Green low-carbon building civil engineering integration efficient construction building method

Abstract

The application belongs to the field of green building and building construction technology, and specifically discloses a green low-carbon building civil engineering integrated efficient construction building method. In view of the problems of design construction disconnection, multi-specialty cross conflict, high carbon emission and serious resource waste in traditional building civil engineering construction, the application constructs a 'cooperative design-factory prefabrication-assembly construction-low-carbon operation and maintenance' integrated system, and the method comprises the following steps: multi-specialty cooperative deepening design and carbon emission calculation based on BIM; factory prefabrication of low-carbon concrete components and integration of thermal insulation structure exterior wall; on-site assembly type construction and dry method connection; renewable energy system and photovoltaic building integrated synchronous installation; and whole life cycle carbon footprint monitoring and closed loop optimization. The application realizes the synchronous construction of the envelope structure and the main structure by driving the deep integration of industrialized production and assembly type construction through digital design, so that the construction period can be shortened, the whole life cycle carbon emission of the building can be reduced, and the civil engineering integrated green construction is realized.

Description

Technical Field

[0001] This invention relates to the field of green building and construction technology, specifically to a green and low-carbon building integrated civil engineering efficient construction method based on the deep integration of digital design, industrialized production and prefabricated construction. Background Technology

[0002] The construction industry is a vital pillar of my country's national economy and a major contributor to carbon emissions, accounting for over 50% of the country's total carbon emissions throughout its entire lifecycle. Green and low-carbon construction has become an essential path for the transformation and upgrading of the construction industry. However, the following prominent problems currently exist in my country's civil engineering construction: First, there is a serious disconnect between design and construction. The design phase fails to fully consider construction feasibility and the needs of industrialized production, leading to numerous on-site changes, rework, and material waste. Second, multiple disciplines (architecture, structure, mechanical and electrical, insulation, and decoration) operate independently, resulting in frequent overlaps and extremely high on-site coordination costs. Third, traditional cast-in-place wet construction involves a large volume of water usage, generating significant dust and construction waste, resulting in persistently high carbon emissions. Fourth, insulation and decorative elements are constructed separately after the main structure is completed, leading to a long and sequential process, and the mismatch in lifespan between the insulation layer and the structural layer poses a high risk of long-term detachment. Fifth, renewable energy systems are installed separately from the building envelope, compromising the integrity of the exterior walls and waterproofing.

[0003] While existing technologies include precast concrete structures and BIM applications, most focus on improvements in specific areas, failing to achieve integrated green and low-carbon practices across the entire design-production-construction-operation-maintenance chain. For example, some precast technologies only address the prefabrication of the main structure, leaving insulation for the building envelope to be applied on-site; some BIM applications are limited to clash detection, failing to create a data loop with carbon emission calculations; and building-integrated photovoltaics (BIPV) is often added retroactively, not integrated during the civil construction phase. These shortcomings prevent the full realization of the overall benefits of green buildings, necessitating a comprehensive and systematic integrated civil engineering construction method. Summary of the Invention

[0004] To address the technical problems existing in the prior art, this invention provides a green and low-carbon building construction method that integrates civil engineering and construction for high efficiency. By driving the deep integration of low-carbon prefabrication in factories and on-site assembly construction through digital collaborative design, the building envelope, main structure and renewable energy system are constructed simultaneously, achieving carbon emission reduction throughout the entire life cycle from design to operation and maintenance. This solves the problems of design and construction disconnect, serious professional conflicts, high carbon emissions and long construction periods in traditional construction.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A green, low-carbon, integrated, and efficient construction method for civil engineering includes the following steps: Step 1: BIM-based multidisciplinary collaborative design and carbon emission calculation. Based on traditional construction drawings, models of architecture, structure, MEP, decoration, and insulation are integrated on the BIM platform. Automatic clash detection is performed, and the layout of densely packed pipelines is comprehensively optimized, eliminating professional conflicts in actual construction from the virtual model. A carbon emission factor database covering all stages of raw material mining, material transportation, component production, on-site construction, building operation, and demolition and recycling is embedded in the model to pre-calculate carbon emissions for the design scheme. When the calculation results exceed the preset target, design parameters are reverse-optimized by adjusting component size modulus, prioritizing the use of industrial solid waste-based cementitious materials to replace ordinary cement (with a carbon emission factor not exceeding 40% of ordinary cement), and increasing the proportion of recycled aggregates, until the carbon emission reduction target is met and the construction scheme is locked. Simultaneously, the BIM model directly outputs processing drawings and material lists for each prefabricated component, interfacing with the factory production management system to achieve paperless data transfer.

[0006] Step Two: Factory-prefabricated low-carbon concrete components and integrated thermal insulation structure for exterior walls. In a factory environment, low-carbon concrete is prepared using optimized high-volume industrial solid waste-based cementitious materials (composed of slag, fly ash, steel slag, etc., after mechanical and chemical activation and compounded with an alkaline activator, with the total mass of industrial solid waste accounting for ≥60%). The concrete has a 28-day compressive strength ≥40MPa and a carbonization depth ≤15mm. Precast components such as beams, columns, floor slabs, and shear walls are cast in molds, with electromechanical pipelines and sensor installation sleeves pre-embedded simultaneously. For exterior wall components, an integrated reverse-casting one-time molding process of "structural layer-insulation layer-decorative layer" is adopted: first, decorative layer materials (such as ceramic tiles or stone) are laid on the bottom surface of the mold, then insulation layer materials (such as vacuum insulation panels) are laid, followed by the installation of the structural layer steel reinforcement skeleton and pre-embedded pipelines. Finally, low-carbon concrete is poured, vibrated, and after curing and demolding, a three-layer permanent composite integrated exterior wall panel with structural load-bearing, thermal insulation, and decorative functions is formed. This process completely eliminates the traditional on-site wet bonding process for insulation layers, and solves the problem of mismatch between the lifespan of the insulation layer and the structural layer.

