Floor plan tube house L-shape triangular plot including oak tree

How about a penthouse instead of a basement? Living room and study all the way at the top

How about a split-level instead of a basement? Living room and study all the way at the top

The basement is indispensable for us. As I said, I would rather do without the garage.

To be honest: Inside it creates a nicer space. Also, the energy that enters the room through one window immediately escapes through the opposite window.

We thought that this would make the relatively small room (living room) appear larger...

Hello Oakland

I really wish you a nice house. What you are planning is a compromise. It can't be more than that. And this compromise will be expensive. Building a house is simply expensive and it regularly becomes more expensive than planned.
Just something to think about: First, get a cost estimate. Then calculate whether the loss from selling this weird plot and buying a reasonable one is not less than building this house compared to a "normal" one. I fear that realizing this project will cause a lot of headaches.
Perhaps a nighttime action with the chainsaw and the fine would be the cheaper option.

Steven

We thought that this would make the relatively small room (WZ) appear larger...

I would have claimed the opposite and therefore recommended the window.

It is your decision and the property is not flat.

Just a thought. Building services on the ground floor
Living room and study at the very top