Concept design, technical design and detailed design for industrial installations: what is the difference?

Concept design helps select a solution, technical design defines its parameters and how it will meet requirements, while detailed design turns decisions into the information needed for pricing and construction. In industrial plants, these terms are used inconsistently; ordering an “installation design” alone does not establish what documents the investor will receive. The scope of design work must match the investment stage, technical risks and applicable procedures.

Concept, technical design and detailed design: a comparison

This is a comparison of the practical purposes of each design stage, not a universal division imposed by law on every project. Stages may be combined, and “technical design” as defined in Polish construction law differs from the term used informally for the design of an individual machine or production line.

A useful test of completeness is to ask: what decision can safely be made on the basis of the documents delivered? When the client is still choosing an upgrade option, not every detail is needed. When the goal is to compare installation bids, however, a general conceptual drawing will usually be insufficient.

When should each stage be commissioned?

Concept design: before selecting an option and budget

Concept design is useful when a plant is considering, for example, changing the power supply to a production line, expanding a compressor room or rerouting piping in an operating hall. It should show what is known, what has not yet been measured and which assumptions have the greatest influence on the choice of solution.

At a minimum, expect:

• project boundaries and a description of the existing system;
• technical options and the criteria used to compare them;
• a preliminary balance of power, flows or utility demand, depending on the industry;
• identification of clashes, shutdowns, space constraints and potential approvals;
• a list of data required for the next stage and a decision to “proceed / change the option / pause”.

Concept design may include an indicative cost estimate and schedule, but their accuracy depends on the quality of the site survey and the assumptions made. Such estimates should not be compared with a binding construction bid as though they were equivalent.

Technical design: when solutions and requirements need verification

At this stage, the installation’s parameters and interaction with other systems are verified. For an electrical system, this may involve load balance, short-circuit conditions, protection selectivity, voltage drop, protection against electric shock and the effects of motor starting. For a compressed air system, the checks may cover required pressure at points of use, air flow, pressure losses, air quality and condensate drainage.

The scope of calculations and documentation always depends on the installation. An equipment list or a drawing taken from a manufacturer’s catalogue is no substitute for assessing how components will operate together within the existing plant. For electrical installations, the designer selects the standards applicable to the specific solution. For example, PN-HD 60364-4-43:2024-04 addresses overcurrent protection in low-voltage installations; it does not cover every aspect of installation design.

Detailed design: before accurate pricing and construction

Detailed design for an industrial installation should minimise decisions left to be made on site. Useful deliverables include routing and installation heights, support and suspension methods, wall and floor penetrations, connection details, cable and pipe identifiers, material schedules, and testing and acceptance requirements.

A large number of drawings alone is not enough, however. The documents must define supply boundaries: who supplies the control cabinet, who installs the wiring, who configures the automation system and who is responsible for functional testing. Without these arrangements, two bids described as being “to the design” may cover entirely different scopes.

What is required by law, and what is defined by contract?

Under Polish Construction Law, a technical design is a formal component of the building design, alongside the site or land development design and the architectural and construction design, in cases where such a building design is required. Article 34 covers, among other matters, structural solutions, necessary technical and material solutions and the consistency of the technical design with the other parts of the building design. This does not mean that replacing any item of equipment in a factory automatically requires a complete building design. The actual scope of the works must be assessed to determine which rules apply. The legal basis includes the Polish Construction Law — consolidated text and subsequent amendments and the regulation on the detailed scope and form of building designs — consolidated text, taking later amendments into account, including the 2026 amendment.

In turn, the Polish regulation of 20 December 2021 on design documentation for public procurement states in § 5 that detailed design develops the building design to the level needed for, among other things, bills of quantities, cost estimates, tender preparation and construction. This requirement applies in the specific context of public procurement; it must not be presented as a general obligation to prepare a separate detailed design for every private industrial installation.

For an industrial investor, the required documents and their scope depend on several factors considered together:

1. Are the planned works subject to Polish Construction Law procedures, and if so, which ones?
2. Are connection conditions, network operator approvals, specialist assessments or equipment-specific requirements needed?
3. What documents has the client commissioned under the contract, technical specification and schedule?
4. Which drawings, calculations and instructions are necessary for safe construction, acceptance and subsequent maintenance of the installation?

If an upgrade affects the point of connection or increases power demand, the current conditions and documents issued by the relevant operator must be checked. Connection procedures in Poland are governed, among other legislation, by the Polish Energy Law. A load balance prepared at concept stage does not establish that sufficient network capacity is available. The Polish General Office of Building Control also explains construction-related procedures.

How does this work in a plant? Example: expanding the power supply

Suppose a company wants to supply a new production line in an existing hall. The preliminary analysis assumes an active power demand of 90 kW, a three-phase supply voltage of 400 V and a power factor of cos φ = 0,90. These figures are illustrative assumptions only.

The approximate current under a balanced load is:

I ≈ P / (√3 × U × cos φ) = 90 000 W / (√3 × 400 V × 0,90) ≈ 144 A.

The result indicates the order of magnitude of the load under these assumptions. It is not sufficient to select cables, protective devices or a distribution board. Among other things, the calculation does not account for motor starting, earthing arrangements, fault levels, cable installation methods, temperature, protection conditions or interaction with other electrical loads.

• Concept design compares, for example, using an existing distribution board with adding a new outgoing feeder or expanding the infrastructure. It reviews the approximate load balance and possible shutdown windows.
• Technical design verifies loads, supply conditions, protective devices, conductor sizes and coordination with automation and other installations.
• Detailed design specifies exact cable routes, connection points, circuit identifiers, installation details and the scope of pre-commissioning tests.

