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Baseline for outdoor air ventilation
This prerequisite establishes a baseline for providing a minimum amount of outdoor air to buildings in order to maintain good indoor air quality and keep occupants comfortable and healthy. This prerequisite references ASHRAE 62.1-2007 (with errata but without addenda) and is often more stringent than local building codes, although it is not likely to entail any added costs.
Two cases, both may be needed
The compliance paths for mechanically ventilated and naturally ventilated spaces, Case 1 and Case 2, are somewhat different and you may need to follow both paths for the same building. Naturally ventilated spaces must follow the distinct requirements set out in Case 2, even if other spaces in the same building are mechanically ventilated and are following Case 1. Mixed-...
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209 Comments
Electric Cigarettes
Dear all,
one of our major clients set an interesting question concerning electronic cigarettes. In the building we already certified smoking is not allowed, but could be electronic cigarettes? It seems they are not emitting ETSEnvironmental tobacco smoke (ETS), or secondhand smoke, consists of airborne particles emitted from the burning end of cigarettes, pipes, and cigars, and is exhaled by smokers. These particles contain about 4,000 compounds, up to 50 of which are known to cause cancer. so the intent of the credit is met.
Do you support this estimation?
Andreas
Andreas,
This appears to be a judgement call. There are no LEED Police that will visit your building after you finish submitting to ensure no one is smoking in your building. Case in point, I visited a LEED Gold project in Vegas where everyone was smoking in the Casio (they did not appear to have the proper separations.
You are required to have signage that prohibits smoking per IEQp2 (consider re-posting your question there).
Dylan,
thank you very much - somehow I switched to p1 ;-)
Actually my client wants ot have a proper LEED policy in his building, though the LEED Police maybe will never show up.
I will repost my question under p2.
Natural Ventilation compliance
Hi,
We´re working on a project that is pursuing IEQ P1 via natural ventilation. The 4% of ventilation surface required could be achieved using operable windows? Or it is mandatory the use of permanent vents?
Thanks for the answer
Guillermo
Hi Guillermo:
ASHRAE 62.1 clearly states: "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."
So the answer to your question would be: yes, operable windows can be used. Hope it helps.
Hi Luis
Thanks for the reply. The confusion came up with the term "permanently" i thought that only vents were allowed to satisfy the credit since operable windows could be closed by employees.
Thanks again
Complying with Natural Ventilation Req. in a Apartment Bldg.
We have a multi unit high rise residential bldg. and we are attempting to provide natural ventilation to all units using the operable windows and sliding doors. We have confirmed the amount of opening area complies with ASHRAE 62.1. The sticky part is that the units are greater than 25 feet in depth from with openings. In reviewing the comments it appears acceptable to use a fan/blower to assist in the movement of the air deeper into the interior of the units and to have a manual switch that the user can operate as needed.
Assuming the above premise is correct, could we not use the central a/c unit air handler to serve the same function. The unit thermostat has an off/on/auto function for the fan that allows the user to operate as needed. The fan (whose intake is located in the first 25 feet) would recirculate the air to distribute the fresh air to areas that are more than 25 feet away from the openings serving the same function as a booster fan. This seems like a more sustainable solution than installing a new system that would accomplish the same function.
A second solution would be to use the same system but install a CO2Carbon dioxide sensor in the area more than 25" away and have it control the fan as needed but this would seem like overkill. Thoughts?
We have the same situation... I was also thinking that the bathroom vent can be use to help circulation of air to the interiors. In our case the bathroom fan is speed controlled, meaning that we can adjust the speed of fan to a low level when the bathroom light is off and to full speed when the light is on. So we can have 24 hour suction from the bathroom fan and it would suck the air from other rooms thus helping the natural ventilation. We would like to this is acceptable but I wonder if anyone else ran into the same situation.
Robert (or anyone) - Did you come up to a solution? Thanks.
Corridors in Dwelling Units
Dear All,
In a residential building with natural ventilation only, should corridors and entry halls in dwelling units be shown to be provided with outdoor air (meaning complying with requirements of Section 5.1 or utilizing an engineered system)? Or are these spaces considered non-occupiable and exempt from the requirements?
When they are enclosed they require ventilation. Typically, we do not provide ventilation or conditioning in corridors and entry halls for multi-family residential because they are not enclosed.
