Additional insulation necessary?

Hello,

I am planning to buy a house, unfortunately no energy consultant is available at the moment, so I am trying to find out myself whether additional insulation is still necessary or not.

The house was built in 1973 and is a solid construction.
According to the energy certificate, the energy quality of the building envelope is 0.81 W. Is that good?

The building is fully basemented and I noticed that the front and back doors have a lot of thin glass. I think replacing the doors would already help somewhat.
All windows are double-glazed with wooden frames.

Basement: KSV 1.8/150, d= 36.5 cm, insulating plaster outside in the soil.

Ground floor: 11.5 cm KSV, 1.8/250, 2 cm Styrofoam, 17.5 cm KSL 1.4/150.

Furthermore, one entire exterior wall has an attached garage and upstairs there is a covered loggia.
The roof is insulated, there is a blue tarp underneath and it partially has slate and concrete tiles, and it is a collar beam roof. Furthermore, the floor of the attic consists of boards and 10 cm steel wool.

The living area and house entrance are additionally covered.

Can you roughly guess from this whether significant additional insulation needs to be installed here, or is it not possible to say at all, so that only an energy consultant can make a statement here?

Thank you very much in advance and have a nice weekend

Can one roughly guess from this whether significant additional insulation needs to be installed,

Where does this "must" come from. First of all, when buying: attic or roof, pipes in unheated basements must be insulated. But only if nothing has been done yet. The next question is whether energy-related measures make sense. This does not necessarily mean insulation; it can also be windows or a modern heating system and/or new radiators. You can also easily answer this question yourself if you know the actual energy consumption of the house. With 6,000 liters of heating oil per year, energy measures already make sense – with only 1,000 liters, hardly. Apart from that, with your information, the answer to your question is: no idea.