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The objective of Annex 80 is to develop, assess and communicate solutions for resilient cooling. The systematic assessment of resilient cooling strategies is one of the main activities of Annex 80. The previous approach for assessing the resilience of cooling strategies is mainly based on qualitative comparison and based on results from individual research, which lacks common boundary conditions and universal indicators for resilience evaluation. This study aims to provide a consistent approach for assessing the resilience of different cooling strategies by dynamic simulation. Various cooling strategies will be tested on the reference buildings under present and future weather conditions in different climate zones, and proposed key performance indicators will be applied to evaluate summertime overheating risk and climate resistance of cooling strategies.

Objectius de Desenvolupament Sostenible::11 - Ciutats i Comunitats Sostenibles

This study proposes a methodology to map urban heat island intensity based on sky view factor (SVF) data, using Barcelona as a case study. We used LiDAR data to generate the SVF map of the city and empirical and simulation data to obtain the relationship between nighttime urban heat island intensity and canyon SVF in Barcelona. The data were processed and interpolated in a GIS software to obtain the micro-scale and local-scale urban heat island map of the city. The methodology proved effective in showing hot and cold spots across the city. Some unexpected results were used to discuss the validity and limitation of the urban canyon model approach for those urban fabrics with more heterogeneous morphology.

This chapter discusses the dominant role played by urban form in determining the local-scale urban heat island intensity across a city. Urban form is intended purely as the geometry of urban surface, determined by the shape and arrangement of buildings at the district scale. The correlation between changes in the urban fabric and urban heat island intensity across a city is described in relation to two features of urban form: urban compactness and vertical density. A set of urban form parameters is provided for applications in urban planning to map the climate performance of different urban textures.

The urban albedo (UA), defined as the ratio of the reflected to the incoming shortwave radiation at\ud the upper edge of urban canyons, quantifies their ability to reflect solar radiation towards the sky. This research\ud investigates the impact of real-world urban geometries and optical properties of facades and roads materials on\ud the UA and street level microclimate in London. The Indexed Sphere (IVS) algorithm of ENVI-met 4.4.4 is used to\ud compute the UA of several canyon configurations. The accuracy of the IVS algorithm is evaluated against\ud measurements on a 1:10 physical model reproducing the geometry and materials of the case study area. The\ud simulation results show that reflective materials applied to the canyon surfaces are more effective in increasing\ud the UA of canyons with low aspect ratios. The use of reflective materials in urban canyons always increases the\ud amount of reflections at the street level, increasing the mean radiant temperature in most cases. Air\ud temperature is not affected by the canyon’s façades reflectivity while it shows a significant daytime reduction for\ud increased roads’ reflectivity. The results provide preliminary guidelines for the control of UA and the\ud improvement of microclimate in London

This report presents simulation results on the impact of climate change and urban environment on energy savings for the ReCO2ST demo buildings and installed technologies. It also presents an assessment of nature-based technologies regarding resulting environmental improvements and related costs. It was found that climate change/urban environment has a marked impact on materialised energy savings and resulting environmental conditions in naturally cooled buildings and should be considered in the design of retrofits. Nature based technologies can offer a holistic improvement of internal environment but costs are higher than conventional systems.

Urban development is facing new challenges to allow the evolution of the environment, in accordance to sustainability principles. In this context, decision makers have to answer to three main issues: how to intervene on the existing compact cities? How to combine and develop interventions on different scales? How to move from requalification to regeneration? The SOS_UrbanLab (Engineering Laboratory for Construction and Environmental Sustainability) researches, starting from a multi-scale analysis, propose a set of ecofriendly solutions to support the potential and capability of territories, integrating their benefits to reach a full sustainable approach.

