The Difference Between Low and High Efficiency Replacement Windows

Dr. Energy Saver's owner and president was On the Job down in Florida helping us understand how to make homes more energy efficient in warmer areas of the country. Today, he focuses on how windows can lose or conserve energy. Clear glass, conventional windows allow infrared rays, the heat component of the solar spectrum, to pass through the pane and heat the interior of the house -- putting an extra load on the air conditioner. Windows with aluminum frames are even greater energy wasters, because aluminum is highly conductive.

Replacement Windows

We are here looking at a Florida home that has an old aluminum frame window and this window is not very energy efficient. It has clear glass and clear glass will let the infrared rays, the heat component of the solar spectrum, through the glass and heat up the inside of the house. When the inside of the house is hot...so we got to add energy. We have got an uncomfortable space, and we also have an aluminum frame and aluminum is the most conductive metal that you can get. So, you know whatever the heat from the outside is, if this frame gets hot from the sun the frame is going to be hot on the inside.

Low-E Glass

So Low E glass has a metallic quoting on the inside of the glass and this is double pane glass, two layers of glass and it has a metallic quoting on the inside to prevent the heat flow into the house in the summer and out of the house in the winter so that really helps us and you are saying down here in Florida it is popular to get even more tinting.

Read Full Transcript:

Larry Janesky: Hey, I am Larry Janesky from Dr. Energy Saver.

Kelly Lafler: Hey, I am Kelly Lafler from Dr. Energy Saver Florida. We are just outside the Orlando area.

Larry Janesky: And we are here looking at a Florida home that has an old aluminum frame window and this window is not very energy efficient. It has clear glass and clear glass will let the infrared rays, the heat component of the solar spectrum, through the glass and heat up the inside of the house. When the inside of the house is hot...

Kelly Lafler: It takes more electricity for the air conditioning.

Larry Janesky: Yup, so we got to add energy. We have got an uncomfortable space, and we also have an aluminum frame and aluminum is the most conductive metal that you can get. So, you know whatever the heat from the outside is, if this frame gets hot from the sun the frame is going to be hot on the inside.

Kelly Lafler: Correct.

Larry Janesky: Now, another thing that we notice in a cooler climate or a hot climate. In southern climates where these homes are constructed, or should be, to have an over hang to try and shade some of the sunlight off of the windows. That is an effective strategy of course. We have to look at the orientation of the house north, southeast, west.

Kelly Lafler: Yes.

Larry Janesky: We know that in the winter the sun is lower in the sky in the summer the sun is higher in the sky and will get more shading on this window from that overhang. So, Kelly we replace windows like this don't we.

Kelly Lafler: Yes, we do.

Larry Janesky: And you have replaced the several windows on the house next door.

Kelly Lafler: We have. We put some newer windows in there. They are low E double pane with tenting.

Larry Janesky: All right, let's go take a look.

Kelly Lafler: All right. Here we have our new windows you can see. And a big consideration in any climate is heat gained through the windows.

Larry Janesky: Okay, so everybody can understand a green house, right.

Kelly Lafler: Yes.

Larry Janesky: A green house is not a glass and we are letting heat through, but we are heating up the inside of the green house and it is the same thing with our houses that have glass as well, right?

Kelly Lafler: Yes.

Larry Janesky: Okay, so this wall would have, depending on what climate you are in. It could have an R13 insulation value, but this window does not have an R13 insulation value.

Kelly Lafler: No, it doesn't.

Larry Janesky: And it lets the heat from the sun through but what about this new glass. What about this glass reflects heat?

Kelly Lafler: Well what you have in here is this is a low E glass which has a little bit of metallic film and this helps reflect the heat.

Larry Janesky: Okay so it is a low emissivity.

Kelly Lafler: It is.

Larry Janesky: Okay.

Kelly Lafler: But also, we have an extra layer of tinting on it to help try and reflect some of that extra sunlight back out.

Larry Janesky: Okay, so Low E glass has a metallic quoting on the inside of the glass and this is double pane glass, two layers of glass and it has a metallic quoting on the inside to prevent the heat flow into the house in the summer and out of the house in the winter so that really helps us and you are saying down here in Florida it is popular to get even more tinting.

Kelly Lafler: Correct, it is.

Larry Janesky: And we can all understand why that is, right just like sunglasses that is going to keep more of that solar heat gain out.

Kelly Lafler: As you can see inside here we have this grills and are inside the glass so it met some requiring a maintenance for painting, it makes it easy to clean because all you have to do is just wipe it out so one sheet of glass from the outside as you can see.

Larry Janesky: And the same on the inside.

Kelly Lafler: Money inside.

Larry Janesky: All right. Well great, so this window will be significantly more energy efficient lower the air conditioning bills in the house and make the house more comfortable.

Kelly Lafler:Correct it will.

Larry Janesky: All right. Good deal. Well if you are looking to make your home more energy efficient, call Dr. Energy Saver.Contact us for a home energy evaluation and written estimate.