Field Case of Multi-span PC Sheet Greenhouse in Romania

The Romanian client operates in the Argeș region, roughly 120 km north of Bucharest. It is a local agricultural enterprise specializing in large-scale tomato cultivation. The client supplies tomatoes to chain supermarkets and fresh produce delivery platforms serving Bucharest and neighboring towns, and has built reliable distribution channels within the domestic tomato supply chain.

Prior to our cooperation, the client operated basic simple steel-framed plastic greenhouses. Romania features a continental climate with four distinct seasons. Internal greenhouse temperatures frequently exceed 42°C in summer, while nighttime temperatures plunge to below -10°C in winter. This leads to highly unstable tomato fruit set, alongside frequent fruit cracking and blossom-end rot. A further critical challenge was the lack of an automated environmental control system. All ventilation, irrigation and temperature management depended on workers' subjective experience: staff uncovered the film in the morning, recovered it at dusk, and irrigated based on guesswork. Sudden weather shifts could trigger devastating losses to the entire crop. The client engaged several local technical consultants successively, yet failed to establish stable, replicable cultivation protocols.

Before the project was launched, we had multiple in-depth communications with the client and identified three core challenges:

● Coordinated Regulation of Multiple Systems Constituted the Primary Technical Challenge

The multi-span PC Sheet greenhouse selected by the client is equipped with a top ventilation system, side ventilation system, internal shading & thermal screen, pad-and-fan cooling system, high-pressure fog humidification system, and automatic irrigation & fertigation system. A diverse range of equipment is involved, governed by cross-coupled temperature and humidity control logic. Although the locally hired agronomists possess rich cultivation experience, they have no experience with coordinated commissioning of this integrated environmental control system. Each subsystem operates reliably when activated independently. However, conflicts frequently emerge when automatic coordinated operation is required according to indoor-outdoor temperature difference, light intensity and CO₂ concentration. For example, cold air will escape if side vents remain closed after the pad-and-fan cooling system starts; simultaneous activation of fog humidification and ventilation for moisture removal counteracts each other. Such faults cannot be accurately diagnosed merely via remote guidance.

● Difficulties in adapting installation standards to local construction teams

The local steel structure construction teams available in Romania are accustomed to installation practices for conventional industrial buildings. They lack experience with greenhouse-specific technical details, including aluminum profile grooves, PC Sheet clip sealing and gutter slope design. In the early phase, we attempted remote video guidance, yet construction proceeded slowly. Particularly when cutting PC Sheets for curved roof sections and installing sealing gaskets, several issues emerged, such as localized water leakage and minor panel deformation induced by uneven surface stress. The client grew anxious, fearing delays to the optimal tomato transplant window.

● The race between the construction cycle and the peak planting season

The client had already raised 20,000 tomato seedlings prior to contract signing, scheduled for transplant into the greenhouse within 45 days. If greenhouse completion fell behind schedule, seedlings would suffer excessive elongation due to overaged growth. Worse still, the client would miss the peak marketing window from August to October, when local tomato prices in Romania reach their highest level. This meant zero margin for error across all stages, from structural assembly and system commissioning through to final handover.

In response to the client's requirements, we delivered an integrated solution covering three dimensions: product adaptation, technical commissioning and on-site personnel deployment.

● Dispatch engineers to conduct joint debugging of the entire system on site

We immediately assembled an on-site team comprising a senior environmental control engineer and a structural engineer. The team carried full calibration equipment and flew directly from China to Bucharest. After arriving on-site, the engineer spent three days carrying out systematic troubleshooting. On Day 1, all sensor locations were inspected, and offsets of temperature & humidity probes and anemometers were calibrated. It was discovered that inconsistent mounting heights for humidity sensors at two side windows caused temperature reading discrepancies exceeding 3°C between the northern and southern zones. On Day 2, the logic chain was reworked, and the PLC program's action priority was rewritten. A clear execution sequence was defined: close internal shading first when cooling is required, then activate the pad-and-fan system, and finally shut the side wind vents. This completely eliminated previous system logic conflicts. On Day 3, full-condition pressure tests were performed, simulating three typical scenarios: extreme summer heat, cold winter nights and sudden heavy rainfall, to verify the stability of the entire control chain. Upon completion of commissioning, the engineer compiled bilingual Chinese-English operation manuals documenting all control logic and provided hands-on training to two of the client's on-site technicians.

