Multi-criteria decision making under uncertainty in building performance assessment

Building performance assessment is complex, as it has to respond to multiple criteria. Objectives originating from the demands that are put on energy consumption, acoustical performance, thermal occupant comfort, indoor air quality and many other issues must all be reconciled. An assessment requires the use of predictive models that involve numerous design and physical parameters as their inputs. Since these input parameters, as well as the models that operate on them, are not precisely known, it is imprudent to assume deterministic values for them. A more realistic approach is to introduce ranges of uncertainty in the parameters themselves, or in their derivation, from underlying approximations. In so doing, it is recognized that the outcome of a performance assessment is influenced by many sources of uncertainty. As a consequence of this approach the design process is informed by assessment outcomes that produce probability distributions of a target measure instead of its deterministic value. In practice this may lead to a “well informed” analysis but not necessarily to a straightforward, cost effective and efficient design process. This paper discusses how design decision making can be based on uncertainty assessments. A case study is described focusing on a discrete decision that involves a choice between two HVAC system designs. Analytical hierarchy process (AHP) including uncertainty information is used to arrive at a rational decision. In this approach, key performance indicators such as energy efficiency, thermal comfort and others are ranked according to their importance and preferences. This process enables a clear group consensus based choice of one of the two options. The research presents a viable means of collaboratively ranking complex design options based on stakeholder’s preferences and considering the uncertainty involved in the designs. In so doing it provides important feedback to the design team

Uncertainty analysis in building performance simulation for design support

Building Performance Simulation (BPS) has the potential to provide relevant design information by indicating directions for design solutions or uncertainty and sensitivity analysis. A major challenge in simulation tools is how to deal with difficulties through large variety of parameters and complexity of factors such as non-linearity, discreteness, and uncertainty. It is hypothesized that conducting an uncertainty and sensitivity analysis throughout key stages of the design process would be of great importance. The purpose of uncertainty and sensitivity analysis can be described as identifying uncertainties in input and output of a system or simulation tool [Lomas, 1992; Fuerbringer, 1994; MacDonald, 2002]. In practice uncertainty and sensitivity analysis have many additional benefits including: (1) With the help of parameter screening it enables the simplification of a model [de Wit, 1997]. (2) It allows the analysis of the robustness of a model [Litko, 2005]. (3) It makes aware of unexpected sensitivities that may lead to errors and/ or wrong specifications (quality assurance) [Lewandowska et al., 2004; Hopfe et al., 2006; Hopfe et al., 2007] (4) By changing the input of the parameters and showing the effect on the outcome of a model, it provides a “what-if analysis”. It is for instance used in multiple decision support tools [Gokhale, 2009]. In this paper a case study is performed based on an office building with respect to various building performance parameters. Uncertainty analysis (UA) is carried out and implications for the results considering energy consumption (annual heating and cooling) and thermal comfort (weighted over- and underheating hours) are demonstrated and elaborated. The added value and usefulness of the integration of UA in BPS is shown

Healthy environments from a broad perspective: an overview of research performed at the unit Building Physics and Systems of Eindhoven University of Technology

The design and realization of a healthy indoor environment is a challenge that is investigated from different perspectives at the unit Building Physics and Systems (BPS; Faculty of Architecture, Building and Planning) of Eindhoven University of Technology. Performance requirements (for instance, with respect to air quality, thermal comfort and lighting) and performance based assessment methods are the point-of-departure, focusing at computational techniques supporting the design process. Different specific application fields such as dwellings, offices, schools, but also, operating theatres, churches, musea and multifunctional stadiums, underline the applied approach that is part of the research within the unit. In the design of healthy environments, the performance based design assessment is crucial in arriving at innovative design solutions and optimized indoor and outdoor environments. In this assessment computational support tools and experimental verification play an important role. However, assessing the right indicators in an objective way, applying the correct tools and correct application of these tools is not yet well established. Alongside, developments are still ongoing. The work performed in the unit by the different researchers relates to the research questions that can be derived from this notice. The paper gives an introduction to the Unit BPS and presents a brief overview of recent and ongoing research. An extensive list of references is provided for further reading and supports the conclusion that healthy environments can and should be addressed from a wide angle