Sustainable management of the building stock: A Delphi study as a decision-support tool for improved inspections
Introduction
Urban development, which is essential to socioeconomic and territorial transformation, plays a key role in climate change. The environmental impact presently attributable to cities calls for urgent measures to ensure more sustainable urban development (UN-Habitat, 2016). Due to the long service life and density of buildings (Aragón-Correa et al., 2018), the construction industry consumes vast natural resources and energy (Zhao, Zhao, Davidson, & Zuo, 2012), which accounts for around 40% of the total energy consumed today in the European Union (EU) (Directive 2018/844/EU, 2018, Directive 2018/844/EU, 2018). At least 40% of the buildings now standing in Europe were erected before the 1960s when building codes envisaged no energy requirements (Sajn, 2016), which were introduced around the 1970s in most of Western Europe. In Spain, with a higher than European average degree of urbanization (around 80% in 2015), regulations designed to save energy were instituted under code NBE-CT-79 (Ministerio de Fomento, 2017; Real Decreto 2429/1979, 1979, Real Decreto 2429/1979, 1979) and came into effect in 1980. Lowering energy consumption attributable to construction is then needed to curb climate change, one of the industry’s major challenges, which cannot be solved under a business-as-usual scenario (Rapf, 2019).
The proper management of building stock should involve conservation mechanisms together with a comprehensive rehabilitation to ensure not only safety but also to reduce its energy demand. There is a close relationship between conservation actions and intervention works since many energy rehabilitations often incur “behind the scenes” of maintenance, modernization or routine restoration works (Cortiços, 2019). The recently revised European energy performance of buildings directive (EPBD) (Directive 2018/844/EU, 2018, Directive 2018/844/EU, 2018) aims to convert Europe’s highly inefficient stock, 97% of the total, into at least nearly zero energy buildings (nZEB), aligned with the EU’s commitment to sustainable, competitive and carbon-free energy in 2050. To comply with the EU Climate and Energy Framework, Member States must establish targets to enhance the energy performance of the building stock, bearing in mind national particularities. In Spain, stock characteristics lie significantly below European standards (Ley 8/2013, 2013, Ley 8/2013, 2013) and its construction industry accounts for 30% of the country’s energy consumption (Ministerio de Fomento, 2017).
The required renovation rates demand that the sector increases its productivity and radically innovate its services (BPIE, 2019). Whilst intervention on buildings throughout their service life is imperative to guaranteeing their conservation, improving their energy performance calls for more comprehensive reform. The established procedure in renovations begin with a thorough technical inspection to suitably characterize any existing flaws (Ferraz, de Brito, de Freitas, & Silvestre, 2016), being necessary reliable data to undertake the works and favor satisfactory building maintenance plans. Inspection and diagnosis, design of renovations, and maintenance works are the main actions for building stock management and improvement, requesting their coordination during the operation stage. Therefore, any intervention on existing buildings must be based on a prior characterization to determine their technical properties and condition (AENOR, 2009), since it is proven that the state of the building impacts its renovation (Konstantinou & Knaack, 2013). Certain technical factors hinder diagnostic inquiry from obtaining such information, and thus fostering research and testing of new solutions are imperative to undertaking such complex works (Directive 2018/844/EU, 2018, Directive 2018/844/EU, 2018). Given that, the renovation of buildings to nZEB levels calls for a commitment from the construction industry and constitutes a substantial industry-wide challenge (PROF/TRAC, 2015).
Being the technology development of paramount importance to increase industry competitiveness (da Silveira, Vasconcellos, Guedes, Guedes, & Costa, 2018), a comprehensive approach together with the stakeholder early involvement in the innovative processes are deemed here to be essential to ensuring the suitability, acceptance and future application of innovations. Based on these premises, a two-round Delphi survey was conducted in Spain in late 2017 to identify possible enablers and restrictors for developing a new inspection technology under the ROBIM project,1 also gaining from the actors’ engagement. That technology is set to ensure comprehensive data collection, processing and management. Knowing that the suitability of renovation design depends on informed decisions (Gbadamosi et al., 2018), this article starts with problem recognition and subsequent Delphi study, which has been designed as a tool to support the development of the inspection technology.
The objective of this Delphi study is to identify the demands of the actors involved in conserving Spanish buildings and exploring the contextual challenges faced during the inspection. The present Delphi study is proposed as a Decision-Support Tool (DST) to guide the design process of a new technology capable of addressing the identified demands and contextual challenges through innovative procedures that contribute positively to building stock management and conservation processes.
After this introductory part, the next section provides an overview of the innovation applied to buildings’ management and contextualizes building conservation in Spain. The third section describes the Delphi methodology and how it has been applied as a DST. The fourth details the questionnaire design and conduction of the surveys, the fifth the results and discussion. The sixth and last sets out the conclusions.
Section snippets
Innovative management of existing buildings
The use of new inspection techniques together with information and communication technology tools (ICTs) not only could help limit building energy demand, but also lower both the resources consumed, and the waste generated, contributing to construction industry decarbonization. Unlike other industries that have undergone an enormous technological change, construction has barely profited from new technologies being usually considered as slows uptake of innovation. Automation, for instance, is
The suitability of the Delphi method for this study
Widely analyzed academically and scientifically from both theoretical and practical perspectives, the Delphi method has proven its value and is a research technique fully accepted by today’s scientific community (von der Gracht, 2012). It has been applied in any number of disciplines since its development in the 1950s by the Rand Corporation for the U.S. Air Force (Linstone & Turoff, 2011) and adaptation a decade later by academia. The constant evolution of the technique (Barnes & Mattsson, 2016
Design of the consultation process
The panel of experts and the survey content were defined in parallel to guarantee a balance between the questions posed and respondents’ ability to reply (Fig. 1). The questionnaires were defined around the main elements of inspection (in particular) and intervention on buildings (in general). For this design, we considered the existing literature and context investigation (see Sections 1 and 2). Since time limitations normally affect researchers’ decisions on the Delphi procedure adopted (von
General: participation and consensus reached
Of the 175 experts initially invited to join the panel, 52 ultimately completed both rounds of the Delphi consultation; 65 (51 invited by the researchers and 14 by panelists) or 37.1% completed R1, 13 of whom did not participate in R2, for which the final response rate was 80.00%. As a rule, participation in Delphi depends on the type of study and size of the panel of experts. Some authors (Sumsion, 1998) recommend a 70% final response rate to maintain the rigor of the method. Although the
Conclusions
This article discusses the findings of a Delphi study used as a decision-making tool for developing a new technology in the field of inspection and diagnosis of existing building envelopes. The design of the consultation is based on relevant background knowledge on innovative management of existing buildings, with special attention to building conservation in Spain.
Since the absence of exhaustive information on existing buildings hinders building stock management and consequently the transition
Declaration of Competing Interest
None.
Acknowledgements
This study was conducted under the ROBIM project (Spanish CIEN Project 00093139), running from 2017 to 2020, and co-funded by the Centre for the Development of Industrial Technolog(Spanish initials CDTI). ROBIM project members’ contributions and survey respondents’ time and commitment are gratefully acknowledged.
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