Abstract
The energy refurbishment of historic buildings is a complex task for building envelope designers who need to carefully consider building conservation guidelines and principles. In most cases, external wall insulation techniques can determine an unacceptable alteration of the historical value of a building. For this reason, internal wall insulation techniques have been used widely in the last few decades. Nevertheless, dealing with internal wall insulation requires a complex design to avoid the risk of condensation and moisture-related pathologies. Moreover, an internal wall insulation may have a relevant impact on indoor comfort conditions. In this paper, the Monastery of Santa Maria de Monfero in Galicia (Spain) has been adopted as a building case study to compare different technological solutions based on: (i) an insulating plaster layer, (ii) dry counter wall systems. In the first step, heat and moisture transfer simulations of the wall components were performed to analyze the hygrothermal behavior of the different alternatives considering two different climate conditions. In a second step, a simulation of the whole building was performed to analyze the impact of the retrofitting strategies on the indoor climate and on the building heating and cooling demand. The obtained results show that the counter wall solution leads to higher energy savings during the heating season in the colder winter climate. However, the use of insulating thermal plaster could also be a viable solution since they lead to several advantages in summer because of their higher thermal inertia. Therefore, the selection of the most appropriate insulation technique has to be evaluated carefully considering the outdoor/indoor climate and using a case-by-case approach.
Highlights
About 40% of the global consumption of primary energy in Europe results from building energy demand, and the building sector is responsible for over 36% of the total amount of greenhouse gas production [1]
About 38% of the existing building stock was built before 1960, when no energy saving laws were in force, and this percentage includes many buildings which have been defined as being part of the historical cultural heritage [2]
Statistical data show that the existing residential building stock is characterized by a higher energy consumption than 270 kWh/m2 per year [2] and that each year, only around 1% of the existing buildings are replaced by new constructions characterized by low energy consumption, i.e., around 30–50 kWh/m2 per year [3]
Summary
About 40% of the global consumption of primary energy in Europe results from building energy demand, and the building sector is responsible for over 36% of the total amount of greenhouse gas production [1]. Statistical data show that the existing residential building stock is characterized by a higher energy consumption than 270 kWh/m2 per year [2] and that each year, only around 1% of the existing buildings are replaced by new constructions characterized by low energy consumption, i.e., around 30–50 kWh/m2 per year [3]. For these reasons, the renewal of the existing building stock is considered the most effective strategy to reduce their energy consumption by as much as 60% [4]. A further concern about internal insulation is its physical compatibility with traditional constructions, since changing the balance between heat, air and moisture can affect a building’s integrity
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