(The red font represents the calculated values for other projects, for reference only. Specific calculations should be recalculated and taken into account based on the actual project.)
Analysis of total annual runoff control within the site
1.1 Reference Values
| Content Name | Calculate numerical values | Runoff coefficient |
| Catchment area within the project site | two hundred and thirty-six thousand and three point five five | zero point six one |
| Green area (excluding sunken green spaces and shallow vegetation ditches) | one hundred and thirty-one thousand two hundred and twenty-one point three nine | zero point two zero |
| Concave green area | 0 | |
| Landscape water bodies | two thousand and fifty-four | one |
| Granite paving | 0 | |
| Anti corrosion wooden platform | 0 | |
| Plastic pavement | seventy-one thousand two hundred and sixteen point five six | zero point eight five |
| Gravel | 0 | |
| Ceramic permeable floor tiles | 0 | |
| Porous Asphalt | 0 | |
| permeable concrete | 0 | |
| Roof catchment area | thirty-three thousand five hundred and sixty-five point six | zero point nine zero |
The runoff coefficient values of relevant materials refer to the following table, and the data is sourced from the “Code for Design of Outdoor Water Supply and Drainage” GB50014 and the “Code for Design of Rainwater Control and Utilization Engineering” DB11/685.
The average runoff coefficient of the site:
Table 1-1 Runoff Coefficient
| Types of water collection surfaces | Rainfall runoff coefficient | Flow runoff coefficient PSI |
| Green roof (green roof, substrate layer thickness ≥ 300mm) | 0.30-0.40 | zero point four zero |
| Hard roof, flat roof without stones, asphalt roof | 0.80-0.90 | 0.85-0.95 |
| Flat roof paved with stones | 0.60-0.70 | zero point eight zero |
| Concrete or asphalt pavement and plaza | 0.80-0.90 | 0.85-0.95 |
| Large stones and other paving materials for roads and squares | 0.50-0.60 | 0.55-0.65 |
| Asphalt surface treated crushed stone pavement and plaza | 0.45-0.55 | 0.55-0.65 |
| Graded crushed stone pavement and plaza | zero point four zero | 0.40-0.50 |
| Dry masonry or gravel pavement and square | zero point four zero | 0.35-0.40 |
| Unpaved soil pavement | zero point three zero | 0.25-0.35 |
| greenland | zero point one five | 0.10-0.20 |
| surface of the water | one | one |
| Underground building covered with soil green space (covering soil thickness ≥ 500mm) | zero point one five | zero point two five |
| Underground building covered with soil green space (covering soil thickness<500mm) | 0.30-0.40 | zero point four zero |
| Permeable pavement | 0.08-0.45 | 0.08-0.45 |
| Sinking Square (once every 50 years or more) | – | 0.85-1.00 |
Note: The above data refers to the “Code for Design of Outdoor Drainage” (GB50014) and the “Code for Design of Rainwater Control and Utilization Engineering” (DB11/685)
1.2 Calculation Method
The calculation methods for rainfall control and annual runoff control within the project site refer to Chapter 9.4 of the “Jiangsu Province Green Building Design Standard” DGJ32/J 173-2014 Promotion and Green Building Technology Application Training on Rainwater Reuse and Infiltration Design.
