Method for calculating carbon emission in production process of precast beam field

Abstract

The invention provides a precast beam field production process carbon emission calculation method, and relates to the technical field of carbon emission calculation, and the method comprises the steps: combing construction production carbon emission sources, and determining a carbon emission quantification accepting and rejecting criterion based on the complexity, importance and contribution degree of the carbon emission sources; determining a time boundary, a space boundary and an emission source boundary; constructing a prefabricated beam field construction production carbon emission chemical index system comprising a first-level index, a second-level index and a third-level index; analyzing internal characteristics and adaptive scenes of existing energy and material carbon emission factors, correcting and optimizing carbon emission factors of fossil energy, electric power and outsourcing materials by combining an energy structure, regional electric power characteristics and precast beam field building material use characteristics, and establishing an emission factor library; calculating the total carbon emission in the production process of the precast beam field by adopting an emission factor method; the total carbon emission is corrected; the data quality can be improved, and the calculation accuracy is guaranteed; accounting benchmarks are unified, and the problem of result difference is solved.

Description

Technical Field

[0001] This invention relates to the field of carbon emission calculation technology, and in particular to a method for calculating carbon emissions during the production process of a precast beam yard. Background Technology

[0002] Bridge construction is characterized by long construction periods and large scale. The significant energy and resource consumption during construction generates substantial carbon emissions, making it a key management aspect of the construction industry's low-carbon transformation. Currently, although the construction industry has established a quantitative system centered on carbon emission factors based on the "Building Carbon Emission Calculation Standard," several bottlenecks remain in the quantitative research of carbon emissions from highway bridge construction and the specific calculations for precast beam yards. These are as follows: Inconsistent Boundary Delineation and Accounting Systems: Existing research and practice show significant differences in the division of construction stages and the definition of carbon emission accounting boundaries for bridge engineering. There is no unified standard for the composition of carbon emissions within the boundaries, and there is a lack of standardized boundary delineation criteria and statistical accounting systems. This results in poor comparability and large differences in the carbon emission quantification results of different projects, making it impossible to form a unified assessment benchmark for the industry.

[0003] Insufficient adaptability of emission factors: The carbon emission quantification of bridge construction mostly adopts emission factors in the IPCC guidelines or other industry standards, without fully considering my country's energy structure (such as the differences in the proportion of thermal power generation in regional power structures and the characteristics of fossil energy consumption) and the characteristics of building material production processes. In addition, the carbon emission inventory data is of low quality and cannot truly reflect the actual carbon emission level of bridge construction in my country.

[0004] Data quality and source deficiencies: The quantification of carbon emissions throughout the life cycle is limited by a lack of data. Existing studies mostly rely on engineering budget tables to determine the engineering quantities rather than on actual construction statistics. At the same time, special studies on precast beam yards have problems such as ambiguous boundary division, insufficient fine-grained unit division, and non-standard collection of activity data, which further reduce the accuracy of carbon emission calculations.

[0005] The lack of a dedicated indicator system for precast beam yards: The exploration of carbon emission quantification for precast beam yards in the highway industry is still in its early stages. A unified standard carbon emission accounting indicator system has not yet been established, and the calculation process is cumbersome and cannot meet the needs of large-scale accounting in the industry. This seriously restricts the research and development of low-carbon construction technology for bridge engineering and the accurate formulation and implementation of carbon management policies. Summary of the Invention

[0006] To address the aforementioned technical problems, the technical solution adopted by this invention is as follows: According to a first aspect of this application, a method for calculating carbon emissions during the production process of a precast beam yard is provided, the method comprising the following steps: S100 takes the precast beam yard production process as the calculation object, takes the consumption of raw materials, fossil energy and electricity as the core line, sorts out the carbon emission sources of construction and production, and determines the carbon emission quantification and trade-off criteria based on the complexity, importance and contribution of carbon emission sources. S200 clearly defines time boundaries, spatial boundaries, and emission source boundaries; S300, based on the identified carbon emission sources and defined boundaries, constructs a quantitative indicator system for carbon emissions from precast beam yard construction and production, including primary, secondary, and tertiary indicators. S400 collects activity data during the precast beam yard production process and uses preset data quality inspection and screening methods to verify the validity of the collected activity data; S500 analyzes the inherent characteristics and applicable scenarios of carbon emission factors of existing energy and materials, and combines the energy structure, regional power characteristics and the characteristics of building materials used in precast beam yards to correct and optimize the carbon emission factors of fossil energy, electricity and purchased materials, and establish an emission factor database. S600, using the emission factor method, calculates the total carbon emissions of the precast beam yard production process based on the activity data verified in step S400 and the emission factor library established in step S500. S700 adjusts the total carbon emissions based on the impact of equipment performance degradation and changes in energy structure on carbon emissions.

[0007] Furthermore, the time boundary mentioned in step S200 is: from the completion of the precast beam yard construction and the start of production of the first beam, until the last beam is shipped out of the factory, excluding the construction and demolition of the precast beam yard.

[0008] Furthermore, the spatial boundary mentioned in step S200 is: the production area, office area, and living area within the red line of the precast beam yard, as well as the production and transportation area for purchased raw materials from the production site / procurement site to the precast beam yard.

[0009] Furthermore, the emission source boundary mentioned in step S200 is: raw materials, transportation of raw materials and finished beams, energy, and construction machinery, excluding activities with small carbon emission proportions and difficult data acquisition, such as personnel accommodation, commuting, catering, and equipment maintenance.

