Energy Efficient Refurbishment towards Nearly Zero Energy Houses, for the Mediterranean Region

A Systematic Literature Review of Multi-Criteria Decision-Making Methods for Sustainable Selection of Insulation Materials in Buildings

The European Commission has recently adopted the Renovation Wave Strategy, aiming at the improvement of the energy performance of buildings. The strategy aims to at least double renovation rates in the next ten years and make sure that renovations lead to higher energy and resource efficiency. The choice of appropriate thermal insulation materials is one of the simplest and, at the same time, the most popular strategies that effectively reduce the energy demand of buildings. Today, the spectrum of insulation materials is quite wide, and each material has its own specific characteristics. It is recognized that the selection of materials is one of the most challenging and difficult steps of a building project. This paper aims to give an in-depth view of existing multi-criteria decision-making (MCDM) applications for the selection of insulation materials and to provide major insights in order to simplify the process of methods and criteria selection for future research. A systematic literature review is performed based on the Search, Appraisal, Synthesis and Analysis (SALSA) framework and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. In order to determine which MCDM method is the most appropriate for different questions, the main advantages and disadvantages of different methods are provided.

Residential Buildings’ Foundations as a Ground Heat Exchanger and Comparison among Different Types in a Moderate Climate Country

Shallow Geothermal Energy Systems (SGESs) constitute Renewable Energy Systems (RES), which find application in the residential sector through the use of Ground Source Heat Pumps (GSHPs). GSHPs are associated with Ground Heat Exchangers (GHEs), whereby heat is gained/lost through a network of tubes into the ground. GSHPs have failed to flourish in the RES market due to their high initial costs and long payback periods. In this study, the use of Energy Geo-Structure (EGS) systems, namely, the foundation (or energy) piles and the foundation bed of a residential building in Cyprus, was computationally modeled in the COMSOL Multiphysics software. First, the single-houses’ trend in number of units and area in Cyprus was examined and a theoretically typical house with nearly Zero Energy Building (nZEB) characteristics was considered. The heating and cooling loads were estimated in the TRNSYS software environment and used as inputs to investigate the performance of the GSHP/GHE systems. Both systems were shown to exhibit steady performance and high Coefficient of Performance (COP) values, making them an alternative RES solution for residential building integration. Next, the systems were economically evaluated through a comparison with a convectional Air Source Heat Pump (ASHP) system. The economic analysis showed that the cost of the suggested conversions of the foundation elements into GHEs had short payback periods. Consequently, either using the foundation piles or bed as a GHE is a profitable investment and an alternative to conventional RES.