A thermal camera can see window inefficiencies.
The homeowners of this house had new windows installed. They had bought into the ads telling them of marvelous savings. "Save 35% on your energy bill!" "100% guarantee!."
Statements like that are true, and FALSE!
A 35% savings may be achieved, but that does NOT apply to the entire energy bill! Energy savings MIGHT be proved, and I say might because proving it would be difficult at best, and that savings are derived from the new windows, but any savings have to be applied to the previous energy cost of the old windows versus the new.
The rule of thumb is that windows and doors have about a 30% effect on the overall energy bill. To keep the numbers simple, of the old windows cost $100 per month in gas or electric during the heating months, a new bill of $65 MIGHT be anticipated from the new windows. But divide that $35 into the total cost of installing the new windows - and in this subject house that cost was $11,000 - to derive how many months of savings would be needed to break even on the installation.
My math says 314 months. That's 26 years! But if heating is only needed 4 or 5 months a year, that break even extends further out. Yes, even a lifetime.
Mighty Mo looked at the windows in this subject house. All looked like the images pictured below. The outdoor temperature at this time was 14F. We actually waited for this cold day to do the inspection.
This is the same window seen with two different thermal image palettes.
On reports I typically use the palette to the left because it is logical.
Yellow and orange indicate warmer temperatures.
Lavender, blue and purple indicate cooler temperatures.
You can see the coldest areas on the window to the left.
The indoor temperature is 75F. The coldest spot near the window is 37F. There is a folding wooden shade at the top blocking the thermal signature of the window at that location.
This window is inefficient at the edges, at the top and bottom, and where the two panels meet in the middle. That is where most windows are most inefficient. But also, this window is cold around around the framing itself!
The palette on the right is most instructive. It looks to me like a good seal around the window was not done when they installed it. See how cold the wall is at the lower edges? You can almost see air "blowing" in.
One complaint in this house was the feeling of blowing air near the windows. Heat seeks cold, and as heat escapes it mixes with the cold outside a convective loop is created. The air begins to move. Looking at the window on the right you can almost see the moving air. And you can see how cold is being conducted into the wall.
This same convection is why wind is created during thunderstorms. Hot and cold air meet, swirl together, and wind is the result. The physics is not different here, albeit on a micro scale, and moving air can be felt.
My recommendation: sales pitches are just that. The pitch MUST have a grain of truth to be believed. Not only do these new windows not provide the energy savings they were advertised to, but the installation seems to lack, and that adds even more inefficiency.
DRAMATICALLY CHEAPER, AND CERTAINLY JUST AS ENERGY EFFECTIVE, IS TO INSTALL GOOD STORM WINDOWS OUTSIDE THE OLDER WINDOWS. THE GAP OF DEAD AIR BETWEEN THE TWO PROVIDES A GOOD ENERGY SEAL. IT WORKS EVERY TIME.
THINK WHAT THE DOOR OF AN IGLOO IS INTENDED TO DO. AND DOES.
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560