Papers by Milica Grahovac
Science and Technology for the Built Environment, Nov 2, 2023
Building Simulation Conference Proceedings
ASHRAE/IBPSA-USA Building Simulation Conference
Building simulation models are typically not used to generate the documentation required for bidd... more Building simulation models are typically not used to generate the documentation required for bidding and project delivery of commercial building systems, or for their semantic modeling and commissioning. This paper presents a software tool that aids in digitizing the control delivery process, spanning simulation during design to implementation and formal verification during commissioning. The tool can generate from Modelica models digital documentation of control sequences. This digital documentation, along with other project drawings and specifications can be used for project bidding. It can also be used for implementation of control sequences through machineto-machine translation to commercial legacy control products, for which we are currently developing the proposed ASHRAE Standard 231P based on the presented work. Moreover, as-installed control sequences can be formally verified against the design specification, and a semantic model in Brick can be exported to aid in configurat...
The main purpose of the software is to model energy use for individual and community scale solar ... more The main purpose of the software is to model energy use for individual and community scale solar water heating projects in California. Usage The user provides a climate zone for a project, an occupancy for each household and whether any of the occupants stay at home during the day. The software can then load a set of example California specific hourly domestic hot water end-use load profiles from a database, size and locate the systems. The user can now simulate the hourly system performance over a period of one representative year, visualize and explore the simulation results using time-series plots for temperature profiles, heat and power rates, or look at annual summaries. Similarly the user can model individual household solar water heating projects and base case conventional gas tank water heater systems, such that the results can be compared between the individual, community and base case systems. This functionality is readily available through a Jupyter notebook and a Django ...
The OpenBuildingControl project develops tools and processes for the performance evaluation, spec... more The OpenBuildingControl project develops tools and processes for the performance evaluation, specification and verification of building control sequences. This paper describes the tools developed to verify that building control sequences are implemented as specified in a vendor-neutral, executable specification. The verification is done by testing whether trended time series, compared to the simulated control response, are within user-specified tolerances for time and for the trended variable. Morever, sequence diagrams are used for inspection of the control response. The paper gives an overview of the OpenBuildingControl process and describes tools for the control verification. It presents and example in which we successfully verified that an actual implemented control sequence conforms to its vendor-independent specification. It closes with discussion of experiences collected during this verification and with alternate approaches that can improve the operational performance of bui...
A simplified model of a primary HVAC system comprising an on-off boiler, thermal storage and sola... more A simplified model of a primary HVAC system comprising an on-off boiler, thermal storage and solar thermal collectors is simulated in hourly resolution. The simulation passes the results to an optimization algorithm that sizes the system. The objective is to minimize total costs and reach a desired solar ratio. Results show good model performance and short simulation run time. A global bounded Nelder-Mead method is implemented to calculate optimal system configurations in two case studies. The amount of user input data is minimised to enable optimal plant configuration selection during early building design, but also to avoid the system oversize.
The described project aims at developing a holistic planning strategy for architects and engineer... more The described project aims at developing a holistic planning strategy for architects and engineers for the construction of administrative buildings in different climate zones. The outcome of the project will be a guideline for predicting the indoor climate and the energy efficiency of a building in the early design stage.
We developed a design optimization tool for a primary HVAC plant consisting of vacuum compression... more We developed a design optimization tool for a primary HVAC plant consisting of vacuum compression chillers and PV panels. If provided with weather data, hourly cooling demand, and PV area limitations, it yields the optimal PV panel dimensions and the number of chillers, as well as their nominal capacities. Additionaly, it provides the costs and the emissions resulting from utilizing such plant to supply the thermal distribution network of the building. The tool is based on a quasi-static system simulation, which calculates objective function values to be evaluated by the optimization algorithm. It targets preliminary building design and planning.
The tool we are developing provides guidelines concerning building envelope and heating/cooling e... more The tool we are developing provides guidelines concerning building envelope and heating/cooling energy sources in order to increase energy efficiency of buildings by including the subject of energy consumption in the very early stage of building design. Building size and climate can be varied. To calculate the right mix of energy sources and conversion equipment that minimizes costs, energy or CO2 emissions numerous parameters concerning various space heating or cooling technologies need to be assessed. To perform multi-energy plant optimization we need to determine the upper boundary of thermal energy gained by solar collectors. Based on weather data and maximal available solar collector area, solar collector gains for different outlet temperatures can be simulated. For design purposes collector tilt angle has been optimized. The developed collector model has a very short calculation time and can easily be integrated into plant system model and its optimization. Due to its hourly r...
The decisions made during conceptual building design irreversibly influence the selection and dim... more The decisions made during conceptual building design irreversibly influence the selection and dimensions of thermal energy generation and storage components and systems. A method to quantify this influence is developed. It consists of the quasi-stationary simulation and the design optimization of the system. Demonstrated on seven preconfigured systems the method is used to propose a tool that, using data available at the conceptual design stage, provides dimensions, costs, energy consumption and emissions of the optimized system to architects.
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Papers by Milica Grahovac