Your apartment feels cold because of one or more fixable problems: poor insulation, air leaks around windows and doors, radiator issues, or the way your building moves air between floors. The thermostat might read 70°F while your actual comfort level is much lower, because air temperature is only part of what determines how warm you feel. Here’s how to figure out what’s going on and what you can do about it.
Cold Surfaces Matter More Than Air Temperature
The biggest surprise for most people is that the temperature shown on your thermostat doesn’t capture the full picture. Your body exchanges heat with every surface around you, not just the air. Researchers call this “mean radiant temperature,” and it’s the average temperature of your walls, floors, ceiling, and windows combined. In an under-insulated building, those surfaces can be dramatically colder than the air, pulling heat away from your body even when the thermostat says you should be comfortable.
Research from the Arizona Institute for Resilience found that in poorly insulated homes, occupants can feel a space as 10°F or more different from the thermostat reading. While that study focused on heat, the same physics works in reverse during winter: cold exterior walls and single-pane windows radiate chill into the room. If you stand near a large window on a freezing day, you’ll feel noticeably colder than someone standing in the center of the room, even though the air temperature is identical. Smaller apartments are especially vulnerable because a higher proportion of your surfaces are exterior walls exposed to the cold.
Air Leaks and Drafts
Gaps around windows, doors, electrical outlets, and pipe penetrations let cold outside air seep in constantly. Even small gaps add up. A quarter-inch gap under your front door, running the full width, creates an opening roughly equivalent to a small window left cracked open all winter. Old double-hung windows are notorious for leaks along the sashes, and the weatherstripping around doors compresses and deteriorates over time.
You can find drafts by holding a lit candle or incense stick near window frames, door edges, and outlet covers on exterior walls. If the flame flickers or the smoke bends sideways, you’ve found a leak. Common trouble spots include where the window frame meets the wall, the bottom of exterior doors, and any spot where pipes or wires enter from outside.
The Stack Effect in Apartment Buildings
If you live in a multi-story building, a phenomenon called the stack effect may be working against you. Warm air is lighter than cold air, so it naturally rises through stairwells, elevator shafts, and gaps between floors. In winter, this creates a pressure difference that pulls cold outside air into lower floors and pushes warm air out through the upper floors. Research from the Council on Tall Buildings and Urban Habitat describes this as a continuous cycle: cold air gets drawn in at the bottom, heated by the building’s systems, then rises and escapes at the top.
The practical result is that ground-floor and lower-floor apartments tend to feel colder and draftier, while upper floors may overheat. In one study of a high-rise in Astana, Kazakhstan, the pressure balanced out somewhere around the 7th to 9th floors. Below that, cold air infiltrated; above it, warm air leaked out. Wind hitting the building’s exterior makes this worse, especially on the windward side. If your apartment is on a lower floor and faces the prevailing wind, you’re getting hit by both forces at once.
Thermal Bridges Through Balconies and Concrete
Apartment buildings are full of “thermal bridges,” spots where a material that conducts heat well (like concrete or steel) connects the inside of your apartment directly to the outside. The most common culprit is a balcony slab. Research published in the journal Buildings found that balcony slabs are the second-largest source of thermal bridging in apartments, after windows and doors. The concrete slab extends from your interior floor straight through the wall to the exterior, conducting cold directly inside.
This shows up as a noticeably cold floor near the balcony door, and it can increase your apartment’s heating energy needs by up to 11%. It also lowers the temperature of your interior floor surface, which contributes to that cold-feet feeling even when the air seems warm enough. Steel beams, concrete columns at exterior corners, and the frames of large windows all create similar cold spots.
Your Heating System Might Not Be Doing Its Job
If your apartment has radiators, check whether all of them are actually heating up. Trapped air inside a radiator prevents hot water from circulating through it. You can fix this by “bleeding” the radiator: open the small valve at the top with a radiator key until you hear air hissing out, then close it once water starts to drip. If your radiator is warm at the top but cold at the bottom, there may be sludge buildup that requires a professional flush.
Forced-air systems have their own problems. A dirty filter restricts airflow and forces your system to work harder while delivering less heat. Filters should be replaced every one to three months during heavy use. Also check that furniture, curtains, or rugs aren’t blocking your supply or return vents. Even partially blocked vents can throw off the balance of your system and leave certain rooms underheated.
Thermostat placement matters too. If your thermostat is near the kitchen, in direct sunlight, or on an interior wall far from the coldest spots, it may “think” the apartment is warmer than it actually is and shut off the heat too soon.
Low Humidity Makes Cold Feel Worse
Dry winter air makes a room feel colder than it actually is. When relative humidity drops below about 30%, moisture evaporates faster from your skin, pulling heat away and making you feel chilled even at a reasonable air temperature. Research suggests that healthy individuals perceive thermal comfort at a relative humidity around 40 to 42%, and most people become uncomfortable when humidity drops below that range.
Apartment buildings with forced-air heating tend to have very dry indoor air in winter, sometimes dropping to 15 to 20% relative humidity. A simple hygrometer (available for a few dollars) can tell you where you stand. If your humidity is low, a portable humidifier or even placing damp towels near a heat source can help. Keeping humidity in the 30 to 50% range will make the same air temperature feel noticeably warmer.
Practical Fixes You Can Do Today
Window insulation film kits are one of the most effective low-cost solutions for renters. These clear plastic films attach to the interior window frame with double-sided tape and shrink tight with a hair dryer, creating a dead air space that acts as insulation. Manufacturers claim these kits can increase a window’s thermal resistance by up to 90%, which is significant for single-pane windows that are often the weakest thermal link in an apartment.
Other quick fixes that make a real difference:
- Draft stoppers along the bottom of exterior doors block one of the largest single air gaps in most apartments.
- Thermal curtains over windows add an insulating layer and reduce the radiant chill from cold glass. Close them at night and open them during the day to capture solar heat.
- Outlet insulation gaskets are foam pads that fit behind the cover plates of electrical outlets on exterior walls, blocking a surprisingly common air leak path.
- Area rugs on bare floors, especially near balconies or over concrete slabs, reduce heat loss through your feet and add a small layer of insulation.
- Rope caulk is a removable, putty-like sealant you can press into window gaps without damaging anything, making it ideal for renters.
When Your Landlord Should Be Involved
Many jurisdictions require landlords to maintain a minimum indoor temperature during heating season. While specific laws vary by city and state, 68°F during daytime hours is a common legal standard. North Carolina’s statute, for example, requires rental properties to be capable of reaching at least 68°F measured three feet above the floor when it’s 20°F outside. New York City requires 68°F during the day and 62°F at night during heating season. If your apartment can’t reach these temperatures with the heat running, the problem is likely structural or mechanical, and your landlord is responsible for fixing it.
Document the issue by taking timestamped photos of your thermostat reading alongside an independent thermometer. If your landlord is unresponsive, most cities have a housing inspection or code enforcement office that handles heating complaints, and these complaints typically get fast responses during winter months.