Computational Building Performance Simulation (BPS) is a powerful strategy, to tackle the complex task of assessing the operational energy demand of buildings. In current design practice it is often restricted to the final design stages, given the difficulty and time intensity of modelling in common BPS tools which is limiting their application to the analysis of a single design solution. However, many decisions taken in the initial design stage, such as the building’s orientation, massing, percentage of glazed area, choice of shading devices etc., strongly influence the operational energy expense. Therefore the potential impact of building simulation would be greatly enhanced if its use was extended to multiple variant design optimization and included much earlier in the design process.
The EnergyFacade tool was developed as plug in for Grasshopper, a graphical algorithm editor tightly integrated with Rhino’s 3D modelling tools. It provides the user with close to real time feedback regarding the impact of design changes on the operational energy performance.
The operational energy is calculated as a sum of the demand for heating, cooling and artificial lighting. These result from thermal and daylight analyses based on simplified dynamic models providing hourly data for a specific location over a year. Results are displayed in form of graphs directly in the modelling environment to facilitate the user interaction.
The integration of BPS in the early design stage showed the possibility of making informed choices regarding the façade design, based on its energy performance. This could eventually lead to a more energy efficient and thus more sustainable construction.
The parametric and associative nature of the tool furthermore stimulates the interaction between designers and engineers. By providing a design environment which offers the possibility to simultaneously model and get near to real time feedback on the energy performance, the engineers are exempted from the task of performing repetitive initial calculations on various design option and assembling laborious models in a BPS software, gaining time for working out details in the later stage of the design. In this way, besides the final design object itself, the design process can be enhanced.
The applied simplified dynamic models showed to be suitable for the conceptual design stage. A bottleneck however is the computational speed in the case of shading assessment over a full year, which would require further research or further simplification of the applied model.
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