3. Development of Building Sustainability Assessment
3.1. Scope of the Work
The Portuguese building technologies and the indoor environmental quality standards are quite different from most European countries. The first situation is mainly related to economic and socio-cultural constraints, while the second is related to the mild climate. This reality normally hinders the use of foreign decision support and sustainability assessment methodologies without prior adaptation of the list of parameters, weights, and almost all benchmarks. Another important reason for the delay in the real implementation of the sustainable assessment is the huge amount of parameters that project teams have to deal with: many of the methodologies presented in the sections above
embrace hundreds of parameters. Most of these parameters are not standard in Portugal and are difficult to deal with for many project teams.
This study intends to be the basis for the future development of an advanced residential building sustainability rating tool, and is to be especially suitable for Portuguese traditions, climate, society, and national standards. The research aims to cope with the mentioned problems and toward the real implementation of building sustainability assessment in Portugal. The name of the methodology that is under development is the Methodology for the Relative Sustainability Assessment of Residential Buildings (MARS-H, from the Portuguese acronym).
In this section, steps to establish the methodology are presented. The indicators inside each sustainable dimension, and their related parameters, will be presented. Additionally, the calculation of the weights will be discussed. This calculation will be based in the local environmental, socio-economic, and legal contexts, and in the type of building that is going to be assessed.
First of all, system boundaries are presented. Then, the approach can be divided into four major stages: selection of indicators and parameters, quantification of parameters, normalization and aggregation of parameters, and representation and the global assessment of a project.
3.2. System Boundaries
In the first stage, the methodology is being developed to assess residential buildings. Most of the Portuguese construction market is related to the residential sector, and therefore, the development of a methodology to support and to rate sustainable residential buildings is a priority.
The object of assessment is the building, including its foundations and external works, within the area of the building site. The impacts of the building upon the surroundings and urban environment are not considered. Some authors concluded that restricted scales of study (corresponding for a single building for example) are too limited to take into account sustainable development objectives correctly [9]. Nevertheless, sustainable urban planning is normally limited to municipalities and regional authorities and therefore, it is more rational and straightforward to limit the physical system boundary to the building itself (or part of it) together with the site. This way, the methodology excludes construction works outside the construction site (including networks for communication, energy, and transportation).
The life cycle’s period boundary should represent the whole life-cycle stages of the building. In a new building, it will consider all life-cycle stages, from construction to final disposal, and in existing buildings, the temporal boundary will start from the moment of the intervention to the final disposal. Besides the time boundary, two other important aspects to define are the hours of normal occupation, the usage of the building, and the building’s occupational density.
3.3. Selection of Indicators and Parameters
After defining the time and physical boundaries of the methodology, the next step is to choose the indicators and related parameters (within the three sustainable development dimensions) that are going to be used to assess the objectives of a project. A parameter is a sign, or a signal, that relays a complex message, from potentially numerous sources, in a simple and useful manner [10]. Therefore, the main three objectives of the parameters are: simplification, quantification, and communication [11].
Categories and related parameters are the basis of the methodology, since objectives and results will be conditioned by them.
Figure 3 illustrates the parameters that are considered in the methodology under development. Other parameters could be included in further phases of development.