If the concept overlooks a clash between a shared cable route and the ventilation system, the problem will emerge only later. For this reason, power supply analysis should also draw on information about electric motors and drives, rather than reducing the investment to the rated power of the machines.

Scope of installation design documentation: what should the order specify?

Before asking several firms to quote, describe the deliverable, not merely the name of the design stage. The table below helps distinguish documents needed for a decision from those needed for installation.

In a major energy system modernisation, changing one system can affect another. In such cases, a list of interfaces and cross-discipline agreements is an important design deliverable, not merely a complete set of separate drawings.

Who is responsible for data and coordination?

Most misunderstandings arise from data that nobody has formally confirmed. Before design work begins, responsibilities should be assigned:

• Client and maintenance team: provide existing documentation, identify access restrictions, shutdown windows and rules for safe entry to the site.
• Process engineering and production: confirm required process parameters, operating states, process reserves and the consequences of stopping the installation.
• Designers in the relevant disciplines: check data, perform the required calculations, coordinate interfaces and document assumptions and constraints.
• Infrastructure owners and operators: specify interface requirements and provide approvals where the scope of work calls for them.
• Contractor and equipment suppliers: check the feasibility of details, installation requirements, service access and manufacturer documentation; these responsibilities must be defined in the contract.

It is worth keeping an assumptions and decisions register recording the document number, date, approver, the effect of each change on other disciplines and a status such as “confirmed / information pending”. This is a straightforward project management practice, not a separate statutory category of documentation.

How can you avoid comparing bids that cover different scopes?

If one firm quotes for a concept and a few diagrams while another offers full detailed design with a site survey and coordination, the price difference says little about competitiveness. Before comparing prices, check:

1. Purpose of the deliverable: investment decision, statutory procedure, construction pricing or execution?
2. Scope of work: which disciplines, sections and equipment are included in the price, and which are excluded?
3. On-site work: does the price include a site visit, measurements, survey and drawing verification?
4. Level of detail: what calculations, cross-sections, diagrams and schedules will be delivered?
5. Coordination and revisions: who manages coordination, how many rounds of comments are included and who approves changes?
6. Required procedures: are approvals and formal documents included where necessary?
7. Access and acceptance: does the design account for an operating plant, occupational safety, final measurements and as-built documentation?

Also ask for a list of exclusions and input data to be supplied by the client. This often determines whether an apparently cheaper bid remains cheaper after work begins. For projects that may affect process continuity, the company’s energy supply security and shutdown scenarios must also be assessed separately.

What documents should you prepare before speaking to a designer?

You do not need a complete archive of measurements to start the discussion. First, prepare:

1. Purpose and investment stage: what is to change, and do you need options, documents for approvals or construction details?
2. Existing conditions: diagrams, hall layouts, technical photographs or an equipment inventory, noting what is outdated.
3. Installation operating data: available power, flows, pressures, temperatures, operating hours, load profiles and production constraints relevant to the discipline.
4. Interface information: power supply, utilities, automation, controls, existing structures and routes.
5. Requirements and approvals: known operator conditions, manufacturer documentation, safety requirements and potential construction procedures.
6. Project execution arrangements: possible shutdowns, access to rooms, people responsible for data and the planned decision date.

If the documentation is incomplete, ask for the scope of the required site survey to be specified separately. Assumed values should remain clearly marked as requiring confirmation, rather than quietly becoming design parameters.

Frequently asked questions

Is detailed design always required?

Not simply because the investment concerns an industrial installation. In Poland, the role of detailed design in certain public procurement projects is regulated by the cited regulation. For other projects, the scope of construction documentation may follow from the contract, safety needs and the complexity of the work. Applicable statutory obligations must still be checked separately.

Can technical design and detailed design be combined into one set of documents?

In practice, a combined deliverable with an appropriate level of detail may be commissioned if its outputs and responsibilities are clearly defined. This does not remove the need to comply with the prescribed form and content of the technical design where it formally constitutes part of the building design under Polish law.

What if there are no up-to-date installation drawings?

First, commission a survey covering what is needed to make the decision, and arrange safe access to the infrastructure. The design must distinguish conditions verified on site from historical information and identify items requiring later opening-up works or measurements.

Is keeping the detailed design enough after the works are completed?

Not always. As-built documentation should reflect the installation as actually constructed and any changes made. Depending on the type of installation and applicable requirements, test reports, measurement records, acceptance records and equipment instructions may also be needed.

Conclusion: commission the deliverable, not merely the name of the stage

Concept design supports the decision, technical design verifies and develops it, and detailed design prepares the work for unambiguous execution. Before commissioning design services, define the installation boundaries, the decision to be made, required approvals and the list of documents to be delivered.

If you are preparing an upgrade or a new installation, describe the current site conditions, investment stage and purpose of the documentation. You can send available diagrams, equipment data and information about required approvals through the Energy Trend contact form. This will help establish which information needs to be completed first and what scope of further work is appropriate.

Sources

• Polish Construction Law — consolidated text, Journal of Laws 2026, item 524, with information on amendments, especially Article 34.
• Polish regulation on the detailed scope and form of building designs — consolidated text, Journal of Laws 2022, item 1679, particularly the chapter on technical design; as subsequently amended, including Journal of Laws 2026, item 597.
• Polish regulation on design documentation, technical specifications for the execution and acceptance of construction works and functional-utility programmes, Journal of Laws 2021, item 2454, especially §§ 3–5; applies to the public procurement documentation defined in the regulation.
• Polish General Office of Building Control — construction procedures.
• Polish Energy Law — consolidated text, Journal of Laws 2026, item 43, and amendments, especially Article 7.
• Polish Committee for Standardization — PN-HD 60364-4-43:2024-04, scope description.