Zone air distribution ventilation effectiveness
I need help with determining proper case for the Air Distribution Configuration per table per Table 6-2. The forth entry required a velocity of 150 cfm to be reached within 4.5 ft of floor levels. Does it mean that this velocity should be achieved at this height or this is the requirements for the velocity measured at grid level. Our mechanical engineer is claiming that this is velocity is too high for that height, and wants to make the case for 150 cfm to be measured at grid levels. Please advise!
ASHRAE 62.1 Calculator
Please guide on how to determine Ds - Percent design primary air flow for worst case condition?
For constant volume systems, Ds is 1.0 at both the system and zones. For 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. systems, Cooling condition: Ds is typically 1.0 for the system
I'm understanding it in this way. Ds is the supply efficiency. However, this is typically assumed to be 95% considering 5% as supply loss. If your design cfm (Vdzd) is 2800, if Ds is 95%, then Vpz becomes 2800*0.95=2660. The supply efficency for the best & worst conditions are same as the duct design remains same.
Ds is a population diversity factor, not a supply efficiency factor. If you don't have a good sense of the diversity to apply, 1.0 is acceptable as a default.
Dear Chang,
Percent of total design airflow rate at conditioned analyzed is Ds interms of %. Occupant diversity is D in terms of % again. The latest version of LEED online templates accounts for these two factors. These two values have to be fed in the template. These are not automatically calculated.
Please refer to page 14 in the following link - http://www.accessengineeringlibrary.com/mghpdf/0071741828_ar022.pdf
I have referred to the above document & came to this assumption.
It will be great if you can guide my on my understanding.
Thanks :-)
Thanks for the clarification about which variable you were inquiring about. The D variable should be adjusted to reflect the realistic zone airflow rate under the condition you're looking at. For heating, this would typically be 30% of the design cooling airflow rate for a 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. system (or the VAV box min setting). D is not a measure of supply efficiency, but rather to account for different operating conditions. You'll find that higher VAV box minimum settings are sometimes necessary to keep the system level ventilation fraction from driving up to 100%. Hope this helps!
Dear Roger Chang,
Thanks for response.
can I assume that 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. box minimum setting is Ds.
For cooling, How Ds can be determined? if any thumb rule is there?
Can I input Ds only for critical zone and blanche zones,I can have 100% for cooling condition.
If it is a design process, how to estimate the Ds for the condition analyzed like worst case condition i.e max occupancy and low load?
For cooling, assume 100% for Ds, if you have no other information. You've touched upon one of the challenges with ASHRAE 62 compliance for 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. systems. You'll find that the design heating condition is going to drive your system level ventilation requirement.
local code IEQ requirements
In New York the local code does not follow IBC or ASHRAE 62.1. It requires 20cfm/person and 0cfm/sf. How do I go about proving to USGBC that the ventilation levels are adeqaute, when all the template references is 62.1 and the 62MZcalc?
You'll want to use all of the ASHRAE 62.1 calculation methods and then compare the ventilation rates to NYC codes on a zone and system level. The NYC code rates tend to end up being higher than ASHRAE 62.1 rates. For NYC code, application of 403.3.2 (multiple-spaces approach) will result in high system-level ventilation rates.
Alternative Compliance path for international projects
The USGBC has published a draft for additional guidance for international projects. That includes alternative compliance paths and even additional LEED online forms for international projects. This credit is included in the guideline. Find more here: http://www.leeduser.com/topic/international-projects-alternative-complia...
Parking garages area - ASHRAE 62.1
According to ASHRAE 62.1 the ventilation rate for the parking area needs to meet 0.75 CFM/sqft.
My question is if the inside parking streets are included in the square footage for the calculation or should I include only the area of parking spots?
Thanks,
Felipe, you should include the entire enclosed parking area, both spots and vehicle traffic aisles.
IEQp1 ASHRAE 62.1 Calculator
I read through previous posts and have not seen an answer to this question so forgive me if I missed it. The ASHRAE calculator does not seem to apply to 100% outdoor air systems. Is this true or am I missing something? According to the standard, Vot = Sum Voz which forgoes the calculation of Ev. I do not see this option in the calculator.
The ASHRAE calculator that LEED supplies does not apply to 100% OSA systems. It applied to Multi-Zone Recirculating Systems. There is a difference calculation method for that type system. It is more straight forward.
See section 6.2.4 in ASHRAE 62.1-2007.
