English

Many buildings under construction or renovation today require a smoke-control system, either to gain building regulations approval or, to protect the building, its contents and occupants, and to offer assurance of business continuity in case of fire. Traditionally natural rather than powered smoke ventilation systems have been preferred. The article considers why this has been the case, and covers failsafe operation, self compensating, quiet operation and cost effectiveness.

Describes how a Wisconsin engineer is using basic thermodynamic principles and readily available equipment to design innovative heating, ventilating and air conditioning systems. The hybrid HVAC designs offer two crucial elements: supply ventilation composed of 100% outdoor air and significantly reduced energy consumption. The new systems are both competitive in price to conventional systems and also less expensive to maintain. In one case study the hybrid system ventilates a 33 year old school building with 100% outdoor air and reduces building energy costs by at least 21%.

Describes a simplified numerical model, POMA (Pressurized zOnal Model with Air-diffuser, intended to predict the airflow pattern and thermal distributions within a room. The authors introduced jet characteristic equations into the model to make its application general for mechanically ventilated buildings. The models prediction was compared with experimental results and with that of another zonal model and a CFD model. Both natural and forced ventilation were considered. States that the findings show that the POMA model is a practical tool for ventilation system design.

The article discusses relationships between indoor and outdoor levels of various air contaminants (nitrogen monoxide, nitrous oxides, sulphur dioxide and ozone), in ten non-smoking residential buildings in Hong Kong. The experiment used passive samplers. Estimated the source and sink strengths of the contaminants, applying an integral approach to the mass balance equation. The results indicated that the buildings acted as sinks for the contaminants. When compared to the newly developed indoor air quality guidance notes in Hong Kong, the nitrogen oxides level gave some cause for concern.

Investigates the ventilation efficiency of different ventilation patterns arranged by two inlet and two outlet diffusers at different locations. First performs a numerical simulation, then a laboratory test in a full scale test chamber to validate the results. A concentration decay of carbon dioxide was used to calculate the ventilation efficiency and air change rate for the test chamber. States that the location of diffuser rather than air change rate might dominate the distribution of supply/exhaust air in the study.

States that there are problems involved with the use of traditional instruments such as vane anemometers and pitot tubes when measuring airflow rates in HVAC systems in order to balance air distribution. Suggests that the simple and useful tracer gas techniques that are commonly used for ventilation measurements in buildings can be a suitable alternative. Describes a preliminary study intended to determine the viability and accuracy of the tracer gas technique. A good correlation between the airflow rates measured by using a pitot tube and tracer technique was found.

States that to control humidity it is necessary to remove moisture load from ventilation air. The combination of increased ventilation and air conditioning brings more humidity in from outdoors with a greater chance that condensation will occur on surfaces chilled by the cooling system. Suggests that rooftop equipment for cooling is frequently oversized. Considers the nature and dimensions of the moisture loads.

Results from pre- and postconstruction radon measurements in a new housing development are presented. The houses were built in an area that had not been previously associated with elevated indoor radon concentrations. Exhalation measurements of gravel and stone from the site and soil gas measurements under several houses did not indicate an elevated radon potential. However, 4 of 21 finished houses (or 19%) exhibited annual average indoor radon concentrations over 200 Bq.m-3 (5.4 pCi/l).

The provision of underground parking facilities (UPFs) has become a necessity particularly in densely populated urban areas and business districts. Indoor air quality (IAQ) in such facilities is of great concern due to vehicle induced emissions. This paper presents and IAQ assessment at six representative UPFs in Beirut using carbon monoxide and volatile organic compounds as IAQ indicators. For this purpose, concentrations of both pollutants were measured at different time intervals throughout the day. Vehicular emission factors (EFs) were estimated using the EMFAC7F1.1 model.

Designing a ventilation system for a laboratory is challenging not only because these facilities consume a lot of energy and may contain materials that are toxic, flammable, explosive, infectious, or radioactive, but because standards and codes concerning them are revised often to reflect stricter health and safety requirements and improvements in technology.