Monday, April 5, 2021

Heat Conduction Through Your Windows

Do Replacement Windows help with heat?

Can Vinyl Windows instead of Aluminum Windows make a difference.

I have to admit I was really excited on this one.  The front of the home had a big triple unit, two sidelites and a transome with one upstairs.  Easy day.  Except my driver didn't get the two sidelites.  

Okay new plan, hang the ones we have and just get those two in the morning.  We told the customer two days and although it could have been one, it was hot, and Chris was sick.

Here's where it gets fun.  The customer had a laser pointer with a temperature display on it.  It was awesome.  You'll never believe what I found so I've provided all the pictures to give it some context.

I did the triple first.  Here's the before shot #throughglass for a time frame.

An hour or so later the old ones were out and I had some new ones starting to go into place.  This is actually three windows mulled together.

This set came in at .27 U Value with a .19 Solar Heat Gain Coefficient.  That's pretty awesome.  The numbers are actually a little better on SHGC when you have grids as they block the sun and lower that number.

So we're making progress.  I noticed once I set the two bottom ones you could almost feel the heat above them immediately.  I tried to catch in on film.  You have to decide if I did or not.

But the process continues.  I set the half circle and started the process of squaring them all up together.  The mullions make it so they have to straight and next to each other, but the new ones being square is more important than being straight with the house.  It's a long story but sort of irrelevant for this story....

I got them in and it was time to seal.  I went out to get caulking guns and glass cleaner.  When I came back, my customer had produced a cool laser light thermometer.  I've seen the air conditioning guy use these before.  They tell you if the air at the vent is coming out cold.  Interestingly enough, it will also tell you an amazing fact about heat reflective glass in modern vinyl replacement windows.

That fact is:  They totally rock.

I got the bead of sealant around the window by around 1:20.  The room was still pretty warm from being wide open just a few minutes earlier.  The sun was heading down in the West right into the front yard we were working on.  As I stood on the ladder caulking the second floor window I could feel the heat being reflected alright....  right into my face...  making me very miserable.

So back to the thermal thingy.  Sill temperature inside on the center of the sill at around 5:30 was 77 to 78 degrees after the house had re-equalized.  I thought that was great. It was working.  This was about the same temperature as the house itself.

Here's where it gets super amazing and brings up an ever interesting subject - Conduction and Convection Heat.   I know you're excited!  Here's the picture that creates the discussion.

Even after the house had reclimatized, this was the center sill temperature inside the sidelight.  This window is aluminum builders grade type double paned clear windows.

There are literally millions of them in North Texas alone.  This was the standard from the 70's into 2008 when aluminum was no longer Energy Star Rated.  Almost 40 years of homes have this window.

There were some that read lower and some were up to 111.  I'll put them below.

Did you know that it being 95 degrees outside in direct sunlight puts 110 degrees on your window sill?  Can you imagine what that does to your air conditioning and the poor machine trying to crank out that nice cold 60 degree air at the vent?

Here's the best explanation I could find on the types of heat transference.

Author and original source:

How is heat transferred?

Heat can travel from one place to another in three ways: Conduction, Convection and Radiation. Both conduction and convection require matter to transfer heat.
If there is a temperature difference between two systems heat will always find a way to transfer from the higher to lower system.


Conduction is the transfer of heat between substances that are in direct contact with each other. The better the conductor, the more rapidly heat will be transferred. Metal is a good conduction of heat. Conduction occurs when a substance is heated, particles will gain more energy, and vibrate more. These molecules then bump into nearby particles and transfer some of their energy to them. This then continues and passes the energy from the hot end down to the colder end of the substance.


Thermal energy is transferred from hot places to cold places by convection. Convection occurs when warmer areas of a liquid or gas rise to cooler areas in the liquid or gas. Cooler liquid or gas then takes the place of the warmer areas which have risen higher. This results in a continous circulation pattern. Water boiling in a pan is a good example of these convection currents. Another good example of convection is in the atmosphere. The earth's surface is warmed by the sun, the warm air rises and cool air moves in.


Radiation is a method of heat transfer that does not rely upon any contact between the heat source and the heated object as is the case with conduction and convection. Heat can be transmitted though empty space by thermal radiation often called infrared radiation. This is a type electromagnetic radiation . No mass is exchanged and no medium is required in the process of radiation. Examples of radiation is the heat from the sun, or heat released from the filament of a light bulb.

While all that is indeed a mouthful, It means the sill is hotter than the temperature outside because my windows is in the sun and not in the shade.  


We can all go home now.  

No I'm kidding.  

It means the metal conducts the heat and gets hotter than 95.  Probably well into 115 or 120 after the sun beats on it for 5 hours.  That the air (and the wooden sill) are convecting heat from the window frame, and the glass. And the entire thing, like the sun on the other side of it, is radiating heat inside towards my precious ice cold air conditioning.