1.3 Design controlled rainfall corresponding to the annual runoff total control rate
This project is located in Suqian City. In the calculation process, the design control rainfall parameters corresponding to the annual runoff total control rate used are based on the parameters of Nanjing City, and are taken from the “Green Building Evaluation Standard” GB/T 50378-2014, as shown in the table below:
| city | Annual rainfall （mm） | Design controlled rainfall corresponding to the annual runoff total control rate (mm) | ||
| 55％ | 70％ | 85％ | ||
| Hohhot | three hundred and ninety-six | seven point three | twelve | twenty-one point two |
| Jinan | six hundred and eighty | thirteen point eight | twenty-three point four | forty-one point three |
| Kunming | nine hundred and eighty-eight | nine point three | fifteen point six | twenty-five point nine |
| Lhasa | four hundred and forty-two | four point nine | seven point five | eleven point eight |
| Lanzhou | three hundred and eight | five point two | eight point two | fourteen |
| Nanchang | one thousand six hundred and nine | thirteen point five | twenty-one point eight | thirty-seven point four |
| Nanjing | one thousand and fifty-three | eleven point five | eighteen point nine | thirty-four point two |
| Nanning | one thousand three hundred and two | thirteen point two | twenty-two | thirty-eight point five |
| Shanghai | one thousand one hundred and fifty-eight | eleven point two | eighteen point five | thirty-three point two |
| Shenyang | six hundred and seventy-two | ten point five | seventeen | twenty-nine point one |
| Shijiazhuang | five hundred and nine | ten point one | seventeen point three | thirty-one point two |
| Taiyuan | four hundred and nineteen | seven point six | twelve point five | twenty-two point five |
| Tianjin | five hundred and forty | twelve point one | twenty point eight | thirty-eight point two |
| Urumqi | two hundred and eighty-two | four point two | six point nine | eleven point eight |
| Wuhan | one thousand three hundred and eight | fourteen point five | twenty-four | forty-two point three |
| Xi’an | five hundred and forty-three | seven point three | eleven point six | twenty |
| Xining | three hundred and eighty-six | four point seven | seven point four | twelve point two |
| Yinchuan | one hundred and eighty-four | five point two | eight point seven | fifteen point five |
| Zhengzhou | six hundred and thirty-three | eleven | eighteen point four | thirty-two point six |
Note: The statistical data in Table 1 is from 1977 to 2005.
The design control usage for other cities can refer to the values listed for similar cities. Or it can be determined through statistical calculations based on local data on southward migration.
(Note: There are currently no other reference requirements for the design control rainfall corresponding to the annual runoff total control rate of various cities and counties in Jiangsu Province. Referring to the design control rainfall requirements of Nanjing City, the design control re quantity corresponding to the 55% annual runoff total control rate is taken as 11 for the Suqian area.) The value is 5mm
1.4 Calculation process
1.4.1 Annual runoff total control rate target of 55%
| Design controlled rainfall (mm) | eleven point five zero |
| Design and control rainfall within the site (m ³) | two thousand seven hundred and fourteen |
| Rainfall control rate achieved through infiltration within the site | zero point four five |
| Rainfall control amount V1 (m ³) achieved through infiltration within the site | one thousand two hundred and twenty-one |
| Volume V2 (m ³) of sunken green space | zero |
| Effective storage capacity of landscape water bodies V3 (m ³) | two thousand and fifty-four |
| The volume of the rainwater recovery tank V4 (m ³) | two thousand and eight hundred |
| The controllable rainfall on the site is V=V1+V2+V3+V4 | six thousand and seventy-five |
| Does it meet the 55% target control rate | yes |
Therefore, this project can achieve an annual runoff control rate of 55% for the site.
Calculation of Water Consumption for Project 2
The water used in this project includes residential water, road and square watering, green irrigation, etc. Referring to the “Design Standard for Water Conservation of Civil Buildings” GB50555-2010 and relevant water use standards, combined with the climate conditions and building types in Nanjing, determine the water quota and calculate the water consumption of the project.
2.1 Domestic Water Use
According to Table 3.1 of the “Design Standard for Water Conservation of Civil Buildings” GB50555-2010 edition 1. Residential Evaluation Daily Domestic Water Conservation Quota Table, this project takes 160L/person · d, the school scale is 5334 people, and the annual water use days are 275 days, calculated according to the formula,
| The annual water-saving water consumption for residential use should be calculated according to the following formula: Qz – Water saving quota, selected according to the provisions of Table 3.1.1 (L/person · d); Nz – Number of residents, calculated at 3-5 people per household, with an occupancy rate of 60% to 80%; Dz – annual water usage days (d/a), which can be taken as Dz=365d/a. |
