English

In order to quantify uncertainty in thermal building simulation stochastic modelling is applied on a building model. Part l deals with the stochastic thermal building model and a test case. This paper deals with the determination of the stochastic input loads. The importance of obtaining a proper statistical description of the input quantities to a stochastic model is addressed and exemplified by stochastic models for the external air temperature and the solar heat gain.

In order to quantify uncertainty in thermal building simulation stochastic modelling is applied on a building model. An application of stochastic differential equations is presented in Part I comprising a general heat balance for an arbitrary number of loads and zones in a building to determine the thermal behaviour under random conditions. Randomness in the input as well as the model coefficients is considered. Two different approaches are presented namely equations for first and second order time varying statistical moments and Monte Carlo Simulation.

In order to simulate indoor air distribution and airflow around buildings quickly and accurately by CFD (Computational Fluid Dynamics) technique, a new zero-equation turbulence model and momentum method for inlet boundary condition are adopted. The new version of STACH-3, a three-dimensional CFD software is developed based on these. An example for outdoor airflow around an isolated building is given as well. For those high-density buildings with complex geometry, the TSM (Two Step Method) is proposed.

This paper proposes a new ductless air supply system with a ceiling plenum chamber using low temperature air as a secondary HY AC system for an ice thermal storage system. The proposed air supply system mixes low temperature air with return air from a room using a mixing fan unit (MFU), pressurizes a plenum chamber with the mixed air and supplies the air to the occupied room from diffusers on the ceiling.

It is well known that the introduction of tracer gas techniques to ventilation studies has provided much useful information that used to be unattainable from conventional measuring techniques. Data acquisition systems (DASs) containing analog-to-digital (ND) converters are usually used to perform the key role which is reading and saving signals to storage in digital format. In the measuring process, there are a number of components in the measuring equipment which may produce system-based noise fluctuations to the final result.

Scale model experiments make it possible to analyse design concepts of ventilation, especially air distribution in large enclosures. The airflow structure similarity is fulfilled when experiment is carried out according to the principles of the approximate scale modelling. Special attention should also be paid to proper simulation of boundary and initial conditions. In a real ventilated object, the air is supplied with standard diffusers equipped with deflecting vanes.

The intention of this paper is not to compare discretization schemes but to show some advantages of a stabilized finite element method for modelling natural ventilation. Based on the finite element theory we present a formulation of boundary conditions that can be used for most ventilation openings in buildings. Stationary as well as transient situations can be considered without modelling of the outdoor space. Mathematical background and implementation details are discussed. Results are presented for ventilation of a living room at typical outdoor conditions.

The effect of the change in object positions (i.e. office furniture) on the air quality in a room was studied using zonal purging flow rates. In relation to the zonal purging flow rate in a room, the transfer probability from the inlet to a certain zone can provide information on the amount of fresh air from the inlet to the zone. In this study, the probability obtained from Markov chain theory was used to analyze the ventilation performance.

The keeping of animals in livestock buildings requires the ventilation of these buildings. On the one hand good climatic conditions for the animals in the livestock building have to be provided, on the other hand the emissions have to be kept at a low level. The airflow through the livestock building plays an important role for both opposing requirements. The targeted control of the climate in the livestock building and for the minimization of emissions calls for knowledge about airflow and emission streams.

Presented in the paper is an efficient and accurate numerical method for simulation of ventilation duct flow. The mathematical method is based on the three-dimensional incompressible RANS equations with isotropic k-w near-wall turbulence closures, written in generalized curvilinear coordinates in strong conservation form. The numerical method presented here is used to calculate the turbulent flow through a bend of rectangular ventilation duct featuring pressure induced secondary motions and rotation effects on turbulence.