We have a factory project with some rooms where I am not sure about their classification as "occupiable" or not. Specifically they are "dirt removal" and "cleaning" rooms. I am still working out the actual type of activity that will occur in these rooms, but I still want to ask the question because I'm having trouble understanding how in practice a room is defined as "occupiable" or not. I have seen in other posts and in ASHRAE 62.1 the definition: "an enclosed space intended for human activities, excluding those spaces intended primarily for other purposes, such as storage rooms and equipment rooms, that are only occupied occasionally and for short periods of time."
I have never had to demonstrate the fresh air supply in Toilets (restrooms) in my LEED submissions, and I see most discussion about toilets on this forum are related to exhaust rates. So am I right to say that Toilets are not considered "occupiable"? We have never included toilets in our ASHRAE 62.1 fresh air calculation and never had a comment about it.
But why would toilets not be considered occupiable but corridors and vestibules be considered occupiable? I saw a comment that a LEED reviewer will usually consider that if the time spent in the room is less than 15mins it would be considered a "short period of time". But I think it could be argued that corridors and vestibules are "occasionally" occupied and in most cases certainly for "short periods of time". A toilet has more of a human activity purpose than these types of spaces. The only explanation I can think of is that ASHRAE included "corridor" as one of its occupancy categories, but at the same time "storage" and "electrical equipment room" are also ASHRAE occupancy categories even though they are specifically mentioned as excluded by the "occupiable" definition as above. Does anybody have further insight about this?
Dave Hubka
Practice Leader - SustainabilityEUA
LEEDuser Expert
528 thumbs up
December 2, 2021 - 8:35 am
my understanding is as follows:
Occupiable = a person can walk into the space. (eg. office, corridor, restroom, inactive storage, etc.)
Unoccupiable = a person can NOT walk into the space. (eg. mechanical shafts, wall space, etc.)
Occupiable is broken down into the following:
regularly occupied (office), non-regularly occupied (corridor, break room), unoccupied (inactive storage), and exhausted (restroom).
Regularly occupied rooms and non-regularly occupied rooms are included within the ventilation calculation. Unoccupied rooms and exhausted rooms are not entered into the ventilation calculation.
When registering the project in LEED Online, the gross floor area of the project is listed. Gross floor area is measured from the exterior wall. When measuring rooms for the ventilation calc, net occupiable space is used - this is measured from the interior wall.
Total floor area within the ventilation calc is typically quite a bit less than the floor area listed when registering the project in LEED Online; you made need to explain the difference to the LEED reviewer when submitting your application.
Hope this Helps!
Timothy Ian Middleton
Worklounge 03- Vietnam1 thumbs up
December 8, 2021 - 5:41 am
Thanks David. Can I ask for clarification on your opinion of one thing:
"Occupiable is broken down into the following:
regularly occupied (office), non-regularly occupied (corridor, break room), unoccupied (inactive storage), and exhausted (restroom)."
Does that mean that if a room may be considered "non-regularly occupied" but it is exhausted (eg restroom), it is considered compliant with this EQ prerequisite even though it may not have direct fresh air supply to that restroom space?
The reason being that in my project there are some very specific spaces, one is a cleaning room like a janitors closet, but bigger. The second room is where some checmicals are applied and then the product is left to dry. Both rooms are exhausted and I believe logically should be treated similarly to a restroom/janitors closet. But how to know for sure?
Dave Hubka
Practice Leader - SustainabilityEUA
LEEDuser Expert
528 thumbs up
December 8, 2021 - 9:10 am
The rooms you describe have exhaust requirements and hence can be excluded from the EQp1 Minimum IAQ Performance ventilation calculations. Direct supply of outdoor air is not required in such rooms.
Think of 'commercial kitchens'. They are regularly occupied and have exhaust requirements as listed in Table 6-4 of ASHRAE 62.1-2010....and therefore are not included in the ventilation calculations.
If the programmatic space type of a room aligns with the use of the rooms listed in 'Table 6-4 Minimum Exhaust Rates' then they would not be included in the vent calc. But GBCI may require the team to confirm the exh rates listed in this table are met. once again, direct supply of outdoor air is not required in rooms with exhaust requirements.
good luck!
Timothy Ian Middleton
Worklounge 03- Vietnam1 thumbs up
December 13, 2021 - 4:09 am
Thanks so much David. What you've written makes sense, and I was having trouble finding it in ASHRAE or LEED.
Fotis Kotsopoulos
December 13, 2021 - 4:26 am
However keep in mind to include some make up air (75-90%) into EQp1 Minimum IAQ Performance ventilation calculations. Especially for WC areas.