Perspectives of building sustainability assessment

The concept of sustainable building is usually related to environmental characteristics although the social, economic and cultural indicators are of substantial importance. Any building level assessment method is complex and involves contradictory aspects; emphasizing the qualitative criteria only increases confusion. The R&D and standardization is thus concentrated to transparency and usability of the environmental methods. Other directions of research are aiming at performance-based design and methods to take regional and cultural aspects into account. In this paper, the perspectives of the sustainability assessment of a whole building are presented based on the state-of-the art, feasibility study on performance analysis and development of extended LCA for buildings. Based on the case studies of building sustainability assessment using various tools, the environmental indicators were shown to be often of lesser importance than the other, soft ones. At the end, will be presented and discussed the first steps in the development of a building sustainability assessment method for Portuguese residential buildings. odological aspects of tools has been made e.g. by Forsberg and Malmborg (2004). The majority of the tools is developed based on a bottom up approach, i.e. a combination of building materials and components sums up to a building, and this even though they are designed to consider the whole building including energy demand, etc (Erlandsson & Borg 2003). Tools to support decision-making in accordance with principles of performance based design have also been developed, mainly in research communities. The assessment tools, either environmental or performance-based are under a constant evolution in order to overcome their various limitations. The main goal, at the moment, is to develop and implement a systematic methodology that supports design process of a building. The methodology should result to the most appropriate balance between the different sustainability dimensions, and be practical, transparent and flexible at the same time. It should be easily adaptable to the different kinds of buildings and to the constant technology evolution. In this paper, approaches to incorporate the three sustainability dimensions within a building project are presented and discussed based on a feasibility study and state-of-the-art. In a more thorough way, the sustainability is dealt with the concepts of eco-efficiency and cost-efficiency that result from a holistic building performance analysis. Then, the potential to introduce the building’s economic and social impacts (“soft indicators”) in the originally environmental LCA methodology is studied, and the new developments and perspectives for the Building Sustainability Assessment (BSA) using global indicators is presented. 2 APPROACHES TO BUILDING SUSTAINABILITY 2.1 Sustainability indicators of a building project The sustainability indicators of the construction and real estate sector give information about the influences of the industry as a whole and about the impacts of construction and operation of buildings and other built assets. Different approaches for indicators exist due to differences between societies, industrial traditions, environment and geography. The sustainability indicators for a building project can be selected from various lists prepared at governmental, sectoral and community level. The Agenda 21 by CIB (1999) states that the framework of relevant issue areas should be based on the assumption that a sustainable building approach includes all factors that may affect the natural environment or human health. For a contactor or facility manager, it is important to differentiate between the criteria and tools used to assess technology at the generic or global level, and the approach used at the site specific application or local level (Environmentally Sound Technologies 2003). In spite of some differences between the lists of indicators, most of them deals directly or indirectly with the following issues: resources consumption, environmental pressure, energy and water efficiency, indoor air quality, comfort and life cycle costs. An indicator is expressed by a value derived from a combination of various measurable parameters (variables). Indicators have to be defined in a clear, transparent, unambiguous and correct way, even before the concern whether they relate and evaluate several parameters. The indicators are usually grouped (aggregated, categorized), and further various aggregated indicators may create subgroups in a hierarchical system. 2.2 Managing and assessing building sustainability Building Sustainability Assessment (BSA) methods can be oriented to different scale analysis: building material, building product, construction element, independent zone, building and neighbourhood. Analysing the scope of the most important sustainability support and assessment systems and tools it is possible to distinguish three types: – Systems to manage building performance (Performance Based Design); – Life-cycle assessment (LCA) systems; – Sustainable building rating and certification systems. i) Managing building performance Performance Based Building is an approach to building-related processes, products and services with a focus on the required outcomes (the 'end'). This approach would allow for any design solution (the 'means') which can be shown to meet design objectives (Koukkari, 2005). The comprehensive implementation of the performance approach is dependent on further advancement in the following three key areas: the description of appropriate building performance requirements; methods for delivering the required performance; methods for verifying that the required performance has been achieved. The main purpose for a generic hierarchical model is to provide a common platform to define the desired qualities of a building and to develop a common language for different disciplines as well as to serve as a basis for development of design and technical solutions. The choice of the objectives in the hierarchical presentation shows also to some extent the values of the developer. Based on the hierarchy of performance objectives and their targeted qualities, alternate design and technical solutions can be developed. The capability of different solutions to fulfil the performance criteria can be studied with verification methods. Figure 1 represents a generic model of building’s performance analysis. Similar hierarchies are introduced by several organisations. COSTS ENVIRONMENTAL PRESSURE