Several previous calculations have shown that many of the measures taken to improve indoor air quality and climate are cost-effective when the potential savings are included into the calculations as benefits. However, general models on how to estimate the cost-effectiveness of various measures and strategies are still missing. This paper presents approach with which the ratio of savings in any of the costs of owning and operating a building can be compared with the real cost at risk which is reduced worker performance.
The study presents a cost analysis including energy calculations for three outdoor climates (cold, moderate and hot) to improve indoor air quality in an existing building considering both variable air volume (VAV) and constant air volume (CAV) systems with heat recovery. The study also simulates different indoor air quality levels due to different airflows of outdoor air.
The study investigates the relationship between ventilation rates and work performance on two specific tasks (talk and wrap-up) in a call-center. CO2 concentrations ranged from 13 to 611 ppm and the study used a multi-variable regression to modelize the association between the predictors and the responses. Influence of ventilation rates and temperature on task performance are commented.
This new standard goes much further than previous one in addressing pre-cleaning assessments, control and containment during the cleaning process as well as a lot of other variables that can impact the indoor environment. This paper looks and comments the new standard and how it addresses the many variables that influence duct cleaning and IAQ and how the document deals with the many different building populations.
The paper presents hygiene requirements to be met by hospital HVAC plants and analyses them critically for different type of rooms (confined rooms sterile protected, operating room, special areas). The tasks of comfort air conditioning are adapted to the improved indoor conditions of intelligent buildings. Air is only used for ventilating, whereas heated and cooled room surfaces generally serve for heating and cooling.
The effect of duct cleaning has been checked on 15 buildings. Indoor air quality measurements and questionnaires have been operated 3 months before cleaning and 1 month after. Questionnaires show that the perceived indoor air quality has been improved. Effects of cleaning on measurements can hardly be measured.
Labelling of HVAC systems is a direct consequence of the publication of test procedures and recommended criteria in Finland. Cleanliness parameters are dust quantity, oil residues and odours emissions. Discussion isf continuing on filters classification including their efficiency (EN 779) but also odour emissions.
Ways of removing from indoor air particulates smaller in diameter than 1 micrometer, through enhancement of particle deposition in a filter, were investigated using numerical simulation. Deposition enhancement is obtained using diamond-shaped three-dimensional roughness elements incorporated into filters. Numerical investigations performed were used to define the enhancement for laminar flow, in order to define the most efficient arrangement of enhancing elements.
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.
On 75 air outlets of HVAC systems from 12 participating companies, fungal contamination was measured and compared to the incoming fresh air. For one of them with a significantly high level of fungi, dominated by one penicillium species, regular checks on a period of 14 months have been realised. The study concludes that this kind of measurement can be used as an indicator of the HVAC system hygienic condition.
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