SBS: Sick Building Syndrome.

SI: International System of Units. In HVAC the more common units are: Litre (L) - Volume; second (s) - time; metre (m) - distance ( A kilometre is 1000 meters. A millimetre is 1/1000 metre); degrees Celsius (^OC) - temperature.

Smog: A mixture of gases and aerosols generated from a variety of sources. Smogs have a damaging effect on respiratory organs of people. Most smog is attributed to the exaust from automobiles and from the discharge of industrial processes.

Smoke: (1) An aerosol of particles usually but not necessarily solid, formed from combustion or sublimation. (2) Carbon or soot particles less than 0.1 micron in size which result from incomplete combustion of carbonaceous materials such as coal, oil and tobacco.

Static Pressure: The potential pressure exerted in all directions by a fluid. For a fluid in motion it is measured in the direction normal to the direction of flow. It has the potential to either burst or collapse a duct or other enclosure.

Static Tip: Device inserted at right angles to an airstream to measure static pressure.

Stratification of Air: Condition in which there is little or no air movement in a room; air lies in temperature layers.

Sublimation: The conversion of a solid phase of a substance to a gaseous phase without going through the liquid phase.

SULPA: Super Ultra Low Penetration, Air (filter). These filters typically have efficiencies of 99.9999% on 0.3 micron DOP particles.

Supply Air: A mixture of recirculated air and outside air which has been conditioned and delivered to the space. Supply air can be 100% outside air and 100% recirculated air.

Surface Area (Carbon): The surface area of granular activated carbon is determined by BET method which utilizes the adsorption of nitrogen at liquid nitrogen temperatures in the calculation. Surface area is usually expressed in square meters per gram of carbon.

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