[0010] Furthermore, the primary indicators of the quantitative indicator system described in step S300 include: the production and processing of raw materials, the transportation of materials to the processing plant, and the off-site processing of raw materials; Secondary indicators include: sand and gravel production and processing, cement production and processing, steel production and processing, asphalt production and processing, cement transportation, sand and gravel transportation, steel bar transportation, concrete mixing, steel bar processing, steel bar transportation, T-beam prefabrication, etc. The third-level indicators are the specific equipment or vehicles corresponding to the second-level indicators, including sand and gravel production and processing equipment, cement transport vehicles, concrete mixing plants, AC arc welding machines, etc.

[0011] Furthermore, the sources of activity data collection in step S400 include: On-site data collection: construction plan, construction records, construction log, including material types and quantities, equipment usage, and project progress; Statistical data: Monthly / quarterly / annual material and energy consumption statistics forms provided by the Materials and Equipment Department of the construction project; Automatic data collection: Data collected in real time by IoT devices.

[0012] Furthermore, the rules for modifying and selecting the carbon emission factor in step S500 include: Fossil fuel carbon emission factor: Based on the carbon oxidation rate and carbon emission conversion factor provided by the IPCC, combined with a preset formula for calculating the average lower heating value of energy sources: E i =A i ×Q i ×∂×44 / 12; Among them, E i Let A be the CO2 emission coefficient of the i-th type of fossil energy; i Q is the carbon emission conversion factor for the i-th type of fossil energy; i is the average lower heating value of the i-th type of fossil energy; ∂ is the oxidation factor of the i-th type of fossil energy. Electricity carbon emission factor: The latest regional power grid emission factor published by the Ministry of Ecology and Environment was selected and determined according to the region where the project is located; Carbon emission factor for purchased materials: Only major materials accounting for 95% of the total quality of bridge engineering are included. Cement carbon emissions are calculated based on clinker production and energy consumption. Steel carbon emissions are calculated based on blast furnace-converter process classification. Sand, gravel, asphalt, etc. are determined according to preset industry correction factors. Priority for selecting emission factors: measurement / mass-energy balance emission factors > regional emission factors > national emission factors > international emission factors.

[0013] Furthermore, the formula for calculating the total carbon emissions in step S600 is: Total carbon emissions E 总 =E 材料 +E 能源 +E 运输 ; Material carbon emissions E 材料 =∑(material consumption × material unit conversion factor × material carbon emission factor). Energy carbon emissions E 能源 =∑(Energy type consumption × Energy type unit conversion factor × Energy type combustion process carbon emission factor). Transportation carbon emissions E 运输 =∑(Carbon emission coefficient of transport vehicle × Material mass × Transport distance).

[0014] Furthermore, the correction index mentioned in step S700 includes: Equipment performance degradation correction: The carbon emissions from electricity and fossil fuels caused by the aging of mechanical equipment are calculated based on an annual increase of 5%; Energy structure change correction: The latest provincial power grid emission factor is adopted every year, and the carbon emissions corresponding to the electricity saved by the use of renewable energy sources such as photovoltaic, wind power and ground source heat pumps in the precast beam yard are deducted.

[0015] Furthermore, among the purchased materials, the carbon emission factor of sand and gravel is 0.002 kg CO2 / kg, that of petroleum asphalt is 2.513 kg CO2 / kg, that of modified asphalt is 2.634 kg CO2 / kg, that of mineral powder is 0.007 kg CO2 / kg, that of C30 concrete is 246.3 kg CO2 / m³, that of C40 concrete is 307.15 kg CO2 / m³, and that of C50 concrete is 365.03 kg CO2 / m³.

[0016] The present invention has at least the following beneficial effects: Unified accounting benchmark to solve the problem of inconsistent results: By clarifying the time, space and emission source boundaries of carbon emission calculation for precast beam yards, a clear hierarchical quantitative indicator system is constructed, filling the gap in the industry's exclusive accounting standards for precast beam yards. This effectively solves the problem of large differences in quantitative results for different projects caused by unclear boundaries and missing indicators in existing studies, and provides a unified benchmark for large-scale carbon emission statistics in the industry.

[0017] Improving data quality and ensuring calculation accuracy: An innovative multi-source activity data acquisition model of "on-site collection + statistical forms + automatic collection via the Internet of Things" is proposed, along with a data quality inspection method, avoiding the drawbacks of traditional reliance on engineering budget forms; at the same time, emission factors are modified according to my country's energy structure and regional characteristics, which greatly improves the adaptability of activity data and emission factors, and the accuracy of calculation results is more than 30% higher than that of traditional methods.

[0018] Dynamically adapting to changes and ensuring long-term effectiveness: The introduction of dual correction indicators for equipment performance degradation and changes in energy structure not only takes into account the actual impact of mechanical equipment aging, but also aligns with the trend of annual reduction in grid emission factors and promotion of renewable energy. This allows carbon emission calculation results to dynamically adapt to the long-term production process and avoids the accumulation of errors caused by static calculations.

[0019] Supporting low-carbon development and empowering policy and technology research and development: The accurate carbon emission data calculated by this method can directly provide a targeted basis for the research and development of low-carbon construction technologies for bridge engineering (such as the selection of low-energy machinery and the application of renewable energy); at the same time, the unified accounting system can provide data support for government departments to formulate carbon management policies (such as carbon quota standards for precast beam yards), and promote the transformation of the bridge industry from "passive emission reduction" to "precise carbon control". Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A flowchart illustrating the carbon emission calculation method for the precast beam yard production process provided in this embodiment of the invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that, based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Furthermore, this device and / or practice the method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.

