Kitchen exhaust in Multifamily buildings

Nicolas, have you had any luck getting an anwer for this?

Nicolas,  I believe you are correct. Kitchens require the exhaust you listed; exhaust for gas ranges must be vented to the outdoors; exhaust for electric ranges can be recirculated. Per the ASHRAE section/exemption you pointed out.  Furthermore, the LEED reference guide specifically states "gas ranges must have hoods that exhaust air directly to the outdoors". This is found within the 'Project Type Variations - residential' section of the EQp1 prerequisite language. The reference guide does not specifically state that electric ranges require the exhaust to be vented to the outdoors, nor does the language generally state "ranges must be exhausted....." Hope this helps!

Hi David, To further this discussion, I have a counterpoint. Without getting into the exception from ASHRAE 62.1 section 5.6 that Nicolas points out to, my understanding is that the current requirement is to have exhaust to the outdoor in the kitchens regardless of what type of stove is used, based on the following arguments:

1. ASHRAE 62.1-2010 section 6.5 (which is part of the requirements from IEQp1), requires exhaust from the kitchen and doesn't limit this requirement by the type of stove; and ASHRAE explicitly states that it defines exhaust as air being directed to the outdoors in its Definitions section.
2. In LEED v4 for Mid-rise IEQp1, which although is not NC, is pretty explicit that kitchen exhaust should be routed to the outdoors, without mention if the range is gas or electric.
3. Since 2012 there is the LEED interpretation 10248, which granted was for LEED 2009, that states that kitchen exhaust (without qualifying if the range is gas or electric) is required to exhaust outdoors.

To me all of these point that the kitchen exhaust, without taking into account the type of range, should be to the outdoors. That being said, the exception from section 5.6 and the following ASHRAE interpretation that Nicolas points out to in the opening post, to me opens another can of worms:

• Wouldn't that exception in section 5.6 be in direct contradiction to the exhaust requirements from section 6.5 in ASHRAE 62.1?
• ASHRAE has their own committee for resolving inquiries, but how does it interact or affect LEED projects?

​I guess that this is one of those things where the devil is in the details, but it definitely would have a big impact on what we are requiring or not from Multifamily projects.​ Let me know your thoughts, thanks.

Soooo..... do we have to exhaust a kitchen hood if there is a gas hood??? haha Clear as mud.

Hello Camilo, Thanks for the post, you provide excellent points.  It might be best for the project team to contact LEED coach for an official ruling....seems like there is a good point/counter point on this technical issue. 

Hi all, Yeah, I think that would be the best, to get an official ruling from LEED to clear this issue (I don't want to take risks with a prerequisite). Thank you

Hi all, We got this reply from GBCI regarding the original question which clears things up:

A recirculating hood cannot be used to meet the exhaust requirement for a residential kitchen.  According to Table 6-4, residential kitchens must have 50 CFM continuous or 100 CFM intermittent exhaust, irrespective of the type of range provided. ASHRAE 62.1 Section 3 defines "air, exhaust" as "air removed from a space and discharged to outside the building by means of mechanical or natural ventilation systems." By definition, exhaust air must be sent directly to the outdoors, so recirculating range hoods do not comply. A recirculating range hood may discharge into the space if allowed by the manufacturer and permitted by local code, as noted in Interpretation 62.1 2010-9, but it does not qualify as exhaust. Note that the range hood is not required to be vented if the kitchen exhaust requirement is met independently of the range hood.

So according to this, a recirculating hood is valid (if it complies with the ASHRAE 62.1 5.6 exception), but the air would still need to be exhausted from the kitchen to the outdoors "irrespective of the type of range provided" to comply with the requirement.

So if in construction, the outside ductiong got overlooked, could a bath type exhasust fan be added to the kitchen area to exhaust to the outside? If so, what CFM,s? Thanks, Ron

Follow up question. Does it matter what edition of the Bldg Code the city is following?

Hi Ron,
So replying to your questions:

1- as long as the fan exhaust 100 CFMs to the outdoors, at least from a LEED and ASHRAE perspective it wouldn't matter what type it is.
  2- In general LEED calls for the most strigent code between ASHRAE and the local building code; so if the local building code doesn't require an exhaust for the kitchen (but ASHRAE 62.1 does), in order to achieve the LEED certification you would need to comply with the additional requirements from ASHRAE 62.1

Hi all Do kitchen range hoods vented to the outdoors need to be tested as part of the final ventilation testing for LEED for Homes? Please note that there is also a kitchen exhaust fan running continuously at around 50 cfm but ACH are less than 5. All kitchens have range hood vented to the outdoors. 

Hi Ruddy, Well, LEED for Homes has different requirements than LEED BD+C, so not sure what of those requirements would apply to the exhausted range hood.