Windows (in your house, not the computer).

[volvoguy87]

This is a new thread to avoid hijacking the oil heat vs. propane heat thread.

Replacement windows are nearly always a bad idea. (Sorry, but I'm in both historic preservation and energy efficiency.) With PROPER weather stripping and glazing putty in good shape you can get close to the efficiency of new windows with just single-pane glass. Add storm windows and you can get BETTER energy efficiency than new windows. Good storm windows increase efficiency even more. Finally, your window treatments (and how and when you use them) can actually play a big role in energy performance.

Read what Bob Yapp has to say about windows. I took his window restoration class and I've found through my experience that, crazy as it sounds, the old windows can really get some spectacular thermal performance. Historic windows are also made of components that are all pretty generic and are individually repairable/replicable, quickly and affordably. Repplacment windows are made from propriatary parts and are neither maintainable, nor repairable. The average life of a new window is about 15 years, then you throw it away and get a new one. Don't believe me? Go out to the suburbs to subdivisions built in the mid 1980s to mid 1990s (which originally had double-pane windows) and see how many original windows are left after 20-25 years. In my parents' subdivision (built 1986-1989) about 3/4 of the windows have been replaced.

This flies in the face of what you are told at Lowe's, Home Depot, HGTV, etc, but if you study the actual performance numbers it all makes perfect sense.

Please read the link attached, it explains everything better than I can.

Clear as mud?
Dave

http://www.bobyapp.com/blog/2007/12/why-shouldnt-i-replace-my-windows

 

[volvoguy87]

The bulk of inefficiency.

Most old windows that leak do so because of air getting past the window, frame, and sash. This is also the primary cause of drafts. By properly weatherstripping the window this is significantly reduced. By adding storm windows, what drafts remain, are stopped (if the storm windows are properly installed). One huge factor that is used against homeowners is that the old windows are in need of some repair (the performance of new windows is compared to the extreme worst of the worst the old windows can offer).

The glazing putty exists to seal the glass to the wood or metal frame of the sash. If this putty cracks apart and starts to fall out, then the glass is no longer sealed and air can go right around the edge of the glass. The solution is simple, fast, and cheap. The glazing must be replaced. It can be a do-it-yourself project. Glazing will last between 20 and 100 years, depending on if the paint is maintained.

Many many old windows I see leak simply because they aren't properly shut. (Yes, there are LOTS of folks who don't know how to properly close their windows!) I find that if I vacuum the window sill where the sash closes and also the interlocking weatherstripping (if present) to remove excess dust and debris, the window closes properly and makes an okay seal. Often, the window lock is broken, missing, or gummed up with slopped-on paint. The window lock isn't there just for security, when you lock it, it pulls the sashes together and makes a tight seal along the lock rail.

To weatherstrip windows, I use Dorbin Weatherstripping products. Dorbin has been in the weatherstripping business for over a century. I use metal fin-type weatherstripping on the sides as shown in the link. I use a router to route a groove in the sides of the sash to hold the fin on the weatherstrip. I attach the weatherstrip to the window frame with screws (so the weatherstrip can be easily removed and reinstalled in the future for cleaning and accessing the weight pockets to replace sash cords, if needed). With this type of weatherstripping, the fin and sash-groove act as the track, so the window glides with one-finger ease. The stops re still used, but I leave them about 1/16 of an inch off the sash to reduce friction.

Along the top of the top sash, the bottom of the bottom sash, and the lock rail of the bottom sash, I route another groove. In that groove, I put a bead of removable weak adheasive (so it can be removed later if needed) and I install a rubber weatherstripping. This weatherstripping is also made by Dorbin. It's a rubber tube with a fin on the back. The fin goes into the groove with the adhesive and the rubber tube gets compressed when the window is closed. I don't use interlocking weatherstripping because I find that the trough piece just fills up with crud over time and the sashes won't close properly. The rubber tube is cheap, effective, easy to replace if needed, and works better.

It's not rocket science, it's just windows,
Dave

http://absupply.net/weatherstripping-double-hung-windows.aspx

 

[3beltwesty]

Windows are the most lossy HVAC item in most house's HVA

A basic single pane glass window has a R value of about 1. ie TERRIBLE.

Compare this 2x4 stud walls with R13 insulation; or 2x6 walls with R19 insulation; and ceilings with R19, R30 and higher.

In many houses the windows are the largest components of heat losses, and incoming solar gains.

In a typical house, *IF* it had no windows one kills two losses, the leaky "crack length" and the losses through the windows. In many houses and buildings 1/3 to 1/2 is lost through the windows with single panes and bad fits. In a car that is moving; it is about 90 to 95 percent.

If you size AC's and heaters for houses, and are ignoring the windows, you just ruled out the most lossy item with many houses. It is sort of like doing a family's budget and saying food, rent and insurance do not matter, ie you own an oilwell!