[0024] The following will refer to Figure 1 The flowchart shown illustrates a method for calculating carbon emissions during the precast beam yard production process, introducing such a method.

[0025] The method for calculating carbon emissions during the precast beam yard production process may include the following steps: S100 takes the precast beam yard production process as the calculation object, takes the consumption of raw materials, fossil energy and electricity as the core line, sorts out the carbon emission sources of construction production, and determines the carbon emission quantification and trade-off criteria based on the complexity, importance and contribution of carbon emission sources.

[0026] In this embodiment, the implementation details of step S100 are as follows: Clearly define the calculation object and core line: The calculation object is strictly limited to the production process of the precast beam yard, focusing on the entire production process of precast components such as T-beams from raw material input to finished beam delivery, without involving the construction, demolition and subsequent bridge installation of the beam yard.

[0027] The core storyline revolves around three key types of consumption: Raw material consumption: covers core raw materials for precast beams, including steel (for steel cage fabrication), cement, sand and gravel, water (for concrete preparation), and asphalt (for auxiliary building materials).

[0028] Fossil energy consumption includes diesel, gasoline, and natural gas used in construction machinery (such as rebar bending machines and mixing plants), as well as diesel consumed by backup generators.

[0029] Electricity consumption: covering electricity consumption for production equipment (intelligent tensioning equipment, steam curing room), office and living facilities, and IoT monitoring equipment.

[0030] Systematically analyze the carbon emission sources of construction and production: Based on the precast beam production process (mold preparation → steel bar processing → concrete mixing → pouring and curing → finished product transportation), the carbon source is broken down step by step: Raw material side: Implicit carbon emissions from raw material mining (such as sand and gravel mining) and production (such as cement clinker burning and steel blast furnace smelting).

[0031] Energy sector: Direct / indirect carbon emissions from fossil fuel combustion (mechanical power) and electricity consumption (equipment operation); Transportation side: Carbon emissions from the transportation of raw materials from the production / procurement site to the beam yard (such as cement transport trucks for cement) and the transportation of finished beams from the beam yard to the construction site (such as beam transport trucks).

[0032] Machinery side: Energy consumption and carbon emissions associated with the operation of various construction machinery (such as concrete mixing plants and gantry cranes).

[0033] Determine the criteria for quantifying carbon emissions: Based on a three-dimensional assessment of carbon sources—complexity, importance, and contribution—selection rules are established: The following are included in the quantification scope: carbon sources in core production processes (raw material production / transportation, material processing, casting and curing, finished product transportation). These carbon sources have clear boundaries (e.g., there are clear vehicle and distance records for raw material transportation), belong to activities directly related to production (affecting the core process of precast beam production), and have a high contribution to carbon emissions (accounting for more than 90% of total emissions).

[0034] Excluded from the scope of quantification: Carbon sources for auxiliary activities (personnel accommodation, commuting, catering, equipment maintenance). These carbon sources have complex boundaries (such as multiple items in commuting services), are difficult to obtain data (there is no unified statistical form), have low contribution (accounting for less than 5%), and have unclear allocation rules (such as maintenance costs cannot be accurately allocated to a single production line).

[0035] Corresponding beneficial effects: Focus on core carbon sources and reduce computational redundancy: By using selection criteria to exclude auxiliary carbon sources with low contribution and high complexity, irrelevant data interference is avoided, reducing computational workload while ensuring that computational resources are concentrated on key emission links.

[0036] Standardize the statistical criteria for carbon sources: Clarify the definition of carbon sources in "core production links", solve the problem of chaotic carbon source composition in existing studies, and lay a unified foundation for subsequent boundary delineation and indicator construction.

[0037] S200 clearly defines time boundaries, spatial boundaries, and emission source boundaries.

[0038] Furthermore, the time boundary mentioned in step S200 is: from the completion of the precast beam yard construction and the start of production of the first beam, until the last beam is shipped out of the factory, excluding the construction and demolition of the precast beam yard.

[0039] Furthermore, the spatial boundary mentioned in step S200 is: the production area, office area, and living area within the red line of the precast beam yard, as well as the production and transportation area for purchased raw materials from the production site / procurement site to the precast beam yard.

[0040] Furthermore, the emission source boundary mentioned in step S200 is: raw materials, transportation of raw materials and finished beams, energy, and construction machinery, excluding activities with small carbon emission proportions and difficult data acquisition, such as personnel accommodation, commuting, catering, and equipment maintenance.

[0041] In this embodiment, the implementation details of step S200 are as follows: 1. Time Boundaries: Locking in the "Entire Production Cycle" Starting point: The precast beam yard is completed and put into operation, marked by the production of the first beam (e.g., the start time of processing the first T-beam steel cage).

[0042] Termination Node: The last finished beam is transported out of the factory area by a beam-carrying truck, as per the "Finished Beam Factory Acceptance Record".

[0043] Exclusion Scope: The construction phase of the beam yard (such as site leveling and factory building construction) and the demolition phase (such as equipment dismantling and site restoration) are explicitly excluded, as these two phases belong to the "beam yard life cycle" rather than the "precast beam production process" and are unrelated to the core production activities.

[0044] 2. Spatial Boundaries: Covering the "Entire Chain of Related Areas" On-site area: All functional areas within the site boundary of the precast beam yard, including production areas (steel processing workshop, concrete mixing area, curing room, beam storage area), office areas (project office building), and living areas (staff dormitory, canteen). Energy consumption (such as office electricity) and material storage (such as sand and gravel silos) in these areas are directly related to production.

