Inefficient Windows
 

Someone at work asked me about inefficient windows and energy comsumption.

Since I spend most of time "under the hood" to save energy, I need some help from the experts...

Bascially they have older windows that could use replacing (which are expensive). In the interim what are the solutions to block Old Man Winter?

In the past, I've seen weatherstripping and plastic "bag" covers. Have there been any advances in technology?

RH77

Tight-fitting storm windows are still an amazing energy saver.

I've been using that plastic stuff from Home Depot for 3 years now. I received a quote recently to replace my basement windows with double-paned windows. It will cost about $1200. According to the window guy, they pay for themselves in 3 years.

There are sereval things that will help. The degree in which they help is usually on par with the cost.

Start with making sure there are no gaps/leaks that will let wind through. Once that is done you are left with surface of single pane glass that are very inefficient, but at least there is no draft.

Now you could put shutters on the outside of solid wood, which will help some. Better are stormwindows. Make sure you have some kind of weatherstrips between the storm windows and the old windows so no wind will come in. Now you have two layers of glass which will not be as efficient as real insulated glass but it's not bad as the air between the windows will still act as an inulating buffer zone.

Best would be storm windows that have insulated glass in them that you screw on the old windows with weatherstriping in between. Expensive option though and most people would then just go for new windows instead. I can still imagien this option if you have a historic home with the old fashioned windows that slide up. If you want to keep those since they are original to the house this might still be an option in the winter.

Finally, if there are some windows in the house that you feel you do not use anyway, or rarely, like some basement windows, you could buy some sheets of rigid foam insulation and wedge those in the windows. that will give those areas a great R value.

Basement windows can be fairly easily replaced by yourself using those glass bricks you see more and more. They insulate good and no burglar will try and get through those. If you do it yourself it'll be a whole lot cheaper than replacement windows.

I've done it for our basement windows. Blocking of windows with wood is good if you have shutters that hinge which you can shut every night.

If they are double hung windows, replacement sash is cheaper than replacing the entire window, and the ones I have used come with channels that the sash slide up and down in that add a lot of tightness to the entire assembly. They made a noticable difference in our house.
https://www.thewindowman.com/sashkits.htm

Some cheap things I've done with some success:

If the weather stripping is old and/or cheap, be sure to replace that. And get the best weather stripping you can find. I personally like the firm thin (aprox 2mm think by 1cm wide) stuff, that looks a bit like grooved extra firm foam (but I think is actually a rubber, vs a foam per se). The idea being, you want something that makes a TIGHT seal. Because the tighter the seal, the less air that will get through.

You will want the windows to latch very tight. So if the window latches don't do that, replace them or adjust them so that your window does latch tightly. And new (firm) weather stripping (above) can also help in this area. For example, extra think and/or firm weather stripping on the windows, means that you actually have to push moderately hard when you latch, which means that the seal is that much tighter (when the windows are closed and latched). Remember, the goal is to have a tight seal, so that air has trouble sneaking in.

And the obvious corollary to that, is to make sure that all your windows are actually "latched", and not just "shut". It's amazing how much difference (in air drafts) there can be between windows that are just pushed "shut", and ones that are actually "latched" (and therefor wedged shut firm against the weather stripping).

I noticed that the seals on our storm windows weren't anywhere near as good as the seals on our main windows. So I took a little tape, and taped over any of the cracks along the (inside) edges of the shut storm windows. This cut down on the drafts past the storm window (actually the small gap between the storm window and its track), which helped lower the heat loss on the primary (interior) window (because the less that gets past the storm window, the less that even has a chance to fight against the main window)!

And sometimes when people frame in a window, they don't bother to insulate around that frame (which was true, in the past, of many of our window frames). So if you can get access to the area where the frame meets the wall, consider squirting a little caulk (silicone caulk works well) and/or expanding foam insulation into those cracks. It's amazing how much that can help! Because a poorly insulated window frame can sometimes be more drafty than the windows themselves. And while you likely won't see this (often it's covered over with molding and/or drywall, it can still be an all too good area for the cold to come in...

And yes, that cheap plastic window film really can help (but can be a minor PITA to put up every fall, and take down in the spring). What the film does, is essentially give you one more air gap (i.e. a very thin extra "window") on the inside. This "extra window" (the extra air gap) does give the window system a little more total insulating ability. So if you need the extra warmth, by all means do so (because it's certainly a cheap, albeit a temporary, "fix"). FWIW: I currently do use the film, but only on a fraction of our windows (and only after I've done all the other tricks, above, and still want more warmth at that particular Window).

