In the last couple of decades cool roofs, i.e. roof surfaces exposed to solar radiation charac-terized by high solar reflectance (albedo) and thermal emittance, are being intensively stud-ied for their ability to reduce the roof temperature, which leads to a lower heat transfer into the building. This acknowledged phenomenon produces better indoor thermal comfort condi-tions and reduced energy requirement for cooling, resulting in lower greenhouse gas emis-sions. Additionally, cool roofs are also studied and optimized for their larger scale effect as Urban Heat Island mitigation strategy in dense cities. In this perspective, several reflective coatings and materials were used for cool roof applications, e.g. light color paintings, roof tiles and waterproof membranes. Recent research developments were also focused on the analysis of natural and sustainable materials having these properties. In particular, stone ag-gregates were studied for their intrinsic cooling potential with varying grain size and stone typology. Roof covered by stone aggregates can be considered as a rigid frame porous mate-rial whose acoustic properties can lead to similar advantages to the thermal ones: (i) a small scale benefit, i.e. an increased sound reduction index of the roof with a consequent lower sound transfer into the building; (ii) a larger scale benefit, i.e. a reduction of the environmen-tal noise thanks to the increased sound absorption coefficient. This paper reports the results of the measurement campaigns of sound absorption and transmission loss carried out on dif-ferent samples of loose gravel with different grain size and thickness. To this aim, several experimental analyses by means of impedance tube according to the transfer function meth-od described in ISO 10534-2 were carried out. Several comparative considerations between acoustic and thermal-energy experimental results represent the object of this contribution, with the final purpose to optimize this roof typology for its twofold potential.
ACOUSTIC PROPERTIES OF STONE AGGREGATES USED IN COOL ROOFS
D'ALESSANDRO, FRANCESCO;COTANA, Franco;PISELLO, ANNA LAURA;SCHIAVONI, SAMUELE;
2015
Abstract
In the last couple of decades cool roofs, i.e. roof surfaces exposed to solar radiation charac-terized by high solar reflectance (albedo) and thermal emittance, are being intensively stud-ied for their ability to reduce the roof temperature, which leads to a lower heat transfer into the building. This acknowledged phenomenon produces better indoor thermal comfort condi-tions and reduced energy requirement for cooling, resulting in lower greenhouse gas emis-sions. Additionally, cool roofs are also studied and optimized for their larger scale effect as Urban Heat Island mitigation strategy in dense cities. In this perspective, several reflective coatings and materials were used for cool roof applications, e.g. light color paintings, roof tiles and waterproof membranes. Recent research developments were also focused on the analysis of natural and sustainable materials having these properties. In particular, stone ag-gregates were studied for their intrinsic cooling potential with varying grain size and stone typology. Roof covered by stone aggregates can be considered as a rigid frame porous mate-rial whose acoustic properties can lead to similar advantages to the thermal ones: (i) a small scale benefit, i.e. an increased sound reduction index of the roof with a consequent lower sound transfer into the building; (ii) a larger scale benefit, i.e. a reduction of the environmen-tal noise thanks to the increased sound absorption coefficient. This paper reports the results of the measurement campaigns of sound absorption and transmission loss carried out on dif-ferent samples of loose gravel with different grain size and thickness. To this aim, several experimental analyses by means of impedance tube according to the transfer function meth-od described in ISO 10534-2 were carried out. Several comparative considerations between acoustic and thermal-energy experimental results represent the object of this contribution, with the final purpose to optimize this roof typology for its twofold potential.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
