Kathy Hopkins, University of Maine Cooperative Extension Educator: Windows present another
insulation problem; they lose a lot of heat through the glass as glass has no insulating
value whatsoever. So, there are some things you can do to help prevent that transfer of
heat through the window. One of the cheapest is to take bubble wrap that you get in something
that you buy and cut it to the shape of the window exactly, spray a little water on the
bubble wrap, put the bubbles toward the glass, and the thin film of water will help the bubble
wrap stay on the glass. You could also tape it along the sides if you wanted. That will
present a little more insulating value to the glass. If you have to see out the window,
then bubble wrap is not your best choice, but if you don’t have to see out through
the glass, it can provide some insulation for the glass.
Another thing you can do on a window to provide some insulation is to put a thin film of plastic
over top of the window. You can use painter’s tape for this because it comes up easily.
It will hold during the winter, but then you can take it off in the spring without having
to worry about peeling the paint off your windows. And so you want to cut the plastic
to size, put the plastic on top, put another piece to seal it on the side and pull that
tight. The object is not to have the plastic flapping in the breeze; you want that tight
and then you’d add more tape on the bottom and then you’d have a nice indoor plastic
storm window that will provide an air space and prevent that air infiltration through
the window. This is also really easy to come up, so if you needed to have access to the
window you could peel that up pretty easily.
Another thing you can do is make your own indoor storm window out of cardboard that
you have laying around, or a few other odds and ends you have in your house. If you take
four layers of cardboard and glue them together, you can make a pretty nice indoor shutter.
The first thing to do is measure your window and get the exact measurements so your shutter
will fit and it will fit right in the window. Glue your cardboard together, layer on layer,
then glue a layer of heavy-duty aluminum foil on top to act as a vapor barrier and a heat
reflector and then seal off the edges with some duct tape. You can make yourself a duct
tape handle and then, at the very end, put a layer of foam insulation right around the
edge of your shutter and then, when you’re ready, you can pop it right into your window
frame so it sits nice and tight, and you’ll have an indoor shutter. You can put this in
at night and take it out during the day, and save yourself some energy.
If you’ve gone through your house and determined that your windows are providing a lot of air
leakage, there are some simple things you can do that can make a difference. One is
lock your window. Just the simple fact of locking it brings this sash down and pushes
the top sash up and seals it tighter in its frame, so that can help as well. The other
thing is if you don’t have curtains or you haven’t made these interior shutters yet,
even pulling your shade will help at night. It would be even better if you could seal
the sides of the shade down once you’ve got them down there. Sometimes you can do
that with magnetic strips and put a little valance or some kind of cornice or something
on the top to keep warm air that goes across the ceiling from going down behind your shade.
So, if you have old windows in your house, often they can be really leaky, sometimes
the sashes themselves are loose in the frame. So again, you want to look at the window first
and make sure that it doesn’t need any major repairs. If you do, than you need to either
repair them yourself or call someone who can repair them or look into replacing them. If
you decide you need to work with the windows you have, there are some things you can use.
You can use a foam caulking and this you would install on the underneath of the sash. This
product is sticky on one side and has a paper backing on the other side, so you’d measure
the size you need and then start sticking this right on the bottom edge of the sash
all the way along, making sure that you get it on there straight, and that it sticks,
and you would apply this to a window that is good and clean, that you’ve cleaned first
so that it will actually stick, and then peel the paper off. And now you have this foam
on the bottom to keep the air from filtering in through the bottom of your sash.
So, rope caulk is another type of caulking you can use. It’s soft like clay, and you
would tear off a little piece and just put that right in between the glass and the wooden
part of your window, and just press it in there. Before you do this, you should make
sure that your windows are clean and that the wood is clean and that any loose paint
has been removed and that it’s all cleaned up because you can pull this off in the spring
so you can open these windows back up again. Now, if the sash is loose, you can use the
rope caulk in between there. Sometimes you have to double it over or use a double strip
of it and you would just pop that down in between the upper sash and the lower sash
and press that in. Come spring, you can take this rope caulk back out, coil it up, put
it in a plastic bag and save it and then re-use it next fall. And now your sash is nice and
tight so the air isn’t leaking in through the cold air.
The third way you can prevent air insulation through the windows and add some extra insulating
value to the glass is to put outdoor plastic storm windows on. To do that, you need some
plastic, you need to measure your window twice each way, cut the plastic two or three inches
larger than the size of your window, get some lath or little wooden strapping, wrap it around,
nail the top on, pull it tight, wrap it around the lath again, pull it tight and nail it
without splitting the lath and go all way around your window pulling that plastic tight,
and that will provide a barrier to the wind getting into your cellar.