Number of heating degree days for the period 1961/62-1978/79...

Number of heating degree days for the period 1961/62-1978/79. The values are calculated for an individual day as the difference between 17 °C — the so-called base temperature — and the average daily temperature. During the summer, from April to October, this applies only if the average temperature is below what is called the fire limit. The fire limit is 10 °C in May-July, as solar radiation contributes most to heating, 11 °C in August, 12 °C in April and September and 13 °C in October. The base temperature of 17 °C used in the calculations corresponds to the indoor temperature of 20 °C, as lighting, stove, fridge and freezer also contribute to heating. The recommended range for the product is 1:10 million. Current values for the number of degree days and more modern products for normal year correction can be ordered from SMHI’s Businesses.