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Natural Ventilation with Pre-cooling

We investigate two different natural ventilation regimes of an auditorium or other occupied open-plan space which is equipped with pre-cooling. The room has a low-level vent and a high level vent. The occupants act as a source of heat, which if without pre-cooling, can lead to the room becoming too warm for comfort. In the first ventilation regime, a chiller is fitted to the low-level vent, and the occupants provide positive buoyancy which drives the ventilation upwards and draws fresh air through the pre-cooling system.

Numerical Evaluation of Wind Pressure Distributions of Buildings by Means of a Modified k-e Model

A modified k-e model that restricts turbulent time scale using Durbin’s limiter was applied for numerical prediction of wind pressure distributions of building models. It is known that the standard k-e model tends to overestimate wind pressure of windward

Numerical modelling of radiative heat exchanges between the human body and surrounding surfaces

In this paper, the development of a radiation module coupled with a previous 3D-CFD code is described. This module takes into account the radiative heat transfer between the active surfaces, including those relative to the occupants.

Integration of HVAC systems and double facades in buildings

Nowadays the awareness concerning the environmental pollution and the demand of transparent facades in architecture, lead research in finding new solutions to increase the energy performances of the building and the installations as well. Among those, different kind of Double Skin Facades have been studied and several laboratories are still working on them to find a suitable way to apply this technology in buildings.

Calculations and Notes on the Quadratic and Power Law Equations for Modelling Infiltration

Calculations using CFD are presented for adventitious openings in which the flow is not fully developed. It is shown that the quadratic equation performs significantly better than the power law i.e. a recent claim that the power law equation is preferable to the quadratic equation under such circumstances is not supported. Other recent claims that have been made to support the power law in preference to the quadratic are also examined and reasons are given as to why they are unfounded for conditions of typical, naturally driven air infiltration.

Use of multizone air exchange simulation to evaluate a hybrid ventilation system

A multizone air flows simulation code (IDA MAE) was used to evaluate a hybrid ventilation system (passive stack with assisting fans) in a Swedish school (9350 m2 - 20 classrooms), in the framework of the HYBVENT project (Annex 35 of IEA). Simulation was operated with 18 zones. Results show the sensitivity of air flows to changes in wind speed and direction.

Capabilities and limitations of thermal models for use in thermal comfort standards.

Describes the thermal model available, both simple and complex and outlines capabilities and limitations. States that all of the models have limitations for use in standards, including the accuracy of the physical simulation and the accuracy of the inputs to the model. States that the biggest limitation is probably the accuracy with which comfort perceptions can be related to the physiological variables simulated in the thermal models.

Extension of the PMV model to non-air-conditioned buildings in warm climates.

States that the PMV model is in good agreement with high-quality field studies in buildings with HVAC systems, located in cold temperate and warm climates, which were studied in both summer and winter. Occupants may sense the warmth in non-air conditioned buildings in warm climates as being less severe than the PMV prediction, probably because of low expectations or because too high an estimate of metabolic rate. Introduces an extension to the model which includes an expectancy factor to be used in non-air conditioned buildings in warm climates.

A simple model to study ventilated facades energy performance.

Aims to supply a simple and useful tool for the analysis of energy performance of different ventilated facades typology. A steady state energy balance was applied to a control volume solving basic equations with finite element code with an iterative procedure, in order to simulate the studied sample. The different surfac3e and air mass temperatures are calculate for each step of the channel height, and the mass flow rate evaluated as overall natural draught.

Formule approchee pour determiner la temperature humide. A formula for the determination of humid temperature.

States that quite simple formulae can be used for humid air, but that this is not the case for humid temperature. Gives an overview of the iterative method to be used in this case.

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