If you want to really do it on the cheap, for areas of the house that are rerely used (basement, etc), you can cut cardboard and put it in the windows or make a quick curtain using a wool blanket. either of these can be hung up tied up or removed during the daytime, or when light is needed.

i live in south florida. we have the opposite problem with efficiency. down here its a battle to keep cool in and heat out. what misty fies me is how houses are built today with 2 or even 4 windows per room. why is this? i guess it is for natural lighting. but its FAR cheaper to have 1 window, or better yet no windows, and just use light bulbs during the day.
think about it, would you rather pay to run a light bulb or pay to run the air conditioner, or heater (for you northern guys).

so based on this idea, i went looking for the best insulation i could find. and i found it in the form of 4x8 foot sheets of Styrofoam at home depot. styrofoam has huge thermal efficency. think about this, a 1/16th inch thick styrofoam keeps boiling hot coffee from burning youre fingers. most coolers are made of styrofoam. styrofoam has better insulating value than the fibreglass pink owens corning insulation, or the blown in shredded newspaper, sor any sort of plastic. about the only thing that beats styrofoam would be asbestos (which i have some of but wont use it indoors due to heath reasons).
each sheet is about $15 bucks. and 1 sheet can do 2-3 windows. each sheet is also 4 inches thick and has a plastic thermal barrier on one side. you cut a square out of the sheet to fit snugly into the window frame, blocking heat and light. this has a HUGE energy savings benefit for my during the summer. it cut my a/c bill by about $75 each month. i blocked nearly all the windows in the house off.
the other neat thing about Styrofoam is that you install the white side facing out, so when you are outside the house looking in, it just looks like you are looking at a white set of curtains or blinds. and if you do have curtains or blinds, keep them shut so you don't see the Styrofoam inside. most people who visit my house don't even know i have Styrofoam in the windows, its that non invasive.

i think it cost me about $60 to Styrofoam all the windows in my house with 4 inch thick styrofoam. i used 1 inch thick styrofoam on my sliding glass door because if i used anything thicker, i wouldnt be able to slide the door open.

the best parts of using styrofoam is that its totally removable, there is NO bolts, screws, glue or tape used. you just cut a square out of the sheet and set it in place. when there is mild weather and you wish to open the windows, the removal of styrofoam is quite easy, just pull it out and set the sheets in the garage or attic. and the real big kicker is that styrofoam sheets make even the most inefficent windows super insulative. so it saves the need to upgrade to expensive double panes, etc.

its cheaper to run a lightbulb than it is to run the air conditioning.

the black hole thing is no big deal. just add a compact fluorescent or even 2. right now its 70 during the day, 60 at night. i have all my styrofoam removed and the windows are all open.

Modern windows have awesome radiation barriers - which is how most of the heat will get in (assuming there's no air leaks) ;) There's a cool display at home depot using two radiometer globes (radiant heat makes them spin), some glass and a halogen light bulb - one with old window glass, and the other that's filtered. The difference in amazing :)

If your windows aren't like this (like most people's), the insulation idea is a pretty good idea. Just make it removable in case of a fire. Adding an attic fan also helps out a whole lot :)

window displays at the depot generally show best case scenario. theres no such thing as a window thats as good as a well insulated wall (as in not having a window). perhaps on the space shuttle or other extreme concept. but not in a house. its just not practical.

there may be modern windows that are well insulated compared to old single pane windows, i cannot argue that fact. but there isn't an actual "well insulated" window. the very nature of a window means it can't be well insulated.
there is generally 3 types of heat transfer. radiation is only 1 of the3 convection and conduction are the other 2. so a radiation display at the depot would only adress 1 of the 3 ways heat and cold gets through windows.

i cut my electric bill by a solid $75 a month just by covering the windows with 4 inch of styrofoam. and i have those double pane agron or whatever filled windows with DIY limo black solar tint on the outside. still i got a $75 a month savings.

besides windows, theres tonnes of things one can do to save electricity, power and gas. when you brush yer teeth or wash yer hands, the water that goes down the sink drain is wasted. its basically clean waste water. why not plumb that water into you're toilets charge tank? could also save the shower water for the same purpose. shower water and sink water is clean waste water and would work well for flushing a toilet. so would the waste water from a washing machine.

theres so many ways to save money but nobody does it. i can guarantee none of you will insulate you're windows with 4 inches of foam like i suggested. none of my friends or family have insulated their windows like mine except for my dad. but he liked it so much that he went a step farther and drywalled over 75% of the windows in his house. he also put new vinyl siding over the outside walls and covered up most of the windows.

down here in the summer there is a 30 degree temparture differential between indoors and outdoors. for you northern types the winter could see temps from 70-100 degree temparture differential from indoors to ourdoors. that means window insulation is even more important up north in the middle of winter than it is for me in the summer.

