Seasonal Insulation for Windows?

In order to reduce home heating bills, I'm considering putting insulation over some of the windows in my home during the coldest months. ON THE INSIDE OF WINDOWS.

During the winter, windows on the north side don't get a lot of sunlight. They are just sinks for letting a lot of heat escape.

I was browsing the insulation aisle of Home Depot and a few varieties of rigid insulating foam caught my eye. These are not the soft fiberglass pink (or white) insulation used between studs of on external wall; these are stiff pieces of rigid styrofoam, about 1" thick. I was thinking I could cut them to form, and hold them into the window frames. If they are cut in half, to cover just the lower half of a window, or perhaps half of the sliding glass door to the patio, that still cuts the surface area of potential heat loss in half. It's got to be better than nothing, right?

However, keeping in mind these would be inside the house, are there any health concerns? Do these rigid pieces of insulation give off any fibers that might cause health problems? Would they exacerbate asthma or eczema?

Any other recommendations?

It would be nice to have something that clips on in winters, comes off in summers, easy-peasy.

Anybody in these forums use seasonal insulation over windows, or parts of windows, to reduce heat loss?

A big issue with heat loss in windows is drafts coming through gaps and cracks.

It seems kind of cheesy, but utilizing the plastic film kits they sell at the big box stores is an effective measure to deal with heat loss.

You are essentially creating a new layer of pane, creating an air bubble that insulates the outside temp from the inside.

Windows can gather condensation which can grow molds, including black (the bad kind).  So insulation you can open and dry at least once a day is best.

We got honeycomb blinds and they are fantastic at keeping the house warm in the winter and cool in the summer.   They are quick to open and close to dry the older windows in the house.  

Drapes from cotton, linen, and wool have good breathability and are more traditional insulation. Two layers maximise insulation as the air trapped between the layers has good r value.  Sunlight can damage wool, thus the cotton or linen against the windows to protect it.

For extreme weather,  we use foam board for windows that are too high for regular curtains.   It works well, but the temperature change between outside and inside warps the boards and pops them out of the windows. Even though they aren't south facing,  the loss of daylight is noticeable and condensation builds up.  We use these for hot and cold extremes,  but I think a permanent lace curtain might do as much good and be more breathable.

I have a leaky house and live in the serious North. My solution was making wooden frames, onto which I fastened a padded cloth. As it is white, it lets some light through. Cheap & easy. I just pop them out when I want to see through - in the bedroom they often stay on during the day as well.

Over the years, I have used a lot of different things to put in windows as an insulating factor.

I have used towels, bubblewrap, window insulating film, etc.

While I have not made these I like the Roman Shade concept the best.

Here are some of my favorite threads on window insulation:

https://permies.com/t/169504/good-layered-winter-curtain-system

https://permies.com/t/62681/journey-find-winter-curtains

Get a PEP BB while making quilted window coverings and help get a Nest badge:

https://permies.com/wiki/157688/pep-nest/Install-Good-Layered-Winter-Curtain

Another option is to Grow Your Own insulation!  


Make panels and put them in your windows!  Fire-proof and resistant to humidity.  R-value out-performs conventional insulation.  

I have been running insulation over 2 of 4 clerestory windows.  It runs up with just a rope pulley set up.  It does help.  The problem is that it does not seal tight to the window frame the whole way around.  There is less than 1/8 inch gap at the worst but this lets it convect behind the insulation.  The down draft of cold air out the bottom with that small a gap is incredible on an a below zero night.  Because it slides up over the window getting a good seal would be nearly impossible.  One window I could do a hinged foam that folded up to the ceiling and maybe seal better but the other one has a heater stove pipe in the way so this foam sliding up over the window is the best possible.  On a really cold night the window which is about 28 X 78 inches gathers enough ice to run about a cup of water down the wall when the insulation is opened in the morning.  Slowly damaging sheetrock and window wood work.  Current plan is to build small gutter system to catch that condensate as it comes off the glass and route it a closed lid 5 gallon bucket.  It should act as a dehumidifier for the house  But I really need to find a better way to seal the foam to the frame minimizing the amount of water gathered by the glass as well as that air leak convecting over the window is costing me bit time still in spite of the insulation blocking direct radiative cooling.  Here is a picture of the foam and a bit of the window beside it.  The window beside is over a stairwell so getting up there to add the 3rd foam window cover has been more than I wanted to tackle.

