Optimization on environmental models: Formal co-simulation to find a sustainable design

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By Pau Fonseca i Casas, professor, Polytechnical University of Catalonia.

Environmental simulation models are difficult to handle due to the inherent complexity of the elements involved on the analyzed systems. How we can deal with the complexity of those systems? How can we work with the diversity of the languages and terminologies used by different experts? How can we allow an extensive Validation and Verification of such models? The use of formal languages and co-simulation techniques allow the combination of several simulation and optimization techniques in a single simulation engine, helping to improve system design concerning environmental issues. New methodologies are emerging, allowing to obtain optimal or sub-optimal solutions for these kind of systems without concessions on the necessary Validation and Verification processes. On the specific area of Smart Cities and Building energy management, different frameworks (e.g. NECADA) use this methodology to improve the sustainability in urban areas or buildings. This allows to combine IoT, Data Mining, Optimization, Simulation and other techniques through the formalized model.

« A formalized model respresents the structure and the behaviour of the model in a clear and unambiguous way. »

NECADA is a hybrid infrastructure that supports the execution of simulation models on cloud, cluster or desktop environments. The NECADA framework can optimize complete life cycles of buildings or urban areas, ranging from the design, building, actual use and the final rehabilitation and deconstruction processes, making the design of Net Zero Energy Buildings possible. The model implemented on NECADA considers the environmental directives and international rules in the design process (CEN TC 350) to optimize the behaviour of buildings or cities from the point of view of sustainability. It is defined using Specification and Description Language (SDL), a formal language from the Telecommunication Standardization Sector (from the UML family) with enhanced graphical capabilities, great expressiveness and easy to combine with other engineering languages. SDLPS, our software that understands SDL, performs an automatic simulation from this graphical representation of the model. No implementation is needed leading to a simplified verification, modification and expansion of the model. The simulation model definition is so simple that it can be accomplished and understood by all the members of the team, simplifying validation processes. Finally, co-simulation techniques are applied to state of the art calculus engines, like EnergyPlus, Trnsys, etc., using building information models to represent the complete building or area life cycles. Thanks to this architecture we can use NECADA to analyze thousands of different alternatives, using the power of super-computing or the precision of optimization algorithms to find the optimal solution for your building or urban area.