[0007] Step 3: On-site prefabricated construction and dry connection. Precast components are transported to the site according to the hoisting sequence. After being hoisted into place by crane according to the plan, vertical connections of the components are achieved using grouting sleeve connections—high-strength grouting sleeves are pre-embedded at the connection ends of the precast components, and the protruding reinforcing bars are inserted into the sleeves. After alignment, non-shrink high-strength grout (strength ≥85MPa) is injected through the grouting holes. Once the grout reaches the specified strength, an integral joint equivalent to cast-in-place construction is formed. Horizontal components can be connected using post-tensioned prestressed tendons or bolts, significantly reducing on-site wet work. The key innovation lies in the simultaneous assembly of the main structure and the enclosure structure: each standard floor is divided into multiple construction sections. Vertical component hoisting precedes the installation of one construction section, followed by the installation of horizontal components and exterior wall panels, forming a three-dimensional, cross-flow operation of "vertical leading, horizontal following, and exterior wall synchronous," completely changing the traditional serial construction mode of "main structure first, enclosure later," and significantly shortening the construction period.

[0008] Step Four: Synchronous Installation of Renewable Energy Systems and Building-Integrated Photovoltaics (BIPV). During the installation of the building envelope's exterior wall panels and roof panels, photovoltaic curtain wall panels, photovoltaic sunshades, or photovoltaic roof tiles are simultaneously embedded. These BIPV components achieve mechanical and electrical integration with the exterior wall panels through pre-embedded aluminum alloy snap-fit ​​connectors or structural adhesive. Electrical wiring is completed within pre-embedded junction boxes on the components and is not exposed. The photovoltaic modules are physically and functionally integrated with the building envelope, serving both as power generation equipment and providing enclosure functionality. Pre-embedded sensor sleeves are simultaneously connected to the building energy management system to achieve real-time monitoring of energy consumption and production capacity.

[0009] Step 5: Full Lifecycle Carbon Footprint Monitoring and Closed-Loop Optimization. Utilizing sensors embedded in prefabricated components for temperature, humidity, strain, and acceleration, energy consumption, environmental, and structural health data during the operational phase are continuously uploaded to a cloud platform via a wireless low-power IoT protocol. This data is then compared in real-time with the BIM digital twin model established in Step 1. When actual carbon emissions exceed the preset target by more than 10%, the system automatically pushes optimization suggestions. Simultaneously, deviation data is fed back to the design and construction ends, providing continuous optimization data for subsequent similar projects, forming a green and low-carbon closed-loop management system throughout the entire lifecycle.

[0010] Preferably, the carbon emission factor database mentioned in step one covers all stages of raw material mining, material transportation, component production, on-site construction, building operation and demolition and recycling, wherein the carbon emission factor of industrial solid waste-based cementitious materials is no higher than 40% of that of ordinary Portland cement; the reverse optimization includes adjusting the size modulus of precast components based on carbon emission calculation results to reduce material loss, and prioritizing the use of recycled aggregates to replace natural aggregates.

[0011] As a preferred option, the high-volume industrial solid waste-based cementitious material in step two is composed of one or more of slag, fly ash, and steel slag, which are then combined with an alkaline activator after being activated by mechanochemical processes. The total mass of industrial solid waste accounts for no less than 60% of the total mass of the cementitious material. The concrete prepared by this cementitious material has a 28-day compressive strength of no less than 40 MPa, and the carbonation depth, as determined by accelerated testing, does not exceed 15 mm.

[0012] As a preferred option, the integrated reverse molding process of the "structural layer-insulation layer-decorative layer" of the exterior wall components in step two is as follows: first, lay the decorative layer material on the bottom surface of the mold, then lay the insulation layer material, then install the structural layer steel reinforcement frame, pre-embed electromechanical pipelines and sensor installation sleeves, and finally pour low-carbon concrete and vibrate it to form an integrated exterior wall panel with three layers of materials permanently composited after steam curing or natural curing and demolding.

[0013] As a preferred option, the grouting sleeve connection in step three specifically refers to: pre-embedding a high-strength grouting sleeve at the connection end of the precast component, inserting the protruding steel bar into the corresponding sleeve during on-site hoisting, and injecting non-shrink high-strength grouting material from the grouting hole after correction and positioning. The strength of the grouting material is not less than 85MPa. Once the grouting material reaches the specified strength, an integral node equivalent to cast-in-place is formed.

[0014] As a preferred option, the specific procedures for the simultaneous assembly of the main structure and the enclosure structure in step three are as follows: the standard floor is divided into N construction sections, and after the vertical components of the current floor are hoisted in the i-th construction section, the vertical components of the next floor are hoisted in the i+1-th construction section. At the same time, the horizontal components and the outer wall panels are installed in the i-th construction section, forming a three-dimensional cross-flow operation of "vertical leading, horizontal following, and outer wall synchronization", so that the installation of the main structure and the enclosure structure can be carried out simultaneously on the work surface at the same time.

[0015] As a preferred option, the BIPV integrated building components in step four include photovoltaic curtain wall panels, photovoltaic sunshade panels, and photovoltaic roof tiles. They are mechanically and electrically integrated with the exterior wall panels or roof panels by means of aluminum alloy snap-fit ​​connectors or structural adhesives embedded in the edges of the components. The electrical wiring is completed in the junction boxes embedded in the components and is not exposed to the outdoor environment.

[0016] As a preferred option, the sensors pre-embedded in step five include temperature sensors, humidity sensors, strain sensors, and acceleration sensors. The data is uploaded to the cloud platform via a wireless low-power IoT protocol and automatically compared with the BIM digital twin model. When the actual carbon emissions exceed the preset target by more than 10%, the system automatically generates optimization suggestions and pushes them to the operation and maintenance management personnel.

[0017] As a preferred option, the construction system formed in steps one through five reduces the amount of on-site construction waste by no less than 70%, construction water consumption by no less than 60%, construction period by no less than 30%, and carbon emissions per unit area throughout the building's life cycle by no less than 40% compared to traditional cast-in-place construction methods.

[0018] As a preferred option, the BIM model described in step one outputs the processing drawings and material lists of each prefabricated component during the detailed design stage, and directly connects with the factory production management system to achieve paperless data transfer from design to production, avoiding errors and material waste caused by secondary re-sampling.

