The shape of residential buildings in Nordic climates impacts their energy demand. Sweden aims to increase energy efficiency in buildings to reduce overall energy use. Energy simulations and measurements show that building shape and design play a crucial role in energy efficiency. Buildings with large heated areas like corridors and storage rooms may not actually be more energy efficient. Efficient thermal envelopes and building shapes are key for reducing heat demand, especially in colder climates with strong winds. Evaluating heating technology and energy supply systems together is important for improving energy efficiency in buildings.