[0045] Off-site related areas: The area covered by the transportation route of purchased raw materials from the "production site / procurement site" to the "precast beam yard" (such as the road transportation route of cement from the cement plant to the beam yard), and the raw material production site (such as the smelting workshop of the steel plant). Since the carbon emissions from the production and transportation of raw materials are a key component of the "implicit carbon" of precast beams, they must be included in the spatial boundaries.

[0046] 3. Emission source boundaries: Clearly define the "four core sources". Raw materials: Steel, cement, sand and gravel, asphalt and other main raw materials for precast beams (accounting for more than 95% of the total material weight).

[0047] Transportation: Raw material transportation (cement trucks, dump trucks, trailers), finished beam transportation (tire-mounted beam transport vehicles).

[0048] Energy: Fossil fuels (diesel, gasoline, natural gas), electricity (electricity for production, office and daily life).

[0049] Construction machinery: equipment covering the entire production process (steel processing center equipment, concrete preparation equipment, formwork system, prestressing equipment, curing equipment, lifting and handling equipment, etc.).

[0050] Exclusions: Electricity for personnel accommodation, fuel consumption for commuter vehicles, spare parts for equipment maintenance (such as welding machine parts), etc., for the same reasons as the S100 selection criteria.

[0051] Corresponding beneficial effects: Addressing boundary discrepancies: Clearly defining the three-dimensional boundaries breaks through the dilemma of "vague stage divisions and arbitrary spatial ranges" in existing studies (such as some studies only calculating emissions within the site and ignoring raw material transportation), making the carbon emission calculation results of different precast beam yards comparable across different regions.

[0052] To avoid “missed or duplicated calculations at the boundary”: for example, clearly include the raw material production location in the spatial boundary to avoid omitting “implicit carbon”; exclude the beam yard construction phase to avoid duplicate statistics with “carbon emissions during the construction phase” and ensure the accuracy of the calculation scope.

[0053] S300, based on the identified carbon emission sources and defined boundaries, constructs a quantitative indicator system for carbon emissions from precast beam yard construction and production, including primary, secondary, and tertiary indicators.

[0054] Furthermore, the primary indicators of the quantitative indicator system described in step S300 include: the production and processing of raw materials, the transportation of materials to the processing plant, and the off-site processing of raw materials; Secondary indicators include: sand and gravel production and processing, cement production and processing, steel production and processing, asphalt production and processing, cement transportation, sand and gravel transportation, steel bar transportation, concrete mixing, steel bar processing, steel bar transportation, T-beam prefabrication, etc. The third-level indicators are the specific equipment or vehicles corresponding to the second-level indicators, including sand and gravel production and processing equipment, cement transport vehicles, concrete mixing plants, AC arc welding machines, etc.

[0055] In this embodiment, a hierarchical system of "first-level indicators - second-level indicators - third-level indicators" is constructed based on "carbon sources identified in S100" and "boundaries defined in S200". Each level of indicator is directly related to the production process and equipment / vehicles, as shown in Table 1. Table 1 The design logic of the indicators is as follows: the first-level indicators correspond to the "core line of S100" (raw materials, transportation, and processing), the second-level indicators break down the specific links of the first-level indicators, and the third-level indicators are implemented as "statistically quantifiable and monitorable" equipment or vehicles, ensuring that each indicator can be linked to specific carbon emission activities (such as S9 concrete mixing plant corresponding to electricity consumption carbon emissions).

[0056] Corresponding beneficial effects: To address the issue of "insufficient granularity in unit segmentation": the three-level indicators are precise down to "equipment / vehicles," avoiding the drawbacks of traditional indicators that are "too macroscopic" (such as only counting "mechanical carbon emissions"). They can pinpoint specific carbon emission links (such as the abnormal carbon emissions of a certain mixing plant), providing a targeted basis for subsequent low-carbon transformation.

[0057] Unified accounting indicator standards: The system covers the entire process of precast beam production, filling the gap in the industry's exclusive indicator system for precast beam yards, and enabling carbon emission data from different projects to be statistically analyzed and compared using the same indicators.

[0058] S400 collects activity data during the precast beam yard production process and uses preset data quality inspection and screening methods to verify the validity of the collected activity data.

[0059] Furthermore, the sources of activity data collection in step S400 include: On-site data collection: construction plan, construction records, construction log, including material types and quantities, equipment usage, and project progress; Statistical data: Monthly / quarterly / annual material and energy consumption statistics forms provided by the Materials and Equipment Department of the construction project; Automatic data collection: Data collected in real time by IoT devices.

[0060] In this embodiment, data is collected from three dimensions, focusing on the "three-level indicators of S300," to ensure the comprehensiveness and authenticity of the data: On-site data collection: provided by the construction team, including the "Construction Log" (recording the daily amount of steel reinforcement processing, concrete pouring, and machinery running time), the "Material Arrival Acceptance Form" (recording the quantity of cement and steel arriving on site, and the production / purchase location), and the "Equipment Operation Record" (recording the start-up and shutdown time of the gantry crane and the mixing plant, and energy consumption data).

[0061] Statistical data: provided by the Materials and Equipment Department of the construction project, including the "Monthly Material Consumption Report" (which counts the monthly consumption of sand, gravel and cement by material type), the "Monthly Energy Consumption Report" (which counts the monthly consumption of diesel, gasoline and electricity by energy type), and the "Quarterly Transportation Ledger" (which records the type of vehicle used for transporting raw materials, the transportation distance, and the quality of the materials).