The equation says that you need to supply the total amount of air required by ASHRAE/Ez. So you don't do the correction for Zp/Ev. On the LEED form just use 1.0 for Ev because they don't let you leave it blank.
ventless fireplace
I'm working on a stand-alone "amenity/community center" adjacent to an apartment buliding, and it will feature a gas fireplace in a common room. Would a ventless fireplace raise red flags with LEED? I honestly don't think it would even show up in any of the documentation we provide under NC 2009, but want to be sure we don't make a decision that will jeopardize our certification or future EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. certification.
Jill, I would argue against using a ventless fireplace on simple building science grounds—forget LEED.
That said, I can't think of any specific way in which it would cause problems in terms of LEED.
Jill, is this a fireplace that uses a gel-type alcohol based fuel?
non default occupancy values
I received a comment on a review that the occupancies used for EQp1 did not meet the peak occupancy listed on PF3. I have always assumed these as separate issues and argued that we used ASHRAE defaults for EQp1 and more realistic occupancy values for PF3. The reply I received said that these had to match. Anyone come across this before? Thanks!
Hi Janika,
I believe these occupancies do need to match and that they auto populate in newer versions of LEED-online forms.
Hi Emily,
They don't auto populate. One of the options for this credit is to use the ASHRAE default occupancies (which we've done) calculated per room type. This is different than what we used to calculate occupancy loads for the building (based on schedule of use) and this is not how occupancy is calculated in PF3. Any other thoughts?
What version of the forms are you using? I may be wrong about the auto-populate, but v04 of this form makes it clearer which occupancy to use. You can download newer forms (assuming you're not already using v04) from LEED-Online under Sample Forms Download. The newer form may shed some light. Otherwise, I'm not sure.
Anyone else have thoughts?
Hi Emily,
We are using V03. I don't see in either V03 or V04 where the occupancy would auto populate. It says that PF3 links to SSc4.2, SSc4.3, SSc4.4, and WEp1. The EAp1 V04 form still gives the option to use the default occupancy rates. Where do you see that it makes it more clear? Thanks
Janika,
I thought you may be using a beta form, since you're not I don't have enough experience with this credit to help, sorry.
Someone else on LEEDUser may have more experience and be able to help.
Seeking Clarification regarding rooms to be listed on LEEDonline
Hi, we have a mechanically ventilated building. In the review comments from our combined design and construction submittal we have received the following comment since the total square footage of the building those not correspond to the square footage of the rooms listed on LEED-online
“Note that all mechanically ventilated spaces must be included in the Ventilation Rate Procedure calculations, including spaces that have exhaust air.”
But our understanding is that only rooms with supply air should be listed on LEED-online?
Version 3 form.
How do we show compliance with the rooms that only have exhaust air?
Version 4 form.
Here my understanding is that we don’t have to comply with the requirement for every room, just in total, which means that a room with high air flows could compensate a room with low air flows, is that correct? But should not be ok for ASHRAE?
And/or should you include rooms with exhaust air in this table?
Thank you! /Veronika
We were planning to submit NET AREAS for the spaces to be submitted this credit. Do you think we should submit Gross areas for the spaces to be ventilated? This doesn't makes much sense, since walls don't need to be ventilated, but it looks like you had some trouble because the areas submitted for this credit didn't agree with the total square footage stated in PIf3. Any idea?
Hi Veronika,
did you get any clarification on how to list rooms that have exhaust air with version 4 form? Or if those rooms should actually be included?
Thanks!
Luis: I would exclude the walls and go with the NET area. If it is a big difference you could explain the reason. But it should not be a problem, it must be the same for all projects? I realized that our project probably had a lot of non ventilated rooms.
Jose: for v4 I have not submitted yet. But my understanding is to exclude them.
Definition of "Outdoor Air"
We are seeking LEED NC certification in a high-tech manufacturing plant, and it is a normally practice to only use natural ventilation (louvers and openings to outside of the building) for spaces such as warehouses, storage, and for equipment spaces that do not require A/C (these are non-occupied areas). These areas are usually very large clearings, but there is sometime a control room or small office in the middle of these spaces. The control room and office should be classified as 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., but they only draw fresh air from those large clearings rather than drawing directly from outside of building. Can this be treated as being complied with 62.1-2007? Please help.
