We have been getting lots of questions regarding radiant barrier products. Radiant barriers seem to make sense to reduce attic temperatures in the summer. You may have seen the home show demonstrations where one side of a mock attic has a high pressure sodium lamp heating one attic with radiant barrier, and one attic without radiant barrier. These are very convincing demonstrations that you can actually feel or see the temperature differences. So does a foil radiant barrier product work?
Let me give you a background of where we are coming from as a US EPA Home Performance with Energy Star energy auditor and contractor. We use a science-based approach to reduce your energy bills and make your home more comfortable. That means our recommendations are based on a comprehensive energy audit using a blower door, thermal camera, energy modeling and heat transfer principals… not on a PowerPoint Presentation someone developed who probably is not an energy auditor. We have performed hundreds of APS energy audits and SRP energy audits so we have some experience under our belt and seen the benefits and a home that performs well, and the broken promises that are not only costly but bring down companies that do quality work. So let’s get back to your question.
Here are the facts -
1. In Phoenix, with an average of 360 days of sun a year, in a house with minimal insulation your home is only getting a maximum of 20% heat gain from the attic. We have written about the importance of your insulation being installed correctly in a previous post. The majority of your heat gain is through the windows.
2. Using the most outrageous radiant barrier savings claims of a 30% cost savings on your heating and cooling bill (sometimes even the sales rep gets confused and says it’s 30% of your total bills), let’s do the math. I’ve provided a radiant barrier savings calculator you can use to get accurate estimates on your savings below, just enter in your highest summer electric bill. Let’s say that’s $300 and 50% of that is from cooling. So that means you are spending $150 on cooling for, let’s be generous and say May, June, July, August, September (5 months). $150 x 5 months = $750 on cooling (overestimated). Then we’ll find how much of your cooling bills is from the attic (20% from #1 above) by taking $750 x 20% = $150. Now take 30% of $150 = $45. That’s your annual savings from a radiant barrier, $45!
Let me give you a background of where we are coming from as a US EPA Home Performance with Energy Star energy auditor and contractor. We use a science-based approach to reduce your energy bills and make your home more comfortable. That means our recommendations are based on a comprehensive energy audit using a blower door, thermal camera, energy modeling and heat transfer principals… not on a PowerPoint Presentation someone developed who probably is not an energy auditor. We have performed hundreds of APS energy audits and SRP energy audits so we have some experience under our belt and seen the benefits and a home that performs well, and the broken promises that are not only costly but bring down companies that do quality work. So let’s get back to your question.
Here are the facts -
1. In Phoenix, with an average of 360 days of sun a year, in a house with minimal insulation your home is only getting a maximum of 20% heat gain from the attic. We have written about the importance of your insulation being installed correctly in a previous post. The majority of your heat gain is through the windows.
2. Using the most outrageous radiant barrier savings claims of a 30% cost savings on your heating and cooling bill (sometimes even the sales rep gets confused and says it’s 30% of your total bills), let’s do the math. I’ve provided a radiant barrier savings calculator you can use to get accurate estimates on your savings below, just enter in your highest summer electric bill. Let’s say that’s $300 and 50% of that is from cooling. So that means you are spending $150 on cooling for, let’s be generous and say May, June, July, August, September (5 months). $150 x 5 months = $750 on cooling (overestimated). Then we’ll find how much of your cooling bills is from the attic (20% from #1 above) by taking $750 x 20% = $150. Now take 30% of $150 = $45. That’s your annual savings from a radiant barrier, $45!
| radiant_barrier_calculation.xlsx |
3. If you are spending $2,000 on a radiant barrier to save only $45 a year, there are much better ways to save money on your bills! One would be to install a solar hot water or even solar electric system for a much quicker payment and ROI. That is why we will never recommend a radiant barrier product without tacking the big items found in a home energy audit first.
We hope that helps and feel free to leave comments below or like us on Facebook for a free Energy Savings Guidebook to learn how you can start saving today.
We hope that helps and feel free to leave comments below or like us on Facebook for a free Energy Savings Guidebook to learn how you can start saving today.