The era we are living calls us to face the environmental and urban issues. As the main source of greenhouse emissions and energy consumption, cities are as well the most vulnerable places as for the effects of climate change and energy scarcity. In densely built urban areas, this condition is exacerbated by the urban heat island effect, which causes higher air temperatures in urban areas than in the rural areas. Understanding the complex physical interaction between the building and the urban context is therefore a preliminary knowledge necessary to steer the urban transformation processes towards more sustainable cities . The thesis investigates the relationship between urban morphology, heat island effect and energy demand in the Mediterranean climate. A set of analysis tools is presented, in order to highlight the direct and indirect relationships between the morphological parameters of the urban textures and the climatic and energetic performance at local scale.The results are based on experimental and computational,as applied to two main fields of investigation: the average intensity of the heat island in Rome and Barcelona and the variabilityof the climatic and energetic performance related to the urban morphology. The experimental study of the heat island intensity was conducted by comparing the temperature data observed at different weather stations and the measurements taken at street level. The phenomenon is significant in both cities .At the street level, higher temperatures are recorded during the day, with an average maximum heat island intensity of more than 4 ºC, both in winter and in summer.M. roof level temperatures are lower, especially in summer, when the sea breeze moderates the phenomenon intensity. The variability of heat island according to the different urban morphologies has been investigated through the "Urban Weather Generator" model, using a representative sample of urban textures as case studies.The analysis of the results shows two distinct relationships between the morphological param eters of urban textures and the summer and winter climatic performance .In winter the heat island is more intense in the urban morphologies characterized by a high "density of horizontal surfaces", in summer in those with high "density of vertical surfaces".Then, the energy performance of the urban textures was evaluated by means of EnergyPlus software; the obstruction of the solar radiation and the heat island effect determined by the urban context were both taken into account. In the Mediterranean climate, these two effects tend to balance out when the density of the urban texture reaches threshold values (site coverage ratio about 0.4,faiyade-to-site ratio about 1.6); beyond these values it is possible to take advantage of both the heat island effect on the heating demand and the radiation obstruction on the cooling demand, achieving a good performance throughout the year. As a result, it can be argued that a rather dense and compact urban layout may help to reduce energy demand in the Mediterranean climate, proving the validity of the principies of ve macular architecture and the efficiency of "density'' in such a climatic context. The many relationships found between the morphological parameters and the performance at local scale provide a fast and operative analysis tool for the recognition of the climatic and energetic vulnerability in the urban a reas, based on readily available data. Further works would allow the identification of adequate design guidelines for energy renewal in each urban context, in order to direct the work of designers and planners toward more sustainable urban systems, L’epoca che stiamo vivendo ci chiama al confronto con la questione ambientale ed urbana. Le città, che rappresentano la fonte principale delle emissioni e del consumo delle risorse non rinnovabili, sono anche il luogo di maggior vulnerabilità rispetto ai rischi connessi al cambio climatico ed alla questione energetica. Nelle aree urbane densamente costruite, tale condizione è ulteriormente aggravata dall’effetto dell’isola di calore, che comporta un aumento della temperatura dell’aria rispetto alle zone non urbanizzate. La comprensione della complessità dei fenomeni fisici-energetici che si instaurano tra l’edificio ed il contesto rappresenta pertanto una base conoscitiva indispensabile per indirizzare processi di trasformazione urbana verso modelli di maggiore sostenibilità. La tesi di dottorato indaga le relazioni tra morfologia urbana, isola di calore e domanda energetica in clima Mediterraneo, presentando un insieme di strumenti di analisi che evidenziano le relazioni, dirette e indirette, tra i caratteri morfologici dei tessuti edilizi e la prestazione climatica ed energetica a scala locale. I risultati conseguiti si basano su analisi sperimentali e modellazioni che riguardano due ambiti principali di indagine: l’intensità media di isola di calore a Roma e Barcellona e la variazione della prestazione climatica ed energetica in funzione della morfologia dei tessuti edilizi. Lo studio sperimentale dell’isola di calore è stato condotto mediante comparazione di dati di temperatura osservati a diverse stazioni meteorologiche e con misurazioni alla quota stradale. Il fenomeno risulta rilevante in entrambe le città. Alla quota stradale le temperature sono maggiori durante il giorno, con un’intensità media massima di isola di calore di oltre 4°C sia in inverno che in estate. Alla quota dei tetti il fenomeno è più moderato, soprattutto in estate, grazie all’effetto mitigatore della brezza marina. La variabilità dell’isola di calore in funzione della morfologia dell’edificato è stata studiata attraverso modellazioni con il software Urban Weather Generator, basate su un campione rappresentativo di tessuti urbani. L’analisi dei risultati evidenzia due relazioni distinte tra i parametri morfologici dei tessuti edilizi e la prestazione climatica estiva ed invernale. In inverno l’isola di calore è più intensa nei tessuti caratterizzati da un elevato grado di “densità di superfici orizzontali”, in estate in quelli con maggiore “densità di superfici verticali”. Mediante modellazioni energetiche con il software Energyplus, è stata inoltre valutata la performance energetica dei tessuti edilizi, tenendo in considerazione il grado di ostruzione della radiazione solare e l’effetto di isola di calore indotti dal contesto. Nel clima mediterraneo, questi due effetti tendano a bilanciarsi quando la densità del tessuto raggiunge dei valori di soglia (rapporto di copertura circa 0.4 e rapporto di facciata circa 1.6), oltre i quali è possibile beneficiare dell’isola di calore sulla domanda di riscaldamento e dell’ostruzione della radiazione solare sulla domanda di raffrescamento, ottenendo una buona performance durante tutto l’anno. Si può pertanto affermare che una struttura urbana sufficientemente densa e compatta contribuisca a contenere la domanda energetica in clima Mediterraneo, comprovando la validità delle strategie messe in campo dall’architettura vernacolare presente in tale contesto climatico. Più in generale, in conclusione, l’insieme delle relazioni individuate si configura come uno strumento speditivo d’indagine urbana, utile per la redazione di mappe di vulnerabilità climatica ed energetica sulla base di dati facilmente reperibili e misurabili. Ulteriori sviluppi della ricerca consentirebbero l’individuazione di linee guida di intervento adeguate a ciascun contesto urbano, in maniera tale da favorire l’efficacia del lavoro di progettisti e pianificatori verso la diminuzione dell’impatto energetico ed ambientale della città esistente, La época que estamos viviendo nos llama a enfrentar las cuestiones ambientales y urbanas .Las ciudades, que son la fuente principalde emisiones y de consumo de recursos no renovables, son también los lugares más vulnerables a los riesgos relacionados con el cambio climático y la cuestión energética. En las áreas urbanas densas, esta condición es aún más perjudicial por el efecto de isla de calor, lo que produce un aumento de la temperaturas respecto a la de las zonas rurales limítrofes .La comprensión de la complejidad de los fenómenos físico-energético que se establecen entre el edificio y el contexto urbano es, por tanto, una base de conocimiento necesaria para establecer criterios de intervención hacia modelos de mayor sostenibilidad. Por lo tanto, se puede afirmar que una estructura urbana suficientemente densa y compacta puede contribuir a la reducción de la demanda de energía en el clima mediterráneo, lo que demuestra la validez y la eficiencia de los principios de arquitectura y urbanismo tradicionalmente presentes en este contexto climático. La tesis doctoral investiga las relaciones entre morfología urbana, isla de calor y demanda energética en el clima mediterráneo, presentando un conjunto de herramientas de anális is que destacan las relaciones, directas e indirectas, entre las características morfológicas de los tejidos urbanos y el comportamiento climático y energético a la escala local. Los resultados se basan en análisis experimentales y simulaciones sobre dos áreas principales de investigación: la intensidad media de la isla de calor en Roma y Barcelona y en rendimiento energético y climático en relación a las características morfológicas de los tejidos. El estudio experimental de la isla de calor se llevó a cabo mediante la comparación de datos de temperatura observados en diferentes estaciones meteorológicas y mediciones a nivel de la calle. El fenómeno es relevante en ambas ciudades. Al nivel de la calle, las temperaturas son mayores durante el día, con una intensidad media máxima de isla de calor de más de 4 ºC en inviemo y en verano. Al nivel de las cubiertas el fenómeno es más moderado, especialmente en verano , debido al efecto mitigador de la brisa marina. El conjunto de relaciones encontradas proporciona una herramienta de análisis adecuada para el reconocimiento de la vulnerabilidad climática y energética a esca la urbana, sobre la base de datos morfológicos fácilmente disponibles. Basándose en estas pautas de funcionamiento, otros desarrollos de la investigación permitirían la identificación de las actuaciones más eficaces por cada contexto urbano, con el fin de dirigir el trabajo de arquitectos y planeadores hacia la reducción del impacto de las ciudades sobre el medio ambiente

