English

This paper presents results of a Large Eddy Simulation (LES) of buoyancy-driven natural ventilation in which two unequal heat sources are used to drive the flow. The aim of this work was to assess the performance of LES in modelling turbulent thermal plumes in a naturally ventilated enclosure and to analyse their interaction with each other. The sub-grid scales of the flow have been resolved by using the Smagorinsky sub-grid scale model. It was found that LES results for the interface height agree well with the theoretical predictions of Linden and Kaye (2006).

In many locations mechanical ventilation has been the most widely used principle of ventilation over the last 50 years but the conventional system design must be revised to comply with future energy requirements. This paper examines the options and describes a concept for the design of mechanical ventilation systems with minimal pressure loss and minimal energy use.  This can provide comfort ventilation and avoid overheating through increased ventilation and night cooling.

A double skin façade (DSF) aims at reducing heating and cooling loads by taking advantage of daylight and utilizing heated air for space heating. To take advantage of a DSF a sophisticated design is required. In this paper a DSF building that has overheating problems was selected to verify the causes and propose remedial solutions. The problem was verified by analyzing the measured solar radiation, inside and outside temperature and air velocity. The results of the measurement analysis showed that airflow congestion caused overheating inside the building.

The paper presents the development of a mathematical model and a simulation tool for the transient prediction of the indoor climate and the heat loads in a car cabin, under real operating conditions. The main objectives were to develop a tool which facilitates, for example, the design of a cabin HVAC system or an on-line control. The model is based on the energy balance between the cabin and the outdoor environment accounting for conduction, convection and shortwave and longwave radiation.

The Spanish Technical Building Code is one of the three royal decrees that were approved in Spain as a consequence of the transposition of the European Directive on the energy performance of buildings (2002/91/EU, 2002). One basic document of the Technical Building Code deals with the limitations of building energy demands. Nowadays, due to the recast of the European Directive on the energy performance of buildings (2010/31/EU, 2010), a revision process of the current regulations has begun, starting with the Technical Building Code, with its first revision envisaged for 2012.

This paper describes a re-analysis of internal pressure and building ventilation in a single-opening enclosure ventilated by winds. The dynamics of internal pressure is governed by a nonlinear oscillation equation. An alternative semi-nonlinear approach is proposed for obtaining the amplitude and phase shift of the periodic motion, the resonant frequency and resonant amplitude. Our new approach reproduced two of the commonly used existing linearization results.

This study employed large-eddy simulation (LES) to investigate wind-driven single-sided natural ventilation for an idealized building model located in an urban environment. Two ventilation cases, single-sided ventilation with an opening on the windward wall and with an opening on the leeward wall, were considered. The airflow rates through the single opening were calculated based on the mean flow fields and the transient flow fields, respectively.

A model tunnel (approximately ten hydraulic diameters) with different designs of the tunnel mouth has been placed in a wind tunnel and has been subjected to the effects of external wind by varying the wind direction at the mouth of the tunnel. In the experimental oriented study pressures have been measured and the airflow has been made visible with smoke and by the sand erosion method (semolina). The relation between the flow ratio and the direction of the wind has been explored.

Although it has been used for many years in commercial buildings, the application of demand controlled ventilation in residences is limited. In this study we used occupant exposure to pollutants integrated over time (referred to as "dose") as the metric to evaluate the effectiveness and air quality implications of demand controlled ventilation in residences. We looked at air quality for two situations. The first is that typically used in ventilation standards: the exposure over a long term.

This study copes with the problem of ventilation in existing educational environments in terms of indoor air quality (AIQ), comfort and energy consumption. In accordance with international regulations, densely occupied environments such as school classrooms need high air change rates in order to provide sufficient fresh air. Nevertheless, in Italian schools, it is rare to see mechanical ventilation systems or natural systems that are mechanically controlled. This means that it is necessary for the users to control air changes by opening or closing the windows.