An Understanding of Process, Tools and Performance in Green Building Design

Green building is often perceived as a building that has photovoltaic system, recycled content materials and waterless urinals. However, that perception is definitely discussing a partial portion of the green building understanding. The green building shall be perceived not only as a sustainable building, but also as a high performance building. This paper will discuss about how to achieve high performance building by implementing integration process and performance simulation tools.

A building delivery process has traditionally been regarded as a discrete and sequential set of activities (Mahdavi and Lam, 1993). This fragmentation in the process makes it difficult for a building to achieve its performance targets. However, recently there is a consciousness driven by green building movement to embrace integration during the process.

Architects and Engineering consultants work separately while in an ideal process, they should work in integrated environment. As addition, a professional fee structure and regulation affect how integration in building delivery can be fulfilled. For example, a mechanical engineer consultant will prefer to wait until an architect finishes a design rather than to involve in early design process. Another issue that may prevent integration is the behavior and custom of the construction professionals, which merely focuses on completing their job portion and avoiding modification.

In addition to the integration in building delivery process, tools also possess an important role in the process to achieve performance targets. The development of tools cannot relinquish from the tradition in the design process. Because of that reason, it is required to understand the historical background and the nature of the complex forces and conditions that affect the development, introduction, and effective integration of new design/construction support tools (Mahdavi, 1998). Therefore, the effectiveness of tools are affected by the process.

In the past, performance assessment relied on the rule of thumb and hand calculation to solve problems. Professionals in the building and construction industry often use these methods to make decisions in their design, even though it lacks accuracy in its results.

Nowadays, computer based performance simulation tools together with BIM and parametric design tools have been developed to proceed as tools in building delivery process. I still perceive these methods as separate domains. Although there are numerous efforts to integrate those three domains, there is still no smooth and easy interoperability process. The interoperability among the tools is still a major issue. Related to the performance issue, the use of the performance simulation tools such as energy simulation, daylight simulation and CFD (computational fluid dynamic) simulation is a key to achieve a high performance building.

The simulation tools have many advantages compared to other approaches such as the rule of thumb and experimental approaches, especially when comparing many design options and producing a more accurate result. The tools enable designers to see the impact of each option in building performance. They can also perform and calculate each option relatively fast. In comparison between experimental approach and computer simulation, Citherlet (2001) mentioned that as the experimental approach is time consuming and expensive, it can be argued that computer simulation is the preferred option for the holistic appraisal of design options. Thus, the computer simulation tool is the best tool to address performance during design process.

Advantages and disadvantages in each design option will be a foundation to formulate a solution. Since the tools will be very helpful to make decisions in design, they should not only be a justification for final design but also become an integral process in building delivery.

Besides of the advantages of providing better solutions, there are two disadvantages of using performance simulation tool, such as a complexity of model and model approximation/error. The complexity to make a model usually becomes the main reason why professionals in construction industry refuse to apply computer simulation model. Lack of integration with CAD programs such as AutoCAD and Revit forces users to have to create a new model to perform building simulation programs. Based on my experience, making a model in computer simulation tools avoid inaccuracy although it may take more time than importing from CAD model.

Another problem in implementing the simulation tools in early stage design is that detailed information which is required in making a model in a simulation tool is often unavailable in early stage design (Mahdavi et al., 1993). However, the problem can be diminished if the users understand the capabilities of the tools which in fact are able to address the problems in the early design stage. Some examples of these tools include Ecotect and a schematic design wizard in Equest. However, knowledge and expertise of the users to interpret and implement the result into the design are really crucial.

Model approximation/error in the simulation programs commonly happens when the model is difficult to build in simulation tools. It usually happens when a simulation took does not have the capability to perform very complicated models and limitations in their algorithms. For example, if an energy performance simulation tool has no facility to create a model with curved surfaces, some approximation must be made to run the model in the tool. This approximation reduces the accuracy on the result.

In the future, the development simulation tools are required to reduce disadvantages and anticipate problems in building delivery process. Therefore, the implementation of the simulation tools can enhance the design and construction process to fulfill the performance target.

A total approach in building delivery process is required to complete performance targets of building. To achieve that goal, fragmentation in building delivery process must be avoided and the integration process is really critical. In addition to the integration process, the simulation tools also become important in order to achieve the performance targets. Therefore, an understanding of process, tool and performance is required to carry on an integrated process in building delivery and it will result high performance buildings.

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