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]