EQc1: Carbon Dioxide Monitoring Review Comments
The signed LEED Letter Template declares that a CO2 monitoring system has been installed. Supporting
documentation includes a mechanical equipment schedules, including the RTU sequence of operation
describing CO2 sensors. However, it is unclear whether or not the sensors are located in the breathing zone of
occupied spaces. Also, no summary of target carbon dioxide differentials per end use has been provided, as
required by the Letter Template.
TECHNICAL ADVICE:
Please provide a summary and calculations of target carbon dioxide differentials per end use, documenting how
these target carbon dioxide differentials are measured and maintained for the building. Also, please provide
HVAC drawings with CO2 sensor locations highlighted in each zone, along with project-specific cut sheets of
the installed carbon dioxide monitoring system components.
Response
Summary of target differentials per end use (calculations attached):
“The CO2 monitoring system was designed to verify the delivered outside air amount to each space based CO2
concentrations for different levels of activity per end use. There are seven different end use zones used. The
carpentry area includes areas for pre-building modular furniture as well as preparing decorative items for the
store displays. This area includes light work suitable for a 2.3 met activity level and .6 L/m CO2 generation.
Dinning includes areas for the kitchen and exit cafe- a very light work met of 2.1 was used with .5 l/min CO2
generation. For the office areas a 2.0 met was used with a .5 l/min CO2 generation. The office at an IKEA is
more active than a typical business office where workers are continually sedentary. For the playground, a 1.9
Met was used. The activity level here is higher but given that the occupants are smaller children, a smaller met
is appropriate. The sales area includes a moderate amount of work at 2.3 mets considering that as a self-service
furniture store, customers will be loading, unloading and carting relatively heavy objects. The warehouse uses
the same met numbers as loading and unloading of heavy objects is also encountered. From the met values and
associated CO2 generation rates along with the outside air to be delivered per person, and expected level
of CO2 was determined. Since CO2 sensor accuracy can vary between 50-100 PPM given the equipment
limitation, a safety factor was implemented for the CO2 sensor set points to assure that excessive CO2 rates will
not be realized.”
The HVAC drawings with CO2 sensor locations highlighted in each zone as well as the cut sheets are attached.
The following narrative describes their vertical placement:
“The current design for the IKEA Brooklyn store incorporates a system of CO2 sensors to assure indoor air
quality. The control system will indicate to the operations staff if the CO2 levels get too high. The LEED 2.1
CIR Ruling dated 3/23/04 states that the CO2 sensors should be in the breathing zone. In the sales areas of the
store, the walls are covered with shelving and movable furniture displays, including fully modeled display
spaces that replicate an actual living space which are changed on a regular basis. There are also display shelved
covering the walls and columns. It would therefore not be feasible to locate the CO2 sensors at 3' to 6' in these
areas. The CO2 sensors have been installed at approximatley 8' above finished floor to avoid obstruction and
continual relocation. In the warehouse area, the CO2 sensors have been raised to avoid furniture carts and
forlifts. All spaces are open to structure. It is very unlikely that the CO2 levels in the breathing zone will differ
from the CO2 levels at 8' high given the constant swirling and air mixing produced by the HVAC supply air
diffusers. I would expect the the CO2 levels at 8' -if any different- would actually be higher than the breathing
zone concentrations given that the air expelled by the occupants is warmer than the space temperature and the
effects of natural convection. This would in effect create a safety factor since the area of detection could have a
higher concentration of CO2 than the actual breathing zone.”
The intent of the credit is to “provide capacity for indoor air quality monitoring to help long-term occupant
comfort and well-being.” We believe we meet the full intent of the credit as the system is adequately
monitoring and reacting to CO2 levels in the building.