Palme, Massimo

The urban heat island (UHI) effect is constantly increasing the energy consumption of buildings, especially in summer periods. The energy gap between the estimated energy performance - often simulated without considering UHI - and the real operational consumption is especially relevant for institutional buildings, where the cooling needs are in general higher than in other kind of buildings, due to more internal gains (people, appliances) and different architectural design (more transparent façades and light walls). This paper presents a calculation of the energy penalty due to UHI in two institutional buildings in Rome. Urban Weather Generator (UWG) is used to generate a modified weather file, taking into account the UHI phenomenon. Then, two building performance simulations are done for each case: the first simulation uses a standard weather file and the second uses the modified one. Results shows how is it necessary to re-develop mitigation strategies and a new energy retrofit approach, in order to include urbanization ad UHI effect, especially in this kind of buildings, characterized by very poor conditions of comfort during summer, taking into account users and occupant-driven demand.

This study aims to determine the optimal approach for evaluating thermal comfort in an office that uses natural ventilation as the main conditioning strategy; the office is located in Quito-Ecuador. The performance of the adaptive model included in CEN Standard EN15251 and the traditional PMV model are compared with reports of thermal environment satisfaction surveys presented simultaneously to all occupants of the office to determine which of the two comfort models is most suitable to evaluate the thermal environment. The results indicate that office occupants have developed some degree of adaptation to the climatic conditions of the city where the office is located (which only demands heating operation), and tend to accept and even prefer lower operative temperatures than those considered optimum by applying the PMV model. This is an indication that occupants of naturally conditioned buildings are usually able to match their comfort temperature to their normal environment. Therefore, the application of the adaptive model included in CEN Standard EN15251 seems like the optimal approach for evaluating thermal comfort in naturally conditioned buildings, because it takes into consideration the adaptive principle that indicates that if a change occurs such as to produce discomfort, people tend to react in ways which restore their comfort.

Ecuador is starting to consider climate change as a priority for the country development. Recently, was founded the Sub-secretariat for climate change, and many Ministry started to insert related topic in the political agenda. Particularly, Urban Development and Housing Ministry, MIDUVI, launched in 2011 the competition “Dwellings for climate change” in order to improve the basic social house that is still constructing in all the climates of the country. For instance, Ecuador, even small, has a unique climatic diversity: in the Andes the climate is tropical mountain, in the Amazons is tropical wet and in the Coast is hot, both arid and humid, depending on the specific position. One of the competition goals was to put in evidence the need of different design for each climate, even for social dwellings, that have to be very cheap. The National Institute of Energy Efficiency and Renewable Energy (INER) is also developing some prototypes for the different climates of Ecuador [1]. In this paper, a simulation study has been conducted in order to estimate the discomfort hours (both undercooling and overheating) that inhabitants could feel in the base case (the actual MIDUVI social house) and in the three competition winner prototypes. Simulations have been conducted for the climate of nowadays (Typical Meteorological Year –TMY) and for the future (2050 and 2080) taking into account the global warming effect under the Intergovernmental Panel for Climate Change (IPCC) A2 scenario. Because of in Ecuador heating and air-conditioning systems are used only by a small part of the population (the richer one), the analysis was conducted thinking in naturally ventilated buildings, searching for the total discomfort hours during the year.

Global warming affects the built environment by changing the environmental conditions under which buildings operate. This change probably means a shift in thermal demand, from a predominant demand for heating to a higher demand for cooling in many climates. For instance, in cold climates global warming seems to be a self-decreasing phenomenon because of lower energy demand in warmer environments. In warmer climates, like the Mediterranean, and in the hottest climates (both humid and arid), global warming must be regarded as one of the main factors (the others are the change in comfort standards and the heat-island effect) in increasing the energy demand to cool buildings. This chapter analyses the environment of various cities, characterised by mild average temperatures and small thermal oscillations, that can be regarded as Mediterranean climate emplacements. Today these cities have more heating than cooling demand but in the future will probably have higher cooling requirements. Results show that by 2050, in most of the considered emplacements, cooling demand will be higher than heating demand and emissions will rise proportionally. Solutions to this problem must be sought in the flexible operation of buildings, and policies should focus on summer-related issues: good natural ventilation, protection from the sun, and internal gain reduction, rather than insulation, air infiltration reduction and solar access.

The concept of urban metabolism was introduced by Wolman in 1965 [1], following insights and suggestions coming from ancient Marxism and the early ecologist theories.

Technological imagination has been, until now, a stronger driver of development and has permitted to scale economy and even to obtain increasing returns of investments. However, times are a changing. Humanity faces now societal and environmental changes that are pushing the planet Earth toward a danger zone, overpassing recommended limits for several critical processes, such as bio-geochemical fluxes of nitrogen and phosphorus, greenhouse gases concentration in the atmosphere, biodiversity loss and land use change. The role of technology applied to built environment design should be redefined to stay within the so-called safe operation space for humanity, considering the limited resources we have and the need of low-energy solutions for buildings and cities. This chapter introduces the key concepts for the understanding the new role that we must assign to technological imagination to face the challenge of the Anthropocene epoch and discusses how to achieve the seven transitions objectives for transforming our world in a sustainable way.

