What Year-Round Daylight Saving Time Would Do to a Household Electricity Bill

On July 14, 2026, the House of Representatives passed H.R. 139, the Sunshine Protection Act of 2025, by a recorded vote of 308 to 117 with 6 not voting, according to the Office of the Clerk of the U.S. House of Representatives (Roll Call 238, 119th Congress, 2nd Session). The bill would repeal Section 3 of the Uniform Time Act of 1966 and adjust the time zone offsets in the underlying statute so that the advanced hour applies all year. It has been referred to committee in the Senate and has not been enacted.

The claim attached to the bill in most coverage is that year-round daylight saving time saves energy. That claim has been measured exactly once by the federal government, on a much smaller change than the one H.R. 139 proposes, and the size of the measured effect is small enough that it is worth writing down precisely before assuming anything about a household electricity bill.

What current law says, and what the bill would change

Under 15 U.S.C. 260a, standard time is advanced one hour "commencing at 2 o'clock antemeridian on the second Sunday of March of each year and ending at 2 o'clock antemeridian on the first Sunday of November of each year." Those dates come from the Energy Policy Act of 2005, which pushed the start three weeks earlier and the end one week later than the previous schedule. The result is roughly 34 weeks of daylight saving time and 18 weeks of standard time.

The same section lets a State exempt itself, but only in one direction. A State may pass a law providing that "the entire State (including all political subdivisions thereof) shall observe the standard time otherwise applicable during that period." A State split across time zones may exempt an entire zone-area. There is no provision in Section 3 permitting a State to adopt daylight saving time year-round on its own. That asymmetry is why the change requires an act of Congress at all.

The one federal measurement of the question

Section 110 of the Energy Policy Act of 2005 required the Department of Energy to report to Congress on what the newly extended schedule did to national energy consumption. The resulting study, Impact of Extended Daylight Saving Time on National Energy Consumption: Report to Congress, was delivered in 2008 and remains the federal government's measurement of record on the effect on the United States grid.

The study compared the four weeks that were newly converted to daylight saving time in 2007 against the same calendar weeks in 2006. The spring window ran March 11 through March 31, 2007, twenty-one days, against March 12 through April 1, 2006. Two methods were run in parallel. The statistical method used 35 utilities in the spring window, covering 32 percent of national electricity consumption; the heuristic method used 67 utilities covering 66 percent.

The headline results:

• Total electricity saved across the four extension weeks: 1.29 TWh by the heuristic method, 1.24 TWh by the statistical method, with an uncertainty of plus or minus 40 percent at 95 percent confidence.
• As a share of the year: 0.03 percent of the national total of 3,900 TWh consumed in 2007.
• Per day during the extension weeks: 0.50 percent in the spring window, 0.38 percent in the November window, averaging roughly 0.46 to 0.48 percent.
• The 95 percent confidence range around the national spring figure ran from 0.35 percent to 0.65 percent per day.

The plus-or-minus-40-percent band matters more than it looks. Applied to the statistical estimate of 1.24 TWh, the true value sits somewhere between roughly 0.74 and 1.74 TWh. The finding is that the effect is positive and small, not that it is 1.3.

The hours that moved

The daily total is the least interesting number in the report. The mechanism sits in the hourly profile, and the report published it. Savings "generally occurred over a period of three to five hours in the evening, offset slightly by small increases in energy consumption in several morning hours, typically the hours ending at 7:00 a.m. and 8:00 a.m."

Table 3-1 of the report gives the Boston-area hourly pattern as an illustration of the shape. The evening reduction is several times larger than the morning increase, but it does not last as long, and the two partly cancel.

Read the chart as a shape rather than a total. Six hours out of twenty-four carry nearly all of the movement, and the single largest change in the day, the 6.7 percent drop in the hour ending 7 p.m., sits squarely in the hours when residential demand is highest. That placement is why the daily total understates what happens on the grid, and it is also why the effect on a household bill depends on how that household is billed.

Converting a percentage into dollars

The Energy Information Administration reports that the average annual electricity consumption of a U.S. residential utility customer was 10,791 kilowatt-hours in 2022, about 899 kWh per month, and that the annual average retail price of electricity to residential customers was 17.30 cents per kWh in 2025. Those two figures make the arithmetic possible.

Calculation one: the four extension weeks, as actually measured

A household at the national average consumes 10,791 divided by 365, or about 29.6 kWh per day. Applying the measured spring rate of 0.50 percent across the 21-day spring window gives 0.148 kWh per day, or 3.10 kWh. Applying the November rate of 0.38 percent across the 7-day fall window gives 0.79 kWh. The total is roughly 3.9 kWh for the year, which at 17.30 cents per kWh is about 67 cents.

That is the effect that has actually been measured on a household of average size. It is under a dollar a year, and it is smaller than the rounding on most utility statements.

Calculation two: the same rate applied to a full year

H.R. 139 does not extend daylight saving time by four weeks. It extends it by the remaining eighteen. Applying the 0.46 percent daily average across all 365 days gives 49.6 kWh, or about $8.59 a year, roughly 72 cents a month. Carrying through the study's own 95 percent confidence range of 0.35 to 0.65 percent puts the figure between $6.53 and $12.13 a year.

This second calculation is arithmetic, not a finding. The Department of Energy measured March and November. Nothing in the report measures December, January, or February, which are precisely the months H.R. 139 would newly convert and precisely the months with the latest sunrises. Extending a March coefficient into January is an assumption, and it should be labeled as one.

Calculation three: how far geography moves it

EIA reports average annual residential consumption of 14,774 kWh in Louisiana and 6,178 kWh in Hawaii for 2022. At the same 0.46 percent rate, the Louisiana average household would see about 68 kWh a year and the Hawaii average household about 28 kWh. The spread between two households in the same country is larger than the entire measured effect in calculation one.