[0062] Automatic data collection: Data is acquired in real time through IoT devices, including electricity meters (recording the real-time electricity consumption of the mixing plant and curing room), water meters (recording the water consumption for concrete mixing), tower crane / gantry crane timers (recording the actual running time of the equipment), and unattended weighbridge systems (recording the quality of raw materials entering the site).

[0063] Preset data quality inspection and screening methods: To ensure data validity, a "three-stage review and screening" mechanism has been established: First-level integrity check: Check if the data is missing (e.g., whether the "transportation distance" field is missing in the "transportation ledger"), and filter out data with more than 2 missing items.

[0064] Secondary review consistency: cross-validate multi-source data (such as whether the steel reinforcement processing volume recorded in the "Construction Log" is consistent with the steel reinforcement consumption volume in the "Monthly Material Consumption Report", with an allowable error range of ±5%), and filter out data with errors exceeding the standard.

[0065] The third verification of authenticity involves checking whether the data conforms to the actual production logic (e.g., the daily operating time of a steel bar bending machine cannot exceed 24 hours, and abnormal data is filtered out), and correcting deviations in manual recording by combining real-time IoT data (e.g., electricity meter data).

[0066] Corresponding beneficial effects: Improve data quality and solve the problem of "low data accuracy": cross-validation of multi-source data avoids the drawbacks of the traditional "relying solely on the project budget table" (the budget table may deviate from the actual consumption by 10%-20%), and the data verification mechanism eliminates invalid data, thereby improving the accuracy of activity data by more than 30%.

[0067] Achieve data traceability: Each data point has a clear source (such as IoT devices or work team records). If carbon emission results need to be verified later, they can be traced back to the original data, enhancing the credibility of the calculation results.

[0068] S500 analyzes the inherent characteristics and applicable scenarios of carbon emission factors of existing energy and materials. Combining the energy structure, regional power characteristics and the characteristics of building materials used in precast beam yards, it corrects and optimizes the carbon emission factors of fossil energy, electricity and purchased materials, and establishes an emission factor database.

[0069] Furthermore, the rules for modifying and selecting the carbon emission factor in step S500 include: Fossil fuel carbon emission factor: Based on the carbon oxidation rate and carbon emission conversion factor provided by the IPCC, combined with a preset formula for calculating the average lower heating value of energy sources: E i =A i ×Q i ×∂×44 / 12; Among them, E i Let A be the CO2 emission coefficient of the i-th type of fossil energy; i Q is the carbon emission conversion factor for the i-th type of fossil energy; i is the average lower heating value of the i-th type of fossil energy; ∂ is the oxidation factor of the i-th type of fossil energy. Electricity carbon emission factor: The latest regional power grid emission factor published by the Ministry of Ecology and Environment was selected and determined according to the region where the project is located; Carbon emission factor for purchased materials: Only major materials accounting for 95% of the total quality of bridge engineering are included. Cement carbon emissions are calculated based on clinker production and energy consumption. Steel carbon emissions are calculated based on blast furnace-converter process classification. Sand, gravel, asphalt, etc. are determined according to preset industry correction factors. Priority for selecting emission factors: measurement / mass-energy balance emission factors > regional emission factors > national emission factors > international emission factors.

[0070] Furthermore, among the purchased materials, the carbon emission factor of sand and gravel is 0.002 kg CO2 / kg, that of petroleum asphalt is 2.513 kg CO2 / kg, that of modified asphalt is 2.634 kg CO2 / kg, that of mineral powder is 0.007 kg CO2 / kg, that of C30 concrete is 246.3 kg CO2 / m³, that of C40 concrete is 307.15 kg CO2 / m³, and that of C50 concrete is 365.03 kg CO2 / m³.

[0071] In this embodiment, the implementation details of step S500 are as follows: 1. Fossil Energy Carbon Emission Factor: Corrected Based on my country's Energy Characteristics Correction basis: Based on the "carbon oxidation rate and carbon emission conversion factor" provided by the IPCC, and combined with the "average lower heating value" of energy in my country's "General Rules for Calculating Integrated Energy Consumption", the correction is made using formula E. i =A i ×Q i Calculate the correction factor using ×∂×44 / 12.

[0072] For example: Diesel: A i =20.2kgC / GJ, Q i =42705kJ / kg (i.e., 42.705MJ / kg), ∂ = 0.98, substituting into the formula, we get E i =20.2×42.705×0.98×(44 / 12)≈3.10kgCO2 / kg.

[0073] Natural gas: A i =15.3 kgC / GJ, Q i =38979kJ / m³, ∂=0.99, and Ei≈2.16kgCO2 / m³.

[0074] Unit conversion: Clarify that the density of gasoline is 0.75 kg / L and the density of diesel is 0.84 kg / L to avoid calculation errors caused by unit confusion (such as directly calculating "liter" as "kilogram").

[0075] 2. Electricity carbon emission factors: Optimized based on regional characteristics Selection Principle: Discard the "national unified power grid factor" and select the latest provincial power grid emission factor published by the Ministry of Ecology and Environment (due to the large differences in regional power structure in my country, such as the high proportion of hydropower in Yunnan, the factor is 0.146 kgCO2 / kWh; and the high proportion of thermal power in Hebei, the factor is 1.092 kgCO2 / kWh).

[0076] Update mechanism: The latest provincial factors are updated annually according to the latest data released by the Ministry of Ecology and Environment to ensure the timeliness of the factors (e.g., if the Guangdong factor is 0.695 in 2020, and it is updated to 0.65 in 2025, then 0.65 will be used for calculation).

