Question on energy certificate

Hi everyone.

To keep it short: I am looking to buy an appartment in berlin. As energy efficiency is a hot topic nowadays, I had a look at the energieausweis as provided by the real estate agent.

Building is from 1900
Total of 18 units.
Energylabel is verbraucherausweis based (made in 2019 based on the preceding 3 years).

When I look at the label it gets a D which is nice but…well weird as its a building from 1900. I need to check whether the building was fully rented out for the calculation years 2016-2017-2018.

It gets a rating of 117 kwh.

When I calculate I get 599415 (kwh total of last 3 years) / 5577 (3x total surface, which is specified as 1859 square meters) = 107,4 kwh.

Anyone who can explain me why I get a different outcome. I have attached the energieausweis in attachment (no private data is captured, only the verbrauch).

Any help would be much appreciated!