Stop cold draughts – It’s never too late to stick a sheep in your chimney

October and November are the peak months for getting the home insulated, ready for the onslaught of winter. By this end of the winter homeowners are thinking of spring things, garden improvements and all that. As the days are getting noticeably longer, it becomes easier to tolerate the cold draughts for a couple of months more, and get around to draught busting later in the year. However the Chimney Sheep will make a massive difference to the cold draughts right now, and will continue giving benefits throughout the summer months.

Lots of warm, expensively heated air lost up the chimney

The Chimney Sheep® is a bung for the chimney made of felted sheep wool. It lodges in the throat of the chimney, preventing precious warm air from the central heating from escaping up the flue. The Buildings Research Establishment* calculate that 80 cubic metres of air travels up the chimney per hour. That’s a couple of roomfuls of air per hour. And if all that lovely warm air disappears up the chimney, it needs to be replaced, so cold air is pulled in from around doors, windows, any little gap it can find, to replace the lost air. These are the cold draughts we feel. And on windy days, the pull up the chimney is increased.

Stack effect

Chimneys work by a phenomenon known as the stack effect. They are designed to draw fumes from the fire up and out of the building. Even if the fire isn’t lit, they will continue to pull air out. The taller the chimney, and the colder / windier it is outside and the warmer it is inside, the more the chimney will pull. However even in mild conditions, the chimney will still cause a current of air to flow up the chimney. And in the summer time, if it’s cooler inside and warmer outside, the chimney will actually work in reverse and pull hot summer air into the property.

Stop cold draughts and air pollution

We are increasingly being warned of the dangers of air pollution in the city, and it feels like we are safe from the city fumes indoors. But if the chimney is causing 80 cubic metres of air to flow through the home per hour, then that is a lot more polluted air being pulled in than we realise. Of course houses need air changes and ventilation, but chimneys cause a much greater amount of air to flow through the property than is necessary.

So if you’re pondering whether it’s worth getting a Chimney Sheep® to keep Doris and her associates at bay at this end of the winter, remember the ‘Sheep will still be a friend to you over the summer months.