[0077] 3. Carbon emission factors of purchased materials: Focusing on core materials and classifying them accordingly. Selection criteria: Only major materials accounting for 95% of the total quality of bridge engineering are included, while minor auxiliary materials (such as a small amount of anti-rust coatings) are excluded.

[0078] Categorized calculation: Cement: Calculated by type (PI52.5 cement 0.768 kg CO2 / kg, PO42.5 cement 0.675 kg CO2 / kg), including the total carbon emissions from clinker production (e.g., PO42.5 clinker accounts for 83%, corresponding to carbon emissions of 0.436 kg CO2 / kg) and energy consumption (coal consumption 0.118 kg / kg, electricity consumption 0.121 kWh / kg).

[0079] Steel: Classified by process (large steel 3.744 kg CO2 / kg, medium and small steel 3.003 kg CO2 / kg), based on energy consumption data of blast furnace-converter steelmaking process (e.g., unit energy consumption of large steel 57265 kJ / kg).

[0080] Other materials: sand and gravel 0.002 kg CO2 / kg, petroleum asphalt 2.513 kg CO2 / kg, C30 concrete 246.3 kg CO2 / m³, C50 concrete 365.03 kg CO2 / m³.

[0081] 4. Prioritize the selection of emission factors: Ensure accuracy The priority should follow the order of "measured / mass-energy balance emission factor > regional emission factor > national emission factor > international emission factor". If a beam yard has its own monitored natural gas emission factor (measured factor) for the mixing plant, then that factor should be used first, rather than the regional or national factor.

[0082] 5. Establish an emission factor database The modified and optimized factors are stored in categories such as "Fossil Energy - Electricity - Purchased Materials", and the source of the factors is marked (e.g., "Diesel factor comes from IPCC modification + "General Rules for Comprehensive Energy Consumption Calculation"), the applicable region (e.g., "Yunnan Power Grid Factor"), and the update time (e.g., "2020 Provincial Factor"), so that they can be called in step S600.

[0083] Corresponding beneficial effects: To address the issue of "insufficient factor adaptability": the revised fossil energy factors, regionalized electricity factors, and categorized material factors are more in line with my country's energy structure (e.g., higher factors for regions with a high proportion of thermal power) and the characteristics of precast beam yard building materials than directly applying IPCC international factors, thus improving factor accuracy by more than 40%.

[0084] Achieve standardized factor management: The factor library is uniformly stored, and its source and timeliness are labeled to avoid "chaotic factor selection" in different projects (such as some using IPCC diesel factors and others using domestic standard factors), and to provide a unified factor benchmark for large-scale accounting in the industry.

[0085] S600 uses the emission factor method to calculate the total carbon emissions of the precast beam yard production process based on the activity data verified in step S400 and the emission factor library established in step S500.

[0086] Furthermore, the formula for calculating the total carbon emissions in step S600 is: Total carbon emissions E 总 =E 材料 +E 能源 +E 运输 ; Material carbon emissions E 材料 =∑(material consumption × material unit conversion factor × material carbon emission factor). Energy carbon emissions E 能源 =∑(Energy type consumption × Energy type unit conversion factor × Energy type combustion process carbon emission factor). Transportation carbon emissions E 运输 =∑(Carbon emission coefficient of transport vehicle × Material mass × Transport distance).

[0087] In this embodiment, the implementation details of step S600 are as follows: 1. Core calculation method: Emission factor method Based on the emission factor method proposed by the IPCC, the core principle is E=AD×EF (E is carbon emissions, AD is the validated activity data, and EF is the optimized emission factor). Combining this with the carbon emission composition of precast beam yards, the total emissions are broken down into three parts: "material carbon emissions, energy carbon emissions, and transportation carbon emissions." The overall formula is: E 总 =E 材料 +E 能源 +E 运输 .

[0088] 2. Implementation of itemized calculations Carbon emissions from materials (E) 材料 For each type of purchased material, the total carbon emissions are calculated by summing the results of "consumption amount × unit conversion factor × material carbon emission factor".

[0089] Example: A beam yard uses 1000t (1,000,000 kg) of PO42.5 cement. The unit conversion factor is 1 (material unit is kg, factor unit is kgCO2 / kg), and the material factor is 0.675 kgCO2 / kg. Then, the E of this cement is... 材料 =1,000,000×1×0.675=675,000kgCO2 (i.e. 675tCO2).

[0090] Energy carbon emissions (E) 能源 For each type of energy source, the total energy carbon emissions are calculated by summing the results of "consumption × unit conversion factor × carbon emission factor of combustion process".

[0091] Example: A beam yard uses 5000L of diesel fuel. The density of diesel fuel is 0.84kg / L (unit conversion factor), and the diesel fuel factor is 3.10kgCO2 / kg. Then, the E of this diesel fuel is... 能源 =5000×0.84×3.10=13,020kgCO2 (i.e. 13.02tCO2).

[0092] Carbon emissions from transportation (E) 运输 For each type of material, the total carbon emissions are calculated by summing the carbon emission coefficient of the transport vehicle × the mass of the material × the transport distance.

[0093] Example: A beam yard transports 1000t of PO42.5 cement from a cement plant using cement trucks (vehicle factor calculated based on diesel consumption, assumed to be 0.05kgCO2 / (t・km)). The transport distance is 50km. What is the energy efficiency (E) of this transport? 运输 =0.05×1000×50=2500kgCO2 (i.e. 2.5tCO2).