[0019] Compared with existing traditional building construction methods, this invention has the following significant advantages: (1) Design and construction integration eliminates professional conflicts and reduces waste from changes at the source; The BIM-based multi-disciplinary collaborative design platform established in Step 1 integrates models from architecture, structure, MEP, decoration, and insulation. During the design phase, automatic clash detection identifies and resolves issues such as pipeline conflicts and deviations in reserved holes, completely changing the passive "modifying as you go" approach of traditional construction. The BIM model directly outputs processing drawings and material lists for each prefabricated component, seamlessly integrating with the factory production management system to achieve paperless data transfer from design to production, avoiding errors and material waste caused by secondary redesigns. Implementation examples have verified that 127 pipeline conflicts were resolved during the design phase, and the number of on-site design changes was reduced by more than 85% compared to traditional projects.

[0020] (2) Carbon emission calculation is carried out in advance to achieve design-driven carbon emission reduction target control; Step one embeds a carbon emission factor database covering the entire lifecycle of a building into the BIM model, encompassing raw material mining, material transportation, component production, on-site construction, building operation, and demolition and recycling. This allows for pre-calculation of carbon emissions throughout the building's lifecycle during the design phase. When the calculated results exceed the preset target, the system reverse-optimizes the design parameters by adjusting component dimensional moduli to reduce material waste, prioritizing the use of industrial solid waste-based cementitious materials with carbon emission factors no higher than 40% of ordinary cement, and increasing the proportion of recycled aggregates, until the carbon reduction target is met. This "calculate first, then optimize" forward design process ensures that green and low-carbon goals are rigidly constrained from the design stage, rather than requiring post-hoc remediation.

[0021] (3) The large-scale application of industrial solid waste-based low-carbon concrete significantly reduces the hidden carbon emissions of building materials; Step two utilizes a cementitious material (comprising at least 60% of the total mass of industrial solid waste such as slag, fly ash, and steel slag, which is mechanically and chemically activated and then compounded with an alkaline activator). The resulting low-carbon concrete exhibits a 28-day compressive strength of at least 40 MPa and a carbonization depth of no more than 15 mm, fully meeting structural safety requirements. Compared to ordinary silicate cement concrete, carbon emissions from the cementitious material stage alone are reduced by over 60%. For example, in the 8600㎡ office building described in the example, approximately 3200 m³ of low-carbon concrete was used, resulting in a reduction of approximately 780 tons of CO2 emissions from this step alone.

[0022] (4) The integrated thermal insulation structure of the exterior wall is prefabricated in the factory, which completely solves the problems of traditional insulation layer detachment and mismatch in service life; In step two, the exterior wall components employ an integrated reverse-molding process combining the structural layer, insulation layer, and decorative layer into a permanent whole within a factory mold. This process completely eliminates the traditional on-site wet-applied insulation layer installation, structurally preventing the risk of peeling and detachment between the insulation and structural layers due to adhesion aging and accumulated temperature-induced deformation. This ensures the insulation system has the same lifespan as the main structure. Furthermore, the factory prefabrication environment offers controllable temperature and humidity, and excellent curing conditions. The overall quality and precision of the integrated exterior wall panels far surpass those of on-site manual operations, with a measured factory pass rate of 100%.

[0023] (5) The main structure and the enclosure structure are assembled simultaneously, which greatly shortens the construction period; Step three breaks away from the traditional sequential construction model of "main structure first, then enclosure," and innovatively proposes a three-dimensional, cross-flow operation method of "vertical leading, horizontal following, and exterior wall installation simultaneously." The standard floor is divided into multiple construction sections, with vertical component hoisting preceding the first section, followed by the installation of horizontal components and integrated exterior wall panels. This allows for simultaneous installation of the main structure and enclosure structure on the same work surface. In this example, the main structure and enclosure structure of the 6-story building are constructed simultaneously, shortening the construction period by 32 days compared to the traditional cast-in-place method, a reduction of 32%, creating significant economic benefits for the project's early commissioning.

[0024] (6) Dry connection significantly reduces on-site wet operations, resulting in outstanding green construction benefits; In step three, vertical connections of components are achieved using grouting sleeve connections (grout strength not less than 85MPa), while horizontal connections are achieved using post-tensioned prestressed tendons or bolt connections. Dry or semi-dry joints replace traditional cast-in-place wet construction. In this embodiment, the on-site wet construction area is reduced by 82% compared to traditional methods, on-site construction waste is reduced by 75%, construction water consumption is reduced by 65%, and dust and noise pollution are significantly reduced, truly achieving green construction.

[0025] (7) Photovoltaic building integration and synchronous installation to achieve deep integration of renewable energy and buildings; In step four, BIPV components such as photovoltaic curtain wall panels, photovoltaic sunshades, and photovoltaic roof tiles are simultaneously embedded during the installation of the building envelope. Mechanical and electrical integration is achieved through pre-embedded aluminum alloy snap-fit ​​connectors, with wiring completed within pre-embedded junction boxes and not exposed. This simultaneous installation method not only avoids the damage to the integrity of the building envelope caused by traditional post-installed photovoltaic systems but also enables photovoltaic modules to serve both power generation and enclosure functions, saving material and labor costs associated with separately installing photovoltaic brackets and decorative surfaces. In this example, the installed capacity is 70 kWp, with an initial annual power generation of approximately 72,000 kWh, effectively reducing carbon emissions from grid-purchased electricity during the building's operation phase.

[0026] (8) Full life cycle carbon footprint monitoring and closed-loop optimization to achieve continuous improvement; Step five utilizes sensors embedded in prefabricated components to collect operational data via a wireless low-power IoT protocol, including sensors for temperature, humidity, strain, and acceleration. This data is then compared in real-time with the BIM digital twin model established in step one. When actual carbon emissions exceed the preset target by more than 10%, the system automatically generates optimization suggestions and pushes them to operation and maintenance management personnel. Simultaneously, deviation data is fed back to the design and construction ends, providing continuous optimization basis for design parameters and construction processes in subsequent similar projects, forming a closed-loop green and low-carbon management system covering the entire lifecycle of "design-production-construction-operation and maintenance-feedback." Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the construction process of the present invention. Detailed Implementation

[0028] The following is in conjunction with the appendix Figure 1 The present invention will be described in further detail below.

