Carbon Cruncher: Calculating Heat Pump Emission Savings

Heat Pumps are the low-carbon future of home heating, but just how much carbon could they save? Our Carbon Cruncher calculator will show you.

What are Heat Pumps and how do they reduce carbon emissions?

A Heat Pump is a way to heat your home without needing gas like a typical boiler. Air source Heat Pumps use electricity to extract warmth from the air outside, even on a cold winter day. This warm air is then pumped around the pipes in your home, heating things like water and radiators, just like a boiler would but without directly emitting carbon dioxide.

Heat Pumps aren’t a new thing – they’ve been around since the 1970s and have become common sights across many other countries. Here in the UK, though, the technology is only recently taking off, and with government grants available to help eligible households get set up, now could be the perfect time to install a Heat Pump in your home.

UK household heating adds up to almost a third of the country’s annual carbon emissions - that’s as much as all petrol and diesel cars combined. At British Gas, we’re committed to helping the UK reach Net Zero. Heat Pumps are one of the technologies that will help the UK on this journey, but just how much carbon could they help you save?

Let’s find out.

A British Gas engineer installing a new Heat Pump.

The Heat Pump CO2 Emission Savings Calculator

Switching to an air source Heat Pump can help reduce your household’s annual emissions by 1,404 Kg of CO2, on average. Use our calculator to see what these reductions could help to offset, such as the emissions caused by international flights, driving miles and even rocket launches. We have also analysed what these emission savings equate to, like the number of trees required to absorb the same amount of CO2 from the atmosphere.

To see the most accurate results, you’ll need to enter your household’s total energy usage from the past year. This can be found in the annual statement your energy supplier will have sent you. If you don’t know this, our calculator will make an educated guess based on the size of your home and the number of people living there. You’ll also need to enter the energy system you currently use, such as Direct Electric Heating, oil, LPG or mains gas.

Ready to see how much carbon you could save? Find out in just three quick steps.

Carbon Cruncher

Calculating heat pump Emission Savings

How much CO2 could the average UK home save with a Heat Pump?

Based on the average UK household’s annual energy consumption of 12,000kWh (a 2-3 bedroom house currently using a mains gas heating system), we calculate that switching to an air source Heat Pump could save 1,404 Kg of CO2 annually.

Over the course of just one year, you could offset the equivalent amount of CO2 emitted by driving 4,544 miles in a petrol car or the emissions caused by energy-thirsty data centres helping to host 8,926 hours of online video calls. Over 10 years, your Heat Pump emission savings could help to offset the CO2 produced by over 32 economy-class flights from London to New York.

And over a 20-year period - which is how long modern Heat Pumps are designed to last - you’ll be doing the same carbon-saving work as 1,276 trees would in one year. That’s pretty impressive pump power.

Type of equivalent CO2 creator / reducer

1-year CO2
saving equivalent
5-year CO2
saving equivalent
10-year CO2
saving equivalent
20-year CO2
saving equivalent
Number of miles driven
in a typical petrol car
4,544 22,718 45,437 90,874
Number of one-way
economy flights (London to New York)
3.3 16.3 32.7 65.3
Number of hours spent
in online video calls
8,926 44,628 89,256 178,512
Number of trees required
to absorb the same amount of CO2
64 319.1 638.2 1,276.4
amount (Kg) of compost
waste required to absorb the same
amount of CO2
1,496,664 7,483,320 14,966,640 29,933,280
Number of years switching
to a vegan diet for one person
4 20 40 80

If the UK achieves its target for annual Heat Pump installations, by how much could CO2 emissions reduce?

The government has set a target of 600,000 homes to be switching to Heat Pumps every year by 2028. If that happens, the annual amount of C02 we save through the installation of 600,000 Heat Pumps could be equivalent to the Space X rocket launching 7,262 times, and a petrol car driving around the circumference of Earth 109,482 times. It could save as much carbon as 226 square miles of rainforest and keep you toasty in your home while it does it.

The annual emission savings from 600,000 UK homes switching to a Heat Pump could be equivalent to...
Value Metric
7,262 The number of Space X rocket launches
109,482 Number of times driving the earth's circumference (24,901miles)
226 Square miles of rainforest required to absorb the same amount of CO2
508,875 The equivalent number of drivers switching from petrol to Electric Vehicles
60,171 The number of barrels of oil (emissions caused in the production)

Our commitment to Net Zero

Everyone at British Gas is dedicated to getting you closer to a Net Zero future. As a company we’re aiming to reach Net Zero by 2045. Our ‘People and Planet Plan’ will make that a possibility.

We’ve invested in technology such as Mixergy - a smart water heating tank that cuts down on wasted energy to only heat the water you need - and Hive, the smart home-heating app that makes your energy use much more efficient.

But it’s not just in the home where we’re making changes - we’re also busy on the roads! By 2025 all our engineers will be driving 100% electric vehicles, while we’re installing EV home charging points for brands like Ford, Lexus, Lotus and Vauxhall. We even offer a dedicated EV charging tariff, meaning your car gets charged when there’s less demand on the supply, saving you money on your electricity bills.

Net Zero isn’t just a nice idea - it’s a necessity, and we’re committed to helping you achieve it.

A British Gas engineer setting up the thermostat.

Sources and methodology

How do we calculate your CO2 savings when switching to an Air-Source Heat Pump?

Using the average energy usage for space heating and hot water in different sized homes (source: Ofgem), and the emission efficiency ratios (CO₂ per kWh delivered) of different heating systems such as LPG, Oil, Mains Gas and Direct Electric (source: Energy Performance Validation Scheme), we calculate a household’s annual CO2 emissions produced for home heating and hot water.

Next, we compare this value against the CO2 emissions produced by the same property type with an Air Source Heat Pump (ASHP) heating system. The difference between the two final values is the amount of CO2 that can be saved by switching to an Air Source Heat Pump.

We take 97.5% of a household’s total annual gas kWh usage (as 2.5% is typically used for cooking, rather than heat).

A typical UK household is considered to be a 2-3 bedroom house; with 2-3 people using 11,700kWh of energy for space heating and hot water, and using mains gas for its energy source.

How do we know what your potential CO2 savings equate to?

We compare a household’s annual CO2 savings from installing an air source Heat Pump to different metrics using typical CO2 emission rates for common emitters / absorbers / offsetting initiatives:

  • Car miles of a typical medium petrol-powered car (source: 8billiontrees)
  • One-way economy-class flights from London Heathrow to New York (source:
  • Kilograms of burning coal (source: EPA)
  • Emissions produced by data centres supporting online video call software (source: Futurenetzero)
  • Green-house gas emissions produced in the production and supply chain of cheeseburgers (source: Six Degrees News)
  • Recycling biodegradable compost waste (source: drawdown)
  • Tree CO2 Absorbtion (source: EEA)
  • Switching to Vegan and meat-free Mondays (source: Exeter.Gov)
  • Solar panels (source: renewable energy hub)
  • A Space X rocket launch (source: BBC)
  • Driving the circumference of the Earth (source: Coolcosmos)
  • Square miles of rainforest (source: EEA)
  • Electric Vehicle CO2 savings VS a typical medium petrol-powered car (source: 8billiontrees)
  • Number of barrels of oil produced (source: ScienceDirect)