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How Efficient Are Single-Pane Windows?

How efficient are single-pane windows?

Obviously, not very!

Notice the coolest temperatures on the left side of this window.  That is the side where the sliding window is encased by the sash.  That area is typically the most leaky.

In this case the temperature outdoors is about 45F.

And the temperature of the window pane and framing is just above that!

How efficient are single-pane windows?  Not very!

A decent window pane, one that meets Energy Star standards for Virginia, would have a U-factor of .32 or less.  That translates to an R-value of about 3. ** By contrast the walls nearby have insulation with an R-value of about 13 (if you include the brick on the outside).

The R-value of a single-pane window is about .5.  That is virtually nothing.

That is not very efficient!

Remember, heat seeks cold.  In the winter heat is getting out.  In the summer heat is getting in.

My recommendation:  older condos with single-pane windows should have replaced them years ago with something more efficient.  Buying a condo with single-pane windows means the buyer is inheriting high energy costs year round for the life span of the purchase.  Renting a condo with single-pane windows means the renter is inheriting high energy costs year round for the life span of the rental.   Consider carefully!

**  The best windows have U-factors of .12 or .15.  If you are building a home, ask the builder what the U-factor is for the windows being installed.  And you can look at the sticker.  An instructive blog I wrote 2 years ago can be read by clicking here

 

 

Jay Markanich Real Estate Inspections, LLC  

Based in Bristow, serving all of Northern Virginia.

Office (703) 330-6388   Cell (703) 585-7560

www.jaymarinspect.com


Comment balloon 16 commentsJay Markanich • January 13 2016 03:12AM

Comments

Good morning Jay. Great subject! Was giving that consideration looking at apartments for rent in downtown Chicago! Enjoy your day!

Posted by Wayne Martin, Real Estate Broker - Retired (Wayne M Martin) almost 3 years ago

Well, Wayne, break out Mighty Mo and have a look!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 3 years ago

I'm not surprised! Windows can be a huge source of drafts and cold air in the winter. Brrrr. 

Posted by Kat Palmiotti, The House Kat (Grand Lux Realty, Monroe NY, 914-419-0270, kat@thehousekat.com) almost 3 years ago

All true Kat.  And drafts are caused not only by old windows where they poorly fit together, but the convective loop created inside from the meeting of warm and cold air.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 3 years ago

Here it depends on the condo Jay Markanich sometimes it is up to the association to replace them and sometimes the owner.

Posted by Sally K. & David L. Hanson, WI Realtors - Luxury - Divorce (EXP Realty 414-525-0563) almost 3 years ago

Of course it is S&D.  What gets done and not done is always association purview.

Which is why I say to consider everything before purchase.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 3 years ago

Good morning, Jay. Not very is the correct answer. Dual pane are not too much more.

Posted by TeamCHI - Complete Home Inspections, Inc., Home Inspectons - Nashville, TN area - 615.661.029 (Complete Home Inspections, Inc.) almost 3 years ago

The panes are fine, Michael, but the edges leak a lot! 

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 3 years ago

Good morning Jay,

Amazing tat most here also have never been replaced as they thik it is part of HOA.

Make yourself a great day.

Posted by Raymond E. Camp, Licensed Real Estate Salesperson Greater Rochester (Howard Hanna Real Estate Services) almost 3 years ago

Original windows, Raymond, installed oin 1972.  So, seeing this, how diligent is this association about other things?

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 3 years ago

Quick question Jay Markanich .... what about single glass windows with storm windows over them, this is used a lot here on the east coast and the dead air between seems to work well.

Posted by David Popoff, Realtor®,SRS, Green ~ Fairfield County, Ct (DMK Real Estate ) almost 3 years ago

Good morning James. I get it and agree but really old homes have very neat and beautiful windows that are hard to disgard.

Posted by Sheila Anderson, The Real Estate Whisperer Who Listens 732-715-1133 (Referral Group Incorporated) almost 3 years ago

David - good storms over medium or even poor windows are in MANY cases more effective than the super-duper-wooper new windows.  Dead air is indeed an insulator.  Case in point - the igloo.  That portico on the front is an insulator of dead air.

Sheila - true, and some jurisdictions won't allow you to if the house is a historic one, at least on the front elevation.  So what to do?  See comment to David!

 

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 3 years ago

I haven't seen single pane windows since I left Florida! They are all double paned here, even the old ones.

Posted by Fred Hernden, CMI, Albuquerque area Master Inspector (Superior Home Inspections - Greater Albuquerque Area) almost 3 years ago

I've got Anderson casement windows from 1991 installed in my home.  The seals on 2 windows are failing.  Do you have any recommendations for window manufactures in our area?  You hear so much hype in their advertising, it's hard to know which way to go.

Posted by Stephen Weakley (Nationwide Mortgage Services) almost 3 years ago

Fred - well aren't you lucky.

I mean, excellent!  Those efficient Florida windows don't work out there?

Stephen - I think Anderson will actually come to your house to fix broken seals.  You might try that.   And new windows will NOT save you 35% on your energy bills, or so say the ads.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 3 years ago

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