What the report did not settle

Three gaps in the 2008 study bear directly on whether its coefficient transfers to a year-round change.

Heating and cooling were left out of the national total. The report notes that extended daylight saving time "may have led to some increased consumption from air conditioning in some southern locations," but judged the evidence "insufficiently robust to yield uniformly unbiased estimates" and excluded those effects from the national figures. The published number is therefore a lighting-dominated result with the space-conditioning question set aside.

Winter was never in the sample. Both windows sat in shoulder months. A March evening and a January evening differ in outdoor temperature, in sunset time, and in whether the marginal load being shifted is a lamp or a heating system.

The equipment stock has changed. The measurement was taken on 2006 and 2007 load data. EIA's 2020 Residential Energy Consumption Survey puts lighting at about 6 percent of residential electricity consumption, or 81 billion kWh. Space heating and air conditioning together accounted for 52 percent of household energy consumption in 2020, with water heating, lighting, and refrigeration together making up 25 percent. Whether a lighting-driven coefficient measured on an incandescent-era housing stock still holds has not been re-measured by the Department of Energy.

Where the savings were largest and smallest

The report's regional breakdown is the part most often dropped from summaries. Under the heuristic method, California showed the largest daily saving at 0.93 percent per day; the Mid-South regions showed the smallest at about 0.27 percent. The national average across all regions was 0.48 percent.

The statistical method found the same directional split by latitude: northern utilities averaged 0.54 percent per day, southern utilities 0.46 percent. The report attributes the gap to "a small, offsetting increase in household air conditioning usage" in warmer regions, though it declined to quantify that offset in the national figures.

A spread from 0.27 to 0.93 percent is a factor of roughly three and a half. Applied to the average household bill, it is the difference between about $5.04 and about $17.36 a year at 17.30 cents per kWh. Any single national number for what permanent daylight saving time does to a utility bill is averaging over a range that wide.

Three readings the report does not support

"Permanent daylight saving time has been shown to save energy." The report measured a four-week extension of an existing seasonal schedule. It did not measure a year-round change, and it did not measure the winter months that a year-round change would newly cover.

"The savings are 1.3 TWh." The statistical estimate was 1.24 TWh with a plus-or-minus-40-percent band at 95 percent confidence, and the heuristic estimate was 1.29 TWh. The two methods agreeing does not narrow the confidence interval on either. The report's own framing is 0.03 percent of national consumption.

"Evening savings mean lower bills." The reduction and the increase land in different hours, and the price of an hour is set by the tariff, not by the statute. On a flat per-kWh residential rate, only the net kWh matters. On a time-of-use rate, the hours being reduced and the hours being increased may carry different prices, and the tariff periods themselves are typically defined in clock time, so they move with the clock. The 2008 report did not model tariff structures.

Numbers to Re-check

Figure	As used here	Where to verify	When it changes
Residential average retail electricity price	17.30 cents per kWh, 2025	EIA, Electricity Explained and Electric Power Monthly	Monthly, with annual revision
Average annual residential consumption	10,791 kWh, 2022	EIA FAQ and Electric Power Annual	Annually
Daylight saving time start and end dates	Second Sunday of March to first Sunday of November	15 U.S.C. 260a	Only by act of Congress
Status of H.R. 139	Passed the House 308–117 on July 14, 2026; referred in the Senate	Congress.gov bill page; House Clerk roll call records	Any time the 119th Congress acts
Measured extended-DST savings	About 0.46 percent per day; 1.3 TWh over four weeks	DOE, Impact of Extended Daylight Saving Time on National Energy Consumption (2008)	Only if DOE is directed to re-run the study
Lighting share of residential electricity	About 6 percent, 81 billion kWh, 2020	EIA Residential Energy Consumption Survey	Roughly every five years

Where This Doesn't Apply

States and territories already exempt. Under 15 U.S.C. 260a, a State may exempt itself to standard time year-round, and some have. H.R. 139 as passed by the House adds a subsection allowing a State or State area that had previously exempted itself to keep the standard time in effect before enactment rather than move to the new permanent advanced time. For those places the arithmetic above does not describe a change at all, because no clock moves.

Households that do not see an hourly price. On a flat per-kWh residential tariff, only the daily net kWh reaches the bill, and the hourly shape in the chart above is invisible. On a time-of-use or demand tariff, the shape is the whole story, and the direction depends on where the utility has drawn its peak window. No single figure covers both.

Renters and units without individual metering. Where electricity is included in rent or allocated by a submetering formula, a change in consumption timing does not pass through to the occupant in any predictable way. The DOE percentages describe utility system load, not what appears on an individual statement.

Homes heated with gas, oil, or propane. The measured effect is an electricity effect. A household whose winter evening load is dominated by a gas furnace has a different composition of demand in exactly the months H.R. 139 would newly convert, and the electricity coefficient does not describe it.

Northern versus southern latitudes. The report's own split of 0.54 percent north against 0.46 percent south, and the regional range of 0.27 to 0.93 percent, means the national average describes very few actual households. Sunrise and sunset times at a given latitude, not the national mean, determine how many lit hours move.

Housing and equipment built after the sample. The measurement window was 2006 and 2007. Lighting has since fallen to about 6 percent of residential electricity consumption by EIA's 2020 survey. A household with all-LED lighting, an electric heat pump, and rooftop generation has a demand profile that the 2007 sample did not contain.

Everything outside electricity. The report to Congress covered national energy consumption with electricity as the measured component. Effects on motor fuel, on commercial building operation, or on anything else a household spends money on are not in the 0.46 percent figure and should not be read into it.

This article explains how the rules are written. It is not tax, legal, or insurance advice, and it does not account for any individual situation. Amounts and thresholds change; verify the current figures at the source listed above before acting.