A Tool for Design Decision Making Zero Energy Residential Buildings in hot Humid Climates

Abstract

The design and modelling of Net Zero Energy Buildings is a challenging and complex problem of increasing importance. Informing the uncertainty of architects during early design stages for decision making is very important. In this introductory chapter I will first expand on the basis of this uncertainty, examining the implications of NZEBs design in hot climates, the limitation of existing building performance simulation tools and the reasons against their integration in design. Then, in the second part, I will outline the concept of informed decision making, before discussing how simulation based decision making may be of benefit in addressing the design uncertainty of NZEBS. Thirdly, I will present the three research questions of this thesis, and in the final part I will consider how these four questions will be addressed in the thesis. The chapters of the thesis will be presented in three sections: analysis of the problem, development of the decision support tools and evaluation of the decision aid.

1.1 NZEB Design

1.1.1 NZEB Design and Modelling

The modelling of net zero-energy buildings (NZEBs) is a challenging problem of increasing importance. The NZEBs objective has raised the bar of building performance, and will change the way buildings are designed and constructed. During the coming years, the building design community at large will be galvanised by mandatory codes and standards that aim to reach neutral or zero-energy built environments (ASHRAE 2008, EU 2009, IEA 2011). At the same time, lessons from practice show that designing a robust NZEB is a complex, costly and tedious task. The uncertainty of decision making for NZEBs is high (Athienitis 2010, Kolokotsa 2010, Marszal 2011). Combining passive and active systems early on is a challenge, as is, more importantly, guiding designers towards the objective of energy and indoor comfort of NZEB. Table 1.1, shows the six main building design aspects that designers should address early on during the conceptual stage. The integration of such design aspects during the early design phases is extremely complex, time consuming and requires a high level of expertise, and software packages that are not available. At this stage, the architects are in a constant search for a design direction to make an informed decision. Decisions taken during this stage can determine the success or failure of the design. In order to design and construct such buildings it is important to assure informed decision making during the early design phases for NZEBs. This includes the integration of building performance simulation (BPS) tools early on in the design process (Shaviv 1999, Hayter 2001, Charron 2006).

1.1.2 Uncertainty of Decision Making

Architectural design is exploratory, ill-defined and uncertain by nature. The better the search in solution space, the better the outcome. Exploring design during early stages considering multi-disciplinary aspects constitutes the work process of an architect. Consequently, early design support has never been more important, especially for small projects lacking engineering support due to limited budgets. The architectural design process and more specifically early design stages, embrace major opportunities in achieving NZEB. During the early design sortant parameters affecting the building performance are addressed. During early design phases, 20% of the design decisions taken subsequently influence 80% of all design decisions (Bogenstätter 2000).