The end of the day just before I took the thermal shots.  This shows the new triple that had 77 and the sidelite by the door that showed 107 to 111.   Thirty degree difference!  One day, half a day really.
The second floor one was a real hot beast to stand there on an extension ladder and caulk.  Hottest 15 minutes you'll ever experience.  No need for a tanning booth afterwards either.

On this you notice the numbers are at .27 and .20 instead of the .19 on the window under it.  This is a good one to know.  Brochures have approximations and are close but often not accurate.  Also if they test out a 2-0 by 3-0 but you build a 4-0 by 6-0 with that window.....    it won't be the same.

This one is different because the grids are larger, allowing more direct sunlight and therefor having MORE of a SOLAR HEAT GAIN Coefficient.  Cool huh?

Hey send me an email if you'd like!

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Monday, August 24, 2020

Sound Rating Information on Windows

Sound Ratings for Vinyl Replacement Window Glass Packages.

I've been doing some research for a customer by Dallas Fort Worth International Airport.

Noise is a big reason to buy new replacement windows.  Some of the widely accepted and published sound information shows that a typical single glazed window will allow you to hear any noises louder than 21 decibels.  Moving to a double paned glass package will cause a move to 24 decibels.  To add Argon Gas filled insulated glass will raise that noise threshold to 32 decibels.

This is a significant change and effectively makes the window twice as quiet.  From a personal experience standpoint I know that most of my customers say the house is significantly quieter at that point.  It's a huge difference.

The metric most often sited on noise is STC or OITC Rating.   These numbers are hard to gauge on most windows as they vary based on the size of the window.   When you see a manufacturer site numbers they are usually from a specific window and size tested.   Individual results will vary due to window size, siding and other factors.  Some recent (1-2021) stats are as follows:

How glass thickness and type effects sound resistance in replacement windows

This chart from my website was originally put out by Cardinal Glass when Argon Gas first hit the replacement window scene.  Argon being denser than oxygen helps slow sound as well.

Alside is one of my suppliers that does extensive testing on STC and OITC data.  They show their Mezzo Vinyl Replacement Windows, Ultra Max and other models have the following performance increases from varied glass packages.

The actual testing information is attainable for all their products at this link:

These options change the thickness and configuration of the window glass to provide varied results.  Overall consensus is that moving to a thicker pane of glass in a double paned application will change the wave patterns of sound as they pass through the glass package.

Typically double paned builders grade windows use single strength glass.  Modern mid range cost vinyl windows will utilize double strength glass and have a 1/2" dead air space that is optimal for Argon Gas.  Krypton Gas is best served with a smaller dead air space and is the upgrade used in a typical triple paned glass package.

From here the next step up is going to be triple glazed with Krypton Gas filled insulated glass.  This is a considerably better glass package from a thermal standpoint as it can lower the U Value from .30 or .29 down to the .16 or .18 area depending on the manufacturer, but it doesn't offer a huge jump in sound reduction.  It does make it a bit better, but not a significant noise difference.

In fact, as I read the data and research, it appears as though double paned glass with thicker (3/16") glass is a better sound barrier than is triple glazing with typical thickness single strength or double strength glass.

Moving up the sound barrier ladder we'd see a double strength glass over 3/16" annealed glass in a double paned glass package with Argon Gas.

The best performance comes from Hurricane rated windows as they are constructed with Laminated Glass in the insulated glass package.  Laminated glass is glass like in the windshield of a car.  It is effectively two panes of glass with a clear plastic between the two panes of glass.  When this is used as the outside pane of a double paned insulated unit you effectively have three panes of glass and a plastic laminate to block the sound.

Here's what data I could get from Archetectural Testing, an independent testing firm that works with glass manufacturers and curtain wall fabricators.  Many of these glass packages are commercial and not available in residential replacement windows but the data is interesting none the less.

There are two different types of Laminated Glass.  One has a plastic film that is .030 inches thick, the other has a plastic film that is .090 inches thick.  The cost difference is significant between the two.

Upcharges tend to run like this.  Double paned with Argon Gas filled insulated glass in a standard sized window will be around 450 to 550 per window installed from a good reputable manufacturer.  Going to a double paned with 3/16" glass in the package will add about 100 per window to that cost.

To upgrade to Triple Glazing with Krypton Gas will add about 200 per window.  Moving up to a Laminated Glass package will add $200 to $250 to the double paned pricing and the thicker laminated glass package will add about $430 per window to the cost of the double paned unit.

Mid range windows and high end windows use the same frame but the glass packages are generally the big variable as are simulated divided lite grids, two toned color configurations and woodgrain interior appearance.  Those all run the cost of a quality mid range product up to the high end range.

I tell people to budget at $600 to $650 for a double paned Low E with Argon that has a lifetime warranty from a reputable manufacturer.  As you can see this window can easily end up in the $1000 a window range when you put the top of the line glass package in it.  It can get even more costly when you utlilize the other upgrades mentioned.

