CO2 sensors in areas smaller than 150 sf

Hi Amanda,
I don't think you can exempt spaces smaller than 150sf from the CO2 sensor requirement in LEED-NC. The LEED-NC credit is written very differently than the LEED-EB credit. The LEED-EB credit limits the requirements based what the system is serving (either predominantly non-densely occupied spaces or densely occupied spaces). The LEED-NC credit applies to both the individuals spaces ("Monitor CO2 concentrations within ALL densely occupied spaces") and systems ("Provide a direct outdoor airflow measurement device...for mechanical ventilation systems where 20% or more of the design supply airflow serves nondensely occupied spaces"). So, in short, you must install a CO2 sensor in each space deemed to be densely occupied, no matter how small. Hope this helps clarify things. Good luck!

John,
I have seen versions of v4 drafts where rooms under 150 sf are exempt. However in the current draft I can’t find it. Do you have thoughts on this? Will it be included in v4? Am thinking about pursuing this in v2009 as a possible ACP.
See for example the middle of the page in: http://www.usgbc.org/credits/eq12 “Densely occupied space is defined as an area with a design occupant density greater than or equal to 25 people per 1,000 square feet (40 square feet per person). If the total square footage of all dense space is less than 5% of total occupied square footage, the project is exempt from the requirements of this section. Rooms smaller than 150 square feet are also exempt.”
Thanks!

Hi Maria,
I apologize on my delay in responding. The exemption that you cite is only for spaces that are naturally ventilated, i.e., not served by a mechanical ventilation system. If that is the case for you (and very well may be since Sweden is well suited for natural ventilation), then you could potentially use this credit from v4 in lieu of the one in v2009. I suggest you send USGBC an email asking for specific guidance on how to do that and how to let GBCI know your plan.
Good luck,
John

John,
Thank you for responding. Yes I can see now that it says under natural ventilation (although the page is very messy right now!). But I feel I have read about this in more places, I now found this EB:OM form (page 5): https://www.leedonline.com/irj/go/km/docs/documents/usgbc/leed/content/C...
Here they also talk about exemptions for rooms less than 150 sf.
I would say that in Sweden we always have mechanical ventilation with heat recovery. So natural ventilation is out of the question for us. I’m not a mechanical engineer, but for me it would seem logic if this credit also takes into account if it is a 100 % outdoor air ventilation system or not. Also in Sweden we always have 100 % fresh air. And according to the mechanical engineers I come in contact with, CO2 levels is rarely the problem. Temperature however will signal that the air is getting stuffy. Most of my projects don’t want to take this credit because of the small chat rooms. The rest of this credit’s requirements are already standard.
/Maria