"Turning off the lights for an hour fights climate change." Not really.
Most Earth Hour coverage treats the event as if it delivered a measurable carbon outcome. It does not. Every ISO that has measured it (PJM, ConEd, ERCOT and CAISO have all published post-event load curves at one point or another) finds a load reduction in the range of 1 to 4% of evening load in the participating cities. That is often inside normal forecasting error and the system-level CO2 impact rounds to zero.
This is not a criticism of WWF. Earth Hour is, and was always designed to be, a communications campaign. It exists to put climate on the front page for one Saturday in March, generate landmark visuals (Sydney Opera House, Eiffel Tower, Empire State Building going dark), and prompt a conversation. By that metric it is wildly successful: 190+ countries in 2025.
The mistake is treating the gesture as the action. The action that actually moves your bill, and aggregated across millions of homes the action that actually moves the grid, is enrolling in your utility\'s demand-response program. That program pays you, every year, to do an automated version of Earth Hour during the few hours when your grid genuinely needs it. The hour in March is the prompt; the program is the year-round result.
Read the rest of this page if you want both: the WWF event details, and the program that beats it on every dimension that matters.
Earth Hour, in three numbers.
A WWF-organised one-hour lights-off, held annually on the last Saturday of March from 8:30 to 9:30 pm local time. Three facts cover what it is, how big it is, and what it actually changes.
Who and when
Organised by WWF, launched in Sydney in 2007, global from 2008. Always the last Saturday of March, 8:30 to 9:30 pm local time. 2026 edition: Saturday 28 March 2026. No utility, ISO or government runs it.
How big
2025 reach: 190+ countries, all 50 US states, thousands of landmark sites (Empire State Building, Sydney Opera House, Eiffel Tower, Las Vegas Strip casinos, NYC Times Square Ball). Communications and social-media reach is the primary product, not kilowatt-hours saved.
Actual grid impact
Measured load reduction in participating US cities during the 8:30 to 9:30 pm window: 1 to 4% of evening load. Often inside normal forecasting error. System-level CO2 saved during the hour: small enough to round to zero against a typical week of grid emissions.
The detail that surprises most readers. 8:30 pm is chosen because it is dark in most of the participating Northern Hemisphere, but well before peak overnight low. The hour lands during the natural evening ramp-down toward overnight load, which is why the recovery at 9:30 pm produces no visible spike on the grid: underlying demand is already falling.
The Earth Hour hour vs the demand-response year, by city.
For each major US metro: whether the city formally participates in Earth Hour, the local utility demand-response program available year-round, and the typical annual payment for an enrolled residential household with a smart thermostat and (where applicable) a home battery.
| City | Earth Hour landmark | Year-round DR program | Typical $/year, enrolled home |
|---|---|---|---|
| New York, NY | Empire State Building, Times Square Ball | ConEd Smart Usage Rewards + NYISO DR | $25 to $300+ (thermostat to battery) |
| Chicago, IL | Willis Tower, John Hancock Center | ComEd Hourly Pricing + PJM ELR via supplier | $50 to $250 (varies by load shape) |
| Houston, TX | Most of downtown skyline | REP "free nights" plan + ERCOT ERS via aggregator | $100 to $600 (laundry + EV shift) |
| Los Angeles, CA | LA City Hall, Griffith Observatory | LADWP TOU + CAISO DSGS via aggregator | $200 to $1,000+ (with battery) |
| Las Vegas, NV | Strip casinos go dark | NV Energy PowerShift + WEIM via aggregator | $50 to $200 (thermostat events) |
| Boston, MA | Prudential Tower, State House | Mass Save ConnectedSolutions + ISO-NE DR | $225 to $600 (battery enrolled) |
| San Francisco, CA | Coit Tower, Bay Bridge lights | PG&E SmartRate + CAISO DSGS | $100 to $400 (peak-day events) |
| Philadelphia, PA | City Hall, Comcast Center | PECO Smart A/C Saver + PJM ELR via supplier | $60 to $180 (A/C cycling) |
! Numbers are illustrative, not utility quotes
Annual DR earnings depend on the equipment you enrol (thermostat only vs thermostat + battery + EV charger), the number of events called in the year, your local capacity payment, and whether you sign up direct with the utility or via an aggregator. Use the figures above as a planning estimate and ask your utility for the actual rate sheet before enrolling. The PJM, ConEd, ERCOT and CAISO program pages publish current payment formulas.
