AIVC - Air Infiltration and Ventilation Centre

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Assessment of spatial and temporal distribution of thermal comfort and IAQ in low energy houses

According to the International Energy Agency, buildings represent over one-third of total final energy consumption. Thus, a more sustainable future begins with low energy buildings which must combine comfort and function using passive systems and new evolving technologies. Policies to reduce building energy consumption and carbon emissions have been developed worldwide during the last decades.

Detailed numerical modelling of moist air flow through a complex airtightness defect

Mastering building airtightness is essential to meet the requirements of current and future building codes, not only for saving energy but also for ensuring moisture safety. Perfect airtightness is difficult to achieve: failures are often observed, due to bad design or poor workmanship. Some published investigations proved that leaking air mostly flows through porous material and thin air channels, due to material imperfections and construction tolerances.

Simulation of static pressure reset control in comfort ventilation

Variable air volume (VAV) ventilation systems reduce fan power consumption compared to constant air volume (CAV) systems because they supply air according to the airflow demand. However VAV ventilation systems do not take fully into account the potential energy savings as the control strategy operates the terminal boxes and the air handling unit (AHU) independently without pressure integration. The pressure in the main duct is maintained at a constant static pressure (CSP) which corresponds to the pressure required under the design full load condition.

The relationship between permeability and infiltration in conjoined dwellings

The importance of adventitious air leakage under normal operational conditions and its reduction in order to save energy is highlighted by the relvant building standards of many countries. This operational leakage is often inferred via the measurement of air permeability, a physical property of a building that indicates the resistance of its fabric to airflow. A building’s permeability is the measure of airflow rate through its envelope at a constant pressure differential of 50 Pascals.

Effect of Party Wall Permeability on Estimations of Infiltration from Air Leakage

The importance of reducing adventitious infiltration in order to save energy is highlighted by the relevant building standards of many countries.  This operational infiltration is often inferred via the measurement of the air leakage rate at a pressure differential of 50 Pascals.  Some building codes, such as the UK’s Standard Assessment Procedure, assume a simple relationship between the air leakage rate and mean infiltration rate during the heating season, the so-called leakage-infiltration ratio, which is scaled to account for the physical and environmental properties of a dwelling.  The

Analysis of Spot Cooling in an Underground Subway Station

Railway platform spot cooling has become an increasingly attractive means to improve thermal comfort conditions of existing subway stations. This paper presents a systematic approach to evaluate the effectiveness of platform spot cooling. The subway environment is first analysed by a simple onedimensional network model, which is able to estimate the bulk air temperature from the available spot cooling. The localized effects of spot cooling are then investigated using CFD.

3DFLOW Development and Validation for Three Cases - Downward Mixing, Partition and Displacement Ventilation

The 3DFLOW code has been developed based on:
· The standard three-dimensional K-epsilon two-equation turbulence model;
· A modification for buoyancy effects;
· Wall functions applied to deal with solid boundary conditions;
· An adaptation of the SIMPLE algorithm.
The representative indoor air flows in conditioned spaces, including downward mixing, partition and displacement ventilation cases, were simulated and analysed in detail using the 3DFLOW code. Good agreement was found between the numerical predictions and experimental data.

Characteristics of Particles and their Behaviour in Ventilation Air

The behaviour of particles in air flow is important for identifying those in various locations in ventilated space. The main reason for this study is to propose a new modelling concept to determine a realistic distribution of particles of different sizes in a space. The goal for this investigation is to divide particles into groups according to their behaviour in air and to improve the existing settling model. The growth of particle aerodynamic diameter in higher relative humidity is also presented.

Data Exchange for Thermal Modelling and Ventilation Simulation

Data exchange is the process by which information is transferred between the engineer and software and between one piece of software and another. Building and plant simulation involves handling large data sets describing constructional details, system components and reference data. The time required to prepare and check the data is significant and is one obstruction to the widespread use of simulation within the design process. Links between drafting systems and analytical tools offer an obvious way to speed up the process and reduce input errors.

Uncertainty, variability and sensitivity analysis applied to the ragena model of radon generation, entry and accumulation indoors

The application of a radon model is useful to understand the processes that drive the radon gasbehaviour from its sources to its accumulation indoors. Since in a given inhabited house the detailedknowledge of the values of all the parameters that affect indoor radon levels is not available, theresponse of the model has to be explored in a reference site in which all the parameters are supposedto be known. We call this site the reference configuration.