatment groups in the Green Ecological City of Zhangqiu Shuyuan River
The incremental cost and incremental income is as shown in Table 4.
Incremental cost and incremental income
| Reclaimed water system | 3.17 × 103 | 8.73 × 103 | 8.6 × 103 | 1.3 × 102 |
| Rainwater system | 2.09 × 103 | 9.38 × 103 | 9.25 × 103 | 1.3 × 102 |
| Water resources utilisation | 5.26 × 104 | 1.82 × 104 | 1.79 × 104 | 2.6 × 102 |
The cost-earnings evaluation is as shown in Table 5.
Cost-earnings evaluation
| Water system | 2.75 | 2.71 | 0.04 |
| Rainwater system | 4.49 | 4.43 | 0.06 |
| Water resources utilisation | 3.46 | 3.40 | 0.05 |
According to the evaluation results, the overall investment in green small towns in Ningxia's Hongsibao District increased by 37 million yuan, with an average increase of 17,000 yuan per household. Among them, the envelope structure's energy savings account for approximately 66%, and the new direct economic benefit is 108 million yuan, which is the incremental cost of the entire life cycle. This is a significant burden for immigrants who have a low annual per capita income. Despite the fact that the project may provide direct economic benefits to migrants in the subsequent operation process, the cost-effect ratio of direct income over 50 years is 2.92. Similarly, the investment income is substantial. Green small towns, on the other hand, have the flaws of high initial investment and long recovery cycle, which will severely limit their development. Zhangqiu green small towns in Shandong Province have increased their overall investment by 526 million yuan. The cost-effectiveness ratio of construction technology over the entire life cycle of the green small town within 50 years is 3.46, and the cost-effectiveness ratio of direct benefit is 3.40, both of which are higher than the cost-effectiveness ratio of the green small town in Hongsibao District, Ningxia. Their cost-effect ratio for direct economic income over the next 50 years is 3.46. However, there are issues with the project's large initial investment and slow income recovery.
The Ningxia green small town project, on the other hand, has a significant externality. The total income of their project environment and social income is 172 million yuan. The indirect return cost and effect ratio for Ningxia is 4.65, which is 1.6 times the direct income. Furthermore, Zhangqiu's green small town project has a positive externality, but its project environment and social income is only 2.6 million yuan, or 1.5% of the direct economic income. As the voice of social and public interest, the government benefits from increased investment in green small towns, and may even be the winner of the largest interests.
We can conclude the following from the preceding analyses:
First, the entire life economy of green construction technology in small towns differs.
Green small town construction technologies have varying life-cycle economics. Using Ningxia as an example, the direct benefit cost-benefit ratio of building maintenance structure energy saving is the highest, followed by energy saving and solar energy utilisation technology, while the solar water heating system has the lowest direct benefit cost-benefit ratio. It can be seen that, in terms of cost-effectiveness, the development of energy-saving technologies for building envelopes is more conducive to promotion for the Ningxia project, whereas the development of rainwater systems is more economical for the Zhangqiu project. At the same time, the cost-benefit ratio of the Ningxia project's energy-saving and solar energy utilisation technologies is 2.18 times that of the Zhangqiu project's water resource utilisation technologies. In terms of cost-benefit analysis, current green building energy-saving technology is more cost-effective and easier to promote than water-saving technology.
Second, as a beneficiary of green small towns, the government should promote their development and address the issue of initial investment by small town construction owners. As a result, the government must implement an incentive mechanism to encourage the development of green small towns. Furthermore, direct economic support to green small towns is provided in the form of direct capital subsidies, tax preferential treatment, building supporting fee reductions or preferential treatment, and a portion of the burden of increased investment is due to the use of green building technology.
Finally, the indirect income of building energy-saving technology is far greater than the direct income, implying that the environment, society and government have benefitted more than the occupants. As a result, the key point of promoting building energy conservation technology in green small towns is to carry out policy promotion from the standpoint of government fund incentives. Residents are the primary beneficiaries of water-saving technology in green towns, and its promotion should focus on expanding residents’ direct benefits from the perspective of stepped water prices.