Hello Haddirajan!
A newly built house has significantly better insulation than the houses built before the oil crisis of the 1970s.
A newly built house keeps out heat as well as it keeps in heat during the winter. The problem arises when we, like now, have several days or even weeks of very hot weather. It becomes more difficult to protect against the heat because the construction becomes thoroughly warm. A somewhat better cooling effect can be achieved with houses that have a heavy structure. Masonry houses or concrete houses are somewhat cooler than wooden houses.
It is common today to choose a heat exchanger for heating. Some of these can be switched from heating to cooling if desired. This option can mean a more expensive initial cost and higher operating costs, but if you want cooling in your house, it is an alternative. Some municipalities that provide district heating also have district cooling that you can connect to.