A home with a poor duct system can't be energy efficient no matter how tight or well-insulated it is.

A study of test methods for duct leakage revealed that there is room for improvement in this evolving field.

A literature survey was conducted to identify measured airtightness values for various types of large buildings including Multi-Unit Residential Buildings (MURBs); offices; schools; commercial, industrial and institutional structures. Data was identified for 192 buildings in Canada, the United States, Great Britain and Sweden.

This study compares the characteristics of two tracer gases - sulphur hexafluoride (SF 6), and nitrous oxide (N20) – whose densities are different from that of air (i.e. 5.11 and 1.53, respectively). The study is based on exclusively experimental work; and concerns the behaviour of the two gases with regard to their distribution and dispersion in an experimental cell, incorporating into the comparison method an index that is intended to characterise the ventilation of an enclosed space, namely ventilation etfectiveness,

Two-dimensional numerical simulations have been undertaken for the steady turbulent fluid flow in a room containing a fume cupboard which is attached to a wall and a ventilation duct which is situated in the ceiling of the room, see figure 1. The wall opposite to the fume cupboard is assumed to be porous and a fully developed fluid velocity profile is applied far upstream. The calculated flow is considered to be that which is actually found in the central plane of a practical fume cupboard.

When a person works facing a local exhaust ventilation (LEV) hood, it may be possible to obtain higher concentrations of aerosols in the breathing zone (BZ) than without the hood because recirculating eddies form downstream of the body. These eddies shed periodically in an alternating pattern called vortex shedding, which is thought to be a primary determinant of contaminant transport in and out of the breathing zone (1, 2, 3). Previous computational fluid dynamics (CFD) studies have explored the effect of timedependent airflow on occupational exposure to gaseous contaminants (2, 3).

Preliminary numerical simulations of human exposure to paint-spray aerosols demonstrate the ability of computational fluid dynamic (CFD) software to discriminate between two different orientations of spraying a flat plate in a cross-flow ventilated spray booth. To conduct exposure-scenario simulations using CPD, a conceptual model of reality must be created that is compatible with the computer code. If this conceptual model is not a sufficient representation of reality with regard to the desired outcome, then no matter how accurate the simulation, the results will be of limited value.

Productivity is one of the most important factors affecting the overall performance of any organization. Productivity is defined as the ratio output divided by the input used to produce the output. The output refers to products and services produced by an organization (2). Increased attention has been paid to the relationship between the work environment and productivity in the 1990s. Laboratory and field studies show that the air quality and thermal conditions at work may have a notable impact on the performance of the occupants, and consequently on labor productivity (1,3,4).