When I asked to interview Ryan Carson about how he runs Treehouse, his burgeoning high-tech start-up in Portland, Ore. on a four-day work week – not four 10-hour days, like the federal government and other workplaces, but 32 hours, period – he said I could come to his house after 5 p.m. on Tuesday.

He typically works from home on Tuesdays, he explained. And every Tuesday afternoon, he has a “date” with his oldest son, Jackson, six.

When I arrived, Carson opened the door to his gracious colonial revival mansion built in 1915, then quickly headed back to the playroom, where he helped Jackson sound out words and finish his homework, occasionally helping his four year old, Devon, attack some zombies on Minecraft. Then he and Jackson raced up the wide, mahogany-panelled staircase for some wrestling time.

This was not your typical scenario of the haggard, high-tech start-up CEO who sleeps under the desk – as Bill Gates sometimes famously did – rather than a waste a single minute not working.

But Carson has deliberately designed his company to both maximize productivity, he said, and give him time for a life. “I’ve really tried to engineer a sustainable life,” he said. Here’s how.

He starts early. Carson routinely wakes up around 5 a.m. He thinks, answers a few e-mails and plans the day. “I literally love that time,” he said. “It’s my quiet time. I can organize my day, get a couple things done. My day is centered around that.” His two sons wake at 6:30. He brings his wife, Gill, coffee, and the family snuggles in bed until 7 when it’s time to get rolling to school and work.

He focuses intensely at work. “I’m very focused, and I work very hard while I’m working,” he said. “I’m just very careful to not work long hours.”

He got rid of e-mail. “I’ve definitely worked in environments where all I did was e-mail all day,” he said, responding to others’ priorities instead of his own. Instead, Treehouse employees take breaks from their concentrated periods of work, log into a Web forum – they use Canopy – and join ongoing conversations with specific groups discussing specific projects. “So all day I’m not firefighting, trying to figure out if the e-mails in my inbox are important to me or not,” Carson said. “I’m going to Canopy when I have time, read what’s directed to me, reply, then close it. It changes the dynamic from push to pull. The whole key is to figure out how to be extremely efficient, because we’re trying to get five days’ worth of work done in four.”

He cut down on interruptions. Treehouse encourages workers to communicate via Hipchat, which protects them from interruptions and keeps them focused and on task. Studies have found that the typical knowledge worker is interrupted every three minutes — and it can take as long as 27 to get back on track. “Communicating asynchronously is the key,” Carson said.

He takes breaks. Treehouse workers in the Portland office sit down at a long banquet table in the middle of the open floor office and eat lunch together everyday, courtesy of Treehouse. “That really forces people to have that personal time. To speak to people in person. To walk away from their desks,” he said. “We see it as a very small investment for that huge value.”

He has a life. And so do his employees. “It’s just common sense. If your employees are fresh and motivated, they have to perform better,” he said. “If you put them in a race with someone for one month, and one works 60-hour weeks, and one works 32, then yes, the person who worked 60 hours is going to get more done in that one month. How about in 12 months? How about in seven years. When I tell people that, most will say, ‘Yeah, I see that.’”

Want more on innovative workplaces? Try this one about the outdoor company, Patagonia, which is holding true to its founding motto, “Let My People Go Surfing,” even as it goes global: A company that profits as it pampers workers.

And if you’re time challenged, or want to learn to be more productive or efficient, sign up for the 21-Day Timehacker Challenge.