Hello,
Our project is to build a two-story office building in Indonesia. For cooling, the building will be served by AC using VRF system (ceiling cassette) in each designated space that has MERV6 filter. Since this project is located in a tropical climate region (climate zone 1), heating is not applicable.
For ventilation, there is no applicable local code or local equivalent, so we assume ASHRAE 62.1-2007 standard should stand. Our current design is to provide natural ventilation only and no mechanical ventilation.
However, I got confused with the following:
"the naturally ventilated spaces shall be permanently open to and within 8 m (25 ft) of operable wall or roof openings to the outdoors, the openable area of which is a minimum of 4% of the net occupiable floor area". I'm not familiar with ventilation, or let alone ASHRAE.
Operable wall and openable area above are two different things right? Are operable wall include windows only, or could include doors as well?
Subsequently, does the openable area can be in the shape of windows or doors as well?
Do the 4% of the openable area of naturally ventilated space must always be opened or can we close it?
Correct me if I'm wrong, but I got the impression from the statement above that the naturally ventilated space should have distance to the operable windows and have an openable area which is 4% of occupiable floor area
How about if our design is to provide the occupiable space (mainly the regularly occupied space) with operable windows that can be open directly to the outside air. That the openable area are the operable windows area. Can this be acceptable?
Based on the above information, we would likely to fill the leedonline form as follows :
1. Only checks "natural ventilation" and "mechanical condition" box
2. Tick NO for "Is the project located outside of the U.S. and pursuing Option 2 or a local equivalent in Option 1"
3. Filling the Table IEQp1-A5. Natural Ventilation - System Name and Number: (AHU 1) with : Windows
Is this correct?
Andrew Mitchell, P.E.
PrincipalMitchell Gulledge Engineering, Inc.
LEEDuser Expert
126 thumbs up
August 27, 2013 - 10:08 am
Yasir, your approach is correct. For clarification, "operable wall" is not a noun. operable is being used as and adjective to describe the opening. The openable area is the area that will be open to the outside when open. For example, a single hung window that is 2' wide x 4' high is an opening. The openable area would be half (2'x2' area that opens up). That would give you 4sf of area which is good for a 100sf space. I hope that helps.
Julia Weatherby
PresidentWeatherby Design & Co. Engineers
94 thumbs up
August 27, 2013 - 10:20 am
The operable area just needs to be openable. It does not have to be open all the time. It can be closed when the occupants do not feel the need for ventilation.
Adi Negara, LEED AP BD+C
Green Building FacilitatorPT. Indonesia Environment Consultant
30 thumbs up
August 28, 2013 - 1:00 am
Thank you Andrew and Julia for the explanation. I think I have a better understanding now. But I still have some concerns.
ASHRAE: "Naturally ventilated spaces shall be permanently open to and within 8 m (25 ft) of operable wall or roof openings to the outdoors, the openable area of which is a minimum of 4% of the net occupiable floor area"
For example, there's a 2,000 sf office room in our building that have operable windows area of around 40 sf (2%), then we just need to add more windows right?
But, how about if it turned out that there's a portion of that space (say, 1,100 sf) have distances more than 25' (8m) to the windows. It is useless to add more windows now, isn't it? How can we deal with this and is it possible to solve this issue without adding any mechanical ventilation? Does the presence of AC could helped?
Unoccupied areas don't need operable windows, but how about the non-regularly occupied space, such as storage, kitchen/pantry, etc. Do we still have to provide them with 4% of opening area or smaller than 4% can be ok?
Thank you
Andrew Mitchell, P.E.
PrincipalMitchell Gulledge Engineering, Inc.
LEEDuser Expert
126 thumbs up
August 28, 2013 - 8:43 pm
Yasir, if you cannot be within 25' of the exterior wall then you could add some operable opening in the roof. I have only seen this in Europe myself. As for the occupied and unoccupied spaces, all occupiable spaces need to comply with the ventilation requirements. See the definitions section to determine if a space is occupiable or not.
Adi Negara, LEED AP BD+C
Green Building FacilitatorPT. Indonesia Environment Consultant
30 thumbs up
August 29, 2013 - 5:53 am
For room that has direct opening, the openable area should be 4%, and has distance of 8 m. For interior room that is ventilated through adjoining room, openable area is 8%, but how far the distance for this?
When the case is that we couldn't add any opening to the roof, because it's located in the ground floor (there's another room above) and/or the construction of that room is almost finished, how can we deal with this?
There is a possibility that few occupiable rooms cannot comply with the requirements due to certain limiting conditions. Do you think the reviewer would be kind to give us any tolerance/leniency.
Andrew Mitchell, P.E.
PrincipalMitchell Gulledge Engineering, Inc.
LEEDuser Expert
126 thumbs up
August 29, 2013 - 10:08 am
The distance and 4% to outside stays the same. The opening between rooms is 8% or no smaller than 25 sf. If you cannot meet these requirements then you need mechanical ventilation. There is no tolerance by the reviewer. You may be able to get a building permit but I do not think it will be LEED Certified.
Michelle Robinson Schwarting
Re:Vision Architecture139 thumbs up
August 29, 2013 - 10:47 am
I'm not sure if any of this will help in your situation, but here are some things to look in to:
* I believe that "an engineered natural ventilation system can show compliance with acceptable engineering calculations or multinodal bulk airflow simulation" even if parts of the spaces are farther than 25' from the openings. (ASHRAE 62.1-2007 Section 5.1 also has an exception for engineered natural ventilation systems when approved by the authority having jurisdiction...)
* There's a LEED Interpretation that may help. (http://www.usgbc.org/leed-interpretations?keys=10144)
* Also check out the addendums to the ASHRAE standard as there may also be some options there. (Ex. "Addendum n" - http://www.ashrae.org/File%20Library/docLib/Public/20100608_ad62_1_2007_...)
Good luck finding a solution to the prereq!
Michelle Robinson Schwarting
Re:Vision Architecture139 thumbs up
August 29, 2013 - 10:55 am
One more thought -- if you've got AC that's recirculating the air, perhaps you can add a fan to bring in more outside air, and then you've got a mechanically ventilated system (see LEED User Bird's Eye View above) which completely changes your analysis. Perhaps there's a way to use mechanical fans just to get the air to the few rooms that aren't meeting the requirements so those rooms could be considered mechanically ventilated while the rest of the building is naturally ventilated?
Adi Negara, LEED AP BD+C
Green Building FacilitatorPT. Indonesia Environment Consultant
30 thumbs up
August 31, 2013 - 11:50 am
Michelle, the AC will use ceiling cassette type, and yes it recirculates the air, but I don't know about bringing outside air through fan, the team has concerns about the hot outside air that could bring discomfort to the occupant, and will create greater workload as well as power consumption.
Nativa Architecture
Nativa S.r.l SB1 thumbs up
March 7, 2018 - 10:11 am
Shall we use the main entrance doors as openable wall?
Dionisio Franca
DirectorWoonerf Inc.
30 thumbs up
March 7, 2018 - 7:48 pm
Hi Adi,
How do occupants know when they need ventilation? If it is hot outside people might just keep the windows closed. Did you analyze energy recovery ventilation? You can keep your current opening, occupants do not have the risk of having bad indoor air if no one opens the windows. You have a better overall energy efficiency. If possible, controlling the energy recovery ventilation units with CO2 levels can be an optimization too.