Lämpövuorokausia

Lämpövuorokausia, which translates to "heating degree days" in English, is a measure used in meteorology and energy management to quantify the demand for heating an indoor space. It is calculated by comparing the average daily temperature to a base temperature, typically around 17 degrees Celsius (62.6 degrees Fahrenheit). If the average daily temperature is below this base, the difference is summed up for that day. This cumulative value over a period, usually a month or a heating season, represents the heating degree days.

The concept is based on the principle that when the outdoor temperature drops below a certain point, artificial heating is required to maintain a comfortable indoor environment. The lower the average daily temperature, the higher the heating degree days, and consequently, the greater the need for heating energy. This metric is particularly useful for estimating and comparing heating energy consumption across different locations and time periods. For example, a region with more heating degree days will generally require more energy for heating than a region with fewer heating degree days, assuming similar building insulation and occupancy.

Heating degree days are widely used by energy companies to forecast heating fuel demand, by building engineers to design more energy-efficient structures, and by consumers to understand and potentially reduce their heating costs. Variations in the calculation exist, such as using different base temperatures or accounting for solar radiation, but the fundamental principle remains the same: quantifying the need for heating based on outdoor temperatures.