Question & Answer

1. Why CO monitor and control system?
   Mainly for energy conservation/ energy saving. Potential energy saving depends on the car park usage, control strategy, control setting and types of vehicles/ engines (majority) entering/ leaving the car park.
   
2. What is the coverage of the sensor?
   The CO system design is based on the guideline by CP13-1999 (Singapore) and withreference to Australian Standard 1668.2-1991.
   Considerations:
   - Maximum distance of any corner in the car park to the nearest sensor shall be less than 25m.
   - First 12m from fresh air opening are considered as natural ventilation (NV) zone.
   - Sensors are grouped according to the zones by the exhaust fans.
   
3. How to determine number of sensing points required?
   The number of sensing points is calculated using the guidelines of AS1668.2 with the considerations given above.
   N = A /1000 x SQRT (L/W)
   Where N = no. of sensing points
   A : Area of car park in sq meters
   L : Length of car park in meters
   W : Width of car park in meters
   SQRT = square root
   
4. Where to place the sensor?
   Sensor shall be installed at 0.9m ~ 1.8m above floor level (AS1668.2). However, for practical reason (in order to avoid vandalism), the sensors can be installed just above 1.8m.
   
5. Product country of origin?
   CO/CO2 combinational sensors - Sweden
   CO sensor/controller - Singapore
   
6. What are the minimum requirements of a typical CO sensor?
   Sensor shall have:
   - Minimum measuring range : 0 ~ 50 ppm or 0 ~ 100 ppm
   - Accuracy : +/- 10% or less
   
7. What are the different types of control strategy?
   1. ON/OFF control
   The pairs of exhaust & supply fans can be controlled with the following control set-points:
   1st stage : Fans switched ON when CO is above 9ppm (CP13-1999, residential) Fans switched OFF again when CO drops below 6ppm
   2nd stage: Fans switched ON when CO is above 25ppm (CP13-1999, residential) Fans switched OFF again when CO drops below 20ppm If only single stage fans available, the fans shall be controlled at 25ppm. Whereas more than one sensor are to control a fan, the worst case of the sensors’ reading shall be used for control purpose.
   
   2. Variable Frequency Drive (VFD)/ Variable Speed Drive (VSD) Control
   a) Control ventilation at minimum ventilation rate, say 20Hz, when CO measurement is below 20ppm.
   b) Ventilation rate shall increase proportionally when CO level increase beyond 20ppm and reach the maximum when CO level is above 50ppm.
   c) Periodic higher ventilation shall be built-in to the VFD system from the BMS.
   Provisions :
   a) Timer override - The car park ventilation may include timer over ride for periodic
   peak car park usage, for instance, morning and evening rush hours.
   b) Manual override - The car park should also include manual override.
   c) Temperature override – in case of high temperature, the ventilation may be activated so as to create “wind” effect and improve the comfort.
   Note : Control of 1st or 2nd stage fans are only applicable in Normal Mode (NM) operation.
   
8. What is the pay back period?
   Pay back period varies from 9 to 24 months. Typical payback period is around 12 month.
   
9. How to calculate energy saving?
   

   Energy saving and simple payback:
   Item	Unit	Quality
   Total Fan Wattage	KW	A
   Operating hours (daily)	Hour	B
   Nominal energy usage per day	KWH	A X B
   Monthly energy usage	KWH	30 AB
   Energy rate	Cents	0.1675 (low tension rate)
   Monthly energy usage in $ & cents	$	0.1675 X 30 X A X B
   Potential energy saving	%
   Monthly saving from CO system	$
   Capital Investment for CO system	$
   Simple payback	Year

   
   
10. What is the warranty period?
    One year limited warranty against faulty parts & manufacturing defects.
    
11. How many models of CO sensor does Telasia Symtonic have?
    3 models :
    a) CO-M1 (old model, not recommended for new design)
    b) DCO-S1
    c) DCO-S2 (available in mid 2005)
    d) aSENSE-mIII (integrated sensor, CO, CO2, Temp & RH)
    
12. What type of mounting : duct mounted or wall mounted?
    Download PDF file. Under [Space vs Duct Installations].
    
13. How to carry out testing & commissioning?
    Download PDF file. [Total 4 pages]
    
14. Other Considerations
    In addition to CO controlled system, temperature and timer control should also be considered in controlling the car park environment

Special Notes:
1. In case of fire, the Fire Mode (FM) ventilation shall override CO system.
2. In premises where diesel engines out number petrol engines, CO2 sensors should be considered in place of CO sensors.