Your pellet supply is dwindling fast, and you're wondering how many bags it's normal to consume over a winter?
Having seen the energy contained in a kilo of pellets, we'll do some calculations to determine the likely number of bags you'll consume this winter.
The daily consumption of pellets to heat a 100m2 house is 15kg per day, which corresponds to 1 bag per day.
If this result seems to come out of nowhere, it's an approximation for a standard case. In the following, you'll find the details that lead to this result.
Energy contained in 1kg of wood pellets
If oil was so successful in the 20th century, and has made our society what it is today, it's because it's a highly concentrated and easily transportable form of energy. It contains around 10 kWh of energy per liter.
Wood pellets are also very popular, as they are a highly concentrated form of renewable energy, although only about half as concentrated as petroleum. In fact, 1kg of pellets contains around 4.9kWh. Often packaged in 15kg bags, which contain around 75kWh each, pellet appears to be a practical energy source, which is why more and more French people are choosing pellet stoves for their heating needs.
the amount of energy needed to heat a house in winter
There are as many answers to this question as there are different volumes to be heated and different climates. To answer this question, we'll consider a 100m2 house (volume 250m3), which represents a good average for houses in France. We also consider a winter from December 21 to March 21, i.e. a duration of 3 months.
While the amount of heating energy may be around 15W/m3 for very well insulated houses, this is not the case for all houses in France. Some can require up to 60W/m3 and more if they are poorly insulated or very old. A good average is therefore 40W/m3.
The heating capacity for 100m2 would therefore be around 10,000W.
If we consider a 3-month winter, i.e. 180 days, with a heating system that runs 8 hours a day, our heating system operates for 1440 hours during the winter, and our heating requirement is therefore 10kW x 1440h = 14400kWh.
So how many wood pellets will it take to keep you warm this winter?
At 4.9 kWh per kg of wood pellets, the quantity of pellets required is 14400/4.9 = 2938 kg of pellets.
At 15kg per bag, we get 195 bags, which represents just over one bag of pellets per day to heat a 100m2 house.
Case of a very well-insulated house (15W/m3)
If your house is newer or recently insulated, you can divide this consumption by about 2.66 to get your approximate consumption. So the number of bags of pellets needed over a winter is 73 bags, which gives us just under half a bag a day for winter heating
Case of a poorly insulated house (60W/m3)
If, on the other hand, your house is poorly insulated, then you can multiply this consumption by 1.5, which gives you 292 bags of pellets for the winter. that's just over 3 bags every two days, or a dozen bags a week.
How to save on pellet fuel this winter?
Depending on your situation, there are several things you can do to reduce your consumption.
First of all, if your house is not perfectly insulated, this is of course the first action to consider. Insulating your attic, your walls or your floor are the actions that will give you the quickest return on your investment. You'll drastically reduce heat loss and cut your bills.
Then you have all these energy-saving measures more or less popular, such as :
- Reducing the temperature to 19°C
- Shifting the start and end of the heating period by 15 days: this means heating only from November 1st to March 31st, and therefore saving 15 days over the winter, and 1 month in total over the entire heating period. But 15 days represent 15 bags of pellets.
- On days when the power grid is under heavy strain, reduce the heating to 18°C....you can follow this on https://www.monecowatt.fr/ which gives the "weather" of electricity.
For this winter, we recommend that you order your pellets in the form of pallets. A pallet of pellets contains around 65 to 70 bags of wood pellets, each weighing 15 kg, and costs around 450 euros.
=> 3 pallets for a standard house.
=> 1 pallet for a well-insulated house, but 4 to 5 pallets for a fairly poorly insulated house.
Juliena mechanical engineering graduate and specialist in climate engineering since 2009, has become a writer specializing in renewable energies, with expertise in heat pumps and photovoltaic solar panels for individual housing.
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