Midday approached as Ken Kruger pulled his brown cart down the darkened hallway of the empty hotel building.

“Okay, 1207,” he said, parking his operation in front of a hotel room door. “We got an open window in here that needs to close.”

Inside he shut the blinds, turned off a lamp and then consulted his map for his next stop on the top floor of the DoubleTree in Crystal City. Kruger was moving briskly. He was hoping to make quick work of what has become an important and highly visible part of his job: replacing the design displayed on the hotel’s north tower. He’s responsible for opening and closing shades of empty rooms, which trumpet uplifting messages to commuters along Interstate 395, where the busy freeway connects Washington and Northern Virginia.

First, there was a giant heart. And then the word “HOPE,” followed last month by “LOVE.” On Thursday, it was time for a new message that hotel workers hoped would inspire people, however briefly, in a region still very much reeling from the coronavirus pandemic.

“This next room we’ll leave open,” Kruger said, working his way down the hallway, consulting a color-coded map along the way.

“All right, 12′s done,” he said. “Only nine more floors.”

In mid-March, as the virus began seizing American life in ways big and small, hotel occupancy across the country plummeted. The 48-year-old hotel near the airport, perhaps best known for its revolving rooftop restaurant, consolidated its guests into a single building and kept its north tower empty. They were still operational, still booking guests and still meeting each day as a staff.

“We were itching for an idea to do something more,” said Charles Hill, the DoubleTree general manager. “We’re in hospitality; what we do is take care of people. While that’s constrained a little bit right now, we had this really good opportunity.”

They began to focus on the empty tower, so visible from one of the region’s busiest thoroughfares. They viewed the tower as a canvas in need of a message.

“We wanted people to know: You’re not alone. People are thinking about you,” Hill said.

They settled on a heart, which felt like a unifying symbol that also seemed reasonably easy to execute. Kruger initially pulled back enough blinds to create a minimalist outline. A few days later, he went room by room again and filled in the heart. The result was a striking image, especially at night — glowing for commercial planes landing at Reagan National Airport and vehicles zipping through the city.

The feedback was positive and the hotel staffers continued throwing around ideas. They did “LOVE” in mid-April and “HOPE” a couple of weeks later.

As they discussed their options for a new message in May, Hill thought about what he had been seeing in his hotel the past several weeks. He kept coming back to one night, in particular, when a Southwest Airlines pilot approached the front desk. He brought a woman with two children from the airport who had been stranded for the night, their connecting flight canceled.

The pilot offered to pay for their room and then pulled out his wallet, handing the woman cash for a meal.

“The woman started to cry and asked the pilot, ‘Can I give you a hug?’” Hill recalled. “I was watching this whole thing, just an ultimate sign of kindness and humanity where for a minute you stop thinking about social distancing and quarantining and everything going on in the world and all you see is this act of kindness.”

Hill didn’t charge the pilot or the woman for the room, and weeks later, he and Kruger plotted out their fourth design: “KIND.”

“It reminds me why we work in hotels,” Hill said.

As the building’s director of engineering, Kruger is responsible for building operations, which gives him a lead role in the project. In addition to executing each design, he often ends his shift by turning on all of the lights, starting his next morning going room to room to flick them all off.

After the initial heart design, both the planning and the execution have become more sophisticated.

“It’s kind of like a Lite-Brite, if you ever had those,” Kruger said, referencing the 1970s-era children’s toy.

They started with a basic photograph of the tower and a highlighter to mark the windows. Then they plotted out designs in PowerPoint and an Excel spreadsheet. As Kruger turned “LOVE” into “KIND,” he relied on a color-coded sheet that told him which rooms needed blinds opened, which needed them shut and which required no change at all.

There are 10 floors in the tower with 33 windows per floor — 330 windows in all. They figure that’s just enough for four letters, possibly five if they avoid pesky M’s, W’s or other wide-berth letters. “KIND” requires open shades in 74 rooms. Kruger moved from the top floors to the bottom, from left to right, one room at a time. Room 717 needed the blinds closed; next door in 719 they needed to be opened; and in 721 Kruger had to leave one panel but cover two others, a small piece of the “N.”

“Ah, a sofa,” he said after stepping into one room. “Ugh.”

After pulling the blinds open, Kruger pushed the sofa out of the way and moved the lamp. “Wrong lightbulb here,” he said. Kruger wants consistent lighting for the nighttime display, so he makes sure every bulb is 26 watts. He’s particular about these details, so he also positions the lamp two feet from window.

“I’m usually not a fast walker,” he said, moving on, “but it’s important to move through these rooms quickly.”

Kruger wants the turnover to be completed by midafternoon, beating what remains of rush hour traffic.

“I don’t want somebody to have their one drive of the month across the bridge to see half an ‘H’ and an ‘L’ and have no idea what the message is,” he said.

Kruger closed the blinds in room 435 and then checked in to make sure the light was on in 437.

“Last one,” he said after nearly three hours of going door to door. “That should be it.”