Recently, Home Energy Publisher Tom White participated in an interview with "Replacement Windows for Dummies," the popular book series known for approachable information on nearly every topic. They discussed what's new in the world of windows, tips on hiring qualified window installers, and much more. Below is a snippet of their conversation.

RWFD: What are some of the most significant new developments in energy efficient windows that benefit homeowners?

TW:  There are some new technologies that DIYers can take advantage of in terms of different types of windows. In terms of the glazing or the glass unit themselves, there are recent developments in high performance windows and the core of the modern high performance window is the insulating glass unit. That’s the sealed assembly of two or more coated layers of glass and often they’re constructed with inert gas in between the panes that provides insulation. Sometimes they have films applied or even four layers of glass depending on the insulation value that you’re going for.

There are also new coatings that are being applied to lower the emittance of the radiation coming through the window and you can choose spectrally-select coatings which are often referred to as low E coatings. So if you want to have light coming in on the west side of your house but you are concerned about increasing your air conditioning bill because it might get too hot, there are types of spectrally-selective window coatings that will let the visible light in but will block the infra-red light spectrum, which is what we perceive as heat.

Additionally, there are new types of window frames that are low conducting. Typically, aluminum framed windows have a very high conductance but vinyl and composite frames have lower conductance and therefore higher insulating value.  So there have been improvements in the framing as well as in the insulating glass unit and the types of glazings and coatings applied to the glass itself.   

RWFD: What are some simple things a homeowner can do with the windows in their homes--short of replacing them--to save energy and money?

TW: A lot of older homes have windows that just need a little bit of tightening up--perhaps the wood has shrunk over the years or the house may have settled some. So you may just need to add some bronze metal or some other type of weather stripping or air sealing in the window channels. You can also apply felt to the window ledges to keep air out.

The primary concern with older windows is that they’re a source of air infiltration so if you can keep the sides of the windows plumb that helps to seal them. If the windows are not well aligned with the frame and the putty that holds the glass in the frame is not tight, you may be getting air in from around the glass itself. Plus there are films that can be applied to windows that will lower the amount of conductance and lower the heat gain. In order to provide more insulation,  you can add things like storm windows or shutters on the outside of the window and there are even window quilts which you can use to both lower  the amount of air coming into the home and improve the window’s insulation value.

Read the entire interview at

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Comment by Terry D. Davenport on September 28, 2011 at 10:59pm
American windows forget about solar heat gain.  German windows  have the solar gain and the good u values.  I have been told you cannot do a Passivhaus with American windows because of  this.  It costs ten grand to ship them to Montana.  I think we need to rediscover window shutters-- with foam insulating cores.  I can buy an inch and a half piece of polyiso for about $25.  So what would an R 10, U .10 window cost?  More than a shutter.
Comment by Bud Poll on September 27, 2011 at 8:25am

Hi Meni, I guess I need to have you clarify your question, not sure what you mean??


Comment by Meni on September 27, 2011 at 6:50am
So these insulated windows prevent outside temperature changes to affect the temperature inside? Did I get it correct? Based on this it will be a great idea to install them in cities falling in the extreme temperature belts where people spend KW's of power for cooling and heating.
Comment by Bud Poll on September 26, 2011 at 8:33pm

Hi all,

Joe, I hope you don't try to explain that to your customers, especially the ones who LIKE windows, myself included.  I agree that windows have been misrepresented as a great place to begin ones energy improvements, when in fact only a select few are bad enough to justify, if we have to live by SIR, being replaced.  However, they are visible.  I mean, when you replace them the home owner knows something was done.  They look great, they work great (open and close, easy to clean), and if selected properly, they do perform better.  Between the improved r-value, the reduced air leakage, and hopefully the better installation, new windows can put a much needed smile on the owners of the home.  To be honest, I don't care if it's just 3-5%, although I think you are short changing the savings, but if it fits the budget and was on the home owners wish list, I would be proud to have them installed.

As for not needing windows, it all depends upon what you have to look at.  A view has value and it takes a window to allow people to enjoy one from the comfort of their home, then heat loss or gain is of little concern.

But I'll drift a bit as the future will probably eliminate most windows as we know them today.  How about a window with an r-value equal to your walls.  One that can show you what's outside, or the sunset in Hawaii, without having to relocate.  You are probably looking at one right now, it's a flat screen.  Flat screens are good and they are going to get better.  Now fill in all those holes in your walls and hang up a collection of flat panel displays.  Selective place cameras around your home, inside and out, and connect it all through a smart box that can select from home or internet and display anything you want from anywhere in your home or anywhere around the world.  Security, you can check every corner of your home and property on demand.  Empty nesters, enjoy dinner tonight with the kids, now living 2,000 miles away.  Realistically, the possibilities are endless.

Of course we might still have to put faux windows on the outside to keep the house looking good, but the days of glass are coming to an end.




Comment by Macie Melendez on September 26, 2011 at 7:12pm
Joseph, your blog was great - thanks for sharing. Also got a laugh with your new title...
Comment by Al Heath on September 26, 2011 at 7:07pm

Hooorrrraaaay for Joe Novella honesty about new windows. 


Sure they was great if you have an unlimited budget but I've see a lot of great energy renovation project budgets go down the tubes with the $10-20 grand for "energy saving" windows

Comment by Joseph Novella on September 26, 2011 at 4:19pm
Should be titled, "Only Dummies Replace Windows". See my blog on windows.
Comment by Macie Melendez on September 20, 2011 at 1:24pm

Hi Bud, Thank you for your thoughtful feedback! Any interest in writing a blog for Home Energy Magazine about this subject and your experience in the field?

Comment by Bud Poll on September 19, 2011 at 7:31pm

Hi Macie,

I enjoyed the read, but had to chuckle at the contradiction, Replacement Windows for Dummies?  The advice Tom was providing was often well above any understanding of the general public.  Here's an example:

"TW: You’d want to make sure that the sales person is explaining the different insulation, solar heat gain and visual transmittance quality of the window because you will want to have different values for those windows depending on their location on your home. You’ll also want to understand the energy performance of the window as a whole which includes the frame, as compared to the insulation qualities of the actual glass unit. Be sure to ask about expected savings and payback periods for the windows and do they apply window to window or to the house value as a whole. And when asking about lowering your utility bill, ask what kind of model are they using when they project savings as compared to what you can expect from YOUR house."

Now that's a mouth full.  To be honest, I have only encountered a couple of home owners who could follow or understand that level of information and they were both professors at our local state university.  In addition, Tom is suggesting they get this information from a sales person.  I hope you see the humor in that.

The message here is education, but at a level the home owners can use.  In my work as an energy auditor, information like this should be directed to me so I can act as the interpreter for the home owner and that is part of the relationship I create with each.  Expecting a home owner to go up against a polished sales person is beyond the Dummies training.

To give you a touch of the real world, I often ask sales people and contractors if they install different windows on different sides of the house.  Most look at me in a strange way, but NONE have ever said they sell different windows for the same home, let alone explain why.  (of course I do know some green contractors out there that know the difference).  So perhaps the education process needs to be extended to the stores as well, although that could be dangerous.



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