AIVC - Air Infiltration and Ventilation Centre

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carbon dioxide

Dynamic evaluation of airflow rates for a variable air volume system serving an open-plan office

This paper proposes a space zone model for the calculation of all the airflow parameters based on tracer gas measurements, including flow rates of outdoor air, VAV supply. This approach gives a practical protocol for buildings managers to evaluate the performance of airside systems and determine air-conditioning and ventilation system performance parameters within acceptable errors.

Risk of indoor airborne infection transmission estimated from carbon dioxide concentration

Accurate mathematical models of airborne infection are needed to estimate the risk from secondary transmission of biological warfare agents. An equation has been derived by the authors : they determined the fraction of inhaled air that has been exhaled previously by someone in the building by using a CO2 concentration as a marker for exhaled-breath exposure.
There is a critical rebreathed fraction of indoor air below which airborne propagation of common respiratory infections and influenza will not occur.

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.

Carbon Dioxide Levels and Ventilation Rates in Schools

In the following, measurements of CO2 levels in seven classrooms in four schools are reported. Measurements were taken for approximately one week in each classroom during the heating season and the time-varying ventilation rates estimated. The results of the experiments show CO2 concentrations which are far beyond the guideline value of 1000 ppm (the average concentration during the occupied period was 1957 ppm). In some classrooms the level exceeded the range of the detector (4000ppm).

Energy labelling of existing buildings and their equipment: new procedures to assess possiblities for increasing energy efficiency while reducing CO2 emission and improving comfort.

Describes best practice for energy labelling for existing residential buildings in four countries. Also describes the specific features of a Belgian procedure for on-site evaluation of both equipment and building envelope. The results can be used by other countries as general guidelines to develop or optimise efficient and effective energy labelling procedures.

Energy consumption and CO2 emission due to HVAC in commercial buildings.

Describes part of a global study on carbon dioxide emission associated with electricity consumption in Belgium. Two commercial buildings were the subject of a simulation. HVAC energy consumption and corresponding CO2 emission were calculated after an identification of the heating and cooling demands. It was found that they are strongly dependant on occupancy rates, and coexist throughout the year.

Asthmatic symptoms and volatile organic compounds, formaldehyde and carbon dioxide in dwellings.

Explores possible relations between symptoms of asthma, building characteristics and indoor concentration of volatile organic compounds in residential buildings. 88 persons from middle Sweden were studied. Measurements were taken at home of room temperature, air humidity, respirable duct, carbon dioxide, VOCs, formaldehyde and house dust mites. Health tests were also performed. Found that symptoms related to asthma were more common in homes with house dust mites and visible signs of dampness or microbial growth.

Subjective indoor air quality in schools in relation to exposure.

Relates exposure measurements for indoor air quality in schools to perception of IAQ by employees. A questionnaire was used to gather information on subjective air quality, domestic exposures and health aspects. 38 schools were covered in the study. A 53% section of personnel reported bad or very bad indoor air quality. Worst reports came from the younger personnel, those dissatisfied with their psychosocial work climate and those not exposed to domestic tobacco smoke. Less IAQ dissatisfaction was reported for older schools and those with displacement ventilation.

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.

CO2 and radon based dual-mode demand control ventilation strategy.

A dual-mode demand control ventilation strategy was developed targeting at using in institutional or similar buildings where the number of occupants varies frequently. One occupant-related and one non-occupant-related indoor contaminants were used as the indication signals to control the fresh air intake. The first contaminant is carbon dioxide, which is a good surrogate gas for bio-effluent and the second is radon which is non-occupant-related and had been identified as a major indoor air pollutant in some buildings in the university where this project has been carried out.