The heat reached the packing floor before the weather service issued its afternoon warning.
A worker named Liu took off his safety glasses and wiped his forehead with a sleeve. Gao told him to stop at the marked rest area. It was not a dramatic moment. The production line continued and someone else took Liu’s place for ten minutes.
Yanchuan noticed because his pilot dashboard showed a perfectly ordinary rise in cooling demand.
The temperature sensor monitored the equipment room. The packing floor was two buildings away. Its ventilation had a separate maintenance schedule and its workers had a different limit on exposure. The forecast knew nothing of their discomfort.
“Does the heat affect your recommendations?” Gao asked.
“Only where we have approved data about it,” Ning replied.
“So the system might suggest postponing a ventilation load while someone is working there?”
“It won’t control a switch,” Yanchuan said. “But yes, a recommendation could be wrong if we ignored the people the load serves.”
They suspended the relevant suggestions until the production and safety teams could define the limits. The manager responsible for the pilot objected that the demonstration period was precisely when the system needed to show a benefit. Ning pointed to the contract’s stop condition. The pilot had earned a chance to be useful, not permission to keep running every experiment regardless of context.
The heat advisory arrived an hour later. The weather forecast had predicted a warm day. It had not predicted exactly how a poorly ventilated area would feel when the machines ran together.
At lunch the safety officer showed them the existing rest and temperature procedures. A paper log included breaks, water availability and the times additional ventilation had been turned on. No one asked to upload workers’ health details into the forecasting model. They needed a rule saying that certain loads were not available to shift when environmental conditions passed agreed thresholds.
Guo’s analyst wanted a numeric threshold simple enough for the software.
“Different work creates different exposure,” the officer said. “And a number doesn’t excuse someone from looking.”
Yanchuan wrote that down. He had once wanted every useful judgment to fit a column. He now found himself adding columns to record when the table should stop being used.
That night Qiao called from the hospital. A patient transport van had arrived later than planned, leaving an older man waiting in a hot reception area. The staff moved him into a cooler room and found water. No one had lost the paperwork. The schedule simply assumed the vehicle would be there.
“Did your new system make the schedule?” Yanchuan asked.
“The schedule came from three departments,” she said. “The model picked a time from what they entered. The van was late.”
“Could it have predicted that?”
“If it knew the road was blocked, perhaps. But that doesn’t give us a cooler waiting room.”
He thought of the packing floor and the demand curve that had remained attractive while a worker was sent to rest.
An called the following day from Guangzhou. She had been unable to collect their son immediately after an activity because a bus was delayed. Another parent had stayed with him at school. The boy had been cheerful, though An had worried through the journey.
“It’s been a week of people waiting in places they shouldn’t,” she said.
Yanchuan wanted to offer a calculation of transport delays. She asked him instead to tell her whether the heatwave would reach Guangzhou and reminded him to drink water. He answered the question he could and did not offer a spreadsheet.
At the factory the team prepared a new rule for the model. During specified operating conditions, recommendations affecting staff ventilation would be withheld unless the authorized supervisor had confirmed a safe alternative. The decision remained with the safety team. The model could present relevant measurements but could not convert a narrow equipment-efficiency gain into permission to expose workers to heat.
The pilot’s reported savings fell. A proposal that had seemed valuable under the original boundaries was unavailable on the hottest days, precisely when electricity prices were high.
Guo examined the revised estimate.
“Do we need to rewrite the contract?” he asked.
“Yes,” Chen said. “The service definition has changed.”
“Or become clearer,” Ning added.
A production manager complained that every month the pilot found another reason it could not do something. Gao answered that this was the work they were paying for. He did not want a machine discovering its limits by waiting for someone to collapse.
Yanchuan called his father that evening. Jianming said the apartment was hot but the building’s old air conditioner still worked. He had cleaned its filter himself. Qiao had asked him not to climb on a chair to reach the unit again.
“Did you listen?” Yanchuan asked.
“I used the low step,” his father replied.
“That wasn’t the question.”
“Then you already know the answer.”
They argued briefly about the chair, and Yanchuan felt the old comfort of being irritated by something that was not a missing brother.
Before sleep he returned to the factory figures. The temperature curves were legible; their boundaries now included an explicit account of where people stood. Energy efficiency remained a genuine engineering problem. It was not the only one.
He closed the report with the memory of Liu sitting beside a fan, drinking water before returning to his station. Nothing in the day’s final total showed that pause. The following day’s shift plan made room for a second rest break if the packing floor stayed hot. Liu initialed the notice without looking at the energy chart.