How much will spray foam save on my Houston electric bill?
Less than the number most contractors quote, and for a reason worth understanding. ENERGY STAR's own estimate puts air sealing plus added insulation at 15% off heating and cooling nationally, but its zone by zone table puts Climate Zone 2, which is Houston, at 9% off heating and cooling and 6% off the total bill. That estimate models conventional work on a vented attic. It does not model a sealed roof deck, which is a different assembly: it brings the ductwork and the air handler inside the conditioned space. The Department of Energy notes leaky ducts in attics can account for 20% or more of a home's heating and cooling losses, and in Houston those ducts sit in an attic that reaches 140°F. That relocation, not the R-value, is where the money is here. Nobody can give you a number without seeing your attic and your bill.
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Somebody has probably told you spray foam will cut your bill by 30% or 50%. We are not going to tell you that, because we cannot know it, and the published numbers do not support it.
Here is what the published numbers actually say, and then the part that matters more.
The number everyone quotes, and the row they skip
ENERGY STAR publishes an estimate for air sealing a house and adding insulation. The headline is 15% off heating and cooling, or 11% off the total bill. That figure turns up on insulation company websites all over Houston.
It is a national average. The same ENERGY STAR page publishes the breakdown by climate zone, and the breakdown is not flattering to the Gulf Coast:
| Climate zone | Total bill | Heating and cooling |
|---|---|---|
| Zone 8, far north | 16% | 18% |
| Zone 5, Chicago | 12% | 16% |
| Zone 3, Dallas | 8% | 14% |
| Zone 2, Houston | 6% | 9% |
| Zone 1, south Florida | 5% | 7% |
| National average | 11% | 15% |
Greater Houston is Climate Zone 2A. Our row is 9%, not 15%. A company quoting you the national average in Houston is quoting a number from Minnesota.
If a contractor promises you a percentage before they have been in your attic, they are reading marketing copy, not your house.
Why that table understates what we do
Read what the ENERGY STAR estimate actually covers. It models sealing air leaks for a 25% cut in infiltration, and adding insulation to attics, floors and basement walls to meet the 2012 energy code. That is conventional insulation in a vented attic. The attic stays hot. Everything in it stays hot.
A spray foam roof deck is not that job. The foam goes on the underside of the roof deck rather than on the attic floor, which moves the boundary of your conditioned space up to the roofline. The attic stops being outdoors.
That matters in Houston more than almost anywhere, because of where your ductwork lives.
In most Houston homes the ducts and the air handler are in the attic. On an August afternoon that attic runs around 140°F. Your air conditioner is producing roughly 55°F air and pushing it through sheet metal and flex duct sitting in 140°F air, and every foot of that run is fighting the attic. The Department of Energy puts it plainly: leaky ducts in attics or crawlspaces can account for 20% or more of a home's heating and cooling energy losses.
Adding R-value to the attic floor does nothing about that. The ducts are still on the wrong side of the insulation. Sealing the roof deck is what puts them on the right side.
In a cold climate you insulate to slow heat escaping. In Houston you mostly insulate to stop your own cold air being wasted on the attic.
So what is the honest answer?
The honest answer is that your savings depend on four things we cannot see from here:
- Where your ducts are. Attic ducts are the big one. If your system is in a conditioned closet already, a sealed attic saves you less, and we will say so.
- How leaky the house is now. A 1960s house with original windows has more to gain than a 2015 build.
- What is up there today. Going from nothing to a sealed deck is a different job than going from R-30 batts to a sealed deck.
- How you run the thermostat. A house held at 68°F has more to save than one held at 78°F.
The two published figures to anchor on are the ones above: 9% off heating and cooling for conventional work in our zone, and ducts accounting for 20% or more of heating and cooling losses when they sit in the attic. A sealed roof deck is aimed at the second number, which is the larger one, and that is the whole argument for doing it in Houston.
Work it out on your own bill
You do not need us for this part. You need twelve months of statements.
- Find your summer baseline. Take a mild month, March or November, where the air conditioner barely ran. That bill is roughly your house's fixed load: refrigerator, water heater, lights, everything that is not climate.
- Subtract it from August. The difference is what cooling cost you that month. In most Houston houses it is the largest single line in the year.
- Apply a range to the cooling portion only, not the whole bill. This is the step the sales pitches skip. A percentage off "your electric bill" and a percentage off "your cooling" are very different numbers.
For scale, the EIA put the Texas residential average at about 15.9 cents per kWh in July 2026, and the Texas average residential bill at $144.18 for 848 kWh in April 2026. April is a mild month in Texas. Your August number will not look like that, and the gap between them is the part this work touches.
What we will tell you at the assessment
We will get in the attic and look at where the ducts run, what insulation is there, what shape the deck is in, and whether there are gas appliances up there that change what we can do. Then you get a scoped price in writing with the installed thickness and the target R-value on it.
What you will not get from us is a savings percentage with a confident number attached, because the honest version of that sentence has four variables in it. We would rather tell you the mechanism and let you judge it.
Attic jobs here generally run $4,000 to $10,000 depending on roof area. The full breakdown by assembly is in what spray foam insulation costs in Houston, and the code minimums are in what R-value Houston code requires.
Frequently asked questions
Will spray foam cut my bill in half?
No, and we would want to know what else was changed by anyone who says it did. Halving a total electric bill means eliminating nearly all cooling cost plus a good share of everything else. The published zone estimate for conventional work here is 9% off heating and cooling. A sealed roof deck targets duct losses on top of that, which is a bigger lever, but it is not half your bill.
Why do other companies quote 15% or more?
Because 15% is the ENERGY STAR national average and it is easy to find. It is not wrong, it is just not Houston. Our zone's published figure is 9%. Ask anyone quoting a percentage which climate zone their number is for.
Does the attic get cooler after foam?
Yes, substantially, because it is inside the envelope now. People notice it first as the upstairs rooms matching the downstairs rooms, and as the air handler no longer running in a 140°F space.
Is the payback worth it if I am moving in two years?
Probably not on energy alone, and we will tell you that rather than sell you an attic. Comfort and a quieter system are real but they are not a return. If you are staying, the arithmetic changes.
Will my air conditioner be able to keep up better?
That is usually the thing people actually notice. A system that was fighting a 140°F attic and leaking cold air into it is doing less work for the same result. Whether that shows up as lower bills or as a house that finally gets cold enough depends on how you had been living with it.
What to do next
Pull up August and March on your electric account and look at the gap. Then book the free assessment or text a photo of your attic to (281) 703-2700, and we will tell you where your ducts are and what that is costing you.