[0029] Taking a green and low-carbon demonstration office building project, located in a hot-summer and cold-winter region, with 6 floors above ground and 1 floor underground, a total construction area of ​​8600㎡, a prefabricated frame structure, a shear wall structure, a design service life of 50 years, a green building target of three stars, and a preset life-cycle carbon emission target of no more than 25kgCO2 / (㎡·a) as an example, this invention describes in detail the efficient construction method of green and low-carbon building construction integrating civil engineering. The specific implementation process of the method of this invention is as follows: Step 1: Multi-disciplinary collaborative detailed design and carbon emission calculation based on BIM (1) Integration and clash detection of multi-disciplinary models. After the traditional construction drawings were completed and reviewed, the design team converted the two-dimensional construction drawings of the architecture, structure, water supply and drainage, HVAC, electrical, insulation and photovoltaic disciplines into three-dimensional information models and imported them into the BIM collaboration platform (using the Autodesk Revit + Navisworks software combination). A unified origin coordinate, grid and elevation system were set in the platform to ensure that the models of each discipline were accurately superimposed. The automatic clash detection function was run and a total of 127 clashes of various disciplines were found, including: 43 clashes between structural beams and air ducts, 28 clashes between cable trays and water supply and drainage pipes, 19 deviations between fire hydrant boxes and reserved openings in shear walls, 22 clashes between photovoltaic curtain wall embedded parts and main reinforcement of frame columns, and 15 other miscellaneous clashes. The design team optimized and adjusted all conflicts one by one on the platform: for beam-duct collisions, they prioritized adjusting the duct routing or pre-embedding sleeves in the beams; for cable tray-pipe collisions, they re-optimized the integrated pipeline layout scheme, following the "electricity above, water below" principle; for embedded parts-reinforcement collisions, they fine-tuned the position of the embedded parts or locally strengthened the reinforcement around the openings. After optimization, they re-ran the collision detection to confirm that all conflicts had been resolved, resulting in a zero-collision multi-disciplinary collaborative refinement model.

[0030] (2) Carbon emission factor database embedding and initial calculation. In the BIM model, carbon emission factor attribute parameters are added to each component and material. The carbon emission factor database covers each stage of raw material mining (A1), material transportation (A2), component production (A3), on-site construction (A4-A5), building operation (B1-B7), and demolition and recycling (C1-C4). The carbon emission factor values ​​of key materials are as follows: ordinary Portland cement P·O42.5 is 780 kgCO2 / ton, slag-fly ash based alkali activated cementitious material (industrial solid waste accounting for 68%) is 285 kgCO2 / ton (only 36.5% of ordinary cement), natural crushed stone aggregate is 3.2 kgCO2 / ton, recycled aggregate (construction waste crushing and processing) is 1.1 kgCO2 / ton, vacuum insulation board insulation material (including production and transportation) is 28 kgCO2 / ㎡, and steel reinforcement is 2.3 kgCO2 / kg. By utilizing the detailed schedule statistics function of the BIM model, the material usage of various components is automatically summarized, and an initial calculation of the life-cycle carbon emissions is performed in conjunction with the carbon emission factor. The initial calculation result is 38.2 kgCO2 / (㎡·a), which exceeds the preset target of 25 kgCO2 / (㎡·a) by 52.8%, requiring reverse optimization.

[0031] (3) Reverse optimization design.

[0032] In response to the initial calculation results exceeding the standards, the design team implemented systematic optimizations in the following dimensions: First, the frame column cross-section dimensions were adjusted from 600mm×600mm to 550mm×550mm (which still meets the load-bearing requirements after structural verification), reducing concrete usage by approximately 8.3%; Second, the modular dimensions of the precast floor slab components were optimized from 3.0m×6.0m to 3.0m×7.2m (for better coordination with the building's bay width), reducing the proportion of irregularly shaped slabs and material cutting losses by approximately 5.5%; Third, the proportion of recycled aggregate replacing natural crushed stone was increased from 15% to 30%, and the performance of the replaced concrete was verified through testing to still meet design requirements; Fourth, the thickness of the external wall insulation layer was optimized from 80mm to 95mm, reducing heating and air conditioning energy consumption during operation (calculated using EnergyPlus energy simulation software, this resulted in a reduction of approximately 6% in operational carbon emissions); Fifth, the photovoltaic installed capacity was increased from 50kWp in the initial plan to 70kWp, increasing the contribution rate of renewable energy. After optimization, the carbon emissions throughout the entire life cycle were recalculated, and the result was 22.1 kg CO2 / (㎡·a), which meets the preset target of 25 kg CO2 / (㎡·a), thus confirming the low-carbon construction plan.

[0033] (4) Component processing data output. The BIM model in the locked scheme is automatically exported through the secondary development data interface to export detailed processing drawings (including external dimensions, reinforcement layout, embedded part positioning, pipeline reserved holes, etc.) and bill of materials (BOM) of each prefabricated component. The data is then transmitted to the factory's ERP / MES production management system in XML or IFC standard format to realize paperless data transfer from design to production and avoid dimensional errors and material waste that may be caused by manual secondary re-sampling.

[0034] Step Two: Integrated Exterior Wall with Factory-Prefabricated Low-Carbon Concrete Components and Insulation Structure (1) Preparation of low-carbon cementitious materials. A dedicated alkali-activated cementitious material production line was constructed within the precast component factory. The raw materials were granulated blast furnace slag (specific surface area ≥ 420 m² / kg, 28-day activity index ≥ 95%) discharged from a local steel plant and secondary fly ash from a coal-fired power plant (fineness ≤ 12%, water requirement ≤ 100%), prepared at a mass ratio of slag:fly ash = 65:35. The mixture was added to a planetary ball mill for mechanochemical activation treatment for 45 minutes at a ball-to-material ratio of 4:1, to further refine the particles and increase surface reactivity. The activated powder was mixed with an alkaline activator (composed of sodium silicate with a modulus of 1.4 and industrial caustic soda flakes, with Na₂O equivalent accounting for 5.5% of the powder mass) in a twin-shaft forced mixer, with water added to control the water-to-cement ratio at 0.38. After stirring for 180 seconds, an alkali-activated cementitious material slurry was prepared.

