ᐅ Floor Plan Design for a Single-Family Home without a Basement / 4-Person Household

Hello dear forum,

what do the experts say about the following floor plan (especially regarding the questions described below)? Does anything stand out to you as something that should definitely be avoided?

Thank you in advance

Development Plan / Restrictions
Plot size: 447m² (5400 sq ft)
Slope: no, but the plot slopes down about 80cm (31 inches) from the street and needs to be filled
Site coverage ratio 0.4
Floor area ratio 0.4
Building envelope, building line, building boundary
Border development: see attachment
Number of parking spaces: single garage + 2 outdoor parking spaces
Number of floors: 1.5 (only 1 full floor = ground floor)
Roof type: gable roof
Orientation: north/south
Maximum heights / limits: ridge height 5.30m (17 ft 5 in); wall height 5.60m (18 ft 5 in); full height 10.80m (35 ft 5 in); storey height 7.70m (25 ft 3 in)

Homeowners’ Requirements
Style, roof shape, building type: solid house, gable roof approx. 37° pitch, knee wall approx. 95cm (37 inches)
Basement, floors: no basement, 1.5 floors
Number of occupants, ages: 4 (parents 32 and 29, children 5 and 1)
Room requirements ground floor / upper floor: ground floor 90m² (970 sq ft), upper floor 80m² (860 sq ft)
Office: family use or home office? both
Guests per year: 6
Open or closed architecture: closed? see floor plan
Conservative or modern construction: modern
Open kitchen, cooking island: open, with seating (bar)
Number of dining seats: 6-8
Fireplace: no
Music / stereo wall: no
Balcony, roof terrace: no balcony, terrace on ground floor
Garage, carport: single garage, possibly carport for 2 spaces
Utility garden, greenhouse: no
Further wishes / special features: photovoltaic system, half-turned narrow-wing staircase with landing, alternatively solid stair

House Design
Planning by: general contractor and DIY
What do you especially like? Large living/dining area, open kitchen, many storage rooms, large walk-in shower
What do you not like? Why? A lot of space is lost through the hallway/corridor. Perhaps the rooms could be arranged more space-efficiently?
Price estimate according to architect/planner: 400,000 without ancillary construction costs
Personal price limit for the house, incl. equipment: 430,000 without ancillary construction costs
Preferred heating system: air-to-water heat pump with cooling function and underfloor heating

If you had to compromise, on which details / extra features
-can you do without: walk-in closet in the master bedroom, glass sliding door in living/dining room, possibly smaller utility room, cooling function of the air-to-water heat pump
-can’t do without: large living/dining room with open kitchen, spacious shower, storage rooms and attic storage

Why was the design developed like this?
The general contractor planned the house at 10.5m x 8.50m (34 ft 5 in x 28 ft) with basement (waterproof concrete). Because of the groundwater level, the house would be about 80cm (31 inches) higher than the street, knee wall 1.20m (47 inches), attic height only 1.20m (47 inches). A staircase to the house entrance would be necessary. Due to the small rooms and expensive basement, I designed a floor plan without a basement myself. I increased the living room width from 3.85m to 4.50m (from 12 ft 7 in to 14 ft 9 in).

What is the most important / fundamental question about the floor plan in 130 characters?
How can I make the room layout and arrangement more efficient? How and where can I save space? The hallway on the ground floor takes up a lot of square meters, even though it is only 1.25m (49 inches) wide. One reason is the large staircase, but also the long corridor consumes space and feels somewhat narrow. Is it possible to cleverly reduce the living space from currently about 170m² (1,830 sq ft) to 160m² (1,720 sq ft) or less? Different staircase? Move the entrance door? Is there an effective alternative to the cooling function of the underfloor heating? The goal is to save costs through optimization.

I appreciate every opinion, suggestion, and sketch!