> It really doesn't matter how fast you replace the air. If you let in the cold air then you need to warm it up. Ventilating quickly is preferable to ventilati

> It really doesn't matter how fast you replace the air. If you let in the cold air then you need to warm it up. Ventilating quickly is preferable to ventilating slowly. Heat transfer through materials is comparatively slow. That means that exchanging the air in an instant retains the heat in the walls, furniture,… exchanging the air slowly allows heat from materials to „leak out“ as well.