****Windows are so bad in car since is moving ; a car AC has the same capacity as many homes. My Chevys AC unit in the car puts out about 1 ton of AC cooling per 1000 rpms, ie at 3000 rpm it is about 3 tons of AC; ie about 36,000 BTH. If one covered the windows with foam, the AC requirement would be 1/10 to 1/20th.

A single pane window can last 100's of years. The glass does not wear out, the opening and closing of the window frame is what wears.

There is reason freezers do not have windows like houses do, windows are the worst bogey.

 

[volvoguy87]

Insulating value.

Window glass's insulating value is measured not in R-Value, but in U-Value. Glass plays by different rules than solid walls.

Historic windows (I'm talking single-pane with counterweights, pulleys, and sash cords/chains here) are designed so they can be adjusted to compensate for wear. I've used this type of window over 200 years old. With halfway decent maintenance, they will last pretty much indefinitely. Replacement windows last about 15 years and their cost (but not longevity) increases significantly if custom sizes and shapes must be made.

If you're looking into replacement windows for energy efficiency, bear in mind that the time it takes for a new window to pay for itself via energy efficiency is around 90 years, but the replacement window will have to have been replaced quite a few times. The best bang for the buck is insulating your roof or attic. A more efficient HVAC system (either by replacement or a tune-up) is also a far better value for the dollar than replacement windows.

Dave

 

[3beltwesty]

New versus old Houses

In houses that are newer, the whole house is wrapped up and taped and the are as we say "tight", the windows on many houses are just for a view and NEVER can be opened; or if openable are never opened unless to escape a fire; or if painting and have fumes to remove.

As the house gets tighter the things like the doors, attic trap door are leaks to look at.

Example heated bedroom in unheated house:

In my bedroom this morning it was about 70 F inside and it was 26 F outside at 6am.

A temp probe aimed at the ceiling has it about 70 too.

It has R30 above that bedroom, the inside wall facing the outside is R13 and thus colder about 60 to 65F. The other three inside walls have R13 too.

This morning it was 26 outside; 52 in the bulk of the house and 70 in the bedroom.

***The coldest thing in the heated bedroom is the single pane window, ie where heat is flowing out of.

Covering about 2/3's of the 30x50" window with R3 foam means the electric heater was only on 600 watts last night. Without the foam I have to kick the added 900 watt section on.

Last February without the window R3 foam and R13 on the inner 3 walls; I had TWO 1500 watt heaters on when it was 12F outside.

 

[neptunebob]

Two relevant questions...

One is that our house was built in 1972 and always had 2 layer windows. Unfortunately, they were not the best brands, and now we have to replace 3 windows in the back of the house that are exposed to wind and weather. They are typical 70s sliding windows but these were the second ones from 1990 from a company that went out of business and were a ripoff. Should we get double hung windows instead of sliders? Would it be worth it to spend on a brand like Anderson or Pella?

The other question is if glass is so ineffiecient an insulator why are so many office buildings all glass? That seems like a terrible waste.

Oh, I have a third one. Our old high school was built in 1959. The original windows covered most of the building and were 1 layer of glass (if the windows broke, sometimes they would replace it with Plexiglass but then the kids would scratch the F word in them). One winter back in the 70s we had a bad cold snap and businesses and schools were shut down. To conserve the heat, they put down all the cloth shades - like that really made a difference. In the 80s, these windows were replaced with double windows and gray stucco (talk about ugly). Even back in the 50s why would an architect have so much glass area? On a dreary day, it would be more depressing than if there was less.

Oh, guess what though, the new high school will have even more glass, even in the ceilings. The architects claim the new building will be energy efficient. How would that be possible with all that glass?

 

[mattl]

It would be interesting to see how to update and maintain windows from the 50's, 60's and 70's rather than the older windows since odds are there are many more of them. There may be a moderate amount of historic homes that still have them, but in relation to more modern windows the number must be small.

My home is 45 years old and most of the windows are original wood with dual glazing. Only 1 at this point has a bad seal. I have triple track aluminum storms on 80% of the windows, all that are older, and I'm not all that happy with the performance. The storms on all the 2nd story windows are coated in ice most of the time. This indicates to me that warm air is escaping through to them. I like my humidity in the 40's during the winter, though at the moment it's 36%. I have considered replacing the windows, I would NEVER use vinyl windows, and I would never use replacement windows - hate them with a passion.

As a builder when I update a property I use new construction windows that are sized to fit the existing openings as closely as possible. I try to have at least as much glass area as was there if not more. On my last project I replaced single glazed windows with double and the sound transmission reduction was dramatic. And the heat loss was greatly reduced too. I had thought about doing the same to my home but I am open to suggestions, if there are any, on updating existing windows with out replacing them. Mine are wood with aluminum tacks on the side.

