IJV12

The redispersion factor of microbe-carrying particles, which is the ratio of the concentration of floor-derived microbes in room air to those on a floor surface, was determined, as was the percentage of floor-derived microbes in room air. These relationships were shown to vary according to conditions in the room. Equations were derived that allow these relationships to be calculated for a variety of room conditions, including air supply rates, levels of personnel activity, and the effect of gravitational deposition on microbe-carrying particles.

In hot climates a comfortable indoor environment is important. Mechanical fans are often introduced to cool the indoor air. However, it has been found that the airflow from such fans is not comfortable, especially compared with natural wind. Artificial airflow in an enclosure has been known to disturb hair, irritate eyes, and distract occupants. This paper presents the result of an experimental study on the characteristics of household airflow inducing appliances. The details of experiments carried out in the laboratory are described.

Air movement in an indoor space may be experienced in very different ways. For persons feeling cool, air movement tends to be perceived as draught, whilst when feeling warm air movement may provide a desired cooling effect. In the transition zone it therefore seems difficult to use constant air velocity as a tool for cooling without creating draught problems. One possible way to use air movement as a method to improve thermal comfort, without resultant draught problems, could be to use intermittent air velocity instead of constant velocity.

This paper investigates the performance of a new attic ventilation concept using low-cost thermoelectric (TE) modules. Incident solar radiation heats up roof tiles thus creating a temperature difference between tiles and attic. By making use of this temperature difference, laboratory made low-cost thermoelectric modules, assimilated as roof tiles, could produce an electric current to drive a fan for attic ventilation. First, a low-cost TE module consisting of 7 couples of N and P type Bi-Sb-Te materials was fabricated on a 2x2 cm² aluminium substrate.

This paper reports on an investigation of the natural ventilation and heat gain reduction of a new façade design referred to as the Thai modern façade (TMF). Two configurations were considered namely: Thai modern façade wall (TMF) and Thai modern façade wall with fin (TMF-WF). The first (TMF) was composed of two layers which consisted of an inner layer of clear glass and an outer layer consisting of a combination of fibre cement and clear glass slats. The second configuration TMF-WF included an external layer made from aluminium fins and installed at the front of the outer layer.

There is a need for a greater understanding of the acoustical and airflow performance of interior openings, and of silencers implemented to improve their acoustical performance, in naturally ventilated buildings. This paper discusses preliminary, fundamental aspects of a study done to provide engineers and architects with optimal design techniques. It discusses the characterization of ventilator performance, including the definition of the open area ratio - a combined acoustical and airflow performance-optimisation metric.

Buoyancy-driven natural ventilation in ventilation shafts is investigated with a small scale physical experiment within a duct and CFD simulations of an office building. For a fixed exhaust opening, smaller shafts lead to higher flow rates in upper floors of a multi-storey building with a shared ventilation shaft. These higher flow rates are caused by increased vertical momentum within the smaller shafts that induce flow through upper floors, an effect referred to as the “ejector effect”.

The concentration levels of particulate matter (PM), airborne fungi, carbon dioxide as well as temperature and relative humidity were investigated in the indoor and outdoor environment of two schools in Athens, Greece during the period January to May 2011. The overall concentration ranges of the indoor measured pollutants were: PM10: 14.92-166.18 μg/m3, PM2.5: 3.16-31.27 μg/m3, PM1: 0.72-9.01 μg/m3, UFP: 4188-63093 pt/cm3, total airborne fungi: 28-2098 CFU/m3 and CO2: 389-1717 ppm.

The importance of reducing adventitious infiltration in order to save energy is highlighted by the relevant building standards of many countries.  This operational infiltration is often inferred via the measurement of the air leakage rate at a pressure differential of 50 Pascals.  Some building codes, such as the UK’s Standard Assessment Procedure, assume a simple relationship between the air leakage rate and mean infiltration rate during the heating season, the so-called leakage-infiltration ratio, which is scaled to account for the physical and environmental properties of a dwelling.  The

Passive stack ventilation is a key feature of sustainable building design and has particular potential for use in tall, multi-storey buildings. However, natural ventilation flows through multiply connected spaces may not behave as expected. Recirculation of air through occupied parts of the building and bidirectional exchange flows at ventilation outlets may compromise the intended ventilation scheme resulting in an uncomfortable indoor environment.