[0094] 3. Summary of Calculation Results E 材料 E 能源 E 运输 The calculation results are summed to obtain the total carbon emissions of the precast beam yard production process; at the same time, the carbon emission data of each sub-item and each material / energy / transportation link are retained to form a three-level calculation result table of "total emissions - sub-items - links", which facilitates the identification of major emission sources (such as E 材料 If it accounts for 60%, then raw materials are the core emission reduction link.

[0095] Corresponding beneficial effects The calculation logic is clear and the results can be broken down: the itemized calculation makes the total emissions results traceable to specific links (such as a certain type of material or a certain type of energy), which makes it easier for beam yards to identify "high-carbon links" (such as concrete mixing, which has a high proportion of energy carbon emissions, so the energy consumption of the mixing plant can be optimized in a targeted manner), and provides direction for the application of low-carbon technologies.

[0096] In line with industry accounting practices: The emission factor method is the mainstream accounting method in the construction industry (as recommended by the "Building Carbon Emission Calculation Standard"). The calculation results are easily recognized by the industry and can be directly used for project carbon reports and carbon verification.

[0097] S700 adjusts the total carbon emissions based on the impact of equipment performance degradation and changes in energy structure on carbon emissions.

[0098] Furthermore, the correction index mentioned in step S700 includes: Equipment performance degradation correction: The carbon emissions from electricity and fossil fuels caused by the aging of mechanical equipment are calculated based on an annual increase of 5%; Energy structure change correction: The latest provincial power grid emission factor is adopted every year, and the carbon emissions corresponding to the electricity saved by the use of renewable energy sources such as photovoltaic, wind power and ground source heat pumps in the precast beam yard are deducted.

[0099] In this embodiment, the total carbon emissions in step S600 are corrected for two dynamic factors during the precast beam yard production process: "equipment aging" and "changes in energy structure," to ensure the accuracy of long-term calculation results.

[0100] 1. Equipment performance degradation correction Correction basis: As the usage time increases, various construction machinery (such as rebar bending machines and mixing plants) will experience problems such as component wear and efficiency decline, resulting in increased energy consumption per unit output.

[0101] Correction method: Based on the "year of commissioning" of the machinery and equipment, the annual carbon emissions from the original energy source (E) are adjusted accordingly. 能源 The formula is: E_energy after adjustment = E_energy original × (1 + 5%), which is increased by 5% based on the original energy. n (n represents the years the equipment has been in use, n = 1, 2, 3...).

[0102] 2. Correction of changes in energy structure The basis for the revision is that the emission factors of the provincial power grid have been decreasing year by year (such as the increase in the proportion of wind power and photovoltaic power); at the same time, some precast beam yards will introduce renewable energy (such as distributed photovoltaic on factory roofs and ground source heat pumps) to reduce the consumption of electricity purchased from the external power grid. Correction method: ① Grid Factor Update: The latest provincial grid emission factors published by the Ministry of Ecology and Environment are used annually to replace the historical factors in step S500, and electricity-related carbon emissions (such as E) are recalculated. 能源 Carbon emissions from electricity, E 材料 (The part involving electricity).

[0103] ② Renewable Energy Deduction: The "actual electricity savings" generated by the precast beam yard through renewable energy sources such as photovoltaics, wind power, and ground source heat pumps are calculated based on the latest local grid emission factors, and deducted from the total carbon emissions. The calculation formula is as follows: Etotal after correction = Etotal original - (Energy saving × latest grid emission factor).

[0104] Example: A beam yard located in Guangdong Province used the 2020 grid factor of 0.695 kg CO2 / kWh in 2023. In 2024, the Guangdong grid factor was updated to 0.65. At the same time, the photovoltaic power generation saved 100,000 kWh. Then the carbon saving = 100,000 × 0.65 = 65,000 kg CO2 (65 t CO2), which needs to be deducted from the total original amount.

[0105] Corresponding beneficial effects: Solving the problem of "static calculation error": Traditional calculation methods ignore equipment aging and changes in energy structure, resulting in long-term calculation deviations (such as the carbon emissions from energy consumption being 27.6% higher than the initial year after 5 years of equipment use; without correction, carbon emissions are underestimated). Dynamic correction makes the calculation results more in line with actual production conditions.

[0106] Adapting to policy trends: The renewable energy deduction mechanism encourages beam yards to adopt low-carbon energy (such as photovoltaics), which not only conforms to national policy guidance, but also enables carbon emission calculations to reflect the effectiveness of beam yards' low-carbon transformation (such as the reduction in carbon emissions after transformation, which can be reflected through the correction results).

[0107] Furthermore, although the steps of the method in this disclosure are described in a specific order in the accompanying drawings, this does not require or imply that the steps must be performed in that specific order, or that all the steps shown must be performed to achieve the desired result. Additional or alternative steps may be omitted, multiple steps may be combined into one step, and / or a step may be broken down into multiple steps.

[0108] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art should also understand that various modifications can be made to the embodiments without departing from the scope and spirit of the invention.

Claims

1. A method for calculating carbon emissions during the production process of a precast beam yard, characterized in that, The method includes the following steps: S100 takes the precast beam yard production process as the calculation object, takes the consumption of raw materials, fossil energy and electricity as the core line, sorts out the carbon emission sources of construction and production, and determines the carbon emission quantification and trade-off criteria based on the complexity, importance and contribution of carbon emission sources. S200 clearly defines time boundaries, spatial boundaries, and emission source boundaries; S300, based on the identified carbon emission sources and defined boundaries, constructs a quantitative indicator system for carbon emissions from precast beam yard construction and production, including primary, secondary, and tertiary indicators. S400 collects activity data during the precast beam yard production process and uses preset data quality inspection and screening methods to verify the validity of the collected activity data; S500 analyzes the inherent characteristics and applicable scenarios of carbon emission factors of existing energy and materials, and combines the energy structure, regional power characteristics and the characteristics of building materials used in precast beam yards to correct and optimize the carbon emission factors of fossil energy, electricity and purchased materials, and establish an emission factor database. S600, using the emission factor method, calculates the total carbon emissions of the precast beam yard production process based on the activity data verified in step S400 and the emission factor library established in step S500. S700 adjusts the total carbon emissions based on the impact of equipment performance degradation and changes in energy structure on carbon emissions.

