On a Cool Coating for Roof Clay Tiles: Development of the Prototype and Thermal-energy Assessment

Clay tiles are the most common roof covering in Italian buildings, in particular in traditional residential buildings. Given the important role of the roof characteristics for building energy efficiency and indoor thermal comfort conditions, innovative solutions for improving the thermal-energy performance of such diffused roof element has become a key research issue. In this view, cool roof applications represent an effective solution to this aim. The present work deals with the analysis of innovative coatings for traditional clay tiles, aimed at increasing their “cooling” potential. Several pigments with the sodium silicate as binder are tested in terms of reflectance and emittance, which mainly determine the cool roof performance. Additionally, the year-round performance of the proposed tile is evaluated when applied to a single family residential building located in central Italy. The developed cool roof solution is characterized by the same visual appearance of traditional “natural brick” color tiles, while the solar reflectance is higher than natural terracotta tile by 13%. Therefore its thermal performance is optimized in order to reduce the roof overheating and the consequent energy requirement for cooling. Results of dynamic simulation of the case study building show how the proposed tile is able to decrease the number of hours when the indoor operative temperature of the attic is higher than 26 °C by 18%, while the same effect in lowering the indoor temperature below 20 °C in winter is less than 1%. Therefore, the proposed solution could be considered as an interesting strategy for new buildings or for traditional roof retrofitting, without producing any significant architectural impact, even in traditional or historic buildings, where more invasive solutions are too difficult to be implemented.

[1]  E. Pavlidou,et al.  Ochre-differentiation through micro-Raman and micro-FTIR spectroscopies: application on wall paintings at Meteora and Mount Athos, Greece. , 2000, Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy.

[2]  Anna Laura Pisello,et al.  A method for assessing buildings’ energy efficiency by dynamic simulation and experimental activity , 2012 .

[3]  Hashem Akbari,et al.  Energy effects of heat-island reduction strategies in Toronto, Canada , 2004 .

[4]  Antonio Libbra,et al.  Spectral response data for development of cool coloured tile coverings , 2011 .

[5]  Emmanuel Bozonnet,et al.  Cool roofs impact on building thermal response: A French case study , 2010 .

[6]  Anna Laura Pisello,et al.  Development of Clay Tile Coatings for Steep-Sloped Cool Roofs , 2013 .

[7]  Anna Laura Pisello,et al.  Simulating the effect of urban morphology on indoor thermal behavior: An Italian case study , 2013, 2013 Winter Simulations Conference (WSC).

[8]  M. Santamouris,et al.  Experimental and numerical assessment of the impact of increased roof reflectance on a school building in Athens , 2012 .

[9]  M. Santamouris,et al.  On the development, optical properties and thermal performance of cool colored coatings for the urban environment , 2007 .

[10]  M. Santamouris,et al.  Using advanced cool materials in the urban built environment to mitigate heat islands and improve thermal comfort conditions , 2011 .

[11]  Laura Bellia,et al.  Effects of solar shading devices on energy requirements of standalone office buildings for Italian climates , 2013 .

[12]  Anna Laura Pisello,et al.  The thermal effect of an innovative cool roof on residential buildings in Italy: Results from two years of continuous monitoring , 2014 .

[13]  A. Pisello,et al.  ON THE IMPACT OF COOL ROOFS IN ITALIAN RESIDENTIAL BUILDINGS: EXPERIMENTAL ASSESSMENT OF SUMMER AND WINTER PERFORMANCE , 2012 .

[14]  M. Saliari,et al.  Development and analysis of mineral based coatings for buildings and urban structures , 2012 .

[15]  John E. Taylor,et al.  Inter-building effect: Simulating the impact of a network of buildings on the accuracy of building energy performance predictions , 2012 .

[16]  H. Akbari,et al.  Estimating the effect of using cool coatings on energy loads and thermal comfort in residential buildings in various climatic conditions , 2007 .

[17]  John E. Taylor,et al.  Network synergy effect: Establishing a synergy between building network and peer network energy conservation effects , 2014 .

[18]  Lucia Brinchi,et al.  Surfactant effect on titanium dioxide photosensitized oxidation of 4-dodecyloxybenzyl alcohol , 2012 .

[19]  Antonio Libbra,et al.  Assessment and improvement of the performance of antisolar surfaces and coatings , 2011 .

[20]  A. Muscio,et al.  Design of ceramic tiles with high solar reflectance through the development of a functional engobe , 2013 .

[21]  John E. Taylor,et al.  The impact of place-based affiliation networks on energy conservation: An holistic model that integrates the influence of buildings, residents and the neighborhood context , 2012 .

[22]  Jiang Guang-min.  Introductions to ASTM C 1371-04 Standard Test Method for Determination of Emittance of Materials Near Room Temperature Using Portable Emissometers , 2015 .

[23]  Ronnen Levinson,et al.  Potential benefits of cool roofs on commercial buildings: conserving energy, saving money, and reducing emission of greenhouse gases and air pollutants , 2010 .