I bought the window screen frame kits from " the friendly hardware man" (frame material much stronger than the major home improvement stores).  Then, bought the window insulation kit (cellophane and double-sided tape and made my own double later  "storm window inserts" to fit tightly, with the aid of weatherstripping material, inside the window sill.  Just be sure to shrink both sides, and only shrink it a little or you will warp the frame.  Visibility through the plastic is very good.

We have a 1750-built house with thin, historic windows which we are not allowed to replace.  we bought window inserts from
https://www.windowinserts.com/?srsltid=AfmBOoq5RHOqBS3BhPIBnJa6Hy3JjJxjYhkugSiHsufJusi1BIX-KL03  (there are other companies, this is just the one we were referred to)
It's like the plastic film from Home Depot, but on metal frames with soft foam around the edges.  More expensive than the film, but looks better, is a whole lot less work and less frustrating, and they can be removed in summer, and put back up with ease.  Moderate cost, massive benefit!  An IR camera shows a dramatic difference, but it's more obvious if you remove one -- suddenly a wind of cold washes off the windows...put it back up, and it's very pleasant.  I highly recommend this approach.  

We do have one window which is so badly sealed that gusts push the inserts off...those have gone in and out so often that the foam is tearing, after several years.

mlb

A solution  that might appeal to you and fit the bill is bubble wrap: They come in rolls, with different size "bubbles", so they can be cut to size to fit any window and taped/ stapled to the window frames, so they totally cover any gap or cracks. Cut the bubble wrap larger than you need to and poke the bubbles where they overlap the frame of your windows. This way, you will also close any gap if the window is ill-fitting or has gaps.
In a conventional window, you could tape 2 layers of the large bubbles, which give more insulating power, or put 2 different size bubbles?
I have not done a cost effectiveness calculation on it but the cost might be cheaper.
https://www.homedepot.com/p/Pratt-Retail-Specialties-12-in-x-90-ft-Clear-Bubble-Cushion-12X90HEMIBUB/323933982
This one is only 12" wide, but some is 2ft wide or more.
The bubble wrap also has the advantage of letting in the light. and it comes in different colors, to suit the mood of the room even ;-)
Depending on the amount of room you have in the house, you could also consider the north room as a root "cellar", and allow those rooms to stay closed. [but I don't recommend it if you have any water pipes running through that area, of course.]
If you do not care about keeping sunlight in, you could actually screw in a temporary wooden panel and you could place wool, rags or a blanket between the glass and the wood

When I lived in an old leaky trailer house, I built these:  Kume curtains on Instructables

Quick, easy, very effective and look really nice.  I highly recommend them.

Any reason why these types of measures couldn't be implemented on the outside of the window like traditional shutters? It seems that would take care of condensation worries. My Dad-in-law works in the window blind industry and I have never heard him talk of blinds for heat retention but he says that in Europe they install shade blinds on the outside which is much more effective seeing as the heat has already come through your window otherwise.

I would first start with fixing all the drafty windows and doors with seal and peal.
This stuff is awesome.  It fills in the gaps and has an insulation property.
 After the cold season you can easily peal the caulking off.

Here's a little more about DIY window inserts/interior storm windows. We made some for our 1893 Maine house back in 2010, and they are only now needing some new film and weatherstripping. The cost was about $6 a window. At that time, we also insulated the attic and basement, but the window inserts felt like the biggest improvement in comfort, keeping out drafts and chill while allowing the sun in and our view out. What a great investment! With the 2 layers of film, together with the window glass, we get 3 layers with 2 air pockets, like the expensive windows used in passive houses.

