Insulation should always be the key regardless of what method you use to warm or cool a place - I also have a heat pump on old 100 year old house works great
IKEA is now offering air-to-water heat pumps to customers in Germany. Offered in partnership with Svea Solar, it joins the companies' existing solar panel and EV charging solutions. IKEA Family members are offered a discount on their purchases and may be able to claim some money back through government schemes.