【Haichuan EPC】The vague boundaries and key differences between project changes and design refinement in EPC projects

(II) Concept and content of design development: Design development refers to the process by which the contractor refines, supplements, and improves the design documents provided by the client in order to meet the requirements for constructability. Its core objective is to further refine the preliminary or conceptual design without altering the original design requirements, so that it can suit the actual construction needs. According to the work process, design refinement can be divided into two stages: the first is the design refinement stage, during which tasks such as collision detection, headroom analysis, and pipeline layout are carried out to ensure the rationality of the design ； The second stage is the on-site refinement phase, during which the construction drawings are optimized based on the actual conditions at the construction site to reduce the difficulty of construction; this phase includes details such as the refinement of construction drawings, the compilation of a list of construction materials, and the preparation of a construction budget. Classified by professional type, design refinement includes specialized refinement design and comprehensive refinement design. The detailed professional design is carried out based on the professional BIM models provided by the project owner, and covers areas such as civil structures, steel structures, curtain walls, mechanical and electrical systems (HVAC, water supply and drainage, fire protection, strong electricity, weak electricity, etc.), fine finishing, and landscape landscaping ； Comprehensive detailed design relies on the overall model provided by the project owner, and it involves integrating, coordinating, revising, and verifying the preliminary results of the detailed designs for various specialties, in order to create comprehensive floor plans and pipeline diagrams; the key objective is to ensure that the drawings from different specialties are consistent with each other.

II. Blurred boundaries: Dispute scenarios and causes in engineering practice. In practice, contractors often regard unforeseen design refinements as changes, while owners consider them to be part of the normal work included within the fixed price. (1) Common dispute scenarios: In the actual progress of projects, the boundary between project changes and design refinements often becomes unclear, giving rise to various typical dispute scenarios. Here are a few common examples: Disputes over quantity calculations: The tender documents lack key dimensions; after the construction party provides supplementary drawings for refinement, the amount of rebar and concrete used changes by more than 10%, leading to disagreements between the parties regarding who is responsible for these volume changes and who should bear the associated costs. Dispute over code differences: After the construction drawings were completed, new codes came into effect. To meet the requirements of these new codes, designers adjusted the beam heights to comply with the fire resistance standards; there is disagreement among various parties as to whether such adjustments were required by law or represented voluntary changes. Dispute over poor construction methodology: The original design for the steel structure used conventional joints; during the detailed design phase, it was found that cast steel components were necessary to meet the lifting requirements. This upgrade in construction methods resulted in a 20% increase in costs. It is difficult to determine whether this adjustment constitutes a refinement or a significant change. Dispute over brand difference: The tender documents specified that materials of “equivalent quality” should be used, but at the detailed design stage a certain imported brand was designated; the owner gave oral consent, yet the audit department did not approve it, leading to a dispute regarding the nature of this designation of a specific brand. Dispute over interdisciplinary differences: The design of the hardcover drawings calls for 200mm holes to be made in the existing structural beams in order to install air ducts, which requires additional steel for structural reinforcement; the two parties disagree regarding who is responsible for carrying out this reinforcement work. Dispute over BIM differences: BIM collision checks revealed that the bending of the pipelines resulted in insufficient headroom; after adjusting the pipeline routes, the length of the cable trays and ducts increased by 15%. There is a dispute as to whether this level of detail goes beyond what was specified in the contract.

(II) Analysis of the causes of ambiguous boundaries: There are \"gaps\" in the contract texts; many domestic general contract agreements merely state that \"further design work will not result in any changes to costs or timelines,\" without specifying key details such as the acceptable range for volume variations or the boundaries of the scope of further design work, which creates potential for disputes later on. When changes in the volume of work or adjustments to the manufacturing process occur during the deepening phase, the two parties disagree over whom is right, as the contract does not provide clear provisions on such matters. Insufficient design depth leads to \"further design changes\": In some projects, the preliminary or conceptual design lacks depth – only the device models are specified without indication of installation dimensions, and the decorative style is determined without clarity on the materials and assembly methods. When the construction contractor carries out detailed design to advance the construction, it may inadvertently go beyond the original design scope. For example, in a certain commercial complex project, the original design only specified the principles for the placement of fire sprinklers without indicating the exact locations. When the construction contractor carried out further detailed planning to meet fire safety regulations, the owner considered this to be a change that required additional payment, while the contractor argued that it was part of the detailed planning work and should be included in the original contract. This led to delays in the project timeline. The root cause lies in the fact that the original design documents did not clearly distinguish between the \"scope that can be further developed\" and the \"scope that requires approval for changes\", which led to the deepening work ending up in a situation of \"unintended overstepping of boundaries\". There are discrepancies in the transmission of functional requirements: the functional details were not clearly defined during the initial design phase, which makes it difficult to determine, when adjustments to the requirements are needed, whether those adjustments fall within the \"implied scope\" of the original design. In the case of an office building project, the original design only required that the meeting rooms have projection capabilities; later on, the owner requested the addition of a video conferencing system. If the original design already provided the necessary circuit capacity, network interfaces, and other requirements, then optimizing the ways in which these systems are connected constitutes further design work ； If new network cables need to be added or the circuit capacity needs to be expanded, it constitutes an engineering change. However, since the preliminary design did not specify \"whether relevant conditions should be reserved,\" a dispute arose between the two parties regarding the nature of the adjustments. There are gaps in the management process: at the procedural level, design changes require approval through a \"five-party signing\" procedure, yet the detailed drawings often circulate only between the design firm and the construction contractor. Key stakeholders such as supervisors and cost estimators get involved too late to ensure that the details of these designs are reasonable and compliant; by the time issues are discovered, it becomes difficult to determine who is responsible. At the organizational level, the design institute considers the submission of drawings to be the completion of the task, lacking follow-up guidance for the subsequent refinement process ； The construction unit carried out \"modification as work progressed,\" failing to update the relevant adjustment information in a timely manner ； Frequent changes in the owner’s management team lead to disruptions in the transmission of project information and the loss of records of past decisions, further exacerbating the issue of blurred boundaries. The overlap of responsible parties leads to \"ambiguous definition\": In EPC (Engineering, Procurement, and Construction) projects, the same entity is responsible for both design and construction, making it easier for the boundaries of responsibilities to become blurred. For example, when the general contractor carries out further design work, it may discover that the structural elements in the original design collide with the mechanical and electrical pipelines; if only the route of the pipelines is adjusted without changing their specifications or functions, this constitutes further design work ； If increasing the pipe diameter or lengthing the pipeline results in higher costs, it may require engineering changes. At this point, to reduce cost risks, the general contractor tends to consider “changes” as “further development”” ； To control costs, the owner requested approval through the “change” process, leading to disputes over definitions due to differing interests between the two parties. The core reason lies in the fact that, in EPC projects, the general contractor is responsible for the overall design and construction outcomes; the costs associated with detailed design are included in the general contract, while project changes can incur additional expenses. The linkage between responsibilities and benefits leads to disagreements between the parties when defining these aspects.