[0035] (2) Preparation of low-carbon concrete. Using the above-mentioned alkali-activated cementitious material as binder, low-carbon concrete that meets the structural design requirements was prepared. The mix proportion (kg / m³) was as follows: 420 kg of cementitious material, 660 kg of recycled coarse aggregate (5~20 mm continuous gradation, crushing index ≤12%), 330 kg of recycled fine aggregate (0~5 mm, fineness modulus 2.6), 330 kg of natural crushed stone, 330 kg of natural river sand, 160 kg of water, and 5.0 kg of polycarboxylate superplasticizer. The slump of the concrete mixture was controlled at 180±20 mm, and the air content was controlled at 2.0%±0.5%. After curing under standard conditions, the compressive strength reached 42.5 MPa after 28 days (meeting the design grade C40), the ratio of axial compressive strength to cubic compressive strength was 0.78, and the static elastic modulus was 32.5 GPa. Accelerated carbonation testing (carbonation for 28 days under conditions of CO2 concentration 20%±3%, temperature 20℃±2℃, and relative humidity 70%±5%) yielded a carbonation depth of 12mm, which does not exceed the specification limit of 15mm. Compared with ordinary cement concrete of the same strength grade, this low-carbon concrete reduces carbon emissions by approximately 63% in the cementitious material stage alone.

[0036] (3) Precast beams, columns, and floor slabs. Components are produced on the factory PC production line using cleaned steel molds evenly coated with release agent. For precast frame columns: a steel cage (main reinforcement of HRB500 grade, stirrups of HPB300 grade) is placed inside the mold, and a fully grouted sleeve (made of No. 45 steel with threaded ribs in the inner cavity) is pre-embedded at the column end, with the sleeve positioning accuracy controlled within ±2mm. At the same time, electromechanical conduits (PVC-U material) and sensor installation sleeves (stainless steel material, 25mm inner diameter, with removable sealing caps) are pre-embedded in the column body according to the design, and the sleeve positions strictly correspond to the pipeline layout scheme in the BIM model. For precast beams: grouted sleeves or pre-stressed tendon ducts are pre-embedded at the beam end, and junction boxes and lighting fixture mounting bases are pre-embedded at the bottom of the beam. For precast prestressed hollow core slabs: the long-line platform pre-tensioning process is adopted. The prestressed steel strands (tensile strength 1860MPa, tension control stress 0.70fptk) are tensioned on the platform and then low-carbon concrete is poured to extrude and form hollow holes. After steam curing (constant temperature stage 60℃±5℃, continuous for 8 hours), the tension is released and the slabs are lifted.

[0037] (4) Integrated exterior wall panel reverse molding. For the exterior wall enclosure components required for the project, the integrated reverse molding process of "structural layer-insulation layer-decorative layer" is adopted. The specific operation steps are as follows: ① Mold preparation: Clean the steel mold table, apply release agent, and lay the imitation stone ceramic tile decorative surface layer (600mm×300mm, 10mm thickness) on the bottom surface of the mold according to the design. Leave a 4mm gap between the tiles for later filling. The back of the tiles is facing up; ② Insulation layer laying: Lay a 40mm thick vacuum insulation board (thermal conductivity ≤0.006W / (m·K), fire performance Class A) on the decorative surface layer. The board seams are staggered and sealed with aluminum foil tape to ensure that the insulation layer is continuous and without thermal bridges; ③ Reinforcing steel frame and embedded parts installation: Install the structural layer (150mm thick) double-layer reinforcing steel mesh (horizontal reinforcement HRB5) on the top of the insulation layer. 00Φ12@150, vertical ribs HRB500Φ14@200), according to the BIM model, accurately weld and fix the embedded base, junction box (IP65 protection level) and sensor installation sleeve of the aluminum alloy snap-on photovoltaic connector, and control the position deviation of the embedded parts within ±3mm; ④ Low carbon concrete pouring: pour the prepared low carbon concrete evenly into the mold through the concrete placing machine, vibrate it with an attached vibrator to make it dense, and smooth and polish the surface; ⑤ Curing: after covering with plastic film, steam is introduced for curing, the heating rate is controlled at 15℃ / h, the constant temperature stage temperature is 60℃±5℃ for 8 hours, the cooling rate is controlled at 10℃ / h, and after demolding, it is naturally cured to 28 days. After demolding, the integrated exterior wall panel permanently combines the decorative surface layer, insulation layer, and structural layer into a single unit, eliminating the need for subsequent on-site application of insulation or dry-hanging of the decorative surface layer. Upon factory inspection, the appearance quality, dimensional deviation, structural performance, and thermal performance all meet the design requirements and relevant standards, achieving a 100% factory pass rate.

[0038] Step 3: On-site prefabricated construction and dry connection (1) Construction Organization and Flow Section Division. In the construction organization design, each floor of the standard floors (floors 2-6) of this building is divided into two construction sections, A and B, with each section covering an area of ​​approximately 700㎡. The overall construction sequence is as follows: after the completion of the first basement floor using the traditional cast-in-place method, the construction will fully transition to prefabricated construction starting from the first floor. The construction flow adopts a three-dimensional cross-operation mode of "vertical components leading one construction section, horizontal components and exterior wall panels following simultaneously". The specific work sequence arrangement is shown in the table below:

[0039] In this flow-line construction method, the construction period for each standard floor is 5 days, totaling 30 days for 6 standard floors. In contrast, the traditional cast-in-place method requires approximately 9-10 days per floor (including formwork, rebar tying, concrete pouring, and curing), and 55-60 days for 6 standard floors. This method shortens the construction period by approximately 25-30 days for only the main structure and enclosure structure construction phases.

[0040] (2) Transportation and hoisting of precast components. Precast components are shipped from the factory after reaching more than 85% of their design strength (usually 7 days of natural curing or 3 days after steam curing). Flatbed trucks are used for delivery, and the components are secured to the truck frame with a special transport frame and flexible straps to prevent collision damage during transportation.

