The Truth About Windows?

Replies to This Discussion

Permalink Reply by Alexander Bell on May 26, 2011 at 9:03am

If you look closely at the inputs for Manual J in Wrightsoft; exterior storm windows provide some benefit.

Example: single glaze wood

SHCG w/o storm 0.64

SHCG w/storm 0.56

U-val w/o storm 0.90

U-val w/storm 0.57

 

Example: double glaze wood

SHCG w/o storm 0.56

SHCG w/storm 0.51

U-val w/o storm 0.57

U-val w/storm 0.44

 

Actually the larger air gap can create convection loops, so not necessarily a benefit.  Exterior storms are also designed to be sealed on three sides with an allowance for weeping/condensation/drainage on the lower edge.

 

Without first hand experience, interior storm windows seem to be a better option. 

 

Permalink Reply by t hardy on May 27, 2011 at 8:11am

Surely not true.  The bigger spacing allows for more convection and convective losses between the two surfaces.

No?

Permalink Reply by t hardy on May 26, 2011 at 10:54am

I certainly agree with most of the posts in reply, with one additional thought.

Determine the cause of the reasoning.  I have found in some cases that the homeowner is really talking about one or two specific rooms and has then made the mental leap to all rooms.  For instance a bedroom on the north side that is coldish in the winter time, or a favorite sitting room for sedentary activies such as reading.  In these particular cases, it may be perfectly reasonable to swap out the glass for super triple glazing and achieve the comfort  level the customer desires because of radiation effects.  Hot  (the customer) to  fairly cold (the window).

You know, the sort of thing that was happening  when your grandmother still complained of drafts in her house that she had heated to stifling temperatures.

Permalink Reply by John M on June 2, 2011 at 1:51pm

Window salespeople have 'see and feel' going for them:

See- new windows look much nicer than an airsealed attic and basement

Feel - customers will feel less intense convective loops and radiant losses replacing a R-1 single pane with a R-3 double pane. 

 

Customers' 5 senses are hard to argue with! And who actually verifies energy savings anyway?  

Permalink Reply by Timothy DeLuca on October 31, 2011 at 8:05pm

I have seen the same results in my NEAT/MHEA experiments. In our area double panes will never come up cost effective under any conditions if both panes are intact.

Permalink Reply by Avery Ray Colter on November 14, 2011 at 8:53pm

That is a loaded question, and depends a lot on the window to wall ratio of your windows. I just was in a webinar today which spoke of dense-packed insulation, the fact that many older homes have wall cavities which are open into the attic, etc. I looked at windows for my house, but one issue which has kept me away is that I would have to have a larger opening cut for current egress requirements as part of changing out our bedroom window, so add that to all the other costs. I have metal double-panes currently. I can think of a number of air sealing, insulation and radiant barrier tacks to take before looking at windows again.

Permalink Reply by Rob Orchard on December 18, 2012 at 7:42am

We've done audits and upfits to several thousands homes in South Carolina over the past four years. Our customers are interested in lower power bills and are generally on a limited budget. The cost vs. benefit of insulation, air sealing, duct sealing, or even a high efficiency HVAC replacement as compared to replacement windows seems like a no-brainer. In only a couple of cases out of thousands did replacement windows make any economic sense. www.carolinages.com

• ‹ Previous
• 1
• 2
• Next ›
• Page