Convegni ATI - Accesso riservato soci CTI

Autore: F. Cappelletti, A. Prada, P. Baggio

Collana: CA - 66 - Rende 2011

Note:
The introduction of the energy certification of buildings has driven the construction industry to invest on energy performance of products. Many materials declare high performance thermal characteristics, but only a few have been tested on site, under real operating conditions. The thermal resistance of a structure, in fact, can be quite easily estimated under steady state conditions with a hot box apparatus with heat flowmeter and guard ring but on a real site, where the steady state conditions cannot be easily achieved, a simple measurement is not possible. In the present paper an extended series of measurements of temperatures and heat flux in transient regime on a roof component are presented. Temperatures and heat fluxes have been collected during the heating season 2010-2011, from 12 November until 4 January. Two heat flowmeters and
four temperature sensors have been used to measure external and internal heat fluxes, external and internal air temperature and surface temperature. The component analyzed is a brick roof with high mass, covered with a thin multi-foil insulation layer of
about 24 mm and tiles. The measurements have been elaborated with the two methods specified by the International Standard ISO 9869:1994, the average method and the dynamic method so the heat fluxes have been reconstructed according to Annex B.
From the elaboration of the measurements the stationary thermal conductance of the component has been estimated and a method for the determination of dynamic thermal characteristics (periodic conductance, decrement factor and time lag) using
measured values has been proposed.