Este artículo trata acerca de la caracterización de la tecnología de un cielo raso de paja y barro denominada en lengua aymara como “caruna”. El estudio se realizó en viviendas Aymaras a más de 4.000 metros sobre el nivel del mar en la localidad de Tacora, en la región de Arica y Parinacota, Chile. El estudio forma parte del proyecto 49204 financiado por el Servicio Nacional del Patrimonio Cultural. Su objetivo es rescatar esta técnica vernácula como alternativa a los materiales industrializados que han modificado la vivienda andina y la calidad de vida en climas extremos durante los últimos 25 años. Se recogieron muestras de los materiales utilizados en esta técnica, reproducida por un cultor local, y se analizaron en laboratorio para determinar sus propiedades térmicas y de trabajabilidad. Además, se monitoreó el desempeño energético de tres viviendas en el poblado de Tacora para comparar los resultados obtenidos con los de los laboratorios. Los hallazgos revelaron que la matriz de barro utilizada en esta técnica de encielado es predominantemente arcillosa con mediana compresibilidad y baja conductividad térmica, lo que la hace adecuada como aislante en climas desérticos fríos. El cielo de barro y paja alivianado se destacó por su presencia en la cultura local, la disponibilidad de recursos materiales y su facilidad de instalación. Este estudio subraya la importancia de preservar el conocimiento tradicional, respetando los saberes ancestrales y mejorando el desempeño térmico de las viviendas en la cordillera norte de Chile, Perú y Bolivia, destacando su relevancia para el desarrollo de soluciones habitacionales sostenibles y culturalmente pertinentes.

Although Urban Heat Island (UHI) is a fundamental effect modifying the urban climate, being widely studied, the relative weight of the parameters involved in its generation is still not clear. This paper investigates the hierarchy of importance of eight parameters responsible for UHI intensity in the Mediterranean context. Sensitivity analyses have been carried out using the Urban Weather Generator model, considering the range of variability of: 1) city radius, 2) urban morphology, 3) tree coverage, 4) anthropogenic heat from vehicles, 5) building’s cooling set point, 6) heat released to canyon from HVAC systems, 7) wall construction properties and 8) albedo of vertical and horizontal surfaces. Results show a clear hierarchy of significance among the considered parameters; the urban morphology is the most important variable, causing a relative change up to 120% of the annual average UHI intensity in the Mediterranean context. The impact of anthropogenic sources of heat such as cooling systems and vehicles is also significant. These results suggest that urban morphology parameters can be used as descriptors of the climatic performance of different urban areas, easing the work of urban planners and designers in understanding a complex physical phenomenon, such as the UHI.

Urban heat island effect often produces an increase of overheating sensation inside of buildings. To evacuate this heat, the current use of air conditioning increases the energy consumption of buildings. As a good alternative, natural ventilation is one of the best strategies to obtain indoor comfort conditions, even in summer season, if buildings and urban designs are appropriated. In this work, the overheating risk of a small house is evaluated in four South American cities: Guayaquil, Lima, Antofagasta and Valparaíso, with and without considering the UHI effect. Then, natural ventilation is assessed in order to understand the capability of this passive strategy to assure comfort inside the house. Results show that an important portion of the indoor heat can be evacuated, however the temperature rising (especially during the night) due to UHI can generate a saturation effect if appropriate technical solutions, like the increase in the air speed that can be obtained with good urban design, are not considered.

Climate change will worsen the high levels of urban vulnerability in Latin American cities due to specific environmental stressors. Some impacts of climate change, such as high temperatures in urban environments, have not yet been addressed through adaptation strategies, which are based on poorly supported data. These impacts remain outside the scope of urban planning. New spatially explicit approaches that identify highly vulnerable urban areas and include specific adaptation requirements are needed in current urban planning practices to cope with heat hazards. In this paper, a heat vulnerability index is proposed for Santiago, Chile. The index was created using a GIS-based spatial information system and was constructed from spatially explicit indexes for exposure, sensitivity and adaptive capacity levels derived from remote sensing data and socio-economic information assessed via principal component analysis (PCA). The objective of this study is to determine the levels of heat vulnerability at local scales by providing insights into these indexes at the intra city scale. The results reveal a spatial pattern of heat vulnerability with strong variations among individual spatial indexes. While exposure and adaptive capacities depict a clear spatial pattern, sensitivity follows a complex spatial distribution. These conditions change when examining PCA results, showing that sensitivity is more robust than exposure and adaptive capacity. These indexes can be used both for urban planning purposes and for proposing specific policies and measures that can help minimize heat hazards in highly dynamic urban areas. The proposed methodology can be applied to other Latin American cities to support policy making.