The foam idea is actually pretty good for the SUMMER.

However, in the winter you actually want the "greenhouse effect" to warm the house. And you get that by having the sun come in through the (closed, and hopefully well insulated) windows into the room (where the sunlight bounces off things and some of that light gets converted into heat as a result). Effectively, this is a passive form of "solar heating", and it REQUIRES windows that will let light in (but stop drafts). And you prevent that from happening, when you put the foam up.

Of course, as already mentioned, the idea is great for keeping cool in summer (as you are using it for), because the foam will not only provide insulation, but also cut down on the greenhouse effect (and in summer the last thing you want is to heat things up more). But in winter, you want all the passive solar heating you can easily get. And that actually argues for having the shades (or anything else blocking the sunlight) open during daylight hours when the sun is shining (as that sunlight can be usefully turned into HEAT for the home, by use of the same principle that heats a glass greenhouse)!

BTW: I have actually used foam sheets as a makeshift shade (and heat barrier) on my windows in the past. However, I only do this in the summer (when I want to block the sun from heating the house), not in the winter (when you want the passive solar heat), and so far I haven't used as thick of foam as you have (I think my foam sheets are only an inch or two thick).

tomorrow I will be getting some caulk and going to town on all the small edges on my Anderson windows. the north side i use the shrink wrap plastic, i had a small hole last year and the cold air was pouring in fast through the dime sized hole. the 2 east windows i used bubble wrap on the inside of the glass, you can feel the difference in temp, and it lets light in while keeping the view private. the other window on the east is 1pain glass, the wife likes it so i used Plexiglas with foam tape, screwed it right to the window frame outside and inside I'll use shrink wrap plastic. west/south windows i keep them clean as possible and use the sun to heat during the day.

It is funny that up here (Wisconsin) they require you to have 16 sq feet of glass in a bedroom in new construction, that’s typically two 2 foot by 4 foot windows. On the flip side they require you to have a minimum of 6 inches of insulation or R-19. Guess what the BEST windows are, R-2.2 (with storm). A typical window is about R-.75 with some cheap ones at R-.25 and "good" ones about R-1. Anyway I just about fell over, a single 2x4 windows is what we had designed for energy reasons, but they made us add more, crazy.

Oh if you cover the inside of a window make sure it is sealed air tight or you will get a lot of condensation on the interior sill. It is far better to insulate the outside, but typically much more difficult if not impossible in some situations.

One of the neater things I saw were insulated awning that opened and closed with photo cells. So in the daylight they would open, then when the sun went down they closed an R-10 shutter to keep the solar gain in, pricey but neat.

The easiest thing and likely the cheapest is the clear heat shrink inside plastic.

according to https://www.dow.com/styrofoam/media/n...s/bncfacts.htm

styrofoam has an r value of 3.0 per half inch of thickness.

so a typical window of of r1 plus my suggested 4 inches of styrofoam would equal an r value of 25? holy **** thats alot.

can that be true? i always knew styrofoam was one of the best insulators for a house, but that much? look at a cup of hot coffee. the liquid is 180 degrees. 1/16th inch thick styrofoam keeps youre fingers barely warm. thats some good insulation.

wikipedia says per inch 3.6 to 4.7 for low-density, 5 to 5.4 for high-density.


for you northern types, i wonder is styrofoam in the windows could be more efficient than letting the sun in.

An option for those who live in temperate regions where either the night or day is in the desired temperature range is to duct a fan to pump air inside the house from directly outside (better than an exhaust fan because the air sucked in can get heated by walls etc). Often here in summer Australia the nights will be at a tolerable temperature but the days will be intolerably hot. If you have a reasonable amount of thermal mass (i.e. concrete or brick walls) inside, they will keep the inside air cool for several days. You just have to remember to turn the fan off during the day.