CS 2009 IEQc1: Outdoor Air Delivery Monitoring

Mostly right—you do need to required tenants through lease agreements to comply with the credit as well, so that would imply the need to provide infrastructure supporting this.

William, there is no specific requirement for this, no.

You only need to have a system in place, which allows for the installation of CO2Carbon dioxide sensors and demand controlled ventilation. Just like the thermal comfort control (thermostats) for rooms you may not know yet, how this is going to be built out. So you will need for instance VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. boxes (no constant volume) with the possibility to connect to the CO2 sensors. Also the main outdoor air intake need to be monitored.

I don't see any requirement in the credit language (for my CI project) for the CO2Carbon dioxide sensors to actively control ventilation levels. Is this a difference between the CS and CI credits or am I missing something.

Are you sure the circulation area needs to be monitored? It's not regularly occupied space where there are people working, is it?

Usually 800-1000 ppmParts per million. are normal upper bounds. Depends on the outside air condition as well. I think the difference becomes important. I read a good article in ASHRAE Journal on this, but can't remember for sure what the numbers were. Outside normal is about 400 ppm as the standard. 600 ppm would be for offices if the outside is at 400 ppm (I think)...is there not something in the ref guide about this?

CO2Carbon dioxide sensor issue

Those are indeed top notch questions.
1)

If you have automated variable volume control dampers elsewhere in the building, you could program them to turn down airflow to non-CO2 effected zones to say 50% to give you enough air to shortly "flush-out" CO2-effected zones. Remember that normally it takes a long time for CO2 to build up in a large space.

If you have only constant dampers, you could ask the manufacturer if you could increase the max fan speeds for a short flush-out period on the main AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork..

How can I calculate the value of safety margin that will mitigate CO2 levels below 800ppm for example? ---Luckily LEED doesn't ask you to calculate this. There are simulation programs like CONTAM and EnergyPlus that can do this with considerable effort, but I would go on the fact that the AHU / system in place is only capable of delivering an absolute maximum of X and would not over design a system for a scenario that is likely never to happen. That's what smoke exhaust systems are for. The CO2 sensor credit is about alerting to a problem, more than over designing a AHU to fight smoke.

2)see the second part of 1)

3)If you do the american thing and try and combat loads with air from the AHU, you usually end up with huge ducts transporting a mixture of fresh and the much larger volume of recirculated air, meaning the AHU is large enough for transporting 800% the required fresh air if it had to run on 100% outdoor air...so basically you'll tell the system to ignore space loads during the "flush period" and just run as much outdoor air as you can suck in through the ducts to outside.

CO2Carbon dioxide sensors and outdoor air flow monitors are not required in tenant spaces that are not within this scope of work. However the base building mechanical system must be designed so that these sensors can be added during the tenant fit-out. It is recommended to include requirements for monitoring devices in tenant guidelines or lease agreements.

Hi Allison,

Many thanks for the reply.

We will definitely include the requirement in Tenant Guidelines, but could we get the point even if all main occupied areas are tenanted?

The only place I could think of that would be considered "occupied" and C&S is the entrance lobby. Would that be enough to get the credit ?

Thanks,

Sorry for not getting back to you sooner. I would think that you can get the credit with your scenario above, though I am not absolutely positive. I know in CS 2.0 you could get the credit by obligating all tenants through lease agreements to follow the credit requirements, but I have not yet submitted a CS 2009 project. I did a little searching and it is a bit vague whether that path is acceptable for CS 2009. I would think so, but maybe submit a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide to be sure?