What grid operators actually see during Earth Hour.
Every major US ISO has published post-event load analysis for participating cities at some point in the last 15 years. The findings cluster around four observations.
A Load drop is small and noisy
Typical signal: 1 to 4% of evening load in the participating metropolitan area, often inside the forecasting band the operator already runs. Weather, day-of-week and TV programming the same evening can produce comparable swings. Earth Hour 2017 in NYC, for example, was partially masked by NCAA tournament viewership pulling consumption up.
B The marginal generator does not change
At 9 pm on a March Saturday the marginal plant on the wholesale stack is typically a combined-cycle gas unit running mid-range, not a coal or peaker plant. Dropping 200 to 800 MW of city load shaves a sliver off that gas unit\'s output, not a high-carbon plant\'s. CO2 saved per kWh reduced is well below the system average.
C There is no scarcity spike to flatten
Saturday 8:30 to 9:30 pm in late March is structurally low-load: no business HVAC, no commute, mild shoulder-season temperatures across most of the US. Wholesale prices are usually $20 to $60/MWh during the hour. There is no scarcity event for the gesture to be flattening.
D Recovery ramp is uneventful
The 9:30 pm switch-back lands during the natural evening ramp-down toward overnight load, so the bounce is smoothed by falling underlying demand. Operators routinely manage much bigger ramps every weekday morning (5 to 9 am) and evening (5 to 8 pm). No US ISO has ever flagged Earth Hour as an operational concern.
The takeaway: the symbolic act is fine. Just do not confuse it with the technical act. The hours when the grid genuinely needs households to use less are summer 4 to 8 pm heat-dome afternoons, winter morning ramps during a polar vortex, and capacity-emergency events on hot Sunday afternoons. Earth Hour is none of those.
The four US demand-response programs you can actually join in 2026.
Each ISO and RTO runs a residential demand-response track. Names differ, payment structure differs, but the basic deal is the same: in exchange for letting the operator or your utility cycle your A/C, heat pump, water heater, battery or EV charger during a small number of events per year, you get paid a capacity fee plus per-event credits.
PJM ELR + utility, /year
13 states + DC (IL ComEd, OH, PA, NJ, MD, DC, VA, DE, WV, e-KY, NC, IN, MI). Enrol via your retail supplier or default utility A/C cycling program.
ConEd SUR, NYC + Westchester
Smart Usage Rewards: $25/year for a connected thermostat, more if you allow battery dispatch. Active May to September event window.
ERCOT TX, REP free-nights + ERS
Reliant Truly Free Nights, TXU Free Nights & Solar Days, Gexa Saver Free Nights. Aggregator-side: Tesla Energy, Sunrun, Voltus.
CAISO DSGS, CA (with battery)
Demand Side Grid Support: home batteries dispatch during the 4 to 9 pm net-load peak. Top tier reaches $1,000+/year for enrolled Powerwall and equivalent.
Three things to know before enrolling
- A Most events are short, scheduled and override-able. A typical residential DR event runs 2 to 4 hours during a heat dome or capacity emergency, with a few hours\' notice. Almost every program lets you opt out of any specific event without losing your enrolment, you just forfeit the per-event credit for that day.
- B Equipment determines the payment band. A thermostat-only enrolment earns at the low end ($25 to $100/year). A thermostat + battery + EV charger stack earns at the high end ($500 to $1,000+/year), because the operator can call on you for capacity, energy and ancillary services in one bundle.
