SÍNTESIS DE LA EVALUACIÓN

Various tools have been developed for building modeling, simulation and control design. Their strengths and weaknesses vary depending on the application. The most mature ones include Modelica, TRANSYS, ESPr, eQuest, and EnergyPlus [51]. Modelica is an equation- based modeling language that has a free open source building library which covers HVAC systems, multi-zone heat transfer and heat flow. It also enables real-time data exchange with building automation systems. TRANSYS provides a transient simulation environment and is well suited for the detailed analysis of solar systems, HVAC systems, renewable generation, and co-generation systems. ESPr is based on a finite volume, conservation approach and is powerful for simulating scenarios in different operating and environmental conditions. eQuest is a comprehensive building energy simulation tool and supports complex geometries, and many HVAC configurations. EnergyPlus is a very detailed complete building energy simulation software and includes many simulation capabilities.

The main differences between these tools lie in their simulation capabilities, modeling approach, the way they handle interior and exterior surface convection, solar gain, data exchange and the additional software they support. See [52] and Table 2.1 in [51] for a detailed comparison of these tools.

2.2.1 EnergyPlus

EnergyPlus [53] is a detailed building energy simulation software developed by the U.S Department of Energy (DOE) for the simulation of building, HVAC, lighting, occupancy, ventilation, and other energy flows in a building. It is typically used by architects, engineers, and researchers and helps to optimize the building design for energy and water usage. EnergyPlus is a combination of many modules working together to determine the heating or

2.2. Building Simulation Tools

cooling energy requirement of a building. It include modules for shading computation, day lighting, window heat transfer, sky model, air loops simulation, zone equipment simulation, airflow network, and conduction transfer function. Each module simulates and determines its energy impact on the building and the HVAC system. The integrated simulation approach used in EnergyPlus means that all modules are simulated concurrently and a constant feedback between the modules ensures that a physically realistic solution is obtained. Some of the key features of EnergyPlus include the integrated, simultaneous solution of the thermal zone conditions and HVAC system response, heat-balance based solution of radiant and convective effects, sub-hourly user definable time steps for interaction between the thermal zone and the environment, combined heat and mass transfer models, illuminance and glare calculations, component-based HVAC supporting both standard and novel configurations, a large number of built-in HVAC and lighting control strategies, import and export of data with other engines for co-simulation, and generation of detailed output reports with user defined time-resolutions1.

EnergyPlus takes as inputs building description data and weather data as structured ASCII text files. The core of the software is script based and does not have any official GUI or user interface. Third-party software has been developed, e.g., OpenStudio [54] to interface with EnergyPlus. Generally, EnergyPlus, like most of the other detailed building simulation software, is not considered an easy-to-use tool and requires experience.

One of the strengths of EnergyPlus is that it allows the simulation of different types of environments, building types, HVAC types and configurations, and external weather conditions. It also enables the simulation of renewable, e.g., PV’s and co-generation units. Another advantage is the free availability of a validated database of standard building models of different types and locations provided by the Reference Buildings database of the U.S. DOE [55]. It includes models for offices, warehouse, retail stores, malls, schools, supermarkets, restaurants, hospitals, hotels, and apartment buildings. This database is representative of approximately70% of all the commercial buildings in the U.S. and is a good resource to carry out simulations with a wide variety of buildings.

EnergyPlus building models are generally of good quality, and are considered to be a reasonable representation of buildings. Various works have experimentally tested and validated EnergyPlus models [56], [57], [58], [59]. However, EnergyPlus models, because of their complexity, are not suitable as prediction models in optimization based control design. Therefore, there is a need to develop a systematic modeling procedure to obtain simple, yet representative models which can be used for control design.

1_{https://energyplus.net/}

Chapter 2. Literature review

2.2.2 MLE+

MLE+ [60] is a MATLAB / SIMULINK toolbox for co-simulation with EnergyPlus. The toolbox provides an interface between EnergyPlus and MATLAB. It relies on BCVTB [61] to handle the communication of data between the two pieces of software. It is useful to carry out co-simulations where the building energy simulation is performed in EnergyPlus and the controller design and implementation is done in MATLAB. It also helps collecting data from EnergyPlus simulations for system identification or analysis purposes.

Using MLE+ requires the knowledge of EnergyPlus and involves manual processing for setting up the co-simulation which can be cumbersome when a large number of simulations are required.