Hi Allison,

So I followed your advice and submitted this as a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide. The following is the answer I got from the USGBC:

"The applicant is requesting clarification regarding compliance with the credit for spaces with tenant fit out. The applicant notes that it is not yet clear which spaces will be densely occupied. Details for Core and Shell projects with tenant fit out spaces can b e found under the Core and Shell Appendix 4 of the LEED Reference Guide for Green Building Design and Construction. Outdoor air flow measurement devices are required for all mechanical ventilation systems serving the Core & Shell project unless the Core and Shell scope of work includes installing CO2Carbon dioxide monitoring for each regularly occupied area in the space. Per the LEED Design and Construction Reference Guide, project teams may want to design control systems with the capability for future expansion to allow CO2 monitoring for densely occupied spacesDensely occupied spaces are areas with a design occupant density of 25 people or more per 1,000 square feet (40 square feet or less per person).; however, this is not required for compliance with this credit under the LEED Core & Shell rating system.
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Note the following in their answer: "Outdoor air flow measurement devices are required for all mechanical ventilation systems serving the Core & Shell project unless the Core and Shell scope of work includes installing CO2 monitoring for each regularly occupied area in the space". In my opinion, this means that we only need to install the CO2 sensors and Outdoor measurement devices in C&S areas only. They do not mention the need to have a tenant lease agreement requiring tenants to install CO2 sensors and outdoor measurements devices. I welcome your comments on this.

When it is mentioned: "Outdoor air flow measurement devices are required for all mechanical ventilation systems serving the Core & Shell project", does it mean we shall install these devices for each AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. or each end-user devices (such as Chilled beams) ? Thanks

Val,
you only need to install those devices for AHUs providing at least 20% air supply to nondensely occupied spacesOccupied Spaces are defined as enclosed spaces that can accommodate human activities. Occupied spaces are further classified as regularly occupied or non-regularly occupied spaces based on the duration of the occupancy, individual or multi-occupant based on the quantity of occupants, and densely or non-densely occupied spaces based upon the concentration of occupants in the space..

CO2Carbon dioxide monitors cannot replace outdoor air monitors. CO2 sensors do not provide the same benefit in non-densely occupied spacesNon-densely occupied spaces are areas with a design occupant density of less than 25 people per 1,000 square feet (40 square feet or more per person)." as they do in densely occupied spaces. CO2 sensors measure only CO2 generated by human occupants and they are typically not a good way to indicate indoor air quality in non-densely occupied spaces.

I have the same problem: the project is a Comercial Interiors on three floors of a non-LEED building.
The project is reusing the central HVAC form the building which comply with more than a 30% rate of Outdoor Air.
The air flow is constant. The HVAC expert installed CO2Carbon dioxide sensors all over the place with the folowing rationale:
CO2 sensor would indicate the air quality while the flow sensors would measure the air flow, but they do not assure the air quality of that flow. This apparently will jeopardize this credit, however other technicians agree with the criteria. Really, there are no "special circumstances" in this case?
Thank you

It sounds like you have both outdoor airflow measurement devices and CO2Carbon dioxide sensors. Is that correct? If so, CO2 sensors are redundant from a LEED perspective if they are also installed in the non densely occupied spacesDensely occupied spaces are areas with a design occupant density of 25 people or more per 1,000 square feet (40 square feet or less per person).. Though your project will meet the LEED criteria if both are installed.

Allison, thanks for your answer, but no, unfortunately I have only a lot of CO2Carbon dioxide sensors. The HVAC engineer discarded the option of flow meters because of the constant flow from the AHUs and the 30%+ calculated rate of outdoor air. he says that the flow meter is unnecesary because the flow is assured at a constant rate, and the flowmeter will not ensure the "quality" of this flow.

CO2Carbon dioxide sensors cannot replace outdoor air flow monitors in non-densely occupied spacesNon-densely occupied spaces are areas with a design occupant density of less than 25 people per 1,000 square feet (40 square feet or more per person).". And per the July 2010 LEED addenda, it appears that both CO2 sensors and outdoor air flow monitors are required in densely occupied spaces. I can understand your rationale, and we have had an ongoing conversation in our office about this issue, but I think that the value of the outdoor air flow monitors is to confirm that the system is operating as designed and to problem solve later on if any maintenance issues arise.