AIVC - Air Infiltration and Ventilation Centre

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Energy and indoor environmental quality in relocatable classrooms

Four relocatable classrooms were designed, constructed and tested in Californian schools to demonstrate technologies that improve energy efficiency and indoor environmental quality. First results such as CO2 and particle concentrations are presented and discussed.

Vertical distribution of occupant-generated particles in a room with displacement ventilation

Measurements were carried out in a test chamber with displacement ventilation to know the vertical distribution of airborne particles generated by two human subjects having an activity representative of that of people working in an office. Particle concentration was observed as increasing with height. A threshold size of particles was found at 5 to 10 microns above which the displacement effect of particles by air flow started to decline. Negative concentration gradients were observed for large particles at the lowest ventilation rate, when the air flow does not displace them.

Carbon Dioxide Levels and Summertime Ventilation Rates in UK Schools

Measurements of metabolic carbon dioxide concentration made in four classrooms in two schools are reported for both occupied and unoccupied periods. Measurements were taken for approximately one week in each classroom during the unheated season and the time-varying ventilation rates estimated. The results of the experiments show CO2 concentrations that are far beyond the guideline value of 1000 ppm (the maximum concentration during the occupied period was 3756 ppm). Calculated air supply rates vary from unacceptably low levels, to rates that are in line with guidance.

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.

Multizone modeling approaches to contaminant-based design

Design process of buildings currently addresses indoor air quality through ventilation flow rates requirements. In some circumstances, this approach may be not sufficient and an alternative is to determine ventilation rates through contaminant-based design methods. The authors present several examples of such approach, especially using multizone modeling (CONTAMW model) in a two-story classroom/office building equipped with a CO2 demand-controlled ventilation.

Essai d'une methode de verification des performances de la ventilation dans les batiments tertiaries, en France. Trial of a test method for ventilation performance in tertiary buildings in France.

In France, the performance of ventilation systems in existing buildings is poorly understood today and rarely checked. This article shows how a verification method for ventilation system performance, currently in operation in Sweden, can be applied in France.

Volatile organic compounds, respirable dust, and personal factors related to prevalence and incidence of sick building syndrome in primary schools.

This study explored the possible connections between the incidence and prevalence of sick building syndrome (SBS), indoor exposures, and personal factors. This was accomplished by a four year longitudinal study of workers in six primary schools. The mean concentration of Carbon Dioxide exceeded the recommended value of 0.08 microlitres/l (800 ppm) in all schools, which suggested a poor outdoor air supply. Indoor levels of volatile hydrocarbon (VOC) was increased at high room temperatures.

Indoor spread of respiratory infection by recirculation of air.

Analyses the possibility of preventing disease being spread through a school ventilating system. States that the effectiveness of disinfecting recirculated air in blocking person to person transmission of airborne infection can be predicted to be great at the beginning of a potential outbreak and negligible during an established epidemic. Also states that air disinfection would supplement immunization in the control of respiratory infection and might be cost effective.

CO2 concentration in a typical Hong Kong classroom.

This paper presents the feasibility of predicting the transient CO2 levels in a classroom. Air measurements in the classrooms were taken to determine the fresh air change rate and ventilation effectiveness by means of tracer gas method. The fresh air change rate, effectiveness, occupancy, and outdoor CO2 levels were used as inputs for prediction of indoor CO2 concentration. The general profiles of predicted CO2 concentrations are quite similar to that of the measured values. The ventilation rate is often overestimated.

Investigation identifies likely causes of complaints about poor IAQ.

Details a NIOSH (US National Institute of Occupational Safety and Health) investigation of a school whose occupants suffered from allergic symptoms. The investigation found that occupants' symptoms were consistent with sick building syndrome. Many complaints were apparently related to insufficient outdoor air, temperature extremes in some cases, and temperature controls that were inadequately responsive to classroom conditions.