Implementation using parametric design software

In order to apply the parametric LCA model for the evaluation in Chapter 4, it has to be implemented using parametric design software. Any software for parametric design which is based on a 3D model can be employed for implementation. In this thesis, Grasshopper3D71

(GH) is used, a parametric design software program based on the 3D CAD Software Rhinoc-

eros72_{. The parametric tool is named CAALA – Computer-Aided Architectural Life cycle}

Assessment. Both the calculation of the energy demand and of the embodied impact are fully integrated into GH, making exporting and re-importing unnecessary. In this way, CAALA is able to calculate the LCA in real time. Figure 27 shows a screenshot of the user interface of Rhinoceros with CAALA.

Figure 27: Screenshot of Rhinoceros with CAALA with different viewports: a) LCA results, b) 3D drawing of geometry, c) Material control, d) Layers of geometry, e) GH control for parametric adaptation 3.2.1. Input

The geometry can either be directly described parametrically in GH or drawn in Rhinoceros and then transferred automatically to GH. To automatically generate the thermal model, the different surfaces are drawn on pre-defined layers (see Figure 27d). Non-geometric

parameters are defined in GH, including building components with materials and thicknesses and building services. Different means of inputting the data can be employed, such as drop- down lists and number sliders (see Figure 28). These can be linked to Rhinoceros to facilitate

71 _{Grasshopper3D is a graphical algorithm editor for 3D CAD software Rhinoceros and can be downloaded at}

http://www.grasshopper3d.com/page/download-1 (accessed March 14th ₂₀₁₆₎

adjustment while designing (see Figure 27e). If the user does not define these parameters, default values based on typical building materials and services are employed. The necessary data is imported from the combined database described in Section 3.1.1.2.

Figure 28: Example of parametric material definition in GH 3.2.2. Calculation

For the calculation of the energy demand based on QSSM, a plug-in for GH based on DIN V 18599-2:2011 has been developed for this thesis. All main parts of the standard relevant to residential buildings have been implemented in GH and allow for calculation of the energy demand in real time73_{. Development and verification of this implementation are described in}

Lichtenheld et al. (2015, pp.1-3). To enable the application of DBPS within CAALA as well, an existing plug-in called Archsim74 _{is integrated, which uses the EnergyPlus}75 _{simulation engine.}

As such, cooling demand and the influence of shading measures can be simulated in detail. 3.2.3. Output

The results are displayed in the Rhinoceros viewport and can simultaneously be exported to a spreadsheet. Rhinoceros possesses multiple viewports, which allows the user to draw and change the geometry in one (see Figure 27b) and receive feedback on the results on a second one in real time (see Figure 27a). The results can be displayed in different ways, including numerical and graphical representation such as bar charts and pie charts. Further viewports can be used to control the input and display the non-geometric information (see Figure 27c).

73 _{On a standard PC the calculation and output of results takes 0.1 seconds.}

74 _{ArchSim is a plug-in to link EnergyPlus with Grasshopper3D. It is developed by Timur Dogan and can be}

downloaded from http://archsim.com/downloads/ (accessed February, 9th 2016)

75 _{EnergyPlus is an open source whole building simulation software funded by the U.S. Department of Energy’s}

(DOE) Building Technologies Office (BTO), and managed by the National Renewable Energy Laboratory (NREL). The software is available at https://energyplus.net/downloads (accessed February, 9th 2016)

3.2.4. Optimization

In GH an optimizer using evolutionary algorithms (EA) called Galapagos76 _{is implemented.}

The architect can define free parameters to be varied by assigning them to the optimizer using number sliders. The range of a number slider defines the range in which the optimiza- tion algorithm can vary the corresponding input parameter. The objective function can be defined for the minimization of a numerical output assigned to the optimizer (see Figure 29). In addition to Galapagos, further plug-ins from third party developers are available. Goat77

provides five optimization algorithms including global EA and local, derivative-free optimiz- ers. Octopus78 _{provides the possibility to optimize for multiple criteria. The Pareto front is}

directly visualized during the optimization process.

Figure 29: Example of an optimization set-up using Galapagos 3.2.5. Summary of Section 3.2

Which software implementation is necessary to be able to apply the parametric method? The implementation of PLCA requires the use of parametric design software. In this thesis, it has been implemented in Grasshopper3D (GH). Both the calculation of energy demand and embodied impact are fully integrated into GH, making exporting and re-importing unneces- sary. In this way, the parametric tool called CAALA – Computer-Aided Architectural Life cycle Assessment – developed in this thesis is able to provide the LCA results in real time. GH provides different optimizers, which can be linked to CAALA to minimize the environmental impact of a building design.

76 _{Galapagos is an evolutionary algorithm integrated in Grasshopper and developed by David Rutten}

77 _{Goat has been developed by Simon Flöry and can be downloaded for free at}

http://www.rechenraum.com/de/referenzen/goat.html (accessed March 14th ₂₀₁₆₎

78 _{Octopus is an evolutionary multi-criteria optimization plug-in for Grasshopper3D. It is based on SPEA-2 and}

HypE optimization algorithms and developed by Robert Vierlinger. The software is available at