This paper describes a numerical method for the determination of the effective depth of fresh air distribution in rooms with single-sided natural ventilation. The numerical method involves predicting air flow and the local mean age of air. The renormalisation group two-equation model of turbulence is used with the conservation equations of mass, momentum and energy to predict turbulent buoyancy-induced room air flow. The local mean age of air is then obtained from the solution of air flow equations together with the transport equation for the age of air.
The performance of a hybrid air-conditioning system which utilises wind-induced cross ventilation is investigated. The characteristics of flow and temperature fields are examined using CFD simulation under various conditions of inflowing outdoor air i.e. air temperature, air exchange rate and width of the opening for cross ventilation. In this simulation, the room air controlling system (VAV system) which is used to keep the task zone at a target temperature is reproduced through changing the supply airflow rate of the air-conditioning system.
The paper presents a study on application of pressurisation tests of selected apartments as a base for analysis of natural ventilation in multi-family building. The analysis has been performed for 5-floor building constructed in late sixties. 10 apartments from a total number of 45 have been selected for pressurisation tests. The discussion presents estimations of windows' air tightness, the influence of additional air sealing on windows' infiltration coefficient and flow rates at reference conditions.
The design of natural ventilation systems - the configuration and sizing of system components - assumes one of two generic forms: the nasty form based on thermal comfort criteria or the nice form based on specified airflow rates. The nasty form demands consideration of the complex coupled interaction of a building's airflow and thermal systems - a difficult and often intractable challenge. The nice form, on the other hand, is quite tractable, yet it is commonly approached using interactive and approximate techniques.
Many HVAC systems built in the time between 1960 and 1980 have now reached the end oftheir lifetime and require retrofitting. When HVAC retrofits are performed in connection withbuilding renovation, there is often a potential for reduction of thermal loads. The questionwhether a renovated building should have an airconditioning plant or free ventilation oftenrevolves around arguments of energy consumption and investment. However it is not takeninto account that there can be no thermal comfort in many cases of cooling loads and outdoortemperatures.
Classrooms in New Zealand schools are mostly low rise buildings with natural ventilationdesigns, sized for summer cooling. This study has investigated winter ventilationperformance in twenty-four classrooms in twelve primary schools in the Wellington region.Its purpose has been to provide baseline data on the effectiveness of existing naturalventilation, along with approximate pollutant profiles on which to base new mixed modeventilation designs.
This report describe the thermal performance and air distribution of a Kumamoto prefecturalindoor sports ground in Japan. The swirling flow type natural air ventilation system wasadopted in combination with environmental symbiotic technique, and attempts was made topositively harmonize the system with the environment. In the measurements, emphasis wasput on the identification of thermal environment and on the verification of the swirling flowtype natural air ventilation system.
Within an International Energy Agency (IEA) project (Annex 27) experts from 8 countries(Canada, France, Italy, Japan, The Netherlands, Sweden, UK, and USA) have developed toolsfor evaluating domestic ventilation systems during the heating season. Building and useraspects, thermal comfort, noise, energy, life cycle cost, reliability, and indoor air quality(IAQ) tools were developed.
The purpose of this study was to evaluate the indoor air quality parameters in a residentialdwelling using information from the field. The subject was a typical example of the modernItalian dwelling stock, built in the 1980s in a residential area in the northernpart of Rome.The dwelling was constructed from pre-cast panels using industrial building techniques. Thewindows were steel-framed and painted. Airtightness was measured to obtain the ACH (airchanges per hour) at 50 Pa pressure difference, and ELA (equivalent leakage area).
There are often tradeoffs among improving IAQ (Indoor Air Quality), maintaining thethermal comfort, and reducing energy consumption for HVAC (Heating, Ventilating, and Air-Conditioning) systems. A prediction model that can simultaneously treat these factors isrequired to realize good design of sustainable buildings. For this paper, a concept of OccupantContaminant Inhalation is used for long-term assessment of IAQ. A long-term evaluationindicator for other factors such as air temperature is also introduced (Occupancy-weightedAccumulated Deviation from thresholds).
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