The increased awarness of Indoor Air Quality issues has resulted in a greater demand for gas detection in commercial buildings. Carbon monoxide, Carbon dioxide, Ammonia, Freon's, Natural gas, Nitrogen dioxide and VOC's are rypical gases being monitored. As a result, there is a greater need on the part of the building managers to know about the regulations governing the allowable exposure to the gases.

• The "Building code" contains information about Carbon monoxide and Nitrogen dioxide for closed vehicle storage areas.
• The "Chemical Hazards Regulation" section of the "Occupational Health and Safety Act" contains useful information regarding the legal limits for allowable exposure to building occupants.
• The "ASHRAE" standards have a list of suggested gas level for good air quality in an indoor environment.

Gas detectors are being installed in commercial building mainly because of the requirements of the building code or safety consideration and there is little emphasis on the energy efficiency of such systems in operating the ventilation systems. As the need to save energy becomes more important especially with possible legal oblications from the Global warming conference in Kyoto, Japan to cut worldwide emissions, the energy savings aspect of the gas detection device becomes more important. Gasonic Instruments has conducted fieold test on different carbon monoxide sensors to help buildings save on the energy costs associated in running those devices.
Our test involved two Galgary parkades of the same size but with two different carbon monoxide sensors. One of the parkades installed 68 electrochemical sensors six years ago and the other is 1 year old and has 48 solid state sensors. One test looked at the drift of the sensors from their Zero baseline and lab tests on the two types calibration gas after one year operation. The graphs on page 3 shows the considerable difference between stability of the two sensors. We also found that 4 solid state sensors failed after one year of operation and none of the electrochemical sensors had failed in 6 years.

When we analyzed the cost of operating the two systems, we concluded than the electrochemical maintenance costs one third less than the maintenance for the solid state sensors. This does not include the energy savings from reducing the ventilation system run times.