You can just push them in and pull them out, so they are easy to change out in fall and spring, or when you need some fresh air in the winter.

Also, they're easy and fun to make if you have a drill and/or screwdriver, a handsaw, a square, and a hair dryer.

Here's a link to directions on how to make them from the man who, it seems, invented them:
http://www.midcoastgreencollaborative.org/Documents/storm_pamphlet.pdf

Gary Nichols wrote:Any reason why these types of measures couldn't be implemented on the outside of the window like traditional shutters? It seems that would take care of condensation worries. My Dad-in-law works in the window blind industry and I have never heard him talk of blinds for heat retention but he says that in Europe they install shade blinds on the outside which is much more effective seeing as the heat has already come through your window otherwise.

There are 2 main reasons.  

1.  In this area they would need to withstand 60 to 80 mph winds occasionally and regularly 30 to 50 mph winds.  Thus they need to be built heavy and strong.

2. For them to be effective they need to seal well enough that convection doesn't carry the heat away anyway so that means a really good seal in the closed position.

Personally I have (4) 78" x 28" patio glasses laid on their sides for clerestory windows.  To allow sun angles they probably need to be the full 8 ft x just over 3 feet.  If I did 2 layers of 2 inch foam that is another $100.  Add plywood to stiffen and a siding to protect the foam and a sealing frame work that would be another $100 to $200.  Now if I did them using salvage garage door stuff call that one zero.  Then to be really functional they need to be automated.  Using salvage stuff and a lot of time I might be able to get that down to $50 per window.  Alternately using a garage door open each that would be about another $200.  That means $250 to $550 per window.  Practical???  And it will leave sealing surfaces that need a certain amount of maintenance besides.  Now the other other possible gain here is closing in major storm / hail conditions to maybe protect the glass.

So I am currently waiting to see if the vacuum insulated windows come down in price.  The good ones there are an R13 or R14 which almost matches my wall.(with a thick special version it can reach R20.)  I will lose roughly 20% of my solar gain 5 to 6 hours a day while I am dropping my thermal losses hugely 24 hours per day but especially the night hours.  Big thing here is nothing moving to break down or maintain.  The ones of interest have a 20 year warantee and their life expectancy testing is suggesting possibly 25 to 50 years.  There is a lower end version that have a built in port for restoring the vacuum assuming.  The window blocks infrared both incoming and outgoing thus the losses incoming.  But since most of the energy outgoing is infrared it traps the heat too.  It will help with air conditioning in the summer too while letting the light in and allowing seeing out to see moon and stars which shutters wouldn't.  Since they have been in since 1984, two of them have broken seals and moisture in between the panes so need replacement anyway.  So they could be at least $250 more than regular replacement glass and still come out even with shutters of some form

Here is the glass I have been most watching.  It has only been on the market for a year and is supposed to be coming down in price as production ramps up.

vacuum insulating glass

Now there are 2 chinese makers and on european maker that I have also been watching that have been available for a couple of years but the US made one looks like a better answer long term.

Gary Nichols wrote:Any reason why these types of measures couldn't be implemented on the outside of the window like traditional shutters? It seems that would take care of condensation worries. My Dad-in-law works in the window blind industry and I have never heard him talk of blinds for heat retention but he says that in Europe they install shade blinds on the outside which is much more effective seeing as the heat has already come through your window otherwise.

Hello Gary!  


Welcome to permies!

I agree with you.  I much prefer to put the insulation and window covering on the outside of my windows.  


When I had wood heat I covered all my windows with quilts on the inside in winter and never worried about condensation.  

Now that I am on electric heat, I get way too much moisture condensing on windows and building up on the frames.  Moldy yuck if I don't wipe it up regularly.
Last winter I covered the windows on the outside and it worked pretty well.  It is a little inconvenient but I am trying to design something better for this year.