Annual water-saving water consumption for residential living in this project:
Q=160 × 5334 × 275/1000=234696m ³/a
2.2 Greening irrigation water
According to the “Design Standard for Water Conservation of Civil Buildings” GB50555-2010 edition, the annual irrigation quota for greening irrigation in this project is based on the first level maintenance of warm season type, taken as 0.28m ³/㎡· a, with a greening area of 131221.6 ㎡. Therefore, the annual irrigation water consumption is:
Q green=0.28 × 131221.6=36742.05m ³/a
2.3 Pouring Wine on Roads and Squares
According to the “Design Standard for Water Conservation of Civil Buildings” GB505552010 edition, the water quota for pouring on roads and squares can be calculated based on a pouring area of 0.2~0.5L/(m ². d). Based on the climate characteristics of Suqian and the actual situation of this project, the water quota for road and square watering is selected as 0.35L/m2 Secondly, the road surface is washed 30 times a year. The area of watering for the road square in this project is approximately 71216.56 square meters. The annual water consumption for watering the road square is calculated as follows:
Q road=0.35 × 71216.56 × 30/1000=747.77m ³/a
2.4 Statistical Results
According to the above calculation, the total water consumption of the project is summarized in Table 5.4.1
Table 5.4.1 Calculation of Water Consumption for This Project
| Water usage area | Quantity used | Company | Water quota | Water usage days d/a | Annual water consumption m ³/a | |
| quantity | Company | |||||
| domestic water | five thousand three hundred and thirty-four | people | one hundred and sixty | L/person · d | two hundred and seventy-five | two hundred and thirty-four thousand six hundred and ninety-six |
| Greening irrigation | one hundred and thirty-one thousand two hundred and twenty-one point six | ㎡ | zero point two eight | m³/㎡·a | / | thirty-six thousand seven hundred and forty-two point zero five |
| Road and square watering | seventy-one thousand two hundred and sixteen point five six | ㎡ | zero point three five | L/㎡· time | thirty | seven hundred and forty-seven point seven seven |
| No water usage was encountered (taking 10% of the total water usage) | twenty-seven thousand two hundred and eighteen point five eight | |||||
| total | two hundred and ninety-nine thousand four hundred and four point four | |||||
Table 2.1 Monthly Rainfall Data of Suqian from 2007 to 2016
| Year/Month | January | February | March | April | May | June | July | August | September | October | November | December |
| two thousand and sixteen | six | twenty-seven | twenty | twenty-nine | ninety-eight | two hundred and twenty | one hundred and thirty-two | one hundred and thirty-four | twenty | three hundred | sixteen | fifty-two |
| two thousand and fifteen | six | fourteen | thirty-six | forty-eight | thirty-five | one hundred and ninety-nine | fifty-three | sixty-two | one hundred | twenty-eight | one hundred and five | four |
| two thousand and fourteen | ten | thirty-nine | thirty-one | seventy-four | eighty-two | forty-six | one hundred and nine | one hundred and eighty-nine | two hundred and eleven | seventy-seven | fifty-five | one |
| two thousand and thirteen | thirteen | thirty-two | thirty | eight | one hundred and twenty-eight | thirty-eight | one hundred and sixty | sixty-seven | one hundred and seventy-three | three | twenty-seven | one |
| two thousand and twelve | 0 | six | sixty-eight | forty-two | six | one hundred and fourteen | two hundred and twenty-four | one hundred and seventy-four | two hundred and eight | two | forty | fifty-eight |
| two thousand and eleven | 0 | twenty-nine | fourteen | eleven | sixty-eight | sixty-two | two hundred and twenty-one | one hundred and sixty-three | forty-two | ten | fifty-five | thirty-three |
| two thousand and ten | 0 | sixty-eight | twenty-two | seventy-six | sixty-eight | twenty-four | one hundred and thirty-eight | one hundred and fifty-one | four hundred and eighty-two | four | 0 | eight |
| two thousand and nine | one | twenty-two | thirty-one | twenty-one | ninety-four | one hundred and thirty-six | one hundred and eighty | one hundred and forty-one | forty-five | seven | forty-five | twenty-five |
| two thousand and eight | thirty-three | three | nineteen | one hundred and ninety-five | one hundred and eight | one hundred and forty-two | four hundred and forty-seven | one hundred and forty | forty-eight | twenty-five | fourteen | eight |
| two thousand and seven | four | thirty-six | sixty-nine | thirty-one | sixty-three | one hundred and seven | four hundred and thirty-four | two hundred and fifty-eight | one hundred and ninety-five | thirty | eleven | twenty-three |
| average | seven | twenty-seven | thirty-four | fifty-three | seventy-five | one hundred and nine | two hundred and ten | one hundred and forty-eight | one hundred and fifty-two | forty-nine | thirty-seven | twenty-one |
Figure 7.1 Rainfall Statistics of Suqian City in the Past Decade (Average and Monthly Rainfall from 2007 to 2016)
Data source: from the Statistical Yearbook of Jiangsu Provincial Bureau of Statistics
(Note: According to the statistical yearbook of Jiangsu Provincial Bureau of Statistics and the local rainfall data in Suqian, the average annual rainfall is 918mm.)