[0041] (3) Grouting sleeve connection of vertical components. In this embodiment, the frame column and the lower column are connected by a full grouting sleeve. The specific process is as follows: ① Apply a retarding interface treatment agent to the surface of the protruding steel bar at the top of the lower column in advance; ② When hoisting the upper column, align the grouting sleeve pre-embedded at the bottom of the column with the protruding steel bar at the top of the lower column, slowly put it in and position it; ③ Use a theodolite and steel ruler to correct the verticality and plane position of the column, and temporarily fix it with steel wedges; ④ Inject non-shrink high-strength cement-based grout (water-cement ratio 0.13, 28-day compressive strength 85MPa, initial fluidity ≥300mm / 30min and ≥260mm) from the grouting hole below the sleeve. The grouting pressure is controlled at 0.6~0.8MPa. After the grouting hole at the top continuously oozes grout and removes air bubbles, seal the grouting hole and the injection hole with rubber plugs in sequence; ⑤ Do not disturb within 24 hours after grouting. Take heat preservation and heating measures when the ambient temperature is below 5℃. After grouting is completed, at least three nodes are randomly selected from each layer for ultrasonic testing of grout fullness. The fullness of all nodes reaches more than 95%, which meets the design and specification requirements.

[0042] (4) Horizontal component connection. The connection nodes between precast frame beams and columns adopt the post-tensioned prestressed tendon connection method: φ50mm corrugated pipe ducts are reserved at the beam ends, and 1860MPa grade unbonded prestressed steel strands are inserted after hoisting on site. After passing through the multi-span continuous beam, tensioning is performed at the ends with jacks (tensioning control stress 0.65fptk). After anchoring, the ducts are sealed by vacuum grouting. The prestressed connection not only provides reliable structural integrity, but also significantly reduces the amount of on-site reinforcement binding and concrete pouring in the beam-column joint area. The horizontal joints between precast floor slabs and between floor slabs and beams are formed by reserving keyways on the slab side + additional reinforcement + post-poured micro-expansion fine stone concrete (strength grade C45). The width of the post-poured strip is controlled at 300~400mm. Before pouring, the contact surfaces of the precast components are roughened and moistened to ensure a tight bond between the old and new concrete.

[0043] (5) Installation of integrated exterior wall panels. After the horizontal components of each floor are hoisted, the integrated exterior wall panels of that floor are installed immediately. The top of the exterior wall panel is connected to the bolt holes pre-embedded in the bottom of the upper beam through the pre-embedded L-shaped steel plate connectors and is tightened with high-strength bolts. The bottom rests on the load-bearing bracket on the top of the lower exterior wall panel and is padded with elastic sealing strips. The vertical joints of the panels adopt a tongue-and-groove design and leave a 15mm gap. During the installation process, the verticality (deviation ≤ H / 1000 and ≤ 10mm) and flatness (deviation ≤ 3mm / 2m) of the wall panels are checked in real time with a theodolite and a straightedge. Since the exterior wall panels have their own decorative surface layer and insulation layer, a complete building facade is formed after installation. The subsequent insulation pasting and finishing construction processes are no longer required, which completely changes the traditional serial process of "first the main structure, then the enclosure, and then the decoration".

[0044] Step 4: Simultaneous installation of renewable energy systems and building-integrated photovoltaics. (1) Synchronous installation of photovoltaic curtain wall panels. On the exterior wall panels of the 2nd to 6th floors of the south facade (facing 15° west of due south), aluminum alloy snap-fit ​​connector bases have been pre-embedded in the factory during the prefabrication stage (4 connection points per photovoltaic curtain wall panel, distributed in a rectangular pattern). The photovoltaic curtain wall panels use double-layer tempered glass laminated crystalline silicon modules (single panel size 1200mm×600mm, peak power 180Wp, conversion efficiency 18.5%). During installation, the back frame snaps of the photovoltaic curtain wall panels are aligned with the pre-embedded bases on the exterior wall panels, pushed in and locked. No drilling or welding is required during the installation process, and there is no damage to the completed insulation and decoration layer. The electrical wiring between the modules is connected in series with MC4 waterproof connectors in the pre-embedded junction boxes. The connected DC cables are led to the DC combiner box on each floor through the pre-embedded conduit, and then to the inverter room in the basement through the cable shaft. The installation of photovoltaic curtain wall panels and the hoisting of exterior wall panels were carried out simultaneously. A total of 267 photovoltaic curtain wall panels were installed on this facade, with a total installed capacity of 48.06 kWp. The construction period was only 2 working days longer than that of the exterior wall panel installation.

[0045] (2) Synchronous installation of photovoltaic roof tiles. After the precast roof panels are installed, curved photovoltaic roof tiles (500mm×400mm per tile, peak power 28Wp, using monocrystalline silicon + clay substrate composite process, with an appearance consistent with traditional clay tiles) are laid on the aluminum alloy guide rails pre-embedded on their upper surface. The photovoltaic tiles are fixed to the guide rails by the slots on the back. Waterproofing is achieved by overlapping the tiles vertically and snapping them together horizontally. Electrical wiring is completed in series in the miniature junction box integrated on the back of the tile. A total of 786 photovoltaic tiles are installed on the roof, with a total installed capacity of 22.01kWp. The photovoltaic tiles have the dual functions of roof waterproofing and power generation, eliminating the need for additional waterproofing membranes or decorative tiles, saving materials and labor compared to traditional roof construction layers.

[0046] (3) System grid connection and commissioning. After the photovoltaic curtain wall and photovoltaic roof are installed, string open-circuit voltage and short-circuit current tests and insulation resistance tests are performed (DC1000V megohmmeter test, insulation resistance ≥50MΩ). After confirming that all electrical parameters are normal, the string inverter (total rated power 60kW, MPPT efficiency 99.5%, European efficiency 97.8%) is connected. The AC output of the inverter is connected to the building's low-voltage power distribution system through the AC distribution cabinet and bidirectional meter to realize self-consumption of photovoltaic power generation and grid connection of surplus power. The building energy management system (EMS) is installed simultaneously to integrate photovoltaic power generation data, power consumption data of each floor, and sensor data from step five into the EMS platform to realize visualized energy management.

