As the population of millennials surges in Washington and the region, local developers and architects are rethinking the way they create living spaces with this generation’s behaviors in mind.

Generally, the size of rental and condo apartment units targeting people in their 20s and 30s is shrinking while the list of amenities tailored to them — electric-car charging stations, music studios, yoga studios, movie theaters and vegetable gardens — is growing. The rental apartment construction boom has been much stronger than the condo one, even though a monthly mortgage payment in many cases would be less than a rental payment.

The region is becoming a laboratory for cutting-edge designs for apartments — new and renovated ones — for people in this age group.

D.C. is leading the way in the apartment boom for several reasons.

With a substantial transient population, the District has long been a renter’s city. Its homeownership rate is well below the national average of 65.5 percent and the region’s average of 66.6 percent, according to the U.S. Census Bureau. Only about four in 10 households in the city are inhabited by owners — about six in 10 are occupied by renters.

Moreover, more young people are putting off homeownership. They don’t want to get stuck trying to sell a house if they land a job in another part of the country and many simply have too much student debt to get a mortgage.

From 2009 to 2012, according to the Federal Reserve Bank of New York, the portion of people under 30 with more than $50,000 in student debt doubled from 5 percent to 10 percent. During that same time, the homeownership rate fell twice as much for 30-year-olds with student loans as it did for those without such debt.

“We’re loaded down with student loans — we have more than $100,000 between the two of us,” said Lyndsay Meyer, 27, a public relations specialist, referring to herself and husband, Payam. Next month, the Meyers, their toddler son, Clayton, and two dogs will move into a one-bedroom rental in the new PerSei apartments in North Bethesda.

With a $3,000 monthly rental payment, “we’d be able to afford a mortgage payment,” Meyer said. “But we can’t afford to save for that down payment. We like the ease of renting. We’re busy with work and we find it much easier to call the front desk and let them know when something is broken.”

Sandy Silverman, principal of Perkins Eastman in D.C., who has drawn plans for such rental apartments as Waterfront Station in Southwest, said developers are building rental apartments with 300 and 400 units while condo apartments are being built with only 30 and 40 units.

But he said he thinks that will reverse over the next few years.

“Apartment buildings are getting overbuilt in the Washington area. But condos are getting stronger, not weaker,” he said, adding that he thinks some of the rental apartment buildings will switch to condos. “Apartments are in the seventh inning. Condos are more like in the third inning — they’re just getting going.”

Customizable spaces

Many of the new rental and condo apartment buildings are on the high end of the market. For instance, rents at the Ridgewood by Windsor in Fairfax go all the way up to $3,590. Meanwhile, a 1,633-square-foot two-bedroom, two-bathroom unit in the Q14 in Logan Square is listed for $2.1 million.

In an attempt to entice a generation of renters who grew up in the Internet age, property companies like Avalon Bay are constructing high-tech buildings with customizable spaces and social environments. Ava H Street — where rents range from $1,500 to $2,455 per month — exemplifies this trend. The building, which opened about a mile northeast of Union Station in 2012, feels like a cross between a boutique hotel and a luxury college dorm.

You’ll hear music from the White Stripes vibrating over a loudspeaker outside the entryway, where a sign cautions that solicitations are “not cool.” Hallway lighting is designed for conservation — that is, dim until activated by a person passing through — and the parking garage includes an electric-car charging station.

But the core principles at Ava H Street have to do with creating spaces that are social and flexible, a goal Avalon Bay developed by having consumer groups tour mock units with a psychologist. What the company found: Millennials have the same expectations about physical spaces and digital spaces; they want to be able to socialize within personalized spaces that they can break down and rebuild in different ways.

“It’s all geared toward this generation,” said Jeff Wood, development director for Avalon Bay. “These millennials want to be socially connected. This demographic likes to customize their space.”

Ava H Street tenants get retail-style walk-in closets that can be arranged multiple ways, in-unit areas to hang bicycles and kayaks, and sliding doors within apartment units that can enable more opened or closed environments. A “Twitter wall” in the lobby features a word cloud showing the most-tweeted terms from around the neighborhood in real time — minus a blacklist of obscenities. (“Some Urban Dictionary words have gotten through,” Wood says, referencing the online dictionary of often-crude slang words.) In an outdoors courtyard, residents can use a fire pit and control the loudspeaker music with their own iPods.

