Uväärtusega

Uväärtusega is a term used in Estonian-language sources to refer to the U-value, the measure of thermal transmittance of a material or construction. The U-value expresses how well a building element resists heat flow; lower values indicate better insulation. In standard Estonian practice, the term is commonly written as U-väärtus, with the instrumental form U-väärtusega used in sentences such as “U-väärtusega seina…” meaning a wall with a U-value of a certain amount.

Etymology and usage: The word combines the letter U, standing for the thermal transmittance symbol, with Väärtus, meaning value. The instrumental suffix -usega marks the phrase as “with a U-value.” This form appears in technical specifications, energy certificates, and construction documents to describe the property of components in terms of heat transfer.

Calculation and interpretation: The U-value is defined as the heat transfer per unit area per degree of temperature difference, expressed in W/m^2K. It can be computed as U = 1/R_total, where R_total is the sum of the thermal resistances of all layers in a construction and the external/internal surface resistances. For multilayer assemblies, each layer contributes R = d/k (thickness divided by thermal conductivity), while convective resistances are added at the interfaces. A smaller U-value means greater insulation efficiency.

Applications and regulation: U-values are central to energy performance assessments, labeling, and building regulations. They guide design choices for walls, roofs, floors, and fenestration, and influence retrofits to meet efficiency targets. Typical values vary by climate and construction type, with windows generally higher (less insulating) than walls in modern standards.

See also: R-value, thermal conductivity, heat transfer, energy efficiency, building energy performance.