Integration of Prioritisation Criteria in the Design of Energy Efficient Retrofitting Projects at District Scale: A Case Study

Abstract

The evident need for improving the existing building stock still suffers from important barriers, such as the fragmentation of the value chain, the lack of information regarding some solutions, and the lack of confidence with respect to energy savings, which prevent unlocking investments, and the difficult communication among stakeholders. Therefore, new processes based on exploiting the potential of existing and new tools are required. In this framework, the OptEEmAL project has developed a tool that integrates stakeholders, data and tools in order to ease the process of designing energy efficient retrofitting projects at building and district scale. This tool works around an optimisation framework in order to evaluate, compare and optimise candidate retrofitting scenarios against a set of indicators showing the performance of the district. This evaluation and optimisation method is based on aggregating indicators through transforming the priorities of stakeholders into a mathematical weighting scheme, which makes it possible to provide scenarios within their expectations. Therefore, the generation of these scenarios is driven by their design parameters, being thus flexible and adapted to their needs. This paper shows the implementation of this tool and specifically 3 different prioritisation schemes, analysing how they impact into the decision making process and selection of the retrofitting strategy.Buildings account for approximately 40% of energy consumption and 36% of GHG emissions in the context of the EU [1]. When analysing the stock of existing buildings, around 30% of the building stock is more than 50 years old [2] and almost 75% is energy inefficient [3,4]. The implications of this energy inefficiency not only result in an energy and environmental cost, but also provoke other impacts, such as health problems due to the low levels of comfort within these buildings [5]. It is then imperative to focus on upgrading an ageing building stock, whose current renovation rates are low, at~1.2%. To achieve these targets, this rate should increase to 3% [6].On the other hand, the retrofitting market is quite fragmented, with multiple stakeholders with different and often conflicting interests. This is mirrored in the communication and information exchanges between them. This strong barrier is added to others, such as the lack of knowledge of some technologies among construction professionals, the varying ambition of performance requirements present within regulations, lack of awareness, and uncertainty as to the expected savings, which make

Identifying optimal renovation schedules for building portfolios: Application in a social housing context under multi-year funding constraints

“…The smallest building stocks consisted in two buildings [7,36], while some studies considered thousands of buildings [13,23,31,32,38]. Often 5 to 50 different buildings were considered [8][9][10][11]24,34,35,37]. As highlighted in Table 1, building stocks belong to one owner (e.g.…”

“…Buildings were grouped in one district or one city, or they were spread over a large territory such as a region or a country. In most cases, buildings in a stock had the same use, and several types of stock were studied: housing stocks [6,8,13,23,30,32,35,37,38], stocks of schools or university buildings [9,24,36], or stocks of offices or commercial buildings [10,11,33,34].…”

“…Regarding the stock modelling, a bottom-up approach was adopted in all papers of Table 1. For small stocks, the engineering method was chosen and all buildings were fully described based on real buildings [7,10,30,34,36,37]. For larger stocks, when data was available, a set of representative buildings was sometimes selected using clustering methods or expert knowledge.…”

“…In most of the papers however, refurbishment of envelope and energy systems have been studied jointly. In addition to the aforementioned renovations actions, other measures have been investigated such as the implementation of PV panels or solar collectors [11,12,32,37], the improvement of heating control strategies [9,24,35,37], the change of the electrical system [7,23,38], the installation of shading devices [33,35], the change of showerheads [7] or office equipment [11].…”

“…Keirstead and Calderon [31] added constraints in order to avoid that household have solid-wall and cavity-wall insulation at the same time. García-Fuentes et al [37] defined rules of incompatibility in order to avoid solutions that are not compatible with the decision makers expectations. On the contrary, it may be appropriate to jointly perform several renovation actions in order to reduce cost and to improve the building performance.…”