From the above figure, it can be seen that the seasonal distribution of rainwater in Suqian City is uneven. Therefore, storing, treating, and recycling rainwater can effectively utilize water resources and reduce the amount of tap water used.
The non-traditional water source design water consumption for this project includes green irrigation water consumption, road and square watering water consumption, and landscape water consumption.
3. Analysis of non-traditional water sources that can be utilized
The collection scope of this project covers all catchment areas within the project site, so the amount of rainfall that can be collected in a single month is shown in the following table:
Table 3.1 Statistics of Collectable Rainwater Volume
| project | January | February | March | April | May | June | July | August | September | October | November | December | total |
| Average rainfall/mm | seven point four | twenty-seven point five | thirty-three point nine | fifty-three point five | seventy-four point nine | one hundred and seven point seven | two hundred and eight point seven | one hundred and forty-six point eight | one hundred and fifty-one point four | forty-eight point five | thirty-six point seven | twenty-one point two | nine hundred and eighteen |
| Roof green area ㎡ | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
| Normal roof area ㎡ | thirty-three thousand five hundred and sixty-five point six | thirty-three thousand five hundred and sixty-five point six | thirty-three thousand five hundred and sixty-five point six | thirty-three thousand five hundred and sixty-five point six | thirty-three thousand five hundred and sixty-five point six | thirty-three thousand five hundred and sixty-five point six | thirty-three thousand five hundred and sixty-five point six | thirty-three thousand five hundred and sixty-five point six | thirty-three thousand five hundred and sixty-five point six | thirty-three thousand five hundred and sixty-five point six | thirty-three thousand five hundred and sixty-five point six | thirty-three thousand five hundred and sixty-five point six | |
| Green catchment area ㎡ | one hundred and thirty-one thousand two hundred and twenty-one point three nine | one hundred and thirty-one thousand two hundred and twenty-one point three nine | one hundred and thirty-one thousand two hundred and twenty-one point three nine | one hundred and thirty-one thousand two hundred and twenty-one point three nine | one hundred and thirty-one thousand two hundred and twenty-one point three nine | one hundred and thirty-one thousand two hundred and twenty-one point three nine | one hundred and thirty-one thousand two hundred and twenty-one point three nine | one hundred and thirty-one thousand two hundred and twenty-one point three nine | one hundred and thirty-one thousand two hundred and twenty-one point three nine | one hundred and thirty-one thousand two hundred and twenty-one point three nine | one hundred and thirty-one thousand two hundred and twenty-one point three nine | one hundred and thirty-one thousand two hundred and twenty-one point three nine | |
| Road catchment area ㎡ | seventy-one thousand two hundred and sixteen point five six | seventy-one thousand two hundred and sixteen point five six | seventy-one thousand two hundred and sixteen point five six | seventy-one thousand two hundred and sixteen point five six | seventy-one thousand two hundred and sixteen point five six | seventy-one thousand two hundred and sixteen point five six | seventy-one thousand two hundred and sixteen point five six | seventy-one thousand two hundred and sixteen point five six | seventy-one thousand two hundred and sixteen point five six | seventy-one thousand two hundred and sixteen point five six | seventy-one thousand two hundred and sixteen point five six | seventy-one thousand two hundred and sixteen point five six | |
| Total rainfall/m ³ | one thousand and sixty-five | three thousand nine hundred and fifty-eight | four thousand eight hundred and eighty | seven thousand seven hundred and one | ten thousand seven hundred and eighty-two | fifteen thousand five hundred and four | thirty thousand and forty-four | twenty-one thousand one hundred and thirty-three | twenty-one thousand seven hundred and ninety-five | six thousand nine hundred and eighty-two | five thousand two hundred and eighty-three | three thousand and fifty-one | one hundred and thirty-two thousand one hundred and seventy-eight |
| Collectable rainwater volume m ³ | three hundred and thirty | one thousand two hundred and twenty-seven | one thousand five hundred and twelve | two thousand three hundred and eighty-seven | three thousand three hundred and forty-two | four thousand eight hundred and six | nine thousand three hundred and thirteen | six thousand five hundred and fifty-one | six thousand seven hundred and fifty-six | two thousand one hundred and sixty-four | one thousand six hundred and thirty-seven | nine hundred and forty-five | forty thousand nine hundred and seventy |
