General guides to support the refurbishment design indicate separately the solutions to common problems such as thermal loss, interstitial condensation, sound transmission, fire safety etc. This paper deals with combined solutions that take into account simultaneously two of these aspects, aiming both at reducing thermal losses and at avoiding or limiting problems related to moisture transfer and condensation, jointly with an indispensable cost analysis. Improving the energy performance of buildings should start from the evaluation of the building's envelope energysaving options. The subject of the research is oriented to typical buildings, often critical from the energy standpoint, which are represented by social housings. The refurbishment target should be the NZEB model, even if it is very difficult to find suitable general solutions. As the renovation design process depends also on the sustainability of costs, an evaluation procedure, previously proposed, is widened to take into account this aspect, by considering characteristics and constraints, and assuring reasonable costs for the most suitable solutions. The methodology has been applied to a case study represented by a common building unit. The insulation improvement is made through a choice of the most suitable combination of material and thickness, with the aim not only of the energy saving, but also of the reduction of the risk of vapour condensation that depends, among other things, on the position of the insulating materials within the wall's structure. Some combined refurbishment solutions for the building envelope are examined and the corresponding costs are evaluated. Moreover, to show the importance of the problem in mild and continental climates, a comparison of the results in different climatic conditions is presented.
Any intervention on the envelope/HVAC system of existing buildings should start from the evaluation of the building's envelope energy-saving options. Typical buildings critical from the energy standpoint are represented by social housings: in this case the energysaving is not possible without the building's envelope renovation. Their energy retrofit towards NZEB should be the next challenge: it is analysed in the present paper by proposing an evaluation procedure that takes into account different constraints and limits imposed by national laws, following the indications of the European Directives. To illustrate the calculation methodology a case study is examined, by comparing the U-values of the existing walls with the NZEB limits and with the limits considered for the energy refurbishment of the buildings. The insulation improvement of the reference walls depends on both the thermo-physical properties and the thickness of the materials used. The choice of the most suitable combination of material and thickness is related not only to the energy-saving, but also to the risk of vapor condensation that depends on the position of the insulating materials within the wall's structure. Therefore, the outlined procedure takes into account both these aspects. Moreover, as the renovation design process involves a multiplicity of elements and parameters, the proposed procedure could be generalized to consider a wide list of characteristics and constraints that allow to guarantee the most suitable solution with acceptable costs.
The cost optimal methodology indicated by the European Directive 2010/31/UE represents the starting point to support decisions for refurbishment interventions. The procedure is much more useful if considering the limited available investments from Public Authorities or privates and represents an important decision tool to define the owners' constraints and the economic commitment in the years. However, the results are usually affected by the influence of some variables, among which there are the climatic conditions, subject of the present investigation. To quantify some effects, the best costs/benefits ratio is evaluated among some improvement scenarios built on a series of energy efficiency measures, in the climatic conditions of some locations. The first set of calculations compares energy performance and global costs referring to climatic data taken from the Italian National Standard UNI 10349 edition 1994 and 2016. The second analysis is performed, for one location, on the basis of the two reference climatic datasets and the registered climatic data of the last 20 years. From the results analysis, it can be observed the need of indications by the European Commission on a regularly reference climatic data updating, to guarantee in all the countries affordable calculations for the cost optimal refurbishment solutions, and on the introduction of a tolerance/confidence range to take into account the real climate variations.
The paper intends to discuss the use of cavity wall insulation in existing buildings for energy improvement. Cavity walls are widely spread throughout the EU, typically in buildings from the 20th century, which are recognized as the subject of urgent and deep energy renovation interventions. Their main characteristic is an empty air cavity between two layers of building materials (typically brick, stone, or concrete). Filling the empty air cavity with insulating materials reduces energy loss by transmission through opaque envelope surfaces, and therefore, it represents a cheap solution to obtain a significant reduction in building energy consumption. Various aspects should be carefully evaluated for the effectiveness of this type of intervention: The first step is knowing the materials’ behavior depending on their thermal and hygrometric parameters (conductivity and transmittance, thermal bridge transmittance, vapor permeability, and resistance to vapor diffusion). Some indications on limits or reference/target values are usually given by national/regional laws and EU Directives. The filling insulation could lead to collateral problems (thermal bridges, risk of vapor condensation inside walls, etc.). To help understand the relevance and the impact of this insulation technique, an example of the assessments of a common cavity wall type is presented. The analyses highlight the usefulness of an organized and systematic database on building envelope features to set targeted energy-saving actions. Public administrations could base their strategies on this information to promote the reduction of energy consumption on a large scale with efficient and economically sustainable interventions. In the absence of more specific databases, the Energy Performance Certificates (EPC) data consulting could help develop thermal insulation strategies at a regional/national level. In particular, the diffusion of cavity walls can be obtained as a function of wall surface and cavity thickness for estimating the energy saving potential, economic impact, and general feasibility of systematic insulation-filling actions. An example of this kind of database analysis is discussed and carried out on a regional scale to explain how it could represent a useful approach to evaluate potential energy-saving interventions. The sample building stock provides suggestions on the possibility to extend the considerations on a larger scale to help set systematic energy-saving strategies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.