III. Key differences: The essential distinctions between project changes and design refinements Although both project changes and design refinements involve adjustments to the original design, there are significant differences between them in terms of definition, purpose, entity responsible for initiating them, approval requirements, financial implications, legal validity, and typical application scenarios. The specific comparisons are as follows:

Furthermore, special attention should be paid to the concept of “design optimization,” which lies between the two. Design optimization involves the contractor improving and enhancing the design documents provided by the client, and identifying and eliminating from a cost perspective those unreasonable costs in the original design that are excessive, unnecessary, or unsafe. Design optimization may change some of the contents in the \"Client’s requirements,\" which is the key difference between it and design development, where the \"original design requirements remain unchanged.\" At the same time, when determining the nature of the owner’s instructions, if such instructions alter the \"client’s requirements\" or go beyond the core scope of the original design, it is highly likely to constitute a change order ； Conversely, it may merely be part of the design development process. IV. Four international experiences in distinguishing between the two Some mature engineering contract systems and management models around the world have accumulated rich experience in distinguishing between project changes and design refinements, which can serve as a reference for domestic projects: (1) The UK JCT contract: Classification matrix management for changes. The UK JCT (Joint Contracting Committee) contract divides “changes” into two categories, namely “Change” and “Variation”, and uses a “change classification matrix” for management purposes. The horizontal axis of the matrix represents the degree of impact on costs, while the vertical axis represents the degree of impact on time. Based on the different effects of a change on costs and time, it is classified into various quadrants; each quadrant corresponds to different approval processes and responsibility allocation mechanisms. For example, changes that have little impact on costs and time can simplify the approval process ； For changes that have a significant impact on costs and timing, strict multi-party evaluation and approval procedures must be followed to ensure that the decision regarding such changes is scientific and reasonable, thereby effectively avoiding disputes arising from ambiguous classification of changes. (II) FIDIC Yellow Book: The Design Development Impact Statement System. The FIDIC (International Federation of Consulting Engineers) Yellow Book requires that, prior to carrying out design development work, the contractor must submit a \"Design Development Impact Statement (DDSI)\” that details the potential impacts of such development on the project’s functionality, cost, and timeline. The owner must respond within 14 days of receiving the statement, indicating explicit approval of the detailed design plan, requesting adjustments to it, or determining that such detailed work constitutes a change. If the owner fails to give approval within the specified time, it shall be deemed that they acknowledge that such detailed work constitutes a change to the project. By anticipating the impacts in advance and clarifying the responsibilities of the owner for approvals, this system effectively reduces disputes that arise later on, ensuring a smooth integration between the design refinement work and change management. (III) U.S. AIA Contract: Design Development Package and Change Threshold Control. The U.S. AIA (American Institute of Architects) contract introduces a “Design Development Package (CDP)” at the construction drawing stage, specifying the depth standards and scope boundaries for the design documents at that stage. At the same time, it is stipulated that any further adjustment that results in a change in the contract amount of more than 0.5% must go through the \"Change Order\" process, involving formal procedures for submitting change requests, reviewing them, and granting approval. By setting clear change thresholds, a distinct boundary is established between \"routine refinements\" and \"changes requiring approval,\" thereby avoiding cost disputes arising from ambiguous levels of refinement and ensuring the stability of the contract price. (IV) Singapore BCA: BIM Model Depth and Differences Reporting System. The Singapore Building and Construction Authority (BCA) requires that government projects use BIM LOD 300 (Level of Detail 300) for tendering; the BIM model submitted during the tendering phase becomes the contract model, specifying key elements such as the scope of work, volume of work, and technical parameters. All refinement work must meet the BIM LOD 400 standard or higher, and a model difference report must be provided to outline the differences between the refined model and the original contract model in terms of quantities and technical parameters. If the difference exceeds 2%, the engineering change process is automatically triggered, and change approval procedures must be followed. This system leverages BIM technology to enable visual and precise management of design development and change control, and by quantifying threshold values for differences, it effectively reduces issues related to ambiguous boundaries. V. Conclusion: The blurred line between project changes and design refinement is the root of disputes throughout the entire project lifecycle; issues ranging from disagreements over construction costs to disputes during final audits, and even legal actions, all stem from this. In the reality of the \"tripartite projects\", where such situations are common and the level of design detail varies, clearly defining the boundaries between the two is crucial for resolving disputes; it directly determines the efficiency, fairness, and outcome of dispute resolution.

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