● Dispatch a professional installation team to be fully responsible for the main construction process

Rather than relying on local construction crews, we mobilized a five-person professional installation team from China with hands-on experience across seven greenhouse projects. Led by a project manager, the team brought a full set of specialized tools, including aluminum profile cutters, sealing gasket rolling tools and PC Sheet stress testers to the site. The team is fully familiar with critical installation specifications for multi-span PC Sheet greenhouses: the exact expansion gap dimensions matched to Romania's annual temperature variation range, the correlation between bending radius and thickness ratio for curved PC Sheets, and slope consistency control for continuously welded gutters. Local crews would require extensive trial and error to master these technical details, while our team can execute all work strictly following standardized procedures.

● Modular Pre-fabrication Solution for PC Sheet Roof Panels

To ease tight schedule pressure, we optimized the conventional on-site cutting workflow. All roof PC Sheets were pre-cut and pre-numbered at the factory. The design team extracted precise dimensions and installation coordinates for every PC Sheet from the BIM model. The factory carried out cutting, chamfering and pre-drilling according to coordinate codes. Matching installation drawings were enclosed within each package container. Upon receiving the cargo, the on-site crew installed panels sequentially by number, eliminating all time spent on on-site measuring and cutting.

Throughout the whole project, from initial outreach to final handover, we consistently followed the principle of "Products exported, Services delivered locally":

▶ Phase1: Remote Demand Alignment and Solution Design

The sales and design teams collaborated to confirm key information via several video conferences, including site latitude and longitude, historical meteorological data (5-year extreme high/low temperatures, maximum wind speed and maximum snow load), as well as tomato crop requirements for temperature and humidity. Within one week, the design team delivered two alternative proposals. Both schemes adopted dual ventilation systems combining top and side vents to sustain summer cooling capacity. Retractable internal thermal screens were added to cope with low winter temperatures, and integrated fertigation layouts were customized according to the client's planting density. The client expressed high satisfaction with the space utilization rate and equipment configuration of the proposal.

▶ Phase 2: Engineer on-site and system integration debugging

When main structure installation entered the final stage, the environmental control engineer arrived on-site. Within three days, all sensors were calibrated, action priorities within the PLC control program were rewritten, and full-condition testing was carried out under three extreme weather scenarios. The client's technical staff followed the whole commissioning workflow. The engineer explained every segment of control logic and demonstrated operations, then allowed the technician to perform full runs independently. This guaranteed the client could manage daily regulation autonomously after the engineer's departure. Upon finishing commissioning, the engineer additionally verified precision of EC/pH sensors within the fertigation system and the actuation response of irrigation zone solenoid valves, fixing reversed piping connections in two zones.

▶ Phase 3: Planting Connection and Delivery Training

The day before formal greenhouse handover, the project manager organized comprehensive handover training. In the morning, the manager guided the client's technical staff through the full operating workflow of the environmental control system, covering startup self-check, parameter configuration, and switching between manual and automatic modes. In the afternoon, inspections were carried out on the retraction travel of shading screens, the head pressure of pad-and-fan water pumps, and the backwashing function of filters installed at irrigation headers. On the handover date, 20,000 tomato seedlings were transplanted into the greenhouse on schedule without any delays to the client's planting timetable.

Two months after handover, we held a follow-up video call with the client. The tomatoes inside the greenhouse have entered the second fruit expansion stage, and crop uniformity is excellent. The uneven growth featuring shorter plants along edges and taller plants in the middle, which frequently occurred in the old plastic greenhouse, has been eliminated.

"To be honest, before your team arrived, I was worried this greenhouse would just become an expensive decoration with so much equipment if it could not be properly tuned. Your engineer coordinated all systems on-site within only three days — far faster than I expected. Tomato seedlings were transplanted on schedule and now bear fruit, growing far better than in previous years. The installation team delivered very rigorous workmanship. All sealing gaskets for PC Sheets were tightly fitted. Heavy rainfall hit Romania last month, yet not a single drop leaked inside the greenhouse."

*The client finally notified us that they have scheduled the next expansion project. They plan to construct another multi-span PC Sheet greenhouse of identical specifications in spring next year. The client also appointed us to provide a full scope of services covering design, fabrication, on-site installation and system coordinated commissioning.