[0047] Step 5: Full Life Cycle Carbon Footprint Monitoring and Closed-Loop Optimization (1) Sensor System Deployment. During the prefabrication and on-site installation phases, the following sensors were pre-embedded or installed in key parts of the building: ① Vibrating wire strain sensors (4 per floor, 24 in total) were installed near the grouting nodes of the frame columns and shear walls to monitor structural stress and deformation; ② Temperature and humidity sensors (2 in the corridor and 4 outdoors, 16 in total) were installed indoors and outdoors to monitor indoor thermal environment and outdoor climate conditions; ③ Smart meters (12 in total) were installed at the output of the photovoltaic inverter and the incoming line of the distribution box on each floor to collect real-time power and cumulative electricity data; ④ Smart water meters (8 in total) were installed at the main water supply pipe and major water points to collect water consumption data. All sensors uploaded data to the local edge gateway every 15 minutes via the LoRa wireless low-power IoT protocol, and the gateway synchronized the data to the cloud platform via the 4G / 5G network.

[0048] (2) Digital Twin Model Establishment and Data Integration. The BIM refinement model locked in Step 1 is exported as a lightweight digital twin model (using the AutodeskForge platform) and deployed on a cloud server. The digital twin model includes the geometric information, material properties, carbon emission factors, and preset equipment operating parameters of the components. The real-time data stream collected by the sensors is bound to the digital twin model through the API interface to achieve synchronization of the physical building and the virtual model. In the 3D visualization interface, managers can view information such as the temperature distribution of each floor, energy consumption heat map, photovoltaic power generation curve, and structural strain change trend in real time.

[0049] (3) Real-time carbon emission monitoring and deviation warning. The cloud platform has a built-in carbon emission calculation engine. Based on real-time energy consumption data (electricity, water, etc.) and the preset grid carbon emission factor (taking the grid baseline emission factor of 0.5810 kgCO2 / kWh in the project area), it automatically calculates the daily, monthly and annual carbon emissions during the building operation phase and compares them with the full life cycle carbon emission target curve preset in step one. When the average carbon emissions for 30 consecutive days exceed the preset target value by more than 10%, the system automatically sends a warning to the operation and maintenance management personnel through APP push and email, and generates preliminary optimization suggestions (such as: suggesting adjusting the chiller unit outlet water temperature setpoint, suggesting turning on the timed control of lighting in a certain area, suggesting checking whether the air conditioning terminal in a certain area is abnormally overloaded, etc.).

[0050] (4) Feedback loop optimization. After one year of operation, a comprehensive analysis of the actual data for the first full year was conducted. The measured results showed that the total electricity consumption in the first year was 583,000 kWh, of which photovoltaic power generation was 72,000 kWh (approximately 85% for self-consumption and approximately 15% for grid connection), and the actual net electricity purchase was approximately 522,000 kWh. Combined with water consumption data, personnel density data, etc., the actual carbon emissions in the first year were calculated to be 21.5 kg CO2 / (㎡·a), which was lower than the preset target of 25 kg CO2 / (㎡·a), and the target completion rate was 116%, verifying the rationality of the preliminary design optimization and construction plan. At the same time, the actual operation data (including actual energy consumption patterns, equipment operating efficiency, photovoltaic power generation attenuation rate, etc.) were compiled into a structured feedback report and transmitted to the design team and the prefabricated component factory. Based on feedback data, the design team calibrated and revised the BIM carbon emission calculation model for subsequent similar projects, improving prediction accuracy. Based on the fine-tuning suggestions for the pre-embedded positioning of photovoltaic curtain wall connectors, the factory optimized the positioning fixtures for pre-embedded parts on the mold, further improving the pre-embedded accuracy of subsequent projects.

[0051] To objectively evaluate the technical effect of the method of the present invention, this embodiment is compared and analyzed with another office building of similar size constructed at the same time using the traditional cast-in-place construction method (building area of ​​8200㎡, 6 floors above ground, frame structure).

[0052] The above data fully demonstrates that the method of this invention, through a five-in-one system of "collaborative in-depth design → low-carbon prefabrication in factories → prefabricated construction → synchronous energy integration → closed-loop carbon footprint feedback," has achieved breakthrough progress in construction efficiency, green and low-carbon performance, engineering quality, and comprehensive benefits throughout the entire life cycle. This invention is not a partial improvement on a single construction stage, but a systematic innovation from the perspective of the entire industry chain from design to production to construction to operation and maintenance. Each step is interdependent, data-driven, and synergistically efficient. Its overall technical effect far exceeds the simple sum of optimizing each stage individually, exhibiting outstanding substantive characteristics and significant technological advancements.

