English

Indoor climate has a three-dimensional spatial distribution caused by three-dimensional airflow. To obtain the accurate knowledge of building performance, it is demanded to integrate the spatial distribution into building simulations. Thus, CFD analysis is necessary in design process. However, usually only a few case of CFD could be executable in real design process, because of the large computational load.

Computational Fluid Dynamics (CFD) has been introduced to the architectural engineering and HVAC (Heating Ventilation and Air Conditioning) industry for decades. Its effectiveness in assisting the architects and engineers in the design process has been well acknowledged. However, the mesh generation process is complicated and time consuming, especially for modeling free form geometric artifacts, e.g., buildings in complex terrains or human bodies in the room. This paper presents the effort to apply quality mesh generation to CFD simulations in architectural applications.

The paper describes results from a reference study that focuses on the application of the Computational Fluid Dynamics (CFD-) technique for heat and smoke transport in practice. Goal of the study is to obtain insight into the amount and causes of the spread of CFD-results when applied by different users. In this study several CFD-practitioners have solved the same relatively well described flow problem. The obtained results have been compared. They show a clear spread which to some extent can be explained by the assumptions made for the modelling and solving of the problem.

As a cost-effective alternative to experiments, computational fluid dynamics (CFD) can provide new insight in airflow patterns and the related convective heat transfer (CHT). However, together with the governing equations, the description of the boundary conditions determines for a greater part the reliability and the accuracy of CFD simulations. In this study the sensitivity of the predicted CHT to diffuser modelling is studied. Numerical simulations of a modified version of test case E.2 of the IEA Annex 20-project are performed.

In this article, we will present a new multi-level modelling approach to obtain higher precision in HVAC plant simulation models. For this purpose, two different levels of detail in modelling, the coarse component-based approach of Modelica and the detailed physical-based approach of Computational Fluid Dynamics (CFD) were combined. In a first use case, we analysed the thermal hydraulic network of a simple heating system, both with the CFD-approach (3D-model) and the Modelica approach  (1D-model).

A simplified model was developed by use of thermal-ventilation network with the purpose of studying air environment in void space at the central portion of high-rise apartment houses when gas-fired boilers were installed in the void. First, a one-node model was studied assuming uniform temperature distribution in the void space, resulting mismatching between calculated and measured values for building surface temperature. Then, a two-node model was prepared by separating corridor region from void region.

The performance of hot water space heating systems for mild to warm temperate climates is dominated by the efficiency of boiler operation at low load (i.e. below 25% of nameplate capacity). This efficiency is influenced by a number of effects that are poorly represented in common modelling approaches, including static thermal losses from the boiler and distribution system, changes in burner efficiency at different firing rates, thermal inertia in the boiler loop and the effects of cyclic operation. In this paper, a simple model that includes these loss mechanisms is developed.

For the use in Swiss standards on energy performance of cooled buildings, a chiller model for an hourly time step calculation was needed. Unlike the models found in a literature review, the model aimed at should be based only on the information available from standard performance rating, i.e.

This paper reviews the current situation in M&E (services) engineering in the United Kingdom considering the use of simulation in the building design and engineering process. It maps out the different forces that currently act on the deployment of simulation tools in building services design and optimisation. Surveys and in-depth interviews have been used to investigate the factors (key value drivers) that influence the application of simulation technology.

The renovation of a building in terms of thermal insulation will improve the level of energy consumption in winter. To improve the summer comfort, we have simulated the introduction of a phase-change material (PCM) in both situations: removed or not removed building. The dynamic building simulation software CoDyBa has been adapted to consider these materials in the calculations.