Table 3.2 Calculation of Monthly Water Consumption for Greening Irrigation and Road Square Sprinkling
| time interval | Greening irrigation | Road watering | Total water demand | ||||||
| Fixed value | Irrigation frequency | the measure of area | water consumption | Fixed value | Irrigation frequency | the measure of area | water consumption | ||
| m³/㎡ | second | ㎡ | m³ | L/㎡ | second | ㎡ | m³ | m³ | |
| January | one hundred and thirty-one thousand two hundred and twenty-one point three nine | 0 | zero point three five | one | seventy-one thousand two hundred and sixteen point five six | twenty-five | twenty-five | ||
| February | one hundred and thirty-one thousand two hundred and twenty-one point three nine | 0 | zero point three five | one | seventy-one thousand two hundred and sixteen point five six | twenty-five | twenty-five | ||
| March | one hundred and thirty-one thousand two hundred and twenty-one point three nine | 0 | zero point three five | two | seventy-one thousand two hundred and sixteen point five six | fifty | fifty | ||
| April | zero point zero two | one | one hundred and thirty-one thousand two hundred and twenty-one point three nine | two thousand six hundred and twenty-four | zero point three five | two | seventy-one thousand two hundred and sixteen point five six | fifty | two thousand six hundred and seventy-four |
| May | zero point zero two | three | one hundred and thirty-one thousand two hundred and twenty-one point three nine | seven thousand eight hundred and seventy-three | zero point three five | three | seventy-one thousand two hundred and sixteen point five six | seventy-five | seven thousand nine hundred and forty-eight |
| June | zero point zero two | two | one hundred and thirty-one thousand two hundred and twenty-one point three nine | five thousand two hundred and forty-eight | zero point three five | five | seventy-one thousand two hundred and sixteen point five six | one hundred and twenty-five | five thousand three hundred and seventy-three |
| July | zero point zero two | two | one hundred and thirty-one thousand two hundred and twenty-one point three nine | five thousand two hundred and forty-eight | zero point three five | five | seventy-one thousand two hundred and sixteen point five six | one hundred and twenty-five | five thousand three hundred and seventy-three |
| August | zero point zero two | two | one hundred and thirty-one thousand two hundred and twenty-one point three nine | five thousand two hundred and forty-eight | zero point three five | four | seventy-one thousand two hundred and sixteen point five six | one hundred | five thousand three hundred and forty-eight |
| September | zero point zero two | two | one hundred and thirty-one thousand two hundred and twenty-one point three nine | five thousand two hundred and forty-eight | zero point three five | three | seventy-one thousand two hundred and sixteen point five six | seventy-five | five thousand three hundred and twenty-three |
| October | zero point zero two | one | one hundred and thirty-one thousand two hundred and twenty-one point three nine | two thousand six hundred and twenty-four | zero point three five | two | seventy-one thousand two hundred and sixteen point five six | fifty | two thousand six hundred and seventy-four |
| November | zero point zero two | one | one hundred and thirty-one thousand two hundred and twenty-one point three nine | two thousand six hundred and twenty-four | zero point three five | one | seventy-one thousand two hundred and sixteen point five six | twenty-five | two thousand six hundred and forty-nine |
| December | one hundred and thirty-one thousand two hundred and twenty-one point three nine | 0 | zero point three five | one | seventy-one thousand two hundred and sixteen point five six | twenty-five | twenty-five | ||
| total | fourteen | thirty-five thousand seven hundred and thirty-seven | thirty | one thousand three hundred and fifty | thirty-seven thousand and eighty-seven | ||||
Table 3.3 Calculation of Monthly Water Replenishment for Landscape Water Bodies
| Monthly replenishment of landscape water bodies | |||||||||||||||||
| month | January | February | March | April | May | June | July | August | September | October | November | December | |||||
| Evaporation capacity (mm) | twenty-five | thirty-three point eight | fifty-four point nine | seventy-nine | one hundred and four point four | ninety-eight point five | one hundred and eight point five | one hundred and ten point one | ninety point four | seventy point nine | forty-six point nine | thirty-three point two | |||||
