This paper focuses on the degree of flow enhancement achieved by an atrium which is itself ventilated directly by a low-level connection to the exterior.A theoretical model is designed to predict the steady stack-driven displacement flow along with the thermal stratification in the building due to heat gains in the storey and solar gains in the atrium. Comparison is then made with the results of laboratory experiments
This paper aims at comparing calculated and measured air flow distributions inside a naturally ventilated test room. Wind tunnel trials were carried out in the test room.Separate air flow and thermal modelling programs are used to predict the spatial distribution of the air flow and thermal comfort.
A new Adaptive Comfort Standard is included in the recently accepted revisions to Ashrae standard 55. That ACS permits warmer indoor temperatures for naturally ventilated buildings during summer and in warmer climate zones. It is based on the analysis of 21,000 sets of raw data compiled from field studies in 160 buildings located in different climatic zones on the 4 continents.
Experiments were operated to determine the thermal stratification in a full-scale enclosure with natural ventilation driven by thermal source. Results provided by various predictive techniques were compared with experimental data. The salt-bath modelling technique and related mathematical model of Linden appear to be unappropriate for this type of air flow. CFD gives realistic predictions, especially when using a complete thermal radiation model.
That paper deals with the use of nondimensioanl graphs for designing the envelopes of naturally ventilated buildings. The graphs can be generated from theoretical models or from experimental data via a direct measurment of ventilation rates in a wind tunnel model.
Examples of graphs are given: they cover conventional design conditions and off-design conditions.
After a review of CFD models and a simplified (zonal) models predictions, a simplified procedure, based on charts and non dimensional groups, is proposed in order to evaluate the ventilation rate through an open vertical window.
TRNSYS’ thermal building model, type 56, requires air flows between zones as input values. However, in natural ventilation systems these depend on the wind pressures and the inside and outside temperatures. To account for this situation, a coupling with a
This paper describes work currently being carried out to evaluate the environmental impact and energy savings potential from the application of passive ventilation cooling in urban buildings. The work is carried out as part of an ALTENER project focussing on solar and passive ventilation for urban buildings. The study involves the collection of information for current building stock in four European countries; UK, France, Spain and Greece.
Purpose of this study is establishment of energy efficient natural ventilation system for Japanese conventional wooden single-family house, by using humidity-controlled extract units (code name: GHN).To evaluate the effect on energy performance and indoor air quality by adapting the GHN to the passive stack ventilation system, airflow rate, humidity, temperature and CO2 concentration are measured over a period of one year in an experimental house.
In the Mediterranean countries, where the active solutions of air-conditioning must be avoided, natural ventilation allows improvement of indoor comfort which is generally critical in hot season, and reduction of building cooling loads.A three-dimensional zonal model for calculating temperature fields and airflow distributions insideunconditioned buildings was developed.
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