Which is the best temperature a resident should set its apartment heating system when it is outside? For decades thermal-technicians suggested to not completely switch off the heating system because the re-heating process would have consumed a lot of energy. They suggested a low temperature in between 16° and 18°C, without providing any rational mean of calculation. We faced the topic to rationalize this problem and we called the searched low temperature MELT, Most Efficient Low Temperature. The aim of the problem was to determine the best temperature to be set when the apartment residents are outside to decrease the heating consumptions as a function of
- the external temperature
- the desired high temperature (when residents are inside the flat)
- the duration of the period of residents absence
- the thermal inertia of the flat masses
- the thermal insulation factor
This preliminary study of Politecnico di Torino changed the paradigm: it is most probable that a MELT do not exist, the best chance by the solely point of view of single apartment savings is always to completely switch off the heating system. Or at least, the difference between a complete switch off and a reduction of temperature are not so remarkable. The demonstration has been carried on both by math-analytical and math-simulation point of views providing the same results.