| Landscape water area (㎡) | two thousand and fifty-four | two thousand and fifty-four | two thousand and fifty-four | two thousand and fifty-four | two thousand and fifty-four | two thousand and fifty-four | two thousand and fifty-four | two thousand and fifty-four | two thousand and fifty-four | two thousand and fifty-four | two thousand and fifty-four | two thousand and fifty-four | |||||
| Water replenishment required (m ³) | fifty-one point three five | sixty-nine point four three | one hundred and twelve point seven six | one hundred and sixty-two point two seven | two hundred and fourteen point four four | two hundred and two point three two | two hundred and twenty-two point eight six | two hundred and twenty-six point one five | one hundred and eighty-five point six eight | one hundred and forty-five point six three | ninety-six point three three | sixty-eight point one nine | |||||
| Total amount of water to be replenished (m ³) | one thousand seven hundred and fifty-seven point four one | ||||||||||||||||
Table 3.4 Monthly Water Balance Calculation Table
| month | January | February | March | April | May | June | July | August | September | October | November | December | total |
| Rainwater demand for greening irrigation m ³ | 0 | 0 | 0 | two thousand six hundred and twenty-four | seven thousand eight hundred and seventy-three | five thousand two hundred and forty-eight | five thousand two hundred and forty-eight | five thousand two hundred and forty-eight | five thousand two hundred and forty-eight | two thousand six hundred and twenty-four | two thousand six hundred and twenty-four | 0 | thirty-five thousand seven hundred and thirty-seven |
| The amount of rainwater required for road watering is m ³ | twenty-five | twenty-five | fifty | fifty | seventy-five | one hundred and twenty-five | one hundred and twenty-five | one hundred | seventy-five | fifty | twenty-five | twenty-five | one thousand three hundred and fifty |
| The amount of rainwater required for flushing the toilet is m ³ | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Landscape water replenishment m ³ | fifty-one point three five | sixty-nine point four three | one hundred and twelve point seven six | one hundred and sixty-two point two seven | two hundred and fourteen point four four | two hundred and two point three two | two hundred and twenty-two point eight six | two hundred and twenty-six point one five | one hundred and eighty-five point six eight | one hundred and forty-five point six three | ninety-six point three three | sixty-eight point one nine | one thousand seven hundred and fifty-seven |
| Total required rainfall volume m ³ | seventy-six point three five | ninety-four point four three | one hundred and sixty-two point seven six | two thousand eight hundred and thirty-six point two seven | eight thousand one hundred and sixty-two point four four | five thousand five hundred and seventy-five point three two | five thousand five hundred and ninety-five point eight six | five thousand five hundred and seventy-four point one five | five thousand five hundred and eight point six eight | two thousand eight hundred and nineteen point six three | two thousand five hundred and sixty-five point three three | ninety-three point one nine | thirty-nine thousand two hundred and forty-four |
| Collectable rainfall m ³ | three hundred and thirty | one thousand two hundred and twenty-seven | one thousand five hundred and twelve | two thousand three hundred and eighty-seven | three thousand three hundred and forty-two | four thousand eight hundred and six | nine thousand three hundred and thirteen | six thousand five hundred and fifty-one | six thousand seven hundred and fifty-six | two thousand one hundred and sixty-four | one thousand six hundred and thirty-seven | nine hundred and forty-five | forty thousand nine hundred and seventy |
| Profit and loss m ³ | two hundred and fifty-three point six five | one thousand one hundred and thirty-two point five seven | one thousand three hundred and forty-nine point two four | -449.27 | -4820.44 | -769.32 | three thousand seven hundred and seventeen point one four | nine hundred and seventy-six point eight five | one thousand two hundred and forty-seven point three two | -655.63 | -928.33 | eight hundred and fifty-one point eight one | one thousand seven hundred and twenty-six |
| Actual utilization of rainwater volume m ³ | seventy-six point three five | ninety-four point four three | one hundred and sixty-two point seven six | two thousand three hundred and eighty-seven | three thousand three hundred and forty-two | four thousand eight hundred and six | five thousand five hundred and ninety-five point eight six | five thousand five hundred and seventy-four point one five | five thousand five hundred and eight point six eight | two thousand one hundred and sixty-four | one thousand six hundred and thirty-seven | ninety-three point one nine | thirty-one thousand four hundred and forty-one |
