Heating power demand selection:

40 W/m² - very good building heat insulation and other favorable factors: the minimum loss of ventilation and heat, building orientation to the south, i.e. building corresponds to energy efficiency class A +, A ++ (according Lithuanian classification) and passive house requirements. 
60 W/m² - very good building heat insulation and other favorable factors: the minimum loss of ventilation and heat, building orientation to the south, i.e. building corresponds to energy efficiency class A (according Lithuanian classification) requirements. 
80 W/m² - good building heat insulation - newly build house or insulated old building, but there are unfavorable factors: the average loss of ventilation and heat. 
100 W/m² - the average building heat insulation - newly build house or insulated old building, but there are unfavorable factors: the large loss of ventilation and heat. 
120 W/m² - satisfactory building heat insulation - the old building, new windows, insulated some of walls. 
140 W/m² - poor building heat insulation - the old building, old windows