Techniques for envelope retrofit: Energy saving in existing building

The definition of the research topic stems from the concept of sustainability which has been the heart of architectural design for years, but this goal has infinite forms and infinite ways to be achieved, in research we want to deepen one of the many. Carl Elefante, the former chairman of AIA (American Institute of Architecture), once said: “The greenest buildings are those that already exist”. (AIA Conference, 2007) “According to a 2016 report by the National Historic Preservation Trust 30% of brand-new buildings will have to go through 10-80 years of efficient operation to offset the negative impact of climate change during the construction process”. This statement implies the need to focus on reducing carbon emissions in existing buildings: “Retrofitting existing buildings to improve their performance can achieve energy efficiencies equivalent to new buildings, substantially reducing operational emissions while avoiding the immense embodied emissions from constructing a new building”. Following these concepts, the research will be focused on the definition of different methods for the renovation of buildings with poor energy performance: different technologies and different materials will be investigated with the aim of defining which are the most sustainable solutions both during construction and during the future life cycle of the building. Since the topic of energy efficiency is a very broad topic, the research will be focused on the study of the energy saving guaranteed by building envelopes which play a key role in determining the levels of comfort, natural lighting and the amount of energy to heat and cool the building. Building envelope is the physical barrier between the external environment and the internal conditioned space, keeping the residents comfortable; since this function the envelope is one of the key factors that impact building energy consumption. To understand the importance of building envelope’s role, the definition of the element has been extrapolated from the chapter about Energy systems in buildings by Getu Hailu: Building envelopes of energy efficient buildings are systems that create comfortable interior spaces by actively responding to the external environment of the building and that reduce the energy consumption of buildings. The chapter also defines the characteristics that a high performance building envelope should have: - high thermal resistant materials in the facade of the building, - vapor barriers and be effective in vapor control, - efficient window and door seals, - effective airflow control to minimize infiltration of outdoor air. The preliminary research will focus on the definition of which are the internal and external factors that most influence the choice of the intervention technology; these agents can be: solar radiation, temperature, wind, noise, for external ones, internal factors can instead be internal temperature, humidity, lighting and a series of other parameters depending on the intended use of the building. Once the factors to be kept under control have been defined, the goal is to understand which are the possible intervention technologies at a general level; this investigation phase must be conducted by referring to existing case studies that allow us to see the effects of research in practice. In a second phase, a specific case study will be defined on which it will be possible to carry out the investigation for the choice of the most advantageous technology, also considering environmental and economic issues; at this stage it will be essential to consider that the renovation process will be responsible for a large consumption of energy and coal, this requires an assessment of the time needed to cancel these consumptions.