CO2 tracer gas concentration decay method for measuring air change rate

Cui, Shuqing; Cohen, Michael R.; Stabat, Pascal; Marchio, Dominique

doi:10.1016/j.buildenv.2014.11.007

Cited by 183 publications

(91 citation statements)

References 18 publications

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“…After the CO 2 generator was turned off, the time series CO 2 concentration was measured for 1 h using a Telaire T7001 with a data logger. A well-mixed single zone model is assumed in this study, which is found to be sufficiently accurate from the extensive investigation in previous studies [36][37][38]. In a well-mixed single zone, the CO 2 concentration change can be expressed as follows:…”

Section: Experimental Setup For Measuring Outdoor Air Change Ratementioning

confidence: 99%

A field study on indoor environment quality of Chinese inpatient buildings in a hot and humid region

Tang

Ding

et al. 2019

Building and Environment

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In this research, objective physical measurements and subjective questionnaire surveys are used to investigate the indoor environment quality of Chinese inpatient buildings. The relative humidity in the inpatient buildings reaches 65%-75% during summer, resulting in the regular appearance of microbial growth on indoor surfaces. The average outdoor air change rate measured through the CO 2 concentration decay method in the sampled inpatient rooms is 1.1 h −1 , which is 45% below the standard threshold. The CO 2 concentration in over 99% of the functional spaces is below the threshold of 1000 ppm. However, the dissatisfaction rate of the air freshness is higher than 25%, owing to the characteristics of healthcare activities. Insufficient fresh air volume and high supply air humidity ratio of the outdoor air system result in the inadequate dehumidification capacity and the over-humid environment in the inpatient buildings. From the perspective of indoor TVOC and PM2.5 concentration, a hospitable IAQ is achieved in the inpatient buildings. In the nurse unit, the illumination levels in public areas, such as patient corridors and nurse stations, are inadequate. The average noise levels (A) in the inpatient rooms and nurse stations are 50.7 and 61.6 dB, respectively, which exceeds the Chinese standard. According to the subjective survey, the dissatisfaction rates of overall IEQ in the summer for patients and visitors are 7.9% and 10.4%, respectively, while for staff it is 34.8%. Statistical analysis reveals that the satisfaction levels of the patient with the IEQ are higher than that of the visitor and staff.

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Section: Experimental Setup For Measuring Outdoor Air Change Ratementioning

confidence: 99%

A field study on indoor environment quality of Chinese inpatient buildings in a hot and humid region

Tang

Ding

et al. 2019

Building and Environment

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“…Variations between sensors were therefore lower than the 10% prescribed by ASTM E741. The infiltration rates were estimated in air change rates (ACH) from the tracer gas concentration curve considering the twopoint decay method (Cui et al, 2015):…”

Section:  Characterising Air Leakage and Infiltration In The Classroomsmentioning

confidence: 99%

Performance of a natural ventilation system with heat recovery in UK classrooms: An experimental study

Dorizas

Stamp

Mumovic

et al. 2018

Energy and Buildings

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This paper presents the ventilation performance of a Passive Ventilation System with Heat Recovery (PVHR) based on in-situ monitoring in a primary school in London. The study involves long-term (15month) monitoring of temperature, relative humidity and Carbon dioxide (CO 2 ) concentrations in both the classrooms and the outdoor environment. In addition, short term (1&2 week) observational monitoring was performed in two classrooms at ventilation system level and classroom level, during both the heating and non-heating seasons. Temperatures and air velocities were measured within the PVHR system while instances of window opening and the number of students were noted in daily diaries. Air permeability and infiltration measurements were performed to characterise the spaces.Time-varying ventilation rates were estimated through a form of continuity equation considering CO 2 generation rates by occupants. Preliminary results show that the operation of the ventilation system is more sensitive to changes in wind speed and direction than to buoyancy. When negative pressure was observed on the classrooms" facades the ventilation system was supplying two to three times more air in comparison to instances when positive pressures were observed. The assessment of the ventilation performance of such natural ventilation systems depending solely on wind and buoyancy is complicated as they are dynamic systems that constantly balancing with the surrounding conditions, and the operation is highly correlated to the airtightness of the building"s envelope. Highlights: CO 2 concentrations in classrooms with passive ventilation systems (PVHR) were satisfactory  Airtightness significantly affects the performance of the passive ventilation system  Passive ventilation system appears more sensitive to wind changes than to buoyancy ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P T 2  Human behaviour such as window opening can significantly boost the ventilation rate of the PVHR system 1 Introduction According to the Climate Change Act (2008), the UK government is committed to tackling climate change by reducing greenhouse gas emissions for the year 2050 by at least 80% from the 1990 baseline (DECC 2008). Space Heating, Ventilation and Air-Conditioning (HVAC) account about two thirds of the total non-industrial energy use (Deuble and de Dear 2012, Lomabrd et al., 2008, Khan et al., 2008) from which 30-50% is related to ventilation and infiltration and about 40% accounts for heating. A reduction in the energy required to heat and ventilate buildings will contribute to a significant reduction of greenhouse gas emissions. Natural ventilation strategies consume negligible amount of energy by utilizing natural driving forces of wind and buoyancy (temperature differences between the indoor and outdoor environment-stack effect) can provide a viable alternative to energy consumption for mechanical air-conditioning systems and a fundamental method towards energy efficient design of buildings (Calautit and Hughes 2014, Khan et al., 2008). Sev...

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“…To assess the air change rate, the natural infiltration rate was calculated using the decay method [20]. The CO 2 concentration for each apartment was analysed to locate decay situations suitable for calculating the infiltration rate.…”

Section: Infiltration Rate Assessmentmentioning

confidence: 99%

Influence of heat cost allocation on occupants' control of indoor environment in 56 apartments: Studied with measurements, interviews and questionnaires

Andersen

Olesen

2016

Building and Environment

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CO2 tracer gas concentration decay method for measuring air change rate

Cited by 183 publications

References 18 publications

A field study on indoor environment quality of Chinese inpatient buildings in a hot and humid region

A field study on indoor environment quality of Chinese inpatient buildings in a hot and humid region

Performance of a natural ventilation system with heat recovery in UK classrooms: An experimental study

Influence of heat cost allocation on occupants' control of indoor environment in 56 apartments: Studied with measurements, interviews and questionnaires

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