[0053] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A green, low-carbon, integrated, and efficient construction method for civil engineering, characterized in that, Includes the following steps: Step 1: Multi-disciplinary collaborative design and carbon emission calculation based on BIM; On the basis of traditional construction drawings, the building information model (BIM) platform is used to integrate the models of architecture, structure, mechanical and electrical systems, decoration, and insulation. Through clash detection and pipeline optimization, professional conflicts in the design stage are eliminated. At the same time, the carbon emission factor database of each component material is embedded in the BIM model to pre-calculate the implicit carbon emissions at each stage of the building's entire life cycle. Based on the calculation results, the design parameters and material selection are optimized in reverse to form a low-carbon construction plan that meets the preset carbon emission reduction target at the design stage. Step Two: Factory-prefabricated low-carbon concrete components integrated with thermal insulation structure for exterior walls; Inside the factory, low-carbon concrete is prepared using high-dosage industrial solid waste-based cementitious materials optimized by carbon emission calculations. This concrete is then cast into precast components such as beams, columns, floor slabs, and shear walls in molds, with electromechanical pipelines and sensor installation sleeves embedded in the components simultaneously. For exterior wall components, an integrated reverse molding process of "structural layer-insulation layer-decorative layer" is adopted, which integrates the insulation material and the decorative material with the concrete components during the prefabrication stage, forming an integrated exterior wall panel that combines structural load-bearing, thermal insulation, and decorative functions, eliminating the traditional on-site wet bonding process for insulation layers. Step 3: On-site prefabricated construction and dry connection; transport the prefabricated components produced in Step 2 to the construction site and use cranes to hoist them into place in a preset sequence; dry or semi-dry connection methods such as grouting sleeve connection, post-tensioned prestressed tendon connection or bolt connection are used between components to greatly reduce the amount of on-site wet work; after the main structure is constructed to a certain number of floors, the outer wall panels of the enclosure structure are installed accordingly, realizing the synchronous assembly and three-dimensional cross-operation of the main structure and the enclosure structure, completely changing the traditional serial construction mode of "main structure first, enclosure later"; Step 4: Simultaneous installation of renewable energy systems and building-integrated photovoltaics (BIPV); During the installation of the building envelope's exterior wall panels and roof panels, photovoltaic power generation modules, solar thermal collectors, and other renewable energy equipment are simultaneously embedded or fixed via pre-embedded connectors, so that the photovoltaic modules are physically and functionally integrated with the building envelope, becoming a BIPV integrated building component; At the same time, the reserved sensor installation sleeves are connected to the building energy management system to achieve real-time monitoring of building energy consumption and production capacity; Step 5: Full life cycle carbon footprint monitoring and closed-loop optimization; Utilizing sensors and IoT platforms embedded in prefabricated components, continuously collect energy consumption data, temperature and humidity data, and structural health data during the building operation phase. Compare these data in real time with the BIM digital twin model established in Step 1 to assess the deviation between actual carbon emissions and preset targets. Feedback the deviation data to the design and construction ends to provide a basis for continuous optimization of design parameters and construction processes for subsequent similar projects, forming a green and low-carbon closed-loop management system throughout the entire life cycle.

2. The green and low-carbon building integrated civil engineering high-efficiency construction method according to claim 1, characterized in that: In Step 1, the carbon emission factor database covers all stages of raw material mining, material transportation, component production, on-site construction, building operation, and demolition and recycling. Among them, the carbon emission factor of industrial solid waste-based cementitious materials is no higher than 40% of that of ordinary Portland cement. Reverse optimization includes adjusting the size modulus of precast components based on carbon emission calculation results to reduce material loss, and selecting the proportion of recycled aggregate to replace natural aggregate.

3. The efficient construction method for green and low-carbon building construction integrating civil engineering as described in claim 1, characterized in that: In step two, the high-dosage industrial solid waste-based cementitious material is made by combining one or more of slag, fly ash, and steel slag with an alkaline activator after mechanical and chemical activation. The total mass of industrial solid waste accounts for no less than 60% of the total mass of the cementitious material. The 28-day compressive strength of the concrete prepared by this cementitious material is no less than 40 MPa, and the carbonation depth is no more than 15 mm as tested by accelerated testing.

4. The efficient construction method for green and low-carbon building integrated civil engineering as described in claim 1 or 3, characterized in that: The integrated reverse molding process of the "structural layer-insulation layer-decorative layer" of the exterior wall components in step two is as follows: First, lay the decorative layer material on the bottom surface of the mold, then lay the insulation layer material, then install the structural layer steel reinforcement skeleton, pre-embed electromechanical pipelines and sensor installation sleeves, and finally pour low-carbon concrete and vibrate it to form an integrated exterior wall panel with three layers of materials permanently composited after steam curing or natural curing.

5. The efficient construction method for green and low-carbon building integrated civil engineering as described in claim 1 or 3, characterized in that: Step 3, grouting sleeve connection, specifically refers to: pre-embedding high-strength grouting sleeves at the connection end of the precast component; inserting the protruding steel bars into the corresponding sleeves during on-site hoisting; after correction and positioning, injecting non-shrink high-strength grouting material through the grouting hole; the strength of the grouting material is not less than 85MPa; and once the grouting material reaches the specified strength, an integral node equivalent to cast-in-place is formed.

6. The efficient construction method for green and low-carbon building construction integrating civil engineering as described in claim 1, characterized in that: The specific procedures for the synchronous assembly of the main structure and the enclosure structure in step three are as follows: the standard floor is divided into N construction sections, and after the vertical components of the i-th construction section are hoisted, the i+1-th construction section begins to hoist the vertical components of the next floor. At the same time, the i-th construction section carries out the installation of horizontal components and exterior wall panels, forming a three-dimensional cross-flow operation of "vertical leading, horizontal following, and exterior wall synchronous", so that the installation of the main structure and the enclosure structure can be carried out simultaneously on the work surface at the same time.

7. The efficient construction method for green and low-carbon building integrated civil engineering as described in claim 1, characterized in that: Step 4: BIPV integrated building components include photovoltaic curtain wall panels, photovoltaic sunshade panels, and photovoltaic roof tiles. They are mechanically and electrically integrated with the exterior wall panels or roof panels through aluminum alloy snap-fit ​​connectors or structural adhesives embedded in the edges of the components. Electrical wiring is completed in the junction boxes embedded in the components and is not exposed to the outdoor environment.

8. The efficient construction method for green and low-carbon building construction integrating civil engineering as described in claim 1, characterized in that: The sensors pre-embedded in step five include temperature sensors, humidity sensors, strain sensors, and acceleration sensors. The data is uploaded to the cloud platform via a wireless low-power IoT protocol and automatically compared with the BIM digital twin model. When the actual carbon emissions exceed the preset target by more than 10%, the system automatically generates optimization suggestions and pushes them to the operation and maintenance management personnel.

9. The efficient construction method for green and low-carbon building construction integrating civil engineering as described in claim 1, characterized in that: The construction system formed by steps one through five reduces on-site construction waste by no less than 70%, construction water consumption by no less than 60%, construction period by no less than 30%, and carbon emissions per unit area throughout the building's life cycle by no less than 40% compared to traditional cast-in-place construction methods.

10. The efficient construction method for green and low-carbon building construction integrating civil engineering as described in claim 1, characterized in that: In step one, the BIM model outputs processing drawings and material lists for each prefabricated component during the detailed design phase. It directly connects with the factory production management system to achieve paperless data transfer from design to production, avoiding errors and material waste caused by secondary re-sampling.

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