[thedufer]

To agree with chmullig, NYC apartments I've seen are almost all steam heated, but I don't think I've ever heard of a working valve. Most people I know adjust temperature in the winter by opening windows (apartments are largely overheated, for some reason).

The reason we heat with full-apartment systems and cool individually is that landlords are required to pay for heating (and hot water) but don't want to pay for cooling.