Model and tool requirements for co-simulation of building performance

The use of building performance simulation (BPS) can substantially help in improving building design towards higher occupant comfort and lower fuel consumption, while reducing emission of greenhouse gasses. Unfortunately, current BPS tools do not allow inter-tool communication and thus limit a modeler to the component models available in the simulation software which happens to be used. A pragmatic way forward would be to enable cosimulation by externally coupled (legacy) tools. This means that each coupled software would represent only that part of the overall building and system configuration that it is able to model. The overall system is represented by the coupled models, which exchange simulation data during run-time. In this way, shortcomings of each tool can be overcome, and advantages of individual tools can be exploited. The work underlying this paper addresses co-simulation of building energy and heating, ventilation and airconditioning (HVAC) models. So far, the research focus has been on thermodynamic issues such as which variables should be exchanged and at what frequency, rather than on mathematic or computer science aspects. This paper specifies and discusses the requirements for BPS software in order to enable co-simulation of building and HVAC system configurations

HVAC system simulation: overview, issues and some solutions

Integrated performance simulation of buildings’ heating, ventilation and air-conditioning (HVAC) systems can help in reducing energy consumption and increasing occupant comfort. Recognizing this fact, in the last forty years many tools have been developed to help achieving this goal. In this paper we introduce a categorization of these tools with respect to which problems they are meant to deal with and summarize current approaches used for modelling (i) HVAC components, (ii) HVAC control and (iii) HVAC systems in general. Further in this paper, we list issues associated with applications of HVAC modelling and simulation. Finally, we present and discuss co-simulation as one of solutions that can alleviate some of the recognized issues

Comparison of co-simulation approaches for building and HVAC/R system simulation

Appraisal of modern performance-based energy codes, as well as heating, ventilation, airconditioning and refrigeration (HVAC/R) system design require use of an integrated building and system performance simulation program. However, the required scope of the modeling library of such integrated tools often goes beyond those offered in available simulation programs. One remedy for this situation would be to develop the required models in an existing simulation program. However, due to the lack of model interoperability, the model would not be available in other simulation programs. We suggest co-simulation for HVAC/R system simulation as an approach to alleviate the above issues. In co-simulation, each subsystem is modeled and simulated in the appropriate simulation program, potentially on different computers, and intermediate results are communicated over the network during execution time. We discuss different co-simulation approaches and give insights into specific prototypes. Based on the prototypes, we compare the approaches in terms of accuracy, stability and execution time, using a simple case study. We finish with results discussions and recommendations on how to perform co-simulation to maintain the required accuracy of simulation results

An implementation of co-simulation for performance prediction of innovative integrated HVAC systems in buildings

Integrated performance simulation of buildings and heating, ventilation and air-conditioning (HVAC) systems can help reducing energy consumption and increasing level of occupant comfort. However, no singe building performance simulation (BPS) tool offers sufficient capabilities and flexibilities to accommodate the ever-increasing complexity and rapid innovations in building and system technologies. One way to alleviate this problem is to use co-simulation. The co-simulation approach represents a particular case of simulation scenario where at least two simulators solve coupled differential-algebraic systems of equations and exchange data that couples these equations during the time integration. This paper elaborates on issues important for co-simulation realization and discusses multiple possibilities to justify the particular approach implemented in a co-simulation prototype. The prototype is verified and validated against the results obtained from the traditional simulation approach. It is further used in a case study for the proof-of-concept, to demonstrate the applicability of the method and to highlight its benefits. Stability and accuracy of different coupling strategies are analyzed to give a guideline for the required coupling frequency. The paper concludes by defining requirements and recommendations for generic cosimulation implementations

Distributed simulation of building systems for legacy software reuse

The use of integrated building performance simulation can substantially help in improving a building design with regards to comfort levels and fuel consumption, while reducing emission of greenhouse gasses. However, the traditional tools that are closed for inter-communication, limit the modeler to use of components only available within that particular package. This paper gives an overview of distributed simulation approach that can alleviate above limitation. Each program can represent only a part of a building system that is able to model, exchanging the necessary information during the execution and bridging the gaps between the tools. Several important issues closely connected with its implementation, such as synchronization, are pointed out, and the sensitivity of a model on different coupling strategies is studied. The paper concludes with highlighting the gained flexibility in modeling and simulation of building performance that arises from the distributed approach

