14 years ago, Chimney Sheep was registered at Companies House.

Since then, 310,000 Chimney Sheep have gone out into the world. It’s impossible to know what every single one of them is doing, but we do hear from original customers from time to time. Thank you to those early adopters. It’s pleasing to hear that the original ‘Sheep are still going strong.

What 14 years of Chimney Sheep have achieved

We calculated the cumulative savings. Chimney Sheep inserted 14 years ago have 14 years of savings, while ‘Sheep fitted last year have one year of savings. This is based on calculations by BSRIA, an independent laboratory, of how much a Chimney Sheep saves each year:

• 1,449,713,903 kWh of energy saved, heat that stayed in people’s homes instead of going up the chimney.
• £48.4 million kept in customers’ pockets rather than spent on heating.
• 343,443 tonnes of CO₂ that was never released.

That’s roughly the same amount of energy it would take to heat and power over 102,000 UK homes for a year, or the output of around 300 wind turbines running flat out for twelve months. The carbon saved is about the same as taking 136,000 cars off the road for a year.

A realistic view of the numbers

You could be cynical and ask what happens if people aren’t using their Chimney Sheep as they should, if they’ve moved house and taken the ‘Sheep out, or if they’ve had a log-burning stove fitted.

OK. Let’s halve those numbers.

• 724,856,951 kWh of energy saved.
• £24.2 million not spent on heating bills.
• 171,721 tonnes of CO₂ not released.

These are realistic claims, and still very big numbers.

Planting trees, too

Over the last five years, we’ve also donated enough money to Buy Land Plant Trees CIC to purchase 350 acres and plant 420,000 trees. I’m pretty happy about that too, particularly as the trees are doing really well.

We’ve helped pioneer cluster planting, which isn’t widely used but is an effective way of establishing woodland in upland areas. People travel from all over to see how replicating the way nature works can help trees grow. They won’t all reach maturity, but many will, and many will produce more trees as they go. Some are already producing seed or suckers.

So even if you halve that number too, that’s 210,000 trees, each of which will absorb a tonne of CO₂.

Between us, because it’s not just me anymore, it’s a team that includes Chimney Sheep staff past and present, customers, friends and family, donors, and organisations that have assisted and facilitated, we’ve prevented 171,721 tonnes of CO₂ from being released and captured 210,000 tonnes.

I’m proud of that.

One chimney at a time

It’s not a sexy techy gadget. It’s a rather boring, deliberately simple, useful thing. But it is getting on with the job, one chimney at a time.

It’s estimated that there are 11 million homes in the UK with open chimneys. We’ve sold 310,000 in 14 years. So, on the one hand, what we’ve achieved is something big and worth celebrating. But just think how much heat is being wasted in all those chimneys that aren’t blocked.

I developed the Chimney Sheep because I became aware of how much heat was being lost up open flues, literally like leaving a window open permanently, and it seemed to be a colossal waste of resources.

Part of what we’ve been trying to do over the last 14 years is raise awareness of heat loss up chimneys and get the authorities to make draught-proofing a chimney as normal as draught-proofing doors and windows. Cold draughts are exacerbated by an open chimney. The 80 cubic metres flowing up a chimney per hour have to be replaced, which is what causes cold air to be pulled in through leaky parts of a building.

Finally, this year, the Energy Saving Trust put draught-proofing the chimney in its top ten energy-saving tips, at number 2.

So there are things to celebrate and things still to do. But it’s definitely an excuse for cake.