Avalon First and M, a short walk from Ava H Street, has a similar mission. It’s designed to entice millennials with technologies and a variety of community spaces, including an indoor and outdoor movie theater, a test kitchen, two music studios, and a 5,000-square-foot gym that has green “oxygen walls” made of plants meant to keep the air oxygen rich. One-bedroom units range in price between about $2,080 and $3,350 depending on square footage.

The sprawling first floor has two fireplaces and offers free WiFi to residents. (One Yelp review: “This building is siiiiick. The lobby looks like it was furnished for the Jetsons.”) There’s also plenty of room to split into groups in the lobby — there’s a restaurant-like booth in one corner, couches elsewhere, desk space that includes communal desktop computers with a printer, and a separate seating area overlooking the courtyard.

“A lot of people are working remotely,” Wood said. “They want a place to work by themselves and they also want — we have a lot of students — to be able to collaborate.”

One of the larger projects in the region is Pike & Rose, a 24-acre property that’s part of a long-planned transit-oriented development project in White Flint. The mega-complex includes a movie theater, yoga studio, a swimming pool, a beer garden, and parks, as well as bars and restaurants. Its residential building, which began accepting its first rental applications in February, has 173 units. Unlike the cookie-cutter units in many buildings, PerSei apartments have 30 floor plans — a design strategy that reflects the sense of individuality that characterizes the millennial generation.

“It’s important to be at a Metro stop and in the middle of everything,” said Meyer, who is moving into the PerSei apartments. “The White Flint area is turning into something special, I think.”

Millennial-minded upgrades

Owners of some older buildings are taking notice. Deciding to make major renovations comes down to whether rents can offset costs and which demographic a building is wooing, several in the real estate industry said. Some pricier buildings that want millennials are fast-tracking upgrades. In Rockville, the 10-year-old Crest at Congressional Plaza apartment complex is already undergoing multi-million-dollar renovations — far ahead of schedule, according to a spokeswoman.

“Typically, a building of this age wouldn’t go through an extensive renovation after 10 years, but we saw the changes in the demographics happening in the community,” said Elaine De Lude, chief marketing officer for Ross Management Services, the property’s management company. “In order for us to attract the millennials we really looked at what was important to them.”

De Lude said fitness centers and flexible outdoor space topped the list. Crest is swapping out a larger swimming pool for a smaller one, adding an indoor-outdoor cafe to its courtyard, and renovating its library and movie theater. Other properties have made upgrades millennials might not notice.

“There was a building I was working on last year where they were making sure that you would be able to get cell service even all the way into the garage,” said Karen Kossow, director of marketing for Community Realty Company. “A lot of millennials don’t have landlines.”

Flexible use of community space is a popular theme. Transforming an old basketball court into mini-garden plots, for instance, may last longer than high-tech renovations that age quickly. Buildings that outfit their units with iPod docks, for example, might be forced to upgrade when a new version of the phone comes out. That’s a critical point, especially as technology integrates more seamlessly with our lives.

The tech industry calls this movement “the Internet of things,” and includes technology like smart thermometers that self-regulate based on your habits and wearable fitness trackers that automatically send workout data to your smartphone.

Long-lasting effects

Experts say that the millennials will have a lasting impact on residential architecture.

For instance, Bill Bonstra, managing partner of Bonstra Haresign Architects in Washington, said he expects to see more creative designs involving lighting — now that LED bulbs are replacing incandescent ones, which are being phased out.

“You’re seeing glowing floors, lit walls, light boxes, things like that tied with flat-screen technology,” said Bonstra, whose firm has designed several cutting-edge condo apartments in recent years — including the Q14, the Aston and the SoLo Piazza, all in D.C.

“Buildings will glow, buildings will change color,” Bonstra said. “Maybe Washington won’t embrace it as much as some of the more progressive cities, but here they could actually decorate a building so you could actually have visual images on a building. It could change with the weather.”

A “huge convergence of technology” in architecture will minimize the number of gadgets you’ll actually see in home design. In some ways, this means the future of architecture could look more like the past. Somewhat counterintuitively, this makes sense to a generation that already expects their surroundings to fully integrate the physical and the digital.

The millennials’ sensibility, he said, will also influence the design of single-family houses.

“Gone are the days of sprawling mansions in greenfields,” Bonstra said. “Generally, the size of houses will drop the same way the size of condominiums has gotten smaller.”

People will live more modestly, he said, and will not overspend on housing. “We will look for more financial balance in our lives,” he said.

Adrienne LaFrance is a freelance writer.