Some of America's workplace real estate faces a major makeover.

Aging and obsolete office buildings across the country are slated for a refresh as developers and property investors look to convert them into new uses that better cater to changing work and living habits since the pandemic's start.

There are about 100 such conversion projects underway across major cities in the United States, according to CoStar and data from brokerage giant CBRE. That is a significant spike compared to the annual average of about 40 office conversions between 2016 and 2022.

What's more, the trend is expected to continue with more than 200 office conversion developments planned or anticipated to be completed in the next three years.

Of the conversion projects underway or planned, nearly half are slated to be overhauled into a new multifamily property. Office-to-life sciences conversions follow at about 20% of the projects on the table, with mixed-use and industrial conversions representing a much smaller share of the pipeline, according to CBRE.

To be clear, conversions aren't always feasible. Issues such as complicated financing, environmental challenges and stagnating markets have proven to be among the biggest hurdles for those looking to transform some of the nation's older office buildings. Then there are the physical attributes of properties themselves that can deliver their own set of headaches, such as irregular floor plans, unsuitable locations or aging systems that would be too expensive to fix and reuse.

The cost of converting an office building into a new multifamily one, for example, averages about 20% more than ground-up development, said Phil Mobley, CoStar's national director of office analytics. That often means developers have to feel confident they'll be able to achieve top-of-the-market rents in order to make the conversion financially successful.

Public incentives might also be necessary, he added, something local governments such as those in San Francisco, Chicago, Seattle, Los Angeles and New York have said they would pursue.

Steve Cramer, CEO and president of the Minneapolis economic development group Mlps Downtown Council, pointed to an office-to-apartment conversion project called Northstar now underway in his city as a model for what's to come.

"It's a great example of the kind of strategy that, when you find the right building and you put the right financial package together, it can really be a new life for a building," Cramer said. "It's not going to end with Northstar East. There's going to be a number of other buildings that will make this transition."

Here are a few projects that began construction this year that should help set the stage for future developments to come:

Where: 3010 N. Second St. in Phoenix
New Use: Multifamily
Why It Matters: The luxury apartment development is set to include two buildings upon completion, the first of which is an adaptive reuse of a four-story office building. The 114-unit project, half of which is planned to be converted office space, is located in a downtown neighborhood that has been able to maintain record demand growth over the past several years, ahead of some of the city's suburban counterparts.

Where: The Bridgeview Bank Building at 4753 N. Broadway St. in Chicago
New Use: Mixed multifamily, retail and office
Why It Matters: Developer Cedar Street converted the 97-year-old former bank branch and office building into 176 apartments. The $58 million project also created 13,500 square feet of retail, another 19,000 square feet of offices, a fitness center and a rooftop lounge and deck. The former office building on the city's North Side included some nonprofit organizations prior to Cedar Street’s 2019 acquisition and overhaul of the building, which finished construction this year.

Where: The Northstar East building at 608 Second Ave. South in downtown Minneapolis
New Use: Multifamily
Why It Matters: A majority of the 216 units included in the conversion of the Northstar East office building is to be available as workforce housing for tenants such as teachers or police officers, and about 20% of the project will be designated for low-income renters. The $92 million conversion, which began construction earlier this year, takes advantage of nearly $7 million in tax increment financing provided by the city as well as other state and federal historic tax credits to help make the project more economically feasible.

Where: 180 Water St. in New York City
New Use: Multifamily
Why It Matters: The project, which began leasing earlier this month, is billed as New York’s largest office-to-residential conversion, and its rents are more than $1,500 higher than the citywide average. The Gensler-designed conversion includes 588 market-rate units with three floors of amenities, including a bowling alley, a high-tech sports simulator, a pet-grooming salon, a spa featuring a cold-plunge pool and hyperbaric-oxygen therapy chamber, and an outdoor rooftop terrace. The project is one of many moving through the city's pipeline aimed at helping to transform lower Manhattan's financial hub into a more liveable neighborhood.

Where: 5400 Tesson Ridge in Saint Louis, Missouri
New Use: Multifamily
Why It Matters: The 210-unit complex repurposed an office building formerly owned by MetLife and it was the largest development to land in Saint Louis' South County area since the late 1980s. Monthly rents for a typical unit at the new complex now exceed $2,760, according to CoStar data, more than double the $1,182 average reported throughout the rest of the area in a sign that tenants are willing to pay for nicer and newer space.

Where: 7310 and 7410 NW Tiffany Springs Parkway. in Kansas City, Missouri
New Use: Multifamily
Why It Matters: Developer Foutch Brothers spent more than $12 million to convert former office buildings at 7310 and 7410 NW Tiffany Springs Parkway into housing, and that could be just the start. The two buildings reopened this year with about 105 units combined, with a third property eyed for another 100 or so units. The converted offices were part of a seven-building complex developed in the mid-to-late 1980s, some of which Foutch was able to acquire out of foreclosure for roughly $3 million.

Where: The Grant Building at 44 Broad St. NW in Atlanta
New Use: Multifamily
Why It Matters: The former office building is one of the oldest structures in the Georgia metropolis. Work began this year to replace the top seven floors with what's set to ultimately be 165 apartments. It is one of downtown Atlanta’s highest-profile adaptive-reuse projects aimed at replacing some of the city’s outdated and empty office supply with housing.

Where: The Santander Tower in downtown Dallas at 1601 Elm St.
New Use: Multifamily
Why It Matters: High office vacancy rates downtown pushed developer Pacific Elm Properties to convert a chunk of its Santander Tower into housing. The 50-story building, one of Dallas' tallest, now has 14 floors that have been converted into market-rate apartments, turning the unused office space into about 300 units that rent for up to $4,000 per month.