ᐅ Prefabricated Wooden Houses Insulation / Heating

Hello forum,

I am currently looking for a vacation or weekend house.
With a budget of €25,000 (about $27,000), it is quite affordable, reasonably spacious, and attractive. I’m wondering how well insulated these houses are and what they are like in winter. Are there any experiences here with such prefabricated wooden houses? For example, I have chosen the thickest wall thickness available. One idea would be to add extra insulation myself using fiberglass. But is a house like this livable in winter and, above all, affordable in terms of heating costs?

Thanks and best regards

The wall thickness is 95 mm (3.7 inches) and is made of spruce wood. Is it possible to live energy-efficiently in a house like this?