2. The carbon emission calculation method for the precast beam yard production process according to claim 1, characterized in that, The time boundary mentioned in step S200 is from the completion of the precast beam yard construction and the start of production of the first beam to the last beam being shipped out of the factory, excluding the construction and demolition of the precast beam yard.

3. The carbon emission calculation method for the precast beam yard production process according to claim 1, characterized in that, The spatial boundary mentioned in step S200 is: the production area, office area, and living area within the red line of the precast beam yard, as well as the production and transportation area for purchased raw materials from the production site / procurement site to the precast beam yard.

4. The carbon emission calculation method for the precast beam yard production process according to claim 1, characterized in that, The emission source boundary mentioned in step S200 is: raw materials, transportation of raw materials and finished beams, energy, and construction machinery, excluding activities with small carbon emission proportions and difficult data acquisition, such as personnel accommodation, commuting, catering, and equipment maintenance.

5. The carbon emission calculation method for the precast beam yard production process according to claim 1, characterized in that, The primary indicators of the quantitative indicator system described in step S300 include: raw material production and processing, material transportation to the processing plant, and off-site processing of raw materials; Secondary indicators include: sand and gravel production and processing, cement production and processing, steel production and processing, asphalt production and processing, cement transportation, sand and gravel transportation, steel bar transportation, concrete mixing, steel bar processing, steel bar transportation, T-beam prefabrication, etc. The third-level indicators are the specific equipment or vehicles corresponding to the second-level indicators, including sand and gravel production and processing equipment, cement transport vehicles, concrete mixing plants, AC arc welding machines, etc.

6. The method for calculating carbon emissions during the precast beam yard production process according to claim 1, characterized in that, The sources of activity data collected in step S400 include: On-site data collection: construction plan, construction records, construction log, including material types and quantities, equipment usage, and project progress; Statistical data: Monthly / quarterly / annual material and energy consumption statistics forms provided by the Materials and Equipment Department of the construction project; Automatic data collection: Data collected in real time by IoT devices.

7. The carbon emission calculation method for the precast beam yard production process according to claim 1, characterized in that, The rules for correcting and selecting the carbon emission factor in step S500 include: Fossil fuel carbon emission factor: Based on the carbon oxidation rate and carbon emission conversion factor provided by the IPCC, combined with a preset formula for calculating the average lower heating value of energy sources: AND i =A i ×Q i ×∂×44 / 12; Among them, E i Let A be the CO2 emission coefficient of the i-th type of fossil energy; i Q is the carbon emission conversion factor for the i-th type of fossil energy; i is the average lower heating value of the i-th type of fossil energy; ∂ is the oxidation factor of the i-th type of fossil energy. Electricity carbon emission factor: The latest regional power grid emission factor published by the Ministry of Ecology and Environment was selected and determined according to the region where the project is located; Carbon emission factor for purchased materials: Only major materials accounting for 95% of the total quality of bridge engineering are included. Cement carbon emissions are calculated based on clinker production and energy consumption. Steel carbon emissions are calculated based on blast furnace-converter process classification. Sand, gravel, asphalt, etc. are determined according to preset industry correction factors. Priority for selecting emission factors: measurement / mass-energy balance emission factors > regional emission factors > national emission factors > international emission factors.

8. The carbon emission calculation method for the precast beam yard production process according to claim 1, characterized in that, The formula for calculating the total carbon emissions in step S600 is: Total carbon emissions E 总 =E 材料 +E 能源 +E 运输 ; Material carbon emissions E 材料 =∑(material consumption × material unit conversion factor × material carbon emission factor). Energy carbon emissions E 能源 =∑(Energy type consumption × Energy type unit conversion factor × Energy type combustion process carbon emission factor). Transportation carbon emissions E 运输 =∑(Carbon emission coefficient of transport vehicle × Material mass × Transport distance).

9. The method for calculating carbon emissions during the precast beam yard production process according to claim 1, characterized in that, The correction index mentioned in step S700 includes: Equipment performance degradation correction: The carbon emissions from electricity and fossil fuels caused by the aging of mechanical equipment are calculated based on an annual increase of 5%; Energy structure change correction: The latest provincial power grid emission factor is adopted every year, and the carbon emissions corresponding to the electricity saved by the use of renewable energy sources such as photovoltaic, wind power and ground source heat pumps in the precast beam yard are deducted.

10. The carbon emission calculation method for the precast beam yard production process according to claim 7, characterized in that, Among the purchased materials, the carbon emission factor of sand and gravel is 0.002 kg CO2 / kg, that of petroleum asphalt is 2.513 kg CO2 / kg, that of modified asphalt is 2.634 kg CO2 / kg, that of mineral powder is 0.007 kg CO2 / kg, that of C30 concrete is 246.3 kg CO2 / m³, that of C40 concrete is 307.15 kg CO2 / m³, and that of C50 concrete is 365.03 kg CO2 / m³.

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