i would pay extra at the beginning as long as the savings would come in the long term.

in germany, a lot of new houses come with some environmental features. in particular, rain water capture is common. you generally have a massive tank under your garden (they dig a huge hole anyway for the cellar, so it's not much more hassle to mkae it a bit bigger for a water tank). rain water is captured from the roof of the house and stored in he tank for use as toilet flushing, garden watering etc

heat pumps are great if you have the land space needed for the coil (or sink one down). the benefit of a heat pump system is that you can run it in reverse for air conditioning in the summer.

the best bet though is just to have a properly built building in the first place with good insulation.

led lighting is now viable which can reduce the energy usage of a house massively.