Small World’s emissions factors are drawn either from either a top-down or a bottom-up methodology, or a blend of the two. Each has its own strengths and weaknesses, so combining them gives us the best of both worlds.
Ultimately, we rely on the information you give us to ensure you receive the most accurate figures possible, meaning our survey answers are as important as our methods!
To highlight the fact that sustainable choices often have a financial benefit, we’ve attached estimated cost savings to many of our actions. How do we get these estimates, you ask? It’s quite simple—our carbon calculations are based on the energy usage of that action. We then take those numbers, and figure out the monetary cost of that energy.
For example, when we’re calculating the cost savings of, say, cycling or walking instead of driving, we look at the cost of petrol per litre, then multiply that by the miles driven and the vehicle’s fuel efficiency.
Our cost calculations are based on current market rates in the UK and Europe, but that isn’t to say we’re aiming for perfect accuracy! There are plenty of other factors that can influence the cost savings of an action—for instance, some figures are harder to estimate since they use demand-based pricing, like flights and taxis.
This is why each of our calculations comes with a range of savings, rather than a single figure. It allows users to use their own judgement to decide where their personal saving will lie.