What is meant by the Heat Loss Index?
The thermal data used in Calderdale’s Thermal Survey has been measured from the amount of infra red being emitted by surfaces – the emissivity, which can be interpreted as the amount of heat being given out. The Heat loss index is an average emissivity value, which is calculated for each building, relative to the rest of the area surveyed, which is then translated into a colour on the map and separated into three areas (high, moderate and low heat loss). The Heat Loss index is an average value of how much heat is being lost from your building, which ranges from 0 – 254 (low to high heat loss). The following factors can influence the readings picked up by the thermal camera: • Building construction and materials directly affect the thermal values of a roof, as some materials are capable of absorbing more heat and / or retaining heat for longer. For example a slate roof may appear to give out less heat than a concrete tiled roof. • Surface colour can affect the actual temperature: dark s