- C FERC Order 2222 is about to expand the deal. Implementation rolls out ISO-NE 1 Nov 2026, PJM 1 Feb 2028, MISO 1 Jun 2029, SPP Q2 2030. After each ISO\'s go-live, aggregators can bundle thousands of homes into wholesale-energy, capacity and ancillary-service bids, which is expected to push residential DR earnings up across the board.
Why Earth Hour is a successful campaign even if it is not a useful grid event.
The gap between symbolic and technical impact is not a flaw in Earth Hour, it is the design. Four structural reasons explain why WWF keeps running it and why the format keeps growing.
It is a media event, not a grid event
Earth Hour is engineered to produce one extraordinary night-time image (Sydney Opera House dark, Eiffel Tower dark, NYC skyline dark) every year, plus 24 hours of climate-themed news coverage in 190+ countries. Measured by Earned Media Value the campaign delivers hundreds of millions of dollars of attention for a small operating budget. The kilowatt-hours are a side effect of the visual.
It is a recruitment funnel for harder behaviour
A household that turns the lights off for one hour is measurably more likely to enrol in a utility demand-response program, swap a gas water heater for a heat pump, or sign up for a community-solar subscription in the following 90 days. WWF and several state energy offices have documented the effect. The hour primes the year.
It does not need utility cooperation
Demand-response programs require utility tariffs, ISO market rules, equipment certification and a customer enrolment flow. None of that exists uniformly across the 50 states. Earth Hour requires only a light switch. That is why it scales to 190 countries and a US municipal-aggregation pilot does not.
The next 5 years close the gap mechanically
As FERC Order 2222 rolls out across ISO-NE, PJM, MISO and SPP from 2026 to 2030, aggregated households will be able to bid one-hour blocks of consumption reduction directly into wholesale markets. The infrastructure that makes Earth Hour a paid event, not a symbolic one, is being built right now.
The right way to read Earth Hour: it is a public-relations success that uses real electricity as the visual, not an electricity event that needs to be defended as a CO2 saver. The action that pays is enrolling in your utility\'s demand-response program for the year. Doing both is the right answer.
Six things you can actually do.
Diary 28 March 2026, 8:30 to 9:30 pm
Last Saturday of March, your local time. Switch off non-essential lights, electronics and screens for one hour. Use the hour to do something low-energy that is not screen time: a walk, a card game, dinner by candle. The cultural value is in the hour itself, not the kilowatt-hours.
Enrol in your utility\'s DR program
PJM zone: ask your supplier or default utility for A/C cycling or thermostat-control enrolment. NY: ConEd Smart Usage Rewards. TX: switch to a free-nights plan and enrol any battery via ERCOT ERS. CA: CAISO DSGS via PG&E, SCE or LADWP.
If you have a battery, stack the payments
A Powerwall, Enphase or LG battery can enrol in both your utility\'s DR program and a virtual power plant (VPP) aggregator. In CA and TX, top-tier stacked enrolment reaches $1,000+/year in payments. In MA, ConnectedSolutions battery enrolment pays around $225/kW-year.
In TX, pick a free-nights plan
Reliant Truly Free Nights, TXU Free Nights & Solar Days, Gexa Saver Premier Free Nights make 9 pm to 6 am hours free in exchange for a higher day rate. Shift laundry, dishwasher and EV charging into the free window. Saves the equivalent of 200 to 600 kWh per year for most households.
Stack the IRS Residential Clean Energy Credit
If you are replacing equipment in 2026, the IRS Residential Clean Energy Credit covers 30% of solar, battery and geothermal heat-pump cost; the Energy Efficient Home Improvement Credit covers $1,200 to $3,200 in retrofits per year. Pairing them with DR enrolment turns a one-time install into multi-year cash flow.
Track FERC Order 2222 in your ISO
The wholesale revenue you can earn through residential aggregation arrives on a fixed schedule: ISO-NE 1 Nov 2026, PJM 1 Feb 2028, MISO 1 Jun 2029, SPP Q2 2030. CAISO and NYISO already have older DER programs. Watch the FERC Order 2222 explainer for status.
Common questions about Earth Hour and US demand response.
