If all the conditions were right, it would be fun to build an environmentally friendly house according to all the rules of the art, but the reality is that neither time nor money is in abundance. So I wonder where the worst environmental culprits are found in a "normal" house construction? By environmental culprits, I mean not only things that are hazardous to manufacture, dispose of, etc., but perhaps especially those that are not so good to be around, such as gases from plastics, flame retardants, glue, etc. We are planning to completely renovate an old house (including rewiring) and add 50m2. I'm asking for tips on what small measures to consider, for example, "When buying particle boards, you might consider that..."
The first step is actually to plan and coordinate your purchases. It's easy to end up driving many miles to get a small item here and there. Then check where you can find recycling/sales of used building materials. Both cheaper and better to reuse than to build new. I found almost new Gustavsbeg porcelain for the bathroom. WS plus sink for 1500. New toilet seat for 200:-. Definitely good economically too.