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air change rate

Wind-induced pressure coefficients on buildings dedicated to air change rate assessment with CFD tool in complex urban areas

The paper presents a numerical methodology to assess the natural ventilation. UrbaWind is an automatic computational fluid dynamics code. It was developed to model the wind in urban environments. The turbulence modelling, namely the dependence of turbulence length on the distance from wall, and the model constants were calibrated in order to reproduce with good agreements flow separation around buildings walls and pressure coefficient field on façades. Numerical results match well with the experiments: separation patterns and pressure field on walls in dense urban areas.

A multi-criterion method for examining the health and energy impacts of air change rates in dwellings

The global requirement to dramatically reduce greenhouse gas emissions places an increased emphasis on reducing energy demand associated with dwellings. Where improved energy efficiency is in part achieved by tighter control of ventilation, there is potential for both positive and negative impacts on health from reduced air exchange in the indoor environment. Although increased air tightness may help improve indoor temperatures and reduce the ingress of pollutants from the external environment, it may increase concentrations of those from indoor sources.

A Measurement Study on the Indoor Climate of a College Classroom

To clarify the indoor climate in Japanese college classrooms, an air-conditioned, mechanically ventilated classroom of a university was surveyed. Temperatures, humidity and carbon dioxide (CO2) concentration in winter and summer were measured before, during and after lessons. The airtightness of the room and the airflow rate of the ventilation system were also measured. In winter, at an outdoor air temperature around 0 ºC and with the thermostat temperature of the air conditioners set to 30 ºC, the vertical difference in room air temperature exceeded 10 ºC.

Effect of Residential Ventilation Techniques for Hot and Humid Climates on Indoor Concentrations of Volatile Organic Compounds

Mechanical ventilation may be necessary to provide adequate ventilation in new houses due to the relatively low rates of infiltration achieved in new construction. However, in hot and humid climates, increased ventilation may raise indoor humidity to an undesirable level. A study was undertaken by the Florida Solar Energy Center (FSEC) to evaluate the humidity effects of different mechanical ventilation strategies for such climates. The study was conducted in a new 141-m2 manufactured house sited at the FSEC campus.

Volatile Organic Compound Concentrations and Emission Rates Measured over One Year in a New Manufactured House

A study to measure indoor concentrations and emission rates of volatile organic compounds (VOCs), including formaldehyde, was conducted in a new, unoccupied manufactured house installed at the National Institute of Standards and Technology (NIST) campus. The house was instrumented to continuously monitor indoor temperature and relative humidity, heating and air conditioning system operation, and outdoor weather. It also was equipped with an automated tracer gas injection and detection system to estimate air change rates every 2 h.

Air change rates in multi-family residential buildings in northern Portugal

Existing technical recommendations and standards regarding natural ventilation in Portugalestablish one air change rate, ACH, in main rooms (bedrooms and living rooms) and fourACH in service rooms (kitchens and bathrooms).

Post-occupancy monitoring of windcatchers for summer ventilation in the UK

A combined windcatcher and light pipe (SunCatcher) was installed in the building of theSchool of Construction Management and Engineering in the MSc Seminar Room (2N09).Monitoring of indoor environment in real weather conditions was conducted to evaluate theperformance of windcatchers in the room and to conduct occupant survey. External weatherconditions and internal indoor environment and air quality indicators were recorded. Thetracer gas decay method using SF6 was used to establish the air change rate for variousconditions.

The variation of ventilation performance in relation to change in workstation location in a ventilated room

This paper considers the predictions obtained using a recently developed ventilation parameter (VP) for evaluating the ventilation performance which combines the indices for indoor air quality and thermal comfort. This ventilation parameter is used to analyse the changes in ventilation performance with changes in the position of workstation in a room ventilated using mixing ventilation.

Development and application of an indoor air quality audit to an air-conditioned tertiary institutional building in the tropics

This paper is the presentation of the development and application of an IAQ audit methodology applied in tertiary institutional buildings in the tropics. For that study, a staff room and a typical lecture theatre have been selected.The IAQ audit consisted in monitoring thermal comfort parameters. In parallel the staff and students have answered a questionnaire to give a subjective assessment of the indoor air quality.The IAQ results will be then used to develop an IAQ database for institutional buildings in Singapore.

Influence of air diffuser layout on the ventilation of workstations

Seven air supply and return diffusion layouts were tested to determine their effects on air distribution, air change efficiency and ventilation efficiency for workstations in an open-plan office. This document describes and comments the results of these measurements.

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