Energy upgrade in apartment

Isolation where possible Windows walls etc heat pump boiler and airco wil definitely help you up 1 to 2 ratings

To upgrade the energy rating of an apartment, first identify which improvements are possible within your flat (e.g. insulation, glazing, heating system). For any work affecting shared building elements, approval from the Owners’ Association (VvE) may be required. Once the improvements are completed, a certified energy assessor can inspect the property and issue an updated energy label.