English

This paper deals with uncertainty in IAQ performance assessment of a naturally ventilated building in case of combined influence of the stochastic behaviour of both weather parameters and occupancy.

A new ventilation control strategy based on the Multiple Spaces Equation is developed in order to take into account the actual number of building occupants. That strategy is evaluated under steady-state and dynamic conditions of the HVAC system.

Studies on air circulation became of great importance in recent years, since are crucial for the energy consumption of buildings, for the pollutant dispersion within cities and for the good comfort conditions for the pedestrians and the habitants. The semi-empirical model developed in this study aims to accurate wind speed computation inside street canyons. In the framework of the Urbvent European Research project, an extended experimental campaign took place in five different urban street canyons in the centre of Athens during the summer of 2001.

The paper presents a study of the indoor climate of a monumental building with periodic high indoor moisture loads. Several scenarios of the past performance and new control classes are simulated and evaluated. The results include the influence of hygric inertia on the indoor climate and (de)humidification quantities of the HVAC system. It is concluded that: (1) The past indoor climate can be classified as ASHRAE control C with expected significant occurrences of dry (RH below 25%) and humid (RH above 80%) conditions; (2) ASHRAE control C is not suitable for the new hall.

High levels of indoor relative humidity are one of the main causes of moisture damage in buildings. That cause can be removed by an appropriate ventilation system. Relative humidity controlled ventilation systems were designed to increase energy performance of buildings without exposing them to moisture damage. The study of the performance of such a system in terms of energy savings and maximum relative humidity is proposed here using numerical simulations with an appropriate whole building heat, air and moisture modelling approach that is developed in the frame of IEA Annex 41.

The design and realisation of natural ventilation systems is an important research topic into the ability of buildings to respond to climatic conditions, using parts of the buildings themselves as indoor microclimate control systems. This research aims to evaluate how the stairwell can be an essential element of natural ventilation in low-rise buildings. In this study, the main innovation is the different architectural and functional conception of traditional building components such as the stairwell.

The probabilistic model (PROMO) applied to the problem of air infiltration in low-rise buildings is presented. The PROMO model allows the estimation of the effect of variations of climaticconditions on air exchange in a building. In PROMO, experimental data are used in order to evaluate the parameters and types of the distributions of temperature, wind speed, and wind direction. Those distributions are employed to evaluate the distributions of air change rate caused by air infiltration and can be used to estimate probability of inadequate ventilation.

The hybrid ventilation systems have been widely used for livestock barns to provide optimum indoor climate by controlling the ventilation rate and air flow distribution within the ventilated building structure. The purpose of this paper is to develop models for livestock ventilation systems and indoor environments with a major emphasis on the prediction of indoor horizontal variation of temperature and concentration adapted to the design of appropriate controlling strategy and control systems.

This paper investigates the sensitivity of indoor humidity models to the numerical description of water vapour buffering in porous materials in the room. Three different numerical models are compared: a lumped capacity model, which lumps the moisture inertia in a single capacity for the room, a two-node model, which differentiates between the room air humidity and the representative humidity of an equivalent humidity buffering material, and finally a room-wall model, which describes the water vapour transfer and storage in the building fabric through a continuum model.

This work presents simulations results exploring the influence of the building air-tightness on the energy consumption of buildings for different hypothesis on the type of ventilation system. It shows that the energy impact is different depending on the ventilation system, and that buildings ventilated with a supply-extract ventilation system, even those without heat exchanger, are much more sensitive to air infiltrations than buildings ventilated with an extract ventilation system.