Earth Hour 2026 is on Saturday 28 March 2026, 8:30 to 9:30 pm local time. The rule has been the same since 2008: last Saturday of March, 8:30 to 9:30 pm in whatever timezone you are in. Source: WWF Earth Hour.
Marginally. Grid operators in PJM, ConEd, ERCOT and CAISO have measured the load reduction in participating cities at 1 to 4% of evening load during the 8:30 to 9:30 pm window. That is often inside normal forecasting error and rounds to zero CO2 saved at the system level. The symbolic and communications impact is much bigger than the kilowatt-hours.
A residential demand-response program. Most US utilities now offer one: PJM Emergency Load Response Program across 13 states, ConEd Smart Usage Rewards in NYC and Westchester, CAISO Demand Side Grid Support in California, ERCOT Emergency Response Service in Texas. Annual payments run from $50 to $1,000+ per enrolled home depending on equipment (thermostat only vs battery + thermostat) and the number of events called.
It is a different mechanism, same effect for your bill. ERCOT-area retail electric providers (Reliant Truly Free Nights, TXU Free Nights & Solar Days, Gexa Saver Premier Free Nights, Constellation Free Weekends and similar) make 9 pm to 6 am hours free in exchange for a higher day rate. A household that shifts laundry, dishwasher and EV charging into the free window typically saves the equivalent of 200 to 600 kWh per year, which at the EIA-verified US average of 18.83 cents/kWh (March 2026, EIA Electric Power Monthly) is $38 to $113 a year, every year.
No. The recovery ramp is well inside normal evening dispatch capability. Grid operators run far larger ramp events every weekday morning (the 5 to 9 am wake-up ramp) and every evening (the 5 to 8 pm cooking/EV-charging ramp) without incident. Earth Hour's 9:30 pm switch-back lands at a moment when the system is already ramping down toward overnight load, so the bounce is smoothed by falling underlying demand.
It is the 2020 federal order that requires every US wholesale market to let aggregated household-scale equipment (rooftop solar, home batteries, smart thermostats, EV chargers) bid into the same auctions as power plants. Implementation rolls out 2026 to 2030: ISO-NE on 1 November 2026, PJM on 1 February 2028, MISO on 1 June 2029, SPP in Q2 2030. By the late 2020s an Earth Hour-style action will not be symbolic any more; it will be a paid product. Source: FERC Order 2222 explainer.
Yes, as a communications act. It is a one-hour visual statement to family, neighbours and elected officials that climate policy matters to you. But do not confuse the gesture with the action. Pair the hour with one decision the rest of the year supports: enrol in your utility's demand-response program, switch to a Texas free-nights plan if you are in ERCOT, set your smart thermostat to allow utility cycling events, or stack the IRS Residential Clean Energy Credit toward a battery + heat-pump retrofit. The hour is the prompt; the year is the result.
No US utility or ISO runs Earth Hour itself. It is organised by WWF as a global communications campaign. Some city governments (NYC, Chicago, San Francisco, Los Angeles) and landmark venues (Empire State Building, Willis Tower, Las Vegas Strip casinos) coordinate visible lights-off. The utility-run programs are separate and operate year-round.
Keep learning about US energy action
Demand response, explained
Getting paid to use less. How aggregated household load becomes a wholesale resource.
Distributed energy
Rooftop solar, batteries and EVs as wholesale-market resources under FERC Order 2222.
US wholesale electricity markets
Seven ISOs, marginal pricing, and how a five-minute auction reaches your bill.
Electricity prices per kWh
EIA-verified state-by-state residential prices, May 2026.
Deregulated states map
State-by-state status of electricity and gas retail choice in the US.
Tesla and grid-edge storage in 2026
Powerwall, Megapack, VPPs and what they actually changed at the utility.
The future of US nuclear
Vogtle 4 online, data-center deals, and the SMR pipeline in 2026.
America\'s most efficient cities
The ACEEE Scorecard, why cold-climate cities win, and what the South should learn.
Texas energy hub
ERCOT, retail providers, free-nights plans and the RTC+B redesign.