| The required amount of tap water replenishment is m ³ | zero | zero | zero | four hundred and forty-nine point two seven | four thousand eight hundred and twenty point four four | seven hundred and sixty-nine point three two | zero | zero | zero | six hundred and fifty-five point six three | nine hundred and twenty-eight point three three | zero | seven thousand six hundred and twenty-three |
The rainwater reuse system of this project can collect more rainwater annually than the annual usage. Except for April, May, June, October, and November when tap water is needed for replenishment, rainwater is used for greening sprinkler irrigation, road and square flushing, and landscape replenishment in all other months. The amount of tap water needed for April, May, June, October, and November is 449.27m ³, 4820.44m ³, 769.32m ³, 655.63m ³, and 928.33m ³. The amount of rainwater that can be collected is 2387m ³, 3342m ³, 4806m ³, 2164m ³, and 1637m ³. The required amount of rainwater is 2836.27m ³, 8162.44m ³, 5575.32m ³, 2819.63m ³, and 2565.33m ³, all of which are used for green sprinkler irrigation, road and square flushing, and landscape water replenishment. The tap water replenishment is used to meet all the water needs for road and square flushing in April, May, June, October, and November, as well as some green irrigation water needs. Therefore, the total amount of non-traditional water sources used for green irrigation throughout the year is 36742.05-449.27-4820.44-769.32-655.63-928.33=29119.06m ³. According to previous calculations, the total annual water consumption (without cooling water replenishment and excluding outdoor landscape water replenishment) is 299404m ³, The utilization rate of non-traditional water sources is 29119.06/299404=9.7%. This project does not have municipal recycled water supply, therefore, according to the non-traditional water source utilization measures for outdoor greening irrigation calculation, it meets the requirement of 4%, in accordance with section 6 of the “Green Building Evaluation Standard” GB/T 50378-2014 According to Article 2.10, 5 points can be awarded.
4. Calculation of rainwater collection tank capacity
Method 1:
Assuming that the volume of the rainwater recovery tank is calculated based on the amount of rainwater that can be reused for 5 days.
| Water usage area | Quantity used | Company | Water quota | Water usage days | Water consumption m ³ | |
| quantity | Company | |||||
| Greening irrigation | one hundred and thirty-one thousand two hundred and twenty-one | ㎡ | two | L/㎡·d | 5 days | one thousand three hundred and twelve point two one |
| Road and square watering | seventy-one thousand two hundred and sixteen | ㎡ | two | L/㎡·d | 5 days | seven hundred and twelve point one six |
| Landscape hydration | 0 | ㎡ | / | 0 | ||
| Bathroom water consumption (10% of total water consumption) | two hundred and two point four three seven | |||||
| total | two thousand two hundred and twenty-six point eight | |||||
From an economic perspective, as this project can undertake some of the rainwater regulation and storage functions, and after calculation, it has already achieved a site rainwater runoff control rate of 55%.
According to the “Code for Rainwater Collection and Utilization Engineering in Residential Areas” GB50400-2006, if the capacity of the reservoir is determined, the daily water consumption for green sprinkler irrigation is 1312.21m ³, and the daily water consumption for road sprinkler irrigation is 712.16m ³. The total daily water consumption is about 2226.8m ³. Based on the frequency of rainfall and the duration of drought, the effective capacity of the rainwater storage tank is calculated based on the amount of stored and reused rainwater for 5 days: V=2226.8m ³. Considering the amount of water wasted during normal use, as well as the PP rainwater collection module’s volume ratio (98%), evaporation rate, and water loss, the total volume of the collection tank is determined to be V=2800 m ³. The specific location and dimensions are shown in the drawing scheme. In the rainwater recovery equipment of this project, the reservoir is designed to be 2800m ³, which meets the requirements.
Method 2:
According to the requirements of the relevant departments for the construction of sponge cities in Shuyang, a rainwater storage capacity of 100m ³ is required for every 1 hectare. For this project, which covers approximately 23.6 hectares, a rainwater collection and storage tank of approximately 2360m ³ is needed for rainwater storage. The design of the reservoir for this project is 2800m ³>2360m ³, which meets relevant regulations.
