Cool Roof Impact on Building Energy Need: The Role of Thermal Insulation with Varying Climate Conditions

Cool roof effectiveness in improving building thermal-energy performance is affected by different variables. In particular, roof insulation level and climate conditions are key parameters influencing cool roofs benefits and whole building energy performance. This work aims at assessing the role of cool roof in the optimum roof configuration, i.e., combination of solar reflectance capability and thermal insulation level, in terms of building energy performance in different climate conditions worldwide. To this aim, coupled dynamic thermal-energy simulation and optimization analysis is carried out. In detail, multi-dimensional optimization of combined building roof thermal insulation and solar reflectance is developed to minimize building annual energy consumption for heating-cooling. Results highlight how a high reflectance roof minimizes annual energy need for a small standard office building in the majority of considered climates. Moreover, building energy performance is more sensitive to roof solar reflectance than thermal insulation level, except for the coldest conditions. Therefore, for the selected building, the optimum roof typology presents high solar reflectance capability (0.8) and no/low insulation level (0.00-0.03 m), except for extremely hot or cold climate zones. Accordingly, this research shows how the classic approach of super-insulated buildings should be reframed for the office case toward truly environmentally friendly buildings.The work was partially funded by the Spanish government (RTI2018-093849-B-C31). This work was partially supported by ICREA under the ICREA Academia programme. Dr. Alvaro de Gracia has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 712949 (TECNIOspring PLUS) and from the Agency for Business Competitiveness of the Government of Catalonia. This publication has emanated from research supported (in part) by Science Foundation Ireland (SFI) under the SFI Strategic Partnership Programme Grant Number SFI/15/SPP/E3125

Effect of PCM on the Hydration Process of Cement-Based Mixtures: A Novel Thermo-Mechanical Investigation

The use of Phase Change Material (PCM) for improving building indoor thermal comfort and energy saving has been largely investigated in the literature in recent years, thus confirming PCM's capability to reduce indoor thermal fluctuation in both summer and winter conditions, according to their melting temperature and operation boundaries. Further to that, the present paper aims at investigating an innovative use of PCM for absorbing heat released by cement during its curing process, which typically contributes to micro-cracking of massive concrete elements, therefore compromising their mechanical performance during their service life. The experiments carried out in this work showed how PCM, even in small quantities (i.e., up to 1% in weight of cement) plays a non-negligible benefit in reducing differential thermal increases between core and surface and therefore mechanical stresses originating from differential thermal expansion, as demonstrated by thermal monitoring of cement-based cubes. Both PCM types analyzed in the study (with melting temperatures at 18 and 25 ºC) were properly dispersed in the mix and were shown to be able to reduce the internal temperature of the cement paste by several degrees, i.e., around 5 ºC. Additionally, such small amount of PCM produced a reduction of the final density of the composite and an increase of the characteristic compressive strength with respect to the plain recipe.Funding: The research leading to these results has received funding from the European Union’s Horizon 2020 research and innovation program under Grant agreement No. 657466 (INPATH-TES) and No. 765057 (SaferUp!). The authors also thank the Microtek Laboratories, Inc. for providing the capsulated materials. The work is also partially funded by the Spanish government (ENE2015-64117-C5-1-R). Acknowledgments: Acknowledgments are due to the “CIRIAF program for UNESCO” in the framework of the UNESCO Chair “Water Resources Management and Culture”. Luisa F. Cabeza would like to thank the Catalan Government for the quality accreditation given to her research group (2017 SGR 1537)

Thermo-acoustic performance of green roof substrates in dynamic hygrothermal conditions

Green roofs can be considered as effective and esthetically appreciated passive tools for energy saving systems in buildings. In particular, the effect of evapotranspiration and the large thermal inertia of such solutions, represent highly attractive properties to be implemented in advanced building envelope components. Although these properties are deeply influenced by external factors such as weather conditions, and greenery dynamics, the materials used in substrate and drainage layers are too commonly assumed as constant thermal insulation layers depending only on their physical properties and water content. In particular, common disaggregated materials used in internal layers of extensive green roofs, generally are characterized by a highly complex matrix, and consequently, such materials usually lack of realistic thermal-acoustic properties evaluation. The main objective of the study is to investigate the impact of water content on the thermo-acoustic performance of different disaggregated materials from green roofs substrates commonly used in Mediterranean climates. In particular, the TPS method was used to assess the effect of humidification and raining processes on the final performance of the considered samples. An extensive acoustic characterization was also developed, based on the acoustic transfer function method. Results show that raining processes can highly influence the thermal performance of such materials, which depending on their density, can even triple their thermal conductivity value and achieve twice the volumetric specific heat at ambient conditions. Furthermore, the acoustic characterization procedure showed that the biggest modification on the final acoustic absorption and insulation capability, i.e. about 20 dB when the 80 mm samples, was produced by increasing the water content of the system from 10% to 30% RH. On the contrary, the conditioning at 90% RH does not produce significant differences of the final acoustic behavior of the substrates. Keywords: green roofs, substrates, dynamicAcknowledgments are due to the “CIRIAF program for UNESCO” in the framework of the UNESCO Chair “Water Resources Management and Culture”. The research leading to these results has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No. 657466 (INPATH-TES). The work is also partially funded by COOL CRETE Project, under the framework of Call L. 598/94 Art. 11 – Industrial research and experimental development (Energy sector) supported by Luigi Metelli S.p.A., and by the Spanish governmentENE2015-64117-C5-1-R (MINECO/FEDER) in collaboration with the company Buresinnova S.A (Mercabarna Flor - Local n. 412 Ctra. Antiga de València, 1. 08830 Sant Boi de Llobregat. www.buresinnova.com). The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2017 SGR 1537). GREA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. Julià Coma would like to thank Ministerio de Economia y Competitividad de España for Grant Juan de la Cierva, FJCI-2016-30345

