kokonaislämmönsiirtö

Kokonaislämmönsiirto, often abbreviated as U-arvo, is a measure of heat transfer through a building component or structure. It quantifies the rate at which heat flows through a unit area of the component for a unit temperature difference between the two sides. The SI unit for U-arvo is Watts per square meter Kelvin (W/(m²K)). A lower U-arvo indicates better thermal insulation, meaning less heat is lost or gained through the component.

This value is crucial in building design and energy efficiency calculations. It takes into account the thermal resistances of all the layers that make up the building element, including materials, air gaps, and surface resistances. For example, when evaluating a wall, the U-arvo would consider the properties of bricks, insulation, plaster, and any air cavities present.

Accurate U-arvo calculations are essential for determining the heating and cooling loads of a building, selecting appropriate insulation materials, and ensuring compliance with building regulations and energy performance standards. By minimizing U-arvo values in walls, roofs, floors, and windows, designers can significantly reduce energy consumption, improve indoor comfort, and lower the environmental impact of a building. The U-arvo is a key parameter in assessing the overall thermal performance of a building envelope.