ZEMCH 2015 - International Conference Proceedings | Page 672

Introduction
Sustainability researchers can be confident that their discipline has never enjoyed such widespread attention and been assigned so much importance. The importance of the topic extends
outside the Built Environment scientific and technical community, with a number of leading international policy making bodies, most notably the United Nations, placing it at the forefront
(Lukan et al, 2014). This has been accompanied by a number of subsidies and other policy-making
tools to support environmentally-friendly design and other pro-sustainability solutions. The issue
of altering consumers’ preferences by educating them on the economic benefits of sustainable
designs has attracted much less attention in the policy debate.
However, despite the generally wide support, the technical community has not always been able
to deliver the intended outcomes. The term “credibility gap” was first used more than a decade
ago to describe the difference between the design expectations and the actual energy use of a
building (Bordass, 2004). Today this has been established as an accepted reality, with the term
“performance gap” being the most common term employed to describe this phenomenon.

Issues in Environmental Design
Environmental design is meant to rely on standard iterative processes, variations of which are
used in many engineering disciplines: a theoretical approach, is typically developed by researchers, often accompanied by tests in laboratory conditions; this approach is then applied in a real-world building, which functions as a case study; the building is monitored to gather performance-related data, which is analysed to gauge the effectiveness of the design. This then feeds
back into the theory thus helping to optimise the design and lead to further improvements.
While theoretically sound, this approach has many issues when it comes to practical application.
A fundamental issue arises from modelling the proposed design itself, where the designer might
make assumptions that might not be easily implemented in construction practice and building
use. A further problem is associated with the simulation process itself. Most environmental rating systems, such as the Building Research Establishment Environmental Assessment Method
(BREEAM) and the Leadership in Energy and Environmental Design (LEED), rely on digital Building
Performance Simulation tools (BPS) whose effectiveness and consistency has often shown to be
problematic (Schwartz and Raslan, 2013). The problem here is twofold, on par with standard engineering processes. Firstly, there is the issue of the validity of the model itself, i.e. how accurately
the model represents reality. Secondly, there is the issue of the verification of the, often extensive,
calculation processes applied on the model.
While important, these problems are not insurmountable. Other engineering disciplines have
addressed similar issues in the past: the twin issue of validation and verification appears in the
vast majority of methods employed in civil and mechanical engineering. The iterative process described earlier, with the emphasis of gathering results that feed back into the theoretical analysis,
aims to respond exactly to such challenges. There are, however, two key differences that differentiate environmental design for the built environment from other engineering endeavours.
Firstly there is the issue of user behaviour. Unlike disciplines such as structural engineering, assumptions made by environmental designers during the planning and design stage often differ
widely from how the building is utilised once delivered and put to actual use. The precise reasons

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ZEMCH 2015 | International Conference | Bari - Lecce, Italy