Experimental and Numerical Study on Thermal Performance of New Cool Clay Tiles in Residential Buildings in Europe

Abstract Energy demand imputable to buildings corresponds to around 40% of the total in most of the developed countries, showing the great potential in this field to propose and implement effective strategies for energy saving and environmental sustainability. Additionally, urban areas are the most impacted zones by anthropogenic sources and they are often affected by local climate phenomena such as urban heat islands. In this view, several measures to mitigate this effects and to save energy in constructions are dealt with the implementation of cool materials for roofs and urban paving. Since the majority of cities in Europe is characterized by traditional architectures in residential buildings, the implementation of white cool coatings is not feasible and new solutions are being proposed. In particular, starting from previous works of the authors about the development and continuous monitoring of cool clay tiles, this paper deals with the thermal analysis of low-visual-impact cool tiles in single family residential buildings with varying climate conditions (i.e. latitude) in Europe, from hot subtropical semi-arid climate (Tripoli) to oceanic climate (Munich). A calibrated and validated simulation model by mean of experimental in-lab and in-field measurements, has been used for studying the thermal effect of the proposed clay tiles. The analysis shows how the clay tile has a promising potential to decrease the indoor overheating in all the climate conditions, with relatively low penalties in winter even in the coldest areas

Cool, translucent natural envelope. Thermal-optics characteristics experimental assessment and thermal-energy and day lighting analysis

Innovative construction elements are increasingly studied to improve the energy performance of new and existing buildings, to satisfy global regulations and societal needs. In this view, optimizing buildings energy efficiency and sustainability are crucial aspects, given their high energy saving potential with respect to the other sectors characterizing human activities. Natural materials are often preferred to artificial materials, thanks to their more sustainable production and to the reduced content of harmful substances. In particular, light, thin marbles have been recently analyzed as building envelope elements. Their cooling potential demonstrated how such envelopes have the threefold advantages of reducing solar heat gains into the building, accumulating and releasing less heat, reducing the Urban Heat Island (UHI) effect and consequently mitigating global warming. However, an important feature that has not yet been analyzed in literature and that is considered in this research is light passage throughout the translucent envelope, permitting an additional energy saving due to the contribution to artificial lighting. In this work, this feature of the translucent envelope is considered, by experimentally measuring thin, white marble panels’ optic characteristics and implementing them in a thermal-energy dynamic simulation, to demonstrate the additional advantage of natural daylight to the overall building energy balance

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

AbstractClay 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

Phosphorescent-based pavements for counteracting urban overheating – A proof of concept

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Field occupants’ behavior monitoring integrated to prediction models: impact on building energy performance

Given the massive scientific progress on passive and active solutions to reach near-zeroenergy targets, the necessity to consider occupants’ behavior as a key variable affecting field energy performance of buildings has become a crucial issue to face. In this panorama, a variety of deterministic and stochastic models, also supported by experimental investigations have been developed in the last decade. This paper builds upon previous contributions to analyze the real occupancy of an office building populated by peers’ offices monitored for 2 years by means of microclimate and energy-need field stations. After demonstrating that the peers do not behave the same and do not control in equivalent ways indoors microclimate parameters (e.g. air temperature, desk illuminance, etc.), internationally acknowledged models and field-collected data are compared through dynamic simulation. The estimation of final energy need of different considered scenarios is calculated and the relative difference is highlighted as a possible indicator about the role of building occupancy profiles in affecting energy need prediction. Additionally, EEG experimental test are used to assess the correlation of workers’ subjective emotions with external thermal stimuli. Results of final energy need estimation showed to vary by about 20% by only selecting the occupancy simulation scheme, and non-consistent prediction trends are found out while investigating lighting and electric appliances needs. Accordingly, as concerns the human psychological response to the variation of thermal conditions, negligible emotional reactions are found among the different tested workers when suddenly altering comfort conditions indoors

Smart cool mortar for passive cooling of historical and existing buildings: experimental analysis and dynamic simulation

In order to mitigate Urban Heat Island Effect and global warming, both governments and scientific community are working to reduce energy consumptions. In particular, the construction sector has a high potential in reducing energy demand, by means of both active and passive solutions. The European building stock is mainly composed by existing buildings as well as historical ones, which happens to be the less energy efficient ones. Moreover, retrofit operations are more complex on historical buildings, due to strict regulations for the preservation of such historical and cultural heritage. Considering this challenge, in this work we described and in lab analyzed possible passive solutions specifically designed for historical and existing buildings. In particular, we developed innovative cool colored mortars and tested them in lab, as well as investigated cool colored mortars, cool clay tiles and cool natural gravels performance when applied as envelope and roof elements, by means of dynamic simulation

New experimental technique to investigate the thermal behavior of PCM/doped concrete for enhancing thermal/energy storage capability of building envelope

Abstract In recent years, the scientific community has profusely investigated the chance of implementing advanced Thermal Energy Storage (TES) systems within building envelope components. In particular, several contributions have focused on the use of Phase Change Materials as passive TES strategies, to increment the thermal buffer potentiality of the building envelope. In this context, this work is focused on the development of a new experimental methodology for testing PCM-doped concrete composites in thermal-energy dynamic conditions. Such method, coupling controlled environmental forcing and transient plane source analysis, can be considered as an effective procedure for testing composite materials with adaptive thermal performance

Cool marble building envelopes. The effect of aging on energy performance and aesthetics

Marble envelopes represent a relatively common architectural solution used in variety of historic, modern and contemporary building facades. White marble envelopes have been shown to reduce solar heat gains, while improving indoor thermal comfort and energy efficiency in summer time. While marble is useful in this context, the urban atmosphere accelerates the degradation of marble elements. This leads to changes in optical characteristics, hence the aesthetics, and affects the energy efficiency benefits offered by white marble facades. These issues are investigated in order to predict the impact of degradation on energy performance and to the aesthetic value, such as change of color and luminosity. In this study, surface degradation of white marble is analyzed by means of accelerated weathering in the laboratory while examining changes to the optical characteristics of the materials. A dynamic simulation is carried out to assess the energy performance of a building as a case study

New microclimate monitoring method and data process for investigating environmental conditions in complex urban contexts

The rapid urbanization of the last century coupled with local climate change imputable to anthropogenic actions triggered a huge research effort aimed at investigating urban microclimate. Typically, cities present a variety of microclimates due to the internal variation of their landscapes in terms of morphology, surfaces properties, presence of greenery, etc. Location-specific microclimate conditions affect both (i) building energy needs and (ii) citizens’ quality of life. For these reasons, a small-scale analysis from the citizen perspective with high-time-resolution environmental data is required. Recent studies tried to reach that level of precision by using remote sensing, movable observational transects or dense network of weather stations located in specific points of the urban settlement. Within this framework, the current study presents a new bottom-up methodology which aims at identifying granular microclimates within the same built environment. The method consists of a cluster analysis of experimental data collected by a wearable miniaturized weather station which allows the monitoring of outdoor parameters at the pedestrian height and with high-time resolution. Experimental campaigns were conducted in five different case studies, where a planned monitoring path was repeated at different times during the day. The heterogeneity of the context demonstrates the replicability of the proposed method, suitable for clustering different areas of a same urban context characterized by variable local microclimate. The study contributes to better understand the variability of building boundary conditions for energy need prediction and indoor/outdoor environmental comfort assessment