Energy retrofit of residential buildings in hot climate

Abstract

The topic of the research is to analyze the energetic efficiency of residential buildings in hot climates. The idea comes from the need to analyze the "case of hot climates" separately, as the European directives and all the studies so far undertaken in this area, too frequently not suit well to this case. Research begins with the evaluation of the energy performance of buildings (heating and cooling), analyzes the potential for energy retrofit, considers energy savings, economic feasibility and comfort improvements. With appropriate precautions and adopting new and more efficient materials and technologies, it’s possible to significantly reduce the energy consumption of buildings, with an annual energy saving up to 44%. 1. Problem Statement The increasing demand for energy, resulting in cost growth and related environmental problems, led to an increased interest in the design of energy-efficient buildings. In Mediterranean climate, warm and rather humid, it becomes of prime importance to be able to ensure a high indoor comfort. Buildings are built to protect people from adverse weather conditions, and to ensure a comfortable indoor environment. To achieve these goals a huge amount of energy is consumed in heating, ventilation, cooling or dehumidification. Many attempts have been made in order to use low-power strategies consumption. It is necessary however, to think of appropriate solutions in terms of shading and insulation in order to avoid excessive use of air-conditioning systems and reduce power consumption. To solve this problem an integrated approach is essential. This research focuses on energy upgrading of buildings, (belonging to social housing) in Salerno and Naples, acting on the building envelope, that is, proposing an improvement of materials and characteristics. This paper discusses economically feasible ways and means to choose between insulation measures, better glazing, shading systems and ventilation. Finally a hierarchy of energy-savings measures is deduced from the results. The intention is to demonstrate that an effective energy-retrofit can be done without necessarily going through expensive technologies or ex-novo designs, obtaining interesting results in terms of energy consumption and greenhouse gas emissions, at a cost that can be recovered in a few years, making retrofitting possible even on ordinary buildings and therefore desirable at a urban scale. 2. Strategies The case of the warm climate needs to be analyzed separately, as the European directives and studies in the field cannot be fully adapted to the problem. In practice the cold climate strategy is "defensive", or rather of protection from cold, on the contrary an intervention in a hot climate needs more flexibility. Starting from a detailed analysis of the case study, in terms of macroclimate, microclimate, solutions and techniques used, a choice of the interventions that should be made, need to be taken, with the aim of reducing the risk of overheating in the summer, encouraging natural ventilation, maximizing the benefits of the solar gains during winter, in order to reduce annual energy consumption and CO2 emissions. These objectives can be achieved with a bioclimatic approach. The "Climate Responsive Design" is part of an approach to design called "Ecological Sustainable Design (ESD)" based on an analysis of how the shape and structure of a building moderate the climate, in order to obtain a acceptable level of indoor comfort. The active principles of the "Climate Responsive Design" is the understanding of climatic parameters that can influence the process of planning/redevelopment, such as temperature, humidity, wind, light, vegetation, and everything that is related to geographical location. These principles can be applied , even if in a different ways, to retrofitting. We have therefore chosen the case studies in Campania, a region in the south of Italy, buildings belonging to social housing, and signed by designers known and appreciated, objectively valid in terms of design quality, but inevitably obsolete in terms of technological solutions, all these aspects made them particularly indicated for the study. Moreover, in each of the two cases the typology is repeated in the area with variable orientation, which allowed to analyze the effects of orientation on several units. 3. Methodology The buildings analyzed are representative of the Italian building stock, built from 1950 up to 1980. The energy savings measures were applied by steps, analyzing as first intervention the thermal insulation through the cavity(case study 1) or outside the wall (case 2), the replacement of windows, then the use of a proper shading system and finally the integration of natural ventilation. For each item various options have been tested, choosing from time to time, the most advantageous... [edited by author]