AIVC - Air Infiltration and Ventilation Centre

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Comparison of indoor climate and microbial contamination in two office buildings with different ventilation systems.

Describes a survey carried out to investigate microclimatic conditions and microbial contamination in two office buildings with and without central air conditioning. Measured indoor climate factors generally fell within acceptable ranges for the mechanically ventilated buildings, except for the winter sample where relative humidity was low. Microclimatic parameters showed seasonal variation in the naturally ventilated building, and bacterial and fungal contamination was higher.

Microorganism contamination of HVAC humidification systems: case study.

The study collected water samples from 33 of 54 HVAC humidification system water reservoir pans in a large office building. The nature of the contamination that was found indicated that cleaning was ineffective, and may increase the risk of biological contamination. Of the two different humidification systems, air wash and steam injection, the air wash system revealed high contamination of samples.

Prevalence of irritative symptoms in a non-problem air conditioned office building.

The study aimed to assess prevalence of complaints and symptoms in relation to sick building syndrome for workers in an air conditioned building in Italy, in the absence of earlier reported complaints. The control was 281 workers in three naturally ventilated buildings. There was a significantly higher number of complaints from the air conditioned office building's employees, including strong lighting, high temperature and dry, dusty and stuffy air. No significant difference was noted in respiratory or general symptoms.

Predicting sick building syndrome at the individual and aggregate levels.

Environmental conditions, sick building syndrome symptoms, job satisfaction, job stress, and occupational and personal information were assess by questionnaire of 4479 employees from 27 air conditioned offices, and indoor air quality measurements taken. IAQ met the ASHRAE guidelines for all the buildings. Found that the number of sick building syndrome symptoms per employee was linked linearly to computer use, job stress, job satisfaction, number of allergies, migraine and eye wear.

Elevated symptom prevalence associated with ventilation type in office buildings.

Describes the California Healthy Building Study, which attempted to assess the relationship between ventilation system type and employee symptoms. Three naturally ventilated, three mechanically ventilated and six air conditioned buildings were studied. Higher adjusted prevalences of most symptom outcomes were linked with both mechanical and air conditioned ventilation.

Simple and reliable energy saving AC fresh air control scheme.

The substance of AC fresh air control is that fully utilises outdoor fresh air according to enthalpy of outdoor air, so achieves the goal of energy saving and improving indoor quality. The normal way is adjusting the amount of fresh air according to enthalpy which is calculated on the basis of temperature and humidity in and out door, this is called "enthalpy control". But because the cost of humidity sensor cell is high, its life is short, and it is very difficult to maintain, the long time and reliably running control systems are actually very short.

Room airflow distributions and ventilation characteristics by a personal air conditioning system.

This paper investigates ventilation characteristics and room airflow distributions in a workstation area of an office building with a personal environmental system. A personal environmental system is generally believed to be able to provide better thermal environment with less heating and cooling energy consumption. An underfloor air conditioning system with and without a desk-mounted PEM (Personal Environmental Module) is compared. A tracer gas experiment using a SF6 gas is performed to measure local supply index and room mean ventilation effectiveness.

Theory analysis of heat and moisture diffusion strengthened by the pulse blowing.

In air conditioning system, air blowing patterns have very important influence on the comfortable state and the energy consumption of air conditioning environment. When pulse-blowing pattern is adopted, different density particle can gain different acceleration due to the change of airflow acceleration in pulse blowing. For the particle with higher temperature and larger humidity, its density is smaller and its acceleration is smaller in pulse blowing.

Air quality appraisal in air conditioned spaces: numerical analysis.

The conditioned air is an important element in healthcare applications. One of the main objectives of supplying conditioned air to healthcare facilities is to create proper comfortable combination of temperature, humidity, and air motion as well as to remove airborne bacterial, microorganisms, and air contaminants. So the air distribution must meet specified conditions of air change rates, velocity, pressure, cleanliness, temperature, humidity, and noise level.

IAQ related to operation and management of fresh air system for air conditioning.

This paper points out that the operation and management of the system for indoor air quality (IAQ) is more important than the design of air conditioning system. It is a widespread practice that for the sake of saving energy and operating expense, many building owners change the system's installations and operating manners of fresh air system of air conditioning. Almost all the building owners neglect the maintenance and management of air conditioning system. Those behaviours lead to seriously poor IAQ.