In the United States, efforts to improve the squalid living conditions of tenement dwellers led to projects like the now-landmarked apartment houses on Manhattan's Upper East Side built by the City and Suburban Homes Company at the turn of the last century (where this writer happily resided for several years in a rent-stabilized studio). Within the buildings, generous courtyards provide light and air in every room of the units, which average 370 square feet.

At about the same time, local authorities in cities throughout the country passed legislation requiring exposure to light and air in dwellings and setting a minimum size. But those very laws enacted at the turn of this century to protect the quality of housing—which include density and parking regulations—have until recently hampered developments of the existenzminimum of today, namely the micro unit. Targeted at young, college-educated individuals, the micro unit serves as a center-city option for those who prefer to have their own space rather than cramped quarters (often illegally altered) with roommates.

“The thought was that only poor people would live in such tiny apartments,” says David Baker, a San Francisco architect who is working on two market-rate micro-unit developments. “But micro units have become a viable housing niche product.”

A 2012 change to San Francisco codes reducing the total minimum area of a newly constructed legal residential unit from 290 square feet to 220 square feet, including closets and bathroom, has opened the market to a novel type of housing. David Baker Architects is currently designing 1174-1178 Folsom, a 42-unit rental project in the South of Market (SoMa) neighborhood with apartments ranging in size from 290 to 380 square feet. The firm is also working on 388 Fulton in fashionable Hayes Valley, a for-sale development that combines two-bedroom apartments and micro units.

Both projects feature some communal space, such as an outdoor deck and courtyard for all residents to use. “Micro housing is not a trend but a demand. People would rather be in the thick of things in a small space than a commute away in a big space,” says Baker. “Some think it's immoral, but driving 70 miles to work—is that a good idea?”

New York requires units to be at least 400 square feet in most parts of the city. The renovation of an existing 425-square-foot brownstone loft on Manhattan's Upper West Side gave Specht Harpman Architects the opportunity to bring high design to a small walk-up apartment. Though oddly configured, the unit had the advantage of 25 feet in height and access to a roof terrace. The architects created four separate levels, including a cantilevered bed pavilion, that flow into each other. “It was like playing a game of Tetris,” recalls Louise Harpman. “And everything inside does double duty.” Stairs feature built-in storage, and the kitchen contains fully concealed appliances and a countertop that wraps into the raised living platform to accommodate an entertainment system.

While this was a one-off project for the firm, Scott Specht has been passionate about micro housing since his days as an architecture student. It was then that he first experimented with the zeroHouse, a prototype design for a small, fully self-sustaining modular home that can be built anywhere. Though he has raised early investment money to develop the project, it has yet to be realized. In the meantime, the firm is now designing a 12-unit micro-loft building in Austin. “We're not promoting an ascetic lifestyle,” says Harpman. “We're just reacting against the McMansionization of housing.”

In Seattle, where regulations are less restrictive than those of New York, a number of micro-unit developments have already been built and are renting for an average of $660, half the price of a typical one-bedroom. But even New York is moving forward, albeit tentatively, with this type of housing. A waiver by former mayor Michael Bloomberg has allowed a micro-unit development in the Kips Bay neighborhood of Manhattan to get started. Now under construction and expected to open next summer, the nine-story building features 55 prefabricated apartments that range in size from 265 to 360 square feet. Designed by nArchitects, the building combines subsidized and market-rate residences, with 40 percent of the units reserved as affordable housing and several set aside for veterans. While rents for market-rate units have yet to be determined, affordable ones will range from $940 to $1,800 a month.

Mimi Hoang and Eric Bunge, the principals at nArchitects, were not initially on board with the idea of micro housing. “Our first take was that it was horrific to put people in such small spaces,” says Bunge. But after remembering the substandard 350-square-foot East Village apartment the married couple shared for several years when they first moved to New York, he started to think differently. “We recognized [the micro unit] as a necessary type and that we could have an impact on making it a better prototype.”

The firm's Kips Bay building is designed to be fully accessible and to exceed building codes for light and air. The small units are broken up with different flooring materials, because, as Bunge says, “Spaces feel bigger when you divide them and populate them with things.” The 9-foot-8-inch ceiling heights offer a spacious feeling and provide overhead storage. “The proportional relationship of the tall space and very large windows that are typical in luxury and larger apartments create a loft-like feeling here,” says Bunge.

Current New York mayor Bill de Blasio has not excluded micro units in his plan to build hundreds of thousands of affordable-housing units. In Boston, Thomas Menino relaxed existing building codes when he was mayor, allowing for the construction of micro units in the city's waterfront Innovation District to lure young tech workers. Local firm ADD Inc. is currently designing two high-rise projects that include micro units—which rent for 10 to 20 percent less than traditional studios—on lower floors, with luxury apartments on higher floors. “We struggle with affordability in these types of projects,” says ADD principal Tamara Roy. “But those units are definitely at the lowest price point in a very desirable area.”

Critics of micro housing say it is just a way for developers to make more money by squeezing more apartments into a building, and that people tend not to live in tiny spaces for long, so that rapid turnover results in rapid deterioration. The micro-unit projects in New York City and Boston—and to some extent San Francisco, which has capped the number of such developments allowed to be built—are test cases to determine if compact living is a fad or a real housing alternative for a growing population of singles, childless couples, and seniors who see the city as their living room.