Cost Estimation for Outdoor Facilities with Planning

Only if you have provided her with the corresponding information. Or if she obtained the information from the building authority herself. Although it is not uncommon in densely built-up areas for a site coverage ratio including ancillary facilities to go up to 0.8, one should check this before a neighbor points it out to the building authority.

Where could costs be saved?

Pool gone - boom, 70k less

But seriously, sum of the things. Which walls are necessary? "Normal steps" or floating look? Tree at 3.5m height in the Corten steel bed or tree at 1.8m in lawn edging stone border, paving 50€ net or 25€ net.
Sounds silly, but sum of the things.

P.S.: I like the plan, I think it’s basically laid out very nicely.

P.S.: I like the plan, I basically find it very nicely designed.

I am aware of that and that it costs extra again. So was your estimate with or without?

Yes, it was without, although of course the question is what you replace the area with. Are you considering lighting/electricity? Usually, you don’t install something like that without outdoor lighting etc. It also costs a few euros.