 

[sudsmaster]

This is a very mild climate here, but I am considering fabricating my own storm windows out of redwood and plexiglas - or even clear vinyl (cheaper than plexiglas). It would have two purposes: one, to conserve heat and still allow one to leave the shades up for lighting; two, to reduce the condensation inside the inner window so that it doesn't drip down and affect the woodwork.

Of course, using curtains, shades, blinds, and shutters help a lot to conserve inner heat as well as prevent intrusion of hot air in the summer.

The problem with fancy new dual pane windows is that they don't increase the R-value all that much. A single pane glass window might have an R-factor of 1. A dual pane glass window might increase the R-factor to what, two? That's still far less than an uninsulated wall, and far less than an insulated wall.

All too often, as already mentioned, old windows with air leaks are rightly blamed for energy loss, but instead of fixing the air leaks, which is relatively simple and inexpensive, the windows are all replaced at great cost, and sometimes they just don't last very long.

 

[mayguy]

We updated our windows in our house. The windows were single pane Anderson windows with a storm glass in front of it.. There were frost in between these glass every winter, and I was sick of it.

Our basement family room is warm too since we changed out that window, In the past you could feel the cold air falling on me when I'm sitting on the couch. Friday we just had our front door replaced, that was single pane glass all around with hollow door, that no longer feels cold in the landing area!

Photo of our old door.

 

[mayguy]

New door

 

[countryford]

Our house was built in 1949 and has the original metal casement single pane windows. Due to a nasty hail storm we had back in October, it broke nearly every single pane on the front of the house. We just had the glass replaced and them reputty them in. But instead of the thin glass that we had before we went with a glass that was about double the thinkness of the origianl glass. We also have large drapes over all the windows as well. Eventually we still need to put new seals in the windows. All in time I guess.

 

[joey3950]

Replace windows with"current" replacements-NOT!

2 stories. Last home a very well insulated 2 story colonial, with active and passive solar. Previous owner was an engineer,installed solar with a 40' radiator in the basement to remove as much heat as possible to the collectors. Rear enclosed 2 story porch had 6" concrete floor to absorb sun from windows placed to capitalize on thge sun's angle during the fall and winter as sun shown on concrete under house's eave, summer sun's angle was too high to shine under eave. He removed15 of the houses sash windows, removed molding sashes, ropes and weights;filled cavities of sashes with insulation, installed spring tracks,house had original millwork, frames and glass were fine, triple track storm windows were high end and worked smoothly. The new owner after us installed replacement windows... windows with a LIFE EXPECTANCY OF 15-25 YEARS TOP! Before seals go one by one or enmasse! All my friends in their 60's are watching their windows fail,to discover manufacturing companys have gone out of business. Current house has 26 Anderson double pane Anderson windows; house was built in 1971; not one window has failed, they have a lifetime guarantee; I recently bought Anderson storms!

http://[email protected]

 

[volvoguy87]

Andersons.

Anderson used to build some of the best, but now they're about average (with a $$$ name). The Anderson double pane glass panels used to be sealed with glass (molten glass was formed into the panels and the outer edge was all glass). With these types of panels, the glass was 100% of the window panel. Now they make their glass panels like everyone else. Take 2 panes of double-strength glass put a frame around them to maintain the proper separation, and seal the edges with adhesive.

With Anderson's old system, the seal was glass and was an integral part of the window panel. With the new system, the adhesive seal fails and the windows fog up between the layers of glass. There is no effective long-term solution to this.

The most efficient windows are worthless if they have a short lifespan, owing to the use of proprietary parts and low-quality materials. Maintenance free = maintenance proof, a guaranteed short lifespan.

Sorry to sound preachy, but this subject is something about which I am quite passionate.
Dave

 

[circlew]

My parents had our original single pane picture window replaced in 1961. It was always frosting up in cold weather, and made the living room chilly. The replacement was a PPG Twindow double pane insulated glass unit. It never gave us any trouble, and after I removed it a couple years ago during the renovation, it sat outside for several weeks. I cleaned it off, and it's now sitting in the basement - still in perfect condition. This unit is about 4'x4' and VERY heavy. Not sure what I'm going to do with it. The date 8-61 is stamped in the inside of the metal frame.

Former neighbors across the street had vinyl replacement windows installed about 25 years ago, and had to replace them again several years later after they fogged up internaly.

As part of my renovation I've replaced all of the original 1952 wood windows (double-hung); four in their original locations, the rest different. They weren't in terrible condition for their age, but most didn't operate smoothly. They had spring-loaded aluminum tracks that always needed adjusting. Don't know what brand they were, but don't think they were Andersen or Pella. Could have been Curtis, as that was a popular brand at the time. The new windows are Marvin, with wood interior and extruded aluminum exterior. Looked at Pella, but wasn't impressed with the roll-form aluminum on the outside - looked cheap for something so costly.
Am very satisfied so far, and sure hope they will hold up well.