I would consider a company that is specialized first. Kind of like bringing your car to your local mechanic and having them put in a windshield.

I would not consider Home Depot even if they could meet your reqquirements.

Sunrise is a respected name in the window world,so it would be a brand Window World would not carry.

Forget about R value and just stick with u value.
.30 or lower is the minimum U factor to go with.

My recommendation would be to purchase the windows from the company that installs them. That way they are responsible for the correct measurements, not you. If you order them yourself, you will have to deal with the factory if any warranty issues develop. You would also have to provide or pay for the labor even if it's a valid warranty claim.

Sunrise is one of the very best quality vinyl windows you can buy. Factory service is top knotch. Never assume that all warranties are handled equally by all manufacturers. Those of us who have been around can attest to that.

U factors are the inverse of R values. Typically R values are a measure of resistance to energy transfer while U factors actuall are a measurement of the rate. The important thing to remember is the lower the U factor, the less energy is being transferred and thus, the more energy efficient the window is. To convert a U factor to an R value, just divide 1 by the U factor. In other words if the U factor is .25, the R value would be 4. Double pane glass with LoE coatings and argon as will have a U factor between .28 and .32. Some windows could be slightly better and some could be slightly worse.

You also need to consider the solar gain or SHGC. This number measures the amount of infrared or radiant heat that passes through the window. You should employ the assistance of a seasoned window professional to help you decide what SHGC is appropriate for your home based on geographic and the geological position of your home. It is very likely that some windows would perform better with a higher solar gain and some would perform best with a lower solar gain. This is even more reason to hire an experienced window professional.

Todd is saying that Sunrise Windows are good at what they do.

+3

Go with a specialized window company. They will likely save you heartache in the long run.

HD does have a few nice windows but nothing on the level with the upper end Sunrise and their installations have been questioned previously.

Stick with U-Factor as it is the comparative rating used to evaluate the thermal resistant of windows. U-Factor is jut the inverse of R-Value but you won't see R-Value indicated on the NFRC sticker or website and I often see questionable data representation by folks representing R-Value numbers (i.e. Center of Glass R-Value quotes).

And yes....the Sunrise is certainly better at what it does.

See...and you guys thought it wouldn't stick but you are still quoting me...Ha Ha!

You and Bill Clinton are my favorites to quote.
Bill's best is "depends on what the meaning of is is."
WOW's best, " it is better at what it does"
Maybe new career as speachwriter, politician?
You already got my vote.

Thanks very much for everyone's input. It's been very helpful.

What is the possibility my windows are actually okay, and it's the insulation around them that's lacking? In other words, the house is quite old, and insulation technology wasn't very good.

Is it possible (or likely) the issue is with the insulation around the window and how it's sealed?

Would a window replacement company have some method to determine where the drafts are coming from for sure?

You could have an infrared photo of your house done. Don't expect to have it done for free, though. The equipment is very expensive.

Yes it's likely the walls aren't insulated properly because 50 years ago, people weren't really concerned about utility bills. However, I suspect that by the time you spend money on an energy audit, spend money re-sealing the windows, add storm windows and ending up still with 50 year old windows, that it would make more sense to replace them. A 50 year old house isn't exactly considered a historic home unless it was a custom design and build.

Here is a link that might be useful: Infrared scanning

I am in the right city for it Todd.

To the follow up poster, an energy audit with a blower door test and IR camera would tell you everything you need to know.

You can also just pull off some trim and see for yourself.

Thanks for the info on the infrared scanning. I'll ask the window salesperson from the company we're considering about this, and perhaps he knows how this might be done. Looks like something we'd have to have done in the winter, here in northern NJ.

What other typical questions (other than the obvious price/warranty) should I be asking the salesperson?

There are a lot of questions but it depends on the results of the energy audit.
If you decide to tear out the windows and take care of leaks in the walls, it might be advisable to replace the new windows as new construction with nail fins.

First things first, though. Get the energy audit.

new windows most certainly will make a big difference.. be sure to select a quality vinyl window such as Okna ,Sunrise, or Gorell.
i know all 3 of these brands and they are designed very well and have great performance numbers . avoid wasting money on anything sold in building supply houses.
usually a contractor selling the higher end brands will do a proper installtion.