Case studies of co-simulation for building performance prediction

This paper aims to illustrate the usability and benefits of recent developments in co-simulation of building systems by means of several case studies. Co-simulation enables the reuse of models developed in separate simulation tools as well as integration of generic solvers into the computational building performance simulation domain. This in turn facilitates rapid prototype modeling of new and emerging building systems, and thus early performance prediction of innovative systems and concepts, which would not be feasible otherwise

An implementation of co-simulation for performance prediction of innovative integrated HVAC systems in buildings

Integrated performance simulation of buildings and heating, ventilation and air-conditioning (HVAC) systems can help reducing energy consumption and increasing level of occupant comfort. However, no singe building performance simulation (BPS) tool offers sufficient capabilities and flexibilities to accommodate the ever-increasing complexity and rapid innovations in building and system technologies. One way to alleviate this problem is to use co-simulation. The co-simulation approach represents a particular case of simulation scenario where at least two simulators solve coupled differential-algebraic systems of equations and exchange data that couples these equations during the time integration. This paper elaborates on issues important for co-simulation realization and discusses multiple possibilities to justify the particular approach implemented in a co-simulation prototype. The prototype is verified and validated against the results obtained from the traditional simulation approach. It is further used in a case study for the proof-of-concept, to demonstrate the applicability of the method and to highlight its benefits. Stability and accuracy of different coupling strategies are analyzed to give a guideline for the required coupling frequency. The paper concludes by defining requirements and recommendations for generic cosimulation implementations

Building energy simulation and optimization of industrial halls

Industrial halls are characterized with their rectangular shape and relatively simple construction, as contrasted with office buildings with similar floor area. Industrial halls are usually subject to high energy demand due to the many manufacturing processes, lighting, and the corresponding amount spent on space conditioning. Thermal comfort is seldom a concern for industrial halls. By contrast, saving in energy consumption for lighting and space conditioning is a big issue since even the modest percentage change in energy consumption could be translated into a large monetary sum. With relatively loose requirement in space conditioning, and comparatively high internal heat gain; the approach in industrial hall design is quite different from that of office building. In fact, what poses to be an energy efficient design for office buildings might not be appropriate for high internal heat gain halls. The simplicity in the building geometry and the construction method allow the investigation of energy demand for space conditioning to be limited to a few number of demand side parameters (e.g. insulation value of walls); in which, change in values in some of the parameters presents a significant impact on the overall energy demand. This paper investigates the impact of varying different demand side parameters on the energy demand for space conditioning and lighting for a typical industrial hall. Through building energy simulation, such impact can be investigated; and by applying optimization, the configurations of the most optimal combinations of parameters with the lowest energy demand can be identified. The result indicates that the energy demand of the least efficient configuration can be more than double of that of the optimized design solution. This paper will also explore green building assessment systems such as LEED, in terms of energy performance, with the studied industrial hall as an example. The huge energy saving brought by the optimized design solution over the baseline building of LEED suggests that there might be a potential deficiency of LEED rating system at its current state as it applies to industrial halls

PV-systemen voor industriele hallen

Het relatief grote dakoppervlak van veel industriële hallen biedt een kans om photovoltaische (pv) systemen te benutten. In verschillende landen wordt een zogenaamd ‘Feed-in Tariff’, FiT, beschikbaar gesteld om het hoge aankoopbedrag van pv-systemen te compenseren. Voor verschillende scenario’s is met behulp van simulaties een kosten-batenanalyse van pv-systemen uitgevoerd. Daarnaast is de invloed van verschillende economische parameters onderzocht

PV-systemen voor industriele hallen

Het relatief grote dakoppervlak van veel industriële hallen biedt een kans om photovoltaische (pv) systemen te benutten. In verschillende landen wordt een zogenaamd ‘Feed-in Tariff’, FiT, beschikbaar gesteld om het hoge aankoopbedrag van pv-systemen te compenseren. Voor verschillende scenario’s is met behulp van simulaties een kosten-batenanalyse van pv-systemen uitgevoerd. Daarnaast is de invloed van verschillende economische parameters onderzocht