Assuming the indoor air temperature to be constant, the thermal transient behavior of a building envelope’s opaque wall, stressed by external temperature sinusoidal oscillations, is characterized by the following parameters: the decrement factor f, the wall inner surface decrement factor s, the time lag t and the dynamic thermal transmittance UD. Such parameters depending on the wall thermal resistance and thermal capacity, on the period of the external thermal stress and on the stratigraphy of the wall, have been studied by several authors and can be found within the European technical standards (e.g. EN ISO 13786/2007) and Italian national and local rules (e.g. legislative decrees for the implementation of EPBD). In this paper the Author, after deducing by the transmission matrices method the expressions of f, s, t and UD, and discussing in detail their meaning, solve the following problem: to determine (in a lumped-parameter schematization) the stratigraphy of a wall, with given thermal resistance and capacity, minimizing the decrement factor f as well as the stratigraphy of a wall maximizing the time lag t.
On the Parameters Characterizing the Thermal Transient Behavior of the External Walls of Buildings
LECCESE, FRANCESCO;
2009-01-01
Abstract
Assuming the indoor air temperature to be constant, the thermal transient behavior of a building envelope’s opaque wall, stressed by external temperature sinusoidal oscillations, is characterized by the following parameters: the decrement factor f, the wall inner surface decrement factor s, the time lag t and the dynamic thermal transmittance UD. Such parameters depending on the wall thermal resistance and thermal capacity, on the period of the external thermal stress and on the stratigraphy of the wall, have been studied by several authors and can be found within the European technical standards (e.g. EN ISO 13786/2007) and Italian national and local rules (e.g. legislative decrees for the implementation of EPBD). In this paper the Author, after deducing by the transmission matrices method the expressions of f, s, t and UD, and discussing in detail their meaning, solve the following problem: to determine (in a lumped-parameter schematization) the stratigraphy of a wall, with given thermal resistance and capacity, minimizing the decrement factor f as well as the stratigraphy of a wall maximizing the time lag t.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
