Exploring the Interplay between CAD and FreeFem++ as an Energy Decision-Making Tool for Architectural Design

Abstract

The energy modelling software tools commonly used for architectural purposes do not allow a straightforward real-time implementation within the architectural design programs. In addition, the surrounding exterior spaces of the building, including the inner courtyards, hardly present a specific treatment distinguishing these spaces from the general external temperature in the thermal simulations. This is a clear disadvantage when it comes to streamlining the design process in relation to the whole-building energy optimization. In this context, the present study aims to demonstrate the advantages of the FreeFem++ open source program for performing simulations in architectural environments. These simulations include microclimate tests that describe the interactions between a building architecture and its local exterior. The great potential of this mathematical tool can be realized through its complete system integration within CAD (Computer-Aided Design) software such as SketchUp or AutoCAD. In order to establish the suitability of FreeFem++ for the performance of simulations, the most widely employed energy simulation tools able to consider a proposed architectural geometry in a specific environment are compared. On the basis of this analysis, it can be concluded that FreeFem++ is the only program displaying the best features for the thermal performance simulation of these specific outdoor spaces, excluding the currently unavailable easy interaction with architectural drawing programs. The main contribution of this research is, in fact, the enhancement of FreeFem++ usability by proposing a simple intuitive method for the creation of building geometries and their respective meshing (pre-processing). FreeFem++ is also considered a tool for data analysis (post-processing) able to help engineers and architects with building energy-efficiency-related tasks.

Modelling of surface and inner wall temperatures in the analysis of courtyard thermal performances in Mediterranean climates

“…Although there are many simulation tools to predict the energy performance of buildings, the complex thermodynamic effects that happen in courtyards require simulation tools with high computational resources and thousands of simulation hours to calculate and simulate a representative period, based on CFD (Computational Fluid Dynamics) and finite elements (Blocken et al 2011). In the analysis performed by Rojas et al (Rojas-Fernández et al 2018), the main available simulation tools are analysed concerning their capacity to simulate transitional spaces from the point of view of a professional of the building sector. They found that there is no available software that meets all requirements for this reliable microclimate simulation.…”

Applied Machine Learning Algorithms for Courtyards Thermal Patterns Accurate Prediction

“…The courtyard microclimate can be explained in terms of the thermodynamic effects that occur within it, i.e., convection, radiation, stratification, and flow patterns. Among the different parameters affecting these microclimatic conditions, most of the studies emphasize the importance of courtyard geometry [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29], in many cases considered the Aspect Ratio (AR), which is the ratio between the height and the width of the courtyard.…”

“…Courtyard location, implying climatic conditions and specifically outdoor temperature ranges, is another key factor that is becoming commonplace in a large number of publications [14][15][16][17][18][19][20][21][25][26][27][28][29][30].…”

“…One of the most widely used tools is ENVI-met, based on CFD simulation [32]. Other outdoor modeling software alternatives are Urban Weather Generator (UWG), based on energy conservation principles [33]; SOLWEIG, which can simulate spatial variations of 3D radiation fluxes and mean radiant temperatures [34]; Open FOAM, which has been used in previous research to simulate urban wind flows [35]; FreeFem++, employed to perform courtyard microclimate modelling [17,36]; and ANSYS Fluent, which has been applied for the simulation of wind flows in outdoor spaces [17,36]. Most of these tools present adequate accuracy for predicting urban outdoor microclimates, but they tend to show a larger error range when they are used to model the microclimate of smaller-scale spaces, such as courtyards, with greater dependence on the built environment [12,36].…”

Linear Optimisation of a Settlement Towards the Energy-Plus House Standard

“…In contrast to the tools that consider the optimisation of energy systems with detailed building models [13,20], this article focuses on the tools that make a compromise between the accurate calculations of the physical properties of one building, and the optimisation of these properties for multiple buildings and the components of their energy systems. Such tools that can optimise the energy system for a settlement or urban quarter are already available (e.g., RETScreen [21] and the tools developed by the passive house institute).…”