Why It Feels Like Cold Air Is Coming From Your Windows

If it feels like cold air is coming from your windows in winter, there is a good chance no air is moving through them at all. What you are feeling is usually the air in your own room, chilled by the glass and sliding down onto the floor. It is worth telling the two apart, because one of them is worth fixing and the other one mostly is not.

How to tell a real draft from cold glass

A real leak is easy to find on a cold day. Dampen the back of your hand and move it slowly around the whole perimeter of the window: along the meeting rail where the two sashes cross, up both sides, across the top, and along the joint where the frame meets the wall. Moving air on wet skin is unmistakable. A strip of tissue held at the same spots does the same job, and if it flutters you have found a leak.

If the edges are quiet and the only cold you can find is a foot or two out in front of the glass, the window is not leaking. It is just cold, and that is a different problem with a different answer.

What the falling air actually is

Glass sitting well below room temperature chills the air touching it. Cold air is denser than warm air, so it sinks. It slides down the face of the pane, spills out at the sill and spreads along the floor. In a room with a big window it is a slow steady current rather than a gust.

You feel it at your ankles halfway across the room and read it as a draft coming from the window, which is backwards. The air came from the room. It is also why the chair nearest a picture window is the worst seat in the house in January while the thermostat out in the hallway reads seventy.

There is a second thing going on at the same time. Your body radiates heat toward whatever is around it, and a big cold pane gives nothing back. Standing in front of one feels a bit like standing in front of an open door, for the same reason standing in front of a fire feels warm on one side.

Why the glass gets that cold here

A sheet of glass is thin and insulates almost nothing by itself. What does the work is trapped air: the gap between a window and its storm panel, or the sealed space inside a double pane. An old single sash with no storm in place is usually the coldest surface in the house. Metal conducts well too, so aluminum frames and triple track storms are where frost and sweating tend to start.

When the overnight low gets down near zero, which around here it does for weeks at a stretch, the inside face of a window can sit far enough below room temperature to keep that current running all day. The window does not have to leak to make you uncomfortable.

What actually helps

Most of what works is cheap or free.

• Close and latch the storms. On the sliding kind, check that the panel is actually seated at the bottom. A storm left open an inch is doing almost nothing.
• Check the weatherstrip where the two sashes meet. On old double hungs that joint is the usual culprit when there really is a leak.
• Use curtains that reach the sill or below. Closed at night they hold the cold air behind the fabric instead of letting it pour out across the floor.
• Keep furniture off the register or baseboard under the window. The heat there is doing a specific job, which is pushing warm air up the glass against that falling current.

If you want the real fix rather than a workaround, it is a tighter window or a better storm panel, and that is a carpenter or a window company rather than us.

Cleaning the glass will not change any of this

Clean glass is exactly as cold as dirty glass. Washing a window has never warmed a room up, so if the cold is what is bothering you, this is not the job to book.

What is worth doing in the winter is the inside. Interior glass is usually the dirtier side by midwinter anyway, and the haze that builds up indoors has nothing to do with the weather outside. Fog and frost on the inside of the pane are a separate thing again, driven by humidity rather than dirt, and there is a whole piece on winter condensation. If you are closing the storm panels for the season, that is the moment to clean behind them, because once they are shut you are looking through that glass until spring.

Exteriors can wait. There is a point in the fall where washing the outside stops making sense until the weather turns. If you want the insides done while the outside waits, ask for a quote or pick a time on the booking page.