AIVC - Air Infiltration and Ventilation Centre

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Estimated distributions of PM2.5 concentrations in the kitchens of the English housing stock for infiltration and mechanical ventilation scenarios

Exposures to elevated concentrations of airborne fine particulate matter with diameter ≤ 2.5 µm (PM2.5) have been linked to multiple negative health effects. Investigations into PM2.5 exposures primarily focus on external concentrations, which are easier to monitor. However, there is a growing interest in indoor exposures, as people spend up to 70% of their time at home, concentrations in dwellings may have a greater influence on personal exposures.

Residual analysis of UTCI predictions on outdoor thermal sensation survey data

The Universal Thermal Climate Index UTCI assesses the interaction of ambient temperature, wind, humidity and radiant fluxes on human physiology in outdoor environments on an equivalent temperature scale. It is based on the UTCI-Fiala model of human thermoregulation and thus also allows for thermal comfort prediction.

Application of modeling and simulation in fault detection and diagnosis of HVAC systems

Failures can lead to a series of problems in the complex heating, ventilation and air-conditioning (HVAC) systems in buildings. Fault detection and diagnosis (FDD) is an important technology to solve these problems. Models can represent the behaviors of the HVAC systems, and FDD can be realized with models. Using the model as intermediary, a link between system simulation and FDD can be built. Simulation has provided a convenient platform of operation for FDD, the overall simulation methodology in FDD of HVAC systems is briefly introduced.

Energy analysis of ventilated roof with extended top in hot regions

An extended top of the roof can induce the upflowing wind which flows close to the wall and in this way it increases the intake airflow rate in the air gap. A model was set up to save energy with the consideration of a suitable thickness of the air gap and a suitable length of the extended top. The Computational Fluid Dynamics (CFD) was employed to simulate the wind field in the ventilated roofs with extended top and the cases were carried out according to Changsha’s climate parameters in China. The results show that the extended ventilated roof works very well in summer.

Optimizing the operation of earth-to-air heat exchangers in high-performance ventilation systems for low-energy buildings – a case study

Earth-to-air heat exchangers are energy-efficient systems that use the ground for cooling in summer and heating in winter. Design, simulation and planning tools are available in the market, and earth-to-air heat exchangers are well-accepted in the built environment. Furthermore, there is a wide knowledge on their performance in operation. Based on long experiences in the design and operation of earth-to-air heat exchangers, pre-defined operation strategies are applied in ventilation concepts.

A stochastic approach to predict the relationship between dwelling permeability and infiltration in English appartments

Reducing adventitious infiltration in order to save energy is important and is highlighted by the 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 scaling d

Demand-controlled ventilation: An outline of assessment methods and simulation tools

Enhancing the energy efficiency of buildings imposed by global warming and by the perspective of fossil fuel dwindling requires new technical solutions, more efficient. The race for efficiency directly affects ventilation and air tightness of buildings, the main potential causes of heat loss in homes. If heat recovery is emerging as an effective solution to meet energy performance and indoor air quality in climates with harsh winters, some other solutions appear to be very efficient in moderate climates.

ZAER: A Zonal Model for Heat Transfer and Air Flow in Unconditioned Buildings - An Experimental Validation

This paper presents a three-dimensional zonal model, ZAER, for heat transfer and air flow calculations. It is based on an intermediate approach between single-air-node and CFD models. The indoor air volume is divided into macroscopic homogeneous zones. Heat and mass balance equations are written for each zone, while the mass flow rates across the interfaces are calculated by power pressure laws. The simulation tool ZAER allows the determination of temperature fields and air flow distributions inside unconditioned buildings, taking into account external boundary conditions.

Zonal models for indoor air flow - A critical review

A zonal model is an intermediate approach between computational fluid dynamics (CFD) and single-room models. It can give results faster than CFD and be more accurate than single-zone models. It has been used to provide some global information regarding thermal and flow parameters within a room. In this review, due emphasis is given to the commonly used pressurized zonal model - the power law. Qualitative validations show that the power law model reasonably predicts well for natural convection.

A Fundamental Study on the Air Flow Structure of Outflow Openings

A Local Dynamic Similarity Model, applicable to dynamic similarity of cross-ventilation, has been applied to outflow openings. Cross-ventilation performance at the openings on the outflow side has been evaluated, and the structure of air flows around the outflow openings has been studied by LES and wind tunnel experiments. It was found that LES reproduces the wind tunnel experiment results fairly well, such as the extensive increase of discharge coefficient in a small region where dimensionless room pressure, PR*, is low.

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