Insulating drafty windows makes a difference in air quality, not just energy savings!

When you’re trying to make a whole house less drafty, you should go for the low-hanging fruit first.  That means big ol’ holes in the walls, floor or ceiling (like this disconnected register) come first.  If you don’t have any big holes, you can start on the smaller ones–and sometimes the smaller ones can add up.  That was the case in my sunroom. 

My sunroom is west-facing, which means in the summertime it gets brutally hot from sunlight, and in the wintertime it’s brutally cold from westerly winds.  On top of that, it’s fairly dusty and showed some of the highest counts of mold colonies in my home.  When I saw another cold front coming later in the week in December, I finally “made” the time to insulate the windows where I felt the drafts coming in.  I saw that the lower windows didn’t seal at the bottom when closed, AND the previous owner had cut the corners on the lift at the bottom for some reason (they rubbed on the trim?).  Due to these leaks, the room stayed quite “fresh”--meaning the CO2 didn’t really budge from outdoor levels unless I lit a fire in the fireplace on the other side of the room.  If you don’t have a CO2 monitor, I highly suggest getting one: here’s a portable version.

Therefore, the cons of my leaky windows easily outweighed this one “pro”: fixing them was a no-brainer!

Here are the tools I used: 

• A spray bottle of TotalClean and several rags for cleaning the windowsills
• Adhesive-backed weatherstripping in a suitable color to match your windows (low-profile like this one, ¼”, is good unless your windows are very misaligned) 
• Scissors
• Optional: A CO2 monitor is helpful–to see the effect on the room
• Optional: Window locks in case the windows don’t lock afterwards (see below)

If you do have a CO2 monitor, leave the windows closed and take a CO2 measurement before doing the insulation work. You might want to do it while there are a number of people in the room, or you have a propane or natural gas stove burning (I know there are a lot of gas stoves out there!).  Extra people and gas appliances do two things–they consume oxygen and they give off CO2.  These should cause the CO2 to be higher than when the room is empty or no gas appliances are lit.

Next, just get down to it: use the TotalClean and rags to clean off the window sill where the lower half of the window seats.  If you have vertical sliding windows, find the best place to attach the insulation in the vertical track and clean that.  When the track is clean and dry, start peeling the adhesive backing off and apply the weatherstripping a little at a time, cutting it when you get to the end of the track. Close and lock the window to make sure it’s placed correctly.

If you find your windows don’t lock because of the extra height of the insulation (this was the case for my windows) there are a number of window locks available that can be easily removed if you have to open the window for ventilation.  I ended up getting a thumb-screw version that can be moved up a few inches if I decide to ventilate, while still keeping the window secure.  

That’s it!  When you have all of the insulation installed, close the window and repeat the CO2 reading, with or without activity (people or gas-burning appliances).  The CO2 levels should go and stay higher because there is less fresh air coming in.  Fresh air ventilation is needed in a home, but it’s best to do it in a controlled way, not just letting the air come in wherever there’s a small gap or crack.   For more ideas on how to air seal leaky windows, check out this video.

Photo by Rob Wingate on Unsplash