English

Wind approaching a building provided with openings on the windward and leeward sides has a choice, either it flows through the openings or flows around and above the building. This choice gives rise to a dominant stream tube containing the fluid flowing through the openings. In this paper the stream tube is analysed based on wind tunnel measurements and CFD simulation. A house model with dimensions 120 mm (Width)120 mm (Height)180 mm (Length) was provided with rectangular openings of equal size located opposite each other. The end walls were thin giving rise to a sharp edged opening.

This paper presents the preliminary findings from the first stage of a physical survey and modelling case study conducted to obtain modelled and actual energy consumption profiles for a UK multi-storey mixed use educational building (the Bute building at the University of Wales, Cardiff).

Full-scale experimental and computational fluid dynamics (CFD) methods were used to investigate the velocity and temperature fields in a mechanically ventilated room. Detailed airflow fields were measured in three cases of ventilation air temperature: an isothermal case, a hot case and a cold case. The ventilation system created a round jet which developed near the ceiling. The experimental data were used to test two turbulence models: a first order k-e turbulence model and a second order RSM turbulence model.

Internal pressure coefficients in a building with wind-driven cross-ventilation caused by sliding window openings on two adjacent walls are presented and compared with previous works. The study found that internal pressure coefficients vary considerably with the opening area (or wall porosity) and the inlet to outlet ratio. The internal pressure is not uniform in a building with cross-ventilation, particularly for large openings (wall porosity higher than 10%). For inflow calculation, the average internal pressure coefficient should be used as an input in the orifice equation.

A number of methods have been used to quantify the cooling effects of air movement on the human body. For simplicity these methods limit the number of variables influencing the effect. A new method using the difference in Standard Effective Temperature (SET*) values between a condition with 29.5 fpm (0.15 m/s) and the proposed elevated air speed allows all the relevant variables (i.e. air temperature, mean radiant temperature, air speed, humidity, metabolic rate, and clothing insulation) to be taken into account. Cooling effect of air movement is normally based on uniform velocity airflow.

This paper is not a technical paper but, instead, focuses on the methods by which information on recent advances in ventilation technology and systems may be transferred to engineers. This is important because it enables the application of these innovations in the design and maintenance of buildings. In this context, the paper describes the educational material developed by the European project Vent DisCourse. It consists of material specifically written to facilitate distance learning postgraduate study in the area of energy efficient ventilation for buildings.

Measurements of indoor air pollutants covering the concentrations of CO2, CO, TVOC’s, PM2.5, and PM10 were performed in 50 residences in Athens. In addition the ventilation rate in each dwelling was continuously measured by monitoring CO2 concentration. Apart from carbon monoxide, almost all the remaining pollutants showed high concentrations that exceeded the maximum threshold levels of the relevant standards. The rate of ventilation was found to have a very important impact on the concentration of indoor pollutants.

The UK climate is moderately mild and natural ventilation by window opening and passive ‘trickle’ vents is very common. In this paper the natural ventilation rates provided by top-hung windows open to small angles in single-sided designs have been studied using a common whole building simulation tool. It was found that the amount of ventilation greatly depends on how the windows are represented. Such software tools usually assume that the opening area has the same vertical separation as the underlying window (i.e. it is modelled as an arrow slit).

The requirements for good indoor air quality and energy efficiency have often been considered to be in conflict with each other. However, buildings with low energy consumption in Europe also seem to have a lower rate of building related health symptoms. This indicates the importance of proper design and installation as well as qualified, well trained operational personnel, who understand both the requirements for good indoor air quality and energy efficiency. Several strategies for ventilation are described in this paper.

There is a wide range of factors that influence natural ventilation. The uncertainties arising from theunpredictable nature of wind lead to the need to account for periods of time when winds are unable to provide indoor summer comfort. Some methods for estimating natural ventilation are outlined together with the effects of high site coverage, building porosity, insect screens, and local wind shelter from adjacent houses and vegetation. Indoor wind speed coefficients provide a direct method for comparing the natural ventilation potential of housing stock.