Optimization of coupled building roof solar reflectance and thermal insulation level for annual energy saving under different climate zones

The aim of this work is to assess building energy performance optimization potential of cool roof solutions in different climate conditions worldwide through dynamic thermal-energy simulation and optimization analysis. Moreover, given the dependence of roof performance on insulation level, the influence of roof insulation variation on optimum roof solar reflectance is evaluated. Therefore, the multi-dimensional optimization of combined building roof solar reflectance capability and thermal insulation level is carried out to minimize annual energy consumption for air-conditioning of standard ASHRAE building model for small offices, in each considered climate zone. Findings of this research highlight how the classic approach of super-insulated buildings for energy saving needs to be reframed for the office case, by integrating other passive solutions for truly environmentally friendly and comfortable buildings.The research leading to these results has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement N°657466 (INPATH-TES). The work is partially funded by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER) and ENE2015-64117-C5-3-R (MINECO/FEDER)). The authors from the University of Lleida would like to thank the Catalan Government for the quality accreditation given to their research group (2014 SGR 123). Anna Laura Pisello’s acknowledgments are due to the UNESCO Chair “Water Resources Management and Culture”, for supporting her research. Alvaro de Gracia would like to thank Ministerio de Economia y Competitividad de España for Grant Juan de la Cierva, FJCI-2014-19940

Sustainable exploitation of residual cynara cardunculus l. To levulinic acid and n-butyl levulinate

Hydrolysis and butanolysis of lignocellulosic biomass are efficient routes to produce two valuable bio-based platform chemicals, levulinic acid and n-butyl levulinate, which find increasing applications in the field of biofuels and for the synthesis of intermediates for chemical and pharmaceutical industries, food additives, surfactants, solvents and polymers. In this research, the ac-id-catalyzed hydrolysis of the waste residue of Cynara cardunculus L. (cardoon), remaining after seed removal for oil exploitation, was investigated. The cardoon residue was employed as-received and after a steam-explosion treatment which causes an enrichment in cellulose. The effects of the main reaction parameters, such as catalyst type and loading, reaction time, temperature and heat-ing methodology, on the hydrolysis process were assessed. Levulinic acid molar yields up to about 50 mol % with levulinic acid concentrations of 62.1 g/L were reached. Moreover, the one-pot bu-tanolysis of the steam-exploded cardoon with the bio-alcohol n-butanol was investigated, demon-strating the direct production of n-butyl levulinate with good yield, up to 42.5 mol %. These results demonstrate that such residual biomass represent a promising feedstock for the sustainable production of levulinic acid and n-butyl levulinate, opening the way to the complete exploitation of this crop

Plenum window insertion loss in the presence of a line source—a scale model study

The acoustical insertion losses of plenum windows installed on a building facade in the presence of a non-parallel line source are studied by using a 1:4 scaled down model in a semi-anechoic chamber in the present investigation. Two types of insertion losses, weighted by the normalized traffic noise spectrum (from the 100 Hz to 5000 Hz one-third octave bands), are defined with different references. The first one is for the case where the orientation of the building facade relative to the line source is fixed. The reference case is the opened window having the same orientation angle as the plenum window. The maximum and minimum insertion losses under this condition across the orientations tested are found to be around 14 dB and 5 dB, respectively. The other is the opposite situation where such orientation is allowed to change because of practical purposes and the reference for this condition is the opened window with its width span parallel to the line source. The corresponding maximum and minimum insertion losses are found to be around 18 dB and 8 dB, respectively. There are evidences showing that the lower order plenum acoustic modes are responsible for the relatively high low frequency insertion loss