Thanks for you input!

I have used both bubble wrap and rigid foilfaced polyisoboard for many years, carefully cut to exactly fit with no gaps inside each window pane, so they are right up against the glass.   This results in zero condensation and zero mold, since the warm air cannot get to the cold glass,  zero drafts, and has halved my heating bill here in WI.

Edges Of boards are sealed with metal tape and there are metal tape handles so I can easily pop them out if I want to see out the window.   The foil facing reflects most of the heat back intothe room, keeping the glass cool and dry...no condensation.   It cost less than ten bucks per window, was very easy to do, and works great.  

Easy to remove it all in summer and  replace in fall.   If you care about aesthetics and dont have curtains, the boards can be painted or wallpapered or covered with fabric...

North windows and ones where I dont care for the view get the poly board, the ones where I want some light get bubble wrap.  

If you have hard water, I recommend using distilled water or rubbing alcohol to spray with when sticking the bubble wrap to the windows, as otherwise come spring there are little round hard water marks left behind needing a vinegar scrub.  

While renting a house that had single pane windows and a few of them had cracks, we lost lots of heat and a/c through those windows.
We did the thing were you stick bubble wrap to the inside of the windows..  This made a noticeable difference in the comfort level of those rooms as well as the amount of time the furnace had to run.

I prefer bubble wrap,   I do two layers,   gives me light and also insulates.     To hide the bubble wrap you can use window blinds and still get light.

Mart Hale wrote:

I prefer bubble wrap,   I do two layers,   gives me light and also insulates.     To hide the bubble wrap you can use window blinds and still get light.

One layer of the large bubble type is what we used.  It worked well.

I have been thinking about these for what feels like forever but never got around to building them anywhere that I lived. Then my parents moved to Maine, and one time I was visiting them and saw them in their windows! I don't know if they came with the house (not the kind of thing my dad would build, but maybe...), but it was cool to see them being used "in the wild"!

Other than being a little delicate, I love that you can still see out the windows. My head continue to swirl with modifications (usually more complicated and more expensive, but maybe not much) -- solid plastic or plexiglas panels, one that I would like to hinge so that I can still open one of the two windows it would cover......

They are the perfect Kreg jig project!

Anna Demb wrote:Here's a little more about DIY window inserts/interior storm windows. We made some for our 1893 Maine house back in 2010, and they are only now needing some new film and weatherstripping. The cost was about $6 a window. At that time, we also insulated the attic and basement, but the window inserts felt like the biggest improvement in comfort, keeping out drafts and chill while allowing the sun in and our view out. What a great investment! With the 2 layers of film, together with the window glass, we get 3 layers with 2 air pockets, like the expensive windows used in passive houses.

You can just push them in and pull them out, so they are easy to change out in fall and spring, or when you need some fresh air in the winter.

Also, they're easy and fun to make if you have a drill and/or screwdriver, a handsaw, a square, and a hair dryer.

Here's a link to directions on how to make them from the man who, it seems, invented them:
http://www.midcoastgreencollaborative.org/Documents/storm_pamphlet.pdf

Laura K wrote:I have been thinking about these for what feels like forever but never got around to building them anywhere that I lived. Then my parents moved to Maine, and one time I was visiting them and saw them in their windows! I don't know if they came with the house (not the kind of thing my dad would build, but maybe...), but it was cool to see them being used "in the wild"!

Other than being a little delicate, I love that you can still see out the windows. My head continue to swirl with modifications (usually more complicated and more expensive, but maybe not much) -- solid plastic or plexiglas panels, one that I would like to hinge so that I can still open one of the two windows it would cover......

They are the perfect Kreg jig project!

Yes indeed. Have to say, although delicate, they are also really lightweight, which makes them so easy to handle and use. Just have to avoid bumping them into corners of things when we switch them in and out fall and spring. And if that happens, we've been known to mend them with packing tape.
Also, tightening up the plastic film with a hairdryer is so entertaining.