Nowadays, a common service is insulating walls by pumping, for example, small foam balls (or something similar) into the gaps of the walls. Almost a must have for a decent owner.
Since we’re talking about insulation, as they say, so as not to get up twice, I’ll write right away how much energy you need to spend on heating a Dutch house. An average townhouse with an area of 100-130 m2 requires about 900 cubic meters of gas for the heating season (to maintain 21 degrees inside). Please note that this is local gas, which has less calories than, for example, Russian gas. 1m3 of Dutch gas produces 9.8 kWh or 35.1 MJ. Climate must also be taken into account. In winter, temperatures here rarely fall below zero. Usually this is 0-+5 oC. Taking into account local gas prices, heating costs approximately 700 euros per year.
A house that is of the type two under one roof is usually larger in area (130-180 m2) and requires proportionately more gas for heating.
Modern standards require a very high level of insulation and it is desirable to have some additional energy-saving options: solar panels, a heat pump, or all together. In general, the new fashion here is the refusal of gas. Heat pumps are spreading quite quickly. I also installed such a device for myself. I’ll tell you sometime in a separate post. There are solar panels too. It will also take a separate post to explain everything. In principle, if you get a little confused, now you can build a house here that will not consume energy on average per year.