It's wife versus husband. Roommate against roommate. Son versus mother. Tenant against landlord.
The onset of cold temperatures marks the start of winter heat wars. The battlefield is the thermostat, and victory is control of the temperature inside as the chilling wind whips against the windows. What's toasty warm for some is uncomfortably stifling for others, and the result can be tears and arguments.
The routine is all too familiar for Meredith Breuer and her fiance, Eric Spitz. Breuer gets home from work about 5:30 p.m. to find the thermostat at 62 degrees - what she considers positively arctic.
Spitz, who arrives home first to their apartment in Chicago's Wrigleyville, tells her, "Put on a coat; wear a blanket."
Sometimes she gets her way by pouting, and he allows her to ratchet up the heat to 70 or 71. Other times, they end up arguing over whose lap gets warmed by Winston, their Cavalier King Charles Spaniel, whom they describe as "the built-in heater."
"Whoever's in a better mood usually gives in faster," she said.
Not too far away, Hugo Hernandez, 25, lives with his mother, who keeps the temperature of their Melrose Park, Ill., apartment hovering around 75 degrees - much too warm for his tastes.
"I try to stay out of the apartment as much as possible," he said. "I hate it."
As cold snaps promise to chill bones across the nation, fierce thermostat battles are already breaking out across gender lines, generational divides and otherwise blissful domestic arrangements.
So what about the discrepancy in comfort levels between people who, for lots of other reasons, choose to live together in close quarters? Why are some internal thermostats set higher than others? Experts point to all kinds of reasons, including weight, age, sometimes gender and even mental health.
Dr. Ronnie Mandal, who specializes in internal medicine at Swedish Covenant Hospital, addressed the central conflict among couples by noting that men have more muscle mass, causing them to create more heat than women. "We know that muscle burns more calories; that alone lends itself to creating more heat," Mandal said.
One married couple, Bruce Rogers and Jane Kuelbs of Evanston, Ill., stumbled upon an ingenious solution to their thermostat war.
If Rogers had his way, he'd be walking around his family's two-story 1890s-era farmhouse barefoot, in jeans and T-shirt, with the thermostat at 71 degrees. Kuelbs, a knitter, likes it cooler, so she can bundle up in a sweater or wool socks. With a new geothermal heating system, the family keeps it brisk upstairs and toasty downstairs.
"We have different zones," Rogers said.