IBPSA1997

Industry Foundation Classes (IFC) provide an environment of interoperability among IFC-compliant software applications in the architecture, engineering, construction, and facilities management (AEC/FM) industry. They allow building simulation software to automatically acquire building geometry and other building data from project models created with IFC compliant CAD software. They also facilitate direct exchange of input and output data with other simulation software. This paper discusses how simulation software can be made compliant with version 1.5 of the IFC.

The traditionally engineering-oriented approach to thermal building simulations tends to leave such analysis tools out of the reach of general design practitioners, especially during the early stages of building design when many of the most influential decisions regarding the thermal envelope are made.

A series of linked spreadsheets has been developed for the analysis and modeling of thermal and daylighting effects on the flow of energy in buildings. Spreadsheet software is widely available, easily operated and readily adaptable to particular circumstances. Standard engineering formulas are used for heating, cooling, solar radiation and daylighting calculations. "What-if" relationships are established by varying assumptions and measuring their effect on the result.

SOMBRERO, a PC-program running under the operating system WindowsTM, calculates the proportion of shaded area of an arbitrarily oriented surface surrounded by shading elements as a function of time and location. The reduction of (isotropic) diffuse radiation due to different kinds of obstacles is calculated by means of view-factors, too. Calculation results are displayed online, and ASCII output files are produced that can be read into dynamic thermal building simulation systems or spreadsheet programs. Three examples for the practical use of SOMBRERO are presented:

The XCEED™ software tool allows engineers to create textual, mathematical and graphical descriptions of compressed air systems including, but not limited to, compressors, filters, dryers, storage vessels, cooling equipment, piping and utilization equipment. The tool allows drag-and-drop creation of simulations of user-specified compressed air systems and provides engineering and financial calculation functions to aid analysis of such systems. In addition, XCEED™ provides standard report generation and allows user-developed reports.

A simulation program VENTOLA was developed to study behaviour of the microclimatic situation inside buildings housing domestic animals. The model accounts for a large number of parameters including species, category and characteristics of animals, structure of building, local climatic data, ventilation rate, heating and heat recovery systems. The model has been programmed in Excel 5.0. Results are presented in tables and diagrams.

The effectiveness of simple shading devices in reducing the direct, diffuse and ground reflected components of solar radiation has been measured and compared to simulation predictions of the same. The simulation results were found to be very sensitive to the value assumed for ground reflectance, and to the level of detail of the geometrical modelling of the shading devices. The best agreement total incident radiation was within 3% over the course of a day.

The conception of complex buildings with innovative facade elements often demands dynamic building simulations. In some cases the required thermal parameters of the components must be obtained by experimental investigations. This paper describes this procedure exemplary for a photovoltaic facade, which allows the combined utilization of electrical and thermal energy. The parameters for a TRNSYS simulation could be obtained with the help of a PASSYS testcell. The results show that the total energy transmittance (gvalue) of such a facade strongly depends on the ambient air temperature.

The majority of design studies on naturally ventilated that wind power is expected to provide a significant or mechanically ventilated buildings do not take component of the motive force for the ventilation account of the close relationship between ventilation system. and thermal performance. That is it is common to assume that certain ventilation rates can be achieved and then used as input to a dynamic thermal model to assess temperatures within the building.

The simulated cooling plant equips an office building whose maximum cooling demand is about 5 MW. To meet this load, the cooling plant uses five cooling towers, four twin-screw chillers and four encapsulated ice storage tanks. The simulation of the cooling plant is carried out with the software TRNSYS.