The Gigacorn Challenge: Save 1 Gigatonne CO₂/yr

What Is a Gigacorn?

In climate tech, a 'gigacorn' is a company with the potential to cut CO₂ by 1 gigatonne per year — 1,000 million tonnes. For context: the entire EU emits about 3.4 GT per year. A single sector delivering 1 GT of savings is a civilisation-scale shift.

Buildings are responsible for roughly 10 GT of CO₂ globally each year — about 28% of all emissions. The majority of that comes from one thing: heating. Space heating and water heating together account for over 70% of residential energy use. This is where demand flexibility matters most.

The Scale: 91 Million Gas Water Heaters in the EU Alone

The EU has approximately 202 million households. Around 91 million of them heat water with natural gas — either a dedicated gas boiler or a combi unit that handles both space and water heating. These devices emit around 560 kg of CO₂ per household per year just for water heating.

Add North America (~100 million gas water heaters), China (~150 million coal/gas homes), and the rest of the developed world, and the global number of fossil-fuelled residential water heating units exceeds 600 million. The opportunity is not niche — it is one of the largest single sources of addressable residential CO₂ on the planet.

The Hidden Danger: Electric Can Be Worse Than Gas

Here is the truth most energy transition articles skip: simply replacing a gas water heater with an electric one can increase CO₂ emissions — if the electricity comes from today's average grid.

The EU average grid currently emits around 300 g CO₂/kWh. A gas water heater produces roughly 560 kg CO₂/year. An electric water heater drawing the same energy from the average EU grid produces around 750 kg — 34% more than gas. Without smart scheduling, the transition makes things worse.

The Full Calculation: How Elewatt Reaches 1 GT

Stack up every lever — demand shifting for existing electric users, smart water heater replacement, and the renewable enabling effect — and the EU pathway alone reaches ~132 Mt CO₂/year. Scaled globally, the direct savings exceed 500 Mt, and the IEA estimates demand flexibility enables an additional ~500 Mt through renewable integration. The total crosses 1 GT.

Assumptions: electric water heater at 100 g CO₂/kWh (Elewatt off-peak); demand shifting saves 250 g/kWh vs peak. Gas water heater baseline 560 kg/yr. Grid enabling and global enabling based on IEA demand flexibility estimates. Sources: Eurostat 2023, Nesta 2021, IEA Buildings 2023, IEA Demand Response 2023.

The global multiplier is approximately 4×: EU represents roughly one-quarter of global addressable residential fossil heating. Applying the same pattern to North America, China, and the rest of the developed world — where the same smart plug + scheduling approach works — yields the full 1 GT potential.

Calculate Your Contribution

See how much CO₂ your water heater or radiator saves each year when scheduled with Elewatt to run during the cheapest, cleanest hours.

Why Smart Scheduling Is the Missing Link

Electric water heaters and EV chargers are mature, available, and increasingly affordable. The technology barrier is gone. What remains is software: ensuring these devices run when the electricity is clean.

A water heater running during Tuesday morning peak — when gas plants compensate for low wind — can emit more CO₂ than the gas boiler it replaced. The same water heater running at 2am on a high-wind night emits almost nothing. Same device, different timing, radically different outcome.

As renewable capacity grows, the gap between peak (dirty) and off-peak (clean) electricity widens — and off-peak becomes cheaper too. Elewatt users capture both benefits automatically: lower electricity bills and lower emissions, without changing a single appliance.