Automatic IFC data enrichment with space geometries for Building Energy Performance Simulations

The potential of using BIM geometry data to automate the process of setting up the geometry in whole building simulation models is very appealing. This transformation process is far from trivial and relies on good quality data. Missing or incorrect space geometries in the BIM model can create issues, especially in complex geometric configurations. In this paper, we present an algorithm to identify building space volume geometries automatically. The algorithm receives as input the geometric representations of architectural elements surrounding the building spaces and accurately reconstructs the internal building space volumes. The proposed method is tested in real-world examples and can be particularly useful for curved wall geometries. The transformation process relies on good quality geometric input data of the architectural elements avoiding clashes and surface errors; we define criteria to check for such errors and discuss the impact of such errors on the reconstructed space volumes

Second-level space boundary topology generation from CityGML inputs

Although CityGML geometrical data exported either from GIS data or from compatible design software are suitable for scene rendering and navigation, they are not directly usable for energy simulation purposes because the second-level space boundary information, essentially surface pairs through which thermal energy exchange among buildings or building rooms or among a building room and its outside environment occurs, is missing. In order to address this need, a district space boundary topology generation algorithm, that takes as input data formatted according to the CityGML standard, is introduced. The algorithm is based on four main processes and special operations which are designed according to specific input data scenarios. The algorithm is demonstrated with successful results on examples with Level Of Detail 2, 3 and 4, as defined in the CityGML standard. Also certain cases requiring further investigation are discusse

Reduced-basis output bound methods for parabolic problems

In this paper, we extend reduced-basis output bound methods developed earlier for elliptic problems, to problems described by ‘parameterized parabolic’ partial differential equations. The essential new ingredient and the novelty of this paper consist in the presence of time in the formulation and solution of the problem. First, without assuming a time discretization, a reduced-basis procedure is presented to ‘efficiently’ compute accurate approximations to the solution of the parabolic problem and ‘relevant’ outputs of interest. In addition, we develop an error estimation procedure to ‘a posteriori validate’ the accuracy of our output predictions. Second, using the discontinuous Galerkin method for the temporal discretization, the reduced-basis method and the output bound procedure are analysed for the semi-discrete case. In both cases the reduced-basis is constructed by taking ‘snapshots’ of the solution both in time and in the parameters: in that sense the method is close to Proper Orthogonal Decomposition (POD)

Comparing the impact of different thermal comfort constraints on a model-assisted control design process

In the design of supervisory controllers for managing energy in buildings, modelbased control design approaches have recently attracted significant attention. The control-design problem in these cases is typically posed as a constrained minimization problem: given a simulation model acting as a surrogate of the building, identify a controller that minimizes a cost function, say energy, subject to the constraint that thermal comfort stays within acceptable levels. The use of a thermal comfort model can be the means for estimating comfort so that the mathematical programming problem can be formulated. In the present paper, we investigate how the choice of thermal comfort model affects the quality of the resulting controller. We consider a building simulated in EnergyPlus and design, under the same conditions, controllers using three different thermal comfort models: the model of Fanger, the two-node Pierce model, and the KSU two-node model. A comparative study is performed to draw conclusions upon the effects that this selection has with respect to the performance of the resulting controller

From BIM to BEMS, covering the design- to operational-phase interoperability gap

This paper deals with the FP7 EU project “Building as a Service” (BaaS). The BaaS project is a research initiative which aims at providing a generic solution for delivering standardization and interoperability concepts for building data and open middleware platform covering the Design- and Operational-Phase In-teroperability Gap in the application domain of “non-residential buildings.” There are two important phases in the building life-cycle: the design phase and the operational phase. Development and integration of ICT tech-nologies can help best coordinate the building design and operation phases. Overcoming interoperability gaps between both phases so as providing a way of integration to use existing and future tools and services would help to enhance building operations and controls. Better design, standardization and interoperability can con-tribute themselves to the goals of improving energy efficiency. Interoperable components working as services at the building level, will lead naturally to the concept of the Building as a Service ecosystem. This paper aims at analyzing some of the BaaS project topics: (1) building data management and interoperability: data warehouse to collect, organize, store and aggregate static and dynamic data from various in- and out-of-building sources; an IFC-based BIM will act as a central repository for all static building data, and a data warehouse will be used for dynamic data, both schemes mapped using a unique vocabulary. (2) Integration of building energy management Services using Open Service Middleware Platform technologies. A service middleware platform to abstract the building physical devices, support high level services on the cloud and facili-tate secure two-way communication between the physical and ICT layers (building) with high level services (cloud)

Advanced control strategies toward achieving nearly-zero energy consumption in buildings

In this paper the main concept and results of the PEBBLE Project are presented: PEBBLE is an ongoing FP7 Project aiming at the development of advanced ICT tools to support the operation of nearly-zero- and positive energy buildings. In the design and operation of such buildings a pragmatic target is maximization of the actual net energy produced (NEP) by intelligently shaping demand to perform generation-consumption matching. With the belief that maximization of the NEP for Positive-Energy Buildings is attained thru Better ControL decisions (PEBBLE), a control and optimization ICT methodology that combines model-based predictive control and cognitive-based adaptive optimization is presented. There are three essential ingredients to the PEBBLE system: a) thermal simulation models; b) sensors, actuators, and user interfaces; and c), generic control and optimization tools. The potential for energy savings using advanced control strategies is illustrated using simulation-based studies: there are significant benefits in terms of energy-performance of using advanced control strategies, compared to traditional rule-based ones. Ongoing work about demonstration and evaluation of the PEBBLE system in three real world buildings is described

Simulation-time reduction techniques for a retrofit planning tool

The design of retrofitted energy efficient buildings is a promising option towards achieving a cost-effective improvement of the overall building sector’s energy performance. With the aim of discovering the best design for a retrofitting project in an automatic manner, a decision making (or optimization) process is usually adopted, utilizing accurate building simulation models towards evaluating the candidate retrofitting scenarios. A major factor which affects the overall computational time of such a process is the simulation execution time. Since high complexity and prohibitive simulation execution time are predominantly due to the full-scale, detailed simulation, in this work, the following simulation-time reduction methodologies are evaluated with respect to accuracy and computational effort in a test building: Hierarchical clustering; Koopman modes; and Meta-models. The simplified model that would be the outcome of these approaches, can be utilized by any optimization approach to discover the best retrofitting option

Co-simulation setup for online model-assisted control design

For reduction of energy intensity of the building sector, effective and parsimonious use of energy resources and climate control systems is a prerequisite. Intelligent Building Energy Management Systems (BEMS) can be key ingredients towards achieving this goal; the incorporation of forecast data into the decision process can help achieve improved performance compared to existing state-of-the-art approaches. In the present paper, the potential of model-based supervisory control design algorithms for automatically designing BEMS is evaluated by performing experiments in a real building. A co-simulation setup is implemented where the thermal simulation model of the building is warmed up using past sensed data and then, given weather and occupancy forecasts, a controller is designed by solving a constrained minimization problem. A stochastic optimization algorithm is used to intelligently search the controller parameter space and identify a controller that minimizes an energy-related cost function, subject to thermal comfort constraints. A middleware solution is deployed in the building to facilitate two-way communication between the building (sensing and actuation) layer and the algorithmic layer

A discontinuous Galerkin formulation for solution of parabolic equations on nonconforming meshes

Non-conforming meshes are frequently employed in multi-component simulations and adaptive refinement. In this work we develop a discontinuous Galerkin framework capable of accommodating non-conforming meshes and apply our approach to analyzing the transient heat conduction problem