The combined effects of urban heat island (UHI), urban population growth and energy overexploitation are undermining the safety of urban areas. Urban morphology plays a prominent role in this context, because it affects building's energy demand and local climate at urban scale. However, this contribution is recurrently neglected. The present contribution seeks to investigate the direct and indirect effect of urban morphology on buildings energy performance in the Mediterranean climate. Urban morphology affects energy demand by modifying two relevant variables: outdoor air temperatures and incident radiation. The relevance of these effects were studied on a sample of urban textures of Rome and Barcelona. The study is parametric in approach. The textures were modelled and parameterized and their performances were compared. The UHI in different urban textures was calculated, by Urban Weather Generator tool. Then a sensitivity analysis of the building energy demand to the outdoor air emperatures and the incoming solar radiation was carried out, by EnergyPlus engine. Results confirm the relevance of urban morphology to the UHI intensity. Warmer temperatures lead to an average increase of energy demand from 10% to 35%, according to different urban densities. At the same time, the incident radiation reduction due to urban obstruction is desirable in Mediterranean climate; it allows a reduction of annual energy demand up to the 19% compared to an unobstructed environment. Therefore, relevant errors may occur if urban morphology’s contribution to energy demand is neglected, approximately 89% for space heating and 131% for space cooling calculations, depending on the texture density and the building orientation.