FYI:  Simulated divided lite grids are grids that protrude from the surface of the glass.  This is in contrast to grids that are between the two panes.  A simulated divided lite grid is a grid system designed to emulate true divided lites in a window.  SDL's are somewhat costly at around $20 per lite as opposed to grids between the glass which add about $30 to$35 total to the cost of a window.  In a fifteen lite three foot by six foot tall window there are generally 15 lites and the upcharge is $300 to $350 per window for the cooler grids.

Also, custom exterior colors generally add $100 to $150 to the cost of a window.  This creates a two toned window with a painted or laminated exterior color and a vinyl interior color in beige or white.

While I've researched this on several occasions, I find the data to be somewhat incomplete as a whole.  For the purpose of today's post I'll include what I've found to be relevant links.

New information!   My customer came up with these links as well.

Perhaps it would make more sense to solve the sound barrier requirement with an insert: 
MI Industries offers this on STC ratings of glass packages.

Thursday, June 6, 2019

Coppell Vinyl Replacement Windows from NT Window

Vinyl Replacement Windows Coppell Texas

This is a typical starting point for us.   Builders grade aluminum windows that are double paned but often fogged and certainly not energy efficient.  These had grids all the way around.  Grids in replacement windows are usually in front only if used at all.   They are falling out of favor in most remodeling contexts.

Half circle windows are often without insulation in the arches.   This is one of the many reasons they don't work well and seem very hot in the summer and cold in the winter.   We take steps to insulate that void when the old window is out.  No one can see many of the extra steps we take to provide a long lasting, energy efficient solution to modern replacement window and door issues here in the Dallas area.

You never know what you'll find working on an older home...   this time it was apparently a very in tact rat skeleton.   Creepy but kind of cool.

Window installation is the key.  Some crews are in a hurry.  Some are hourly and don't care as much as they should or have the skill level that we'd hope for.   We assure you that 33 years of experience on your job site, at your home, can make all the difference in the world.  We pride ourselves on better installation, better caulking materials and application, better insulation and trim work as well as better care for the property while we're there.

NT Window Energy Master Vinyl Replacement Windows

These are our NT Window Energy Master Vinyl Replacement Windows.  This home in Coppell will be better for decades.   This is a great example of doing it right the first time.

A happy homeowner and his owner....      Replacement Windows add value to the home, and energy efficiency as well as increase your standard of living.   We typically price windows 30% lower than Renewal by Andersen, Clarity Windows, Pella, Statewide Remodeling and many of the best known window installation companies working in North Texas.  We provide great windows with lower markup due to lower overhead.   Find out why we're a Best of Dallas Contractor.   Find out more about us at     

Wednesday, May 2, 2018

Cedar Creek Lake Replacement Windows

We did one in Cedar Creek Lake this last week.   It was a challenge to make the trapezoids look good as the opening was out of square about an inch and a half.  That being said, I covered it up pretty well.

I've actually done around a hundred houses out there over the years.   Kemp, Tool, Gun Barrel City are a few of the small cities around Cedar Creek.  It's an awesome community and I love going out there.  About an hour and a half south of Dallas on HWY 175.

Before we started with Bronze builders grade windows from the 70's.  Fogged and pretty ugly.

The biggest trapezoid was heavy.  Around 300 pounds.  We lowered it with ropes and a suction cup.  It was jammed in there pretty good.   I later determined that the 100 or so square feet of windows was about 1 1/2" out of square.  It became apparent on trying to trim them as one unit.  I found a solution though.

To do these correctly you have to split up the out of square in as many places as possible.  Half inch here or there, eighth inch here and there.  I kept the bottom straight with the lowers and the top angle straight with the house.  It was one of the more challenging ones over the last year or so.

Tuesday, February 20, 2018

NT Window Energy Master White and Presidential Adobe Vinyl Replacement Windows

A few of our NT Window Projects from 2017

We do around a hundred projects a year here in Dallas and Fort Worth.  These are a few cool ones from last year.   We love doing the highest quality installation work in North Texas.

The white ones are NT Window Energy Master Vinyl Single Hung Windows

We are proud to have been the winner of their "Dealer of the Year" Seven times over the last few years.  One of our favorite manufacturers with a locally made product produced in Mansfield Texas using Cardinal 366 Low E Glass with Argon Gas Filled insulated glass.

The Adobe colored ones are NT Window Presidential Vinyl Single Hung Replacement Windows

A relatively new color that's only been in production a few years but offers an alternative to the typical White or Tan colored windows.  We have these available in this color or a close variation to it from three different window manufacturers.  They are available from NT Window, Don Young Company and from AMI Industries.  AMI makes the Alside Mezzo, Sheffield and Ultra Max Windows as well as the Berkshire Model.  AMI is a frequent re-branding organization and they are often called other names by other window and door installation vendors.

NT Window Presidential Vinyl Replacement Windows in Adobe.

This project is actually one we did in 2004 and these pictures are of a product that is now thirteen years old.  When you pick the right window manufacturer you can count on decades of great performance and a look that really stands the test of time.