APP-SYSE-04 — Worked application: obtain climate control for a new greenhouse configuration

This case shows the common Systems Engineering patterns in a small cyber-physical equipment company. It includes physical equipment, control software, provider Work, an AI Agent, internal capability, and continuing support. Greenhouse-control, electrical-safety, commercial, legal, financial, and organization-design results enter as inputs; their Methods remain with those practices.

1. Fix the System, use, and result to obtain

SYSE.1 keeps GreenhouseClimateControl-GH2 as an intended-system designator selected as the project system-of-interest and distinguishes it from greenhouse GH-2, company GreenHeat-4, and any actual System identity that may begin later. SYSE.16 identifies the greenhouse, electrical supply, heating, ventilation, misting, shading, sensors, operator station, weather, and manual fallback that form the relevant operating surroundings. SYSE.17 identifies operators, crops, maintainers, the equipment company, and the greenhouse owner as Systems that can bear consequences.

The receiving use is control during three representative conditions: a cold night, a rapid solar rise, and a failed humidity sensor. SYSE.2 supplies linked use and System concepts. Acceptance requires bounded temperature and humidity performance, no unsafe actuator command after sensor failure, identified controller and software configuration, recoverable observations, and supported manual fallback. These are case inputs from greenhouse- control and electrical-safety Methods. The case takes its thresholds from those specialist results.

2. Construct complete obtaining arrangements

GreenHeat-4’s managers initially propose buying a controller or having an AI Agent write one. The engineering team applies SYSE.24 and rejects those two phrases as a usable option set. A purchase is one relation inside an arrangement; an AI Agent is one possible performer of named Work. The team uses the six arrangement prompts and eight common questions in SYSE.24 to construct four whole arrangements for the same required greenhouse-control result.

The Finance result compares resource and cash consequences. The Organization Change result states the proposed human–AI–provider Work allocation and its authority gaps. The safety result states the protected failed-sensor condition. The commercial and legal results state the proposed access, update, data, and remedy terms. SYSE.24 uses those results but does not recreate their Methods or decide their questions.

3. Restore parity and choose the next probe

The comparison uses the same three operating conditions, commissioning date, field interfaces, configuration evidence, assurance burden, data access, support horizon, internal capability consequence, expected change latency, and exit condition. The provider demonstration is not compared with an unfinished internal prototype; both are compared with the accepted GH-2 configuration and representative conditions.

The internal-only and custom-provider arrangements fail the need-date condition. The ready-controller and hybrid arrangements form a tie-set because the hybrid arrangement is better for later greenhouse-specific change only if the vendor interface preserves timing, configuration export, and supported fallback.

The ready-controller arrangement costs EUR 84,000 and eighteen internal engineering days; the hybrid costs EUR 96,000 and thirty-two internal engineering days. Both fit the need date. The operating plan expects at least three greenhouse-specific changes in the next three years, so the deciding management team will prefer the hybrid when its added price stays within EUR 15,000 and its added internal burden stays within fifteen engineering days, but only after the protected interface and fallback claims are supported.

The same team is authorized to spend up to EUR 7,000, forty engineering hours, two hardware-in-the-loop laboratory days, and five elapsed working days on this decision. The safety specialist separately authorizes the failed- sensor injection in the laboratory. ChoiceResult-GH2-1 is probe again: a EUR 5,500 replay uses thirty-two controls-engineering hours, eight integrator hours, two laboratory days, and the available five-day reserve.

The decision rule distinguishes three outcomes. Unsafe fallback or unusable configuration export rejects both survivors. Safe fallback and export combined with failed supervisory timing or unsupported API retains only the ready-controller arrangement. If fallback, export, API support, and timing all pass, both survive and the stated price-and-burden rule selects the hybrid. Without the replay, neither survivor has enough evidence for a choice under the declared rule; rejecting both would discard an arrangement that the bounded replay can retain.

The performed replay returns the third outcome: the local controller enters the supported fallback without an unsafe actuator command, the supervisory command round trip remains below the application-profile limit, and the configuration export reidentifies the tested controller and software values. The safety specialist limits the first observation to the tested failure and configuration. The deciding Agent applies C.11 again and records ChoiceResult-GH2-2: choose now for the hybrid arrangement under that basis. A different safety limit or withdrawn vendor-update support would reopen the choice.

4. Continue with realization, configuration, and assurance

The realization Agent applies SYSE.3 to the retained arrangement and identifies its first unsupported realization branch: whether the internal integration Agent can configure the supervisory layer and produce the commissioning evidence before the need date. The vendor controller is a supplied System and the AI Agent is a possible performer in selected Work; neither becomes the whole realization arrangement.

SYSE.13 identifies controller, software, interface, sensor, and greenhouse configuration and effectivity. SYSE.10 keeps the hardware-in-the-loop replay results tied to the claims assessed by that replay. SYSE.4 states which acceptance claims may rely on those observations and which still need greenhouse commissioning evidence. SYSE.14 governs the later change and release decision. Performed integration Work, accepted configuration, payment, provider duty, and changed internal capability remain results of their own Methods.

Result, stop, and reopen

The worked application returns a project-System focus, linked use and System concepts, four comparable whole obtaining arrangements, one evidence-qualified C.11 choice, and the first unsupported realization branch. The decision-making Agent can now commit to the hybrid arrangement. Project integration and acceptance remain open.

Stop there. Reopen SYSE.24 when the result, use, need date, provider capability, interface, configuration export, support, internal capability, evidence, or exit condition can reverse the choice. Reopen only the affected realization or assurance result when the arrangement remains preferred but one branch or claim fails.