It seems like you'll want to supply make-up air directly to the control room and office. There's no way to guarantee that ventilation air will make it from the large bayA bay is a component of a standard, rectilinear building design. It is the open area defined by a building element such as columns or a window. Typically, there are multiple identical bays in succession. areas to the 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. otherwise.
non default occupancy numbers
We want to use non default occupancy values for some rooms in our project. Do anyone have experience what the reviewers might have for thoughts regarding this. We will describe why we don’t use the default values.
Thanks /Veronika
Veronika, the main reason not to use the default occupancy numbers is when there's a furniture plan with a defined number of seats. This may apply to a conference room, office, performing arts theater, or cafeteria. What's your particular situation?
Exactly, is it enough to explain, or should we write 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 for the rooms considered?
Thank You
There is Note 4 for Table 6-1 in ASHRAE 62.1: "4 Default occupant density: The default occupant density shall be used when actual occupant density is not known." I would make a definitive statement that you have a known design occupancy that's approved by the Owner/Client and/or based on an actual furniture/seat count.
Okej, good to know. then we will reference to the design values for the rooms given by the client. theese are some conference rooms but also rooms with only one bed for one patient. Thank you Roger.
Watch out on how these values will affect other credits, especially the lighting and thermal control credits. In those credits, the seating plan can throw off your calculations especially in healthcare group work areas.
Ventilation rates in garages
My projects can follow the Ventilation Rate Procedure in ASHRAE 62.1-2007, sections 4 through 7 without bigegr problems. The only thing that is difficult is that we have garages under the buildings that have a lower exhaust rate than stated in ASHRAE. In the garages we always have CO and CO2Carbon dioxide monitors. There is no way that a project of mine would increase exhaust rates to the rates stated in ASHRAE as these are not motivated in our country and since this would mean low energy efficiency, which is an important issue in a cold country. We would like to say that we follow the Ventilation Rate Procedure in all cases of the building except for in the garages, where we would like to follow some form of Indoor Air Quality procedure instead. Is this possible? Would it comply if we have monitors in the garage?
Our local code is more stringent when it comes to outside air rate (100 %) so the other option is to just follow the local code, including the garage rates. Local code does of course take into account number of movements in the garage, number of parking spaces, average driving distance in the garage, probability of congestion and so on when determining ventilation rates. The limit for CO is 50 ppmParts per million. when ventilation rates have to be increased.
The intent of the credit is to have a good air quality in the building, for the occupants well-being!
Please give me opinions and feedback since this has caused a headache for a long time now.
Maria,
Follow this link for more information on this subject - http://www.leeduser.com/topic/leed-certifications-parking-garages-no-lon...
John,
Sorry I don’t think this helps. Many of my office buildings have underground garages and I cannot exclude these from the LEED project, they are part of the office building. So the problem remains.
In October a new set of ACP:s were launched for international projects: https://www.usgbc.org/ShowFile.aspx?DocumentID=10335 This could be something for us and option 1 of IEQp1 states that we can use CEN standards. The problem here is, that although the standards have a status of a Swedish standard, that in its own is not enough. We have to show calculations like everyone else.
These standards have a few room types shown, but not as many as ASHRAE. And for garages there is a formula for “other known emissions” that is supposed to be used for CO. The problem here is that they don’t state what the limit of CO exposure is. Different sources say different. For example 35 ppmParts per million. for long time exposure and 100 ppm for short time exposure. Second problem, they don’t say what formula to be used when calculating CO emission rates from cars. The only one I can find in other places, and Swedish recommendations, is from the 80-ies and not relevant any more. So showing compliance with CEN Standards is hard, there are no actual values to follow. Anyone had experience of CEN Standards and LEED?
Applicable standard?
Have anyone used another reference other than the ASHRAE standard 62 for a hospital project. The rooms in our hospital are not compliant with the standard rooms of table 6.1.
We have a local regulation that we have to follow for all rooms, but it only has requirements on the number of persons in the room.
We are not designing according to ASHRAE 170.
If you want to use another standard than ASHRAE, you will have to show that your local code/standard exceeds ASHRAE requirements. That might be difficult to accomplish, if you are comparing apple with oranges. Also as you have noted your rooms don't meet ASHRAE standards. So showing that your local code meets ASHRAE standard is out of question, I suppose.
Exactly most of our rooms don’t meet the definition in table 6.1. We are thinking about writing 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 and show the rooms where we can follow ASHRAE and then state for all others we will follow the local code, since we can’t compare apples with oranges.
Thank you Susann!
We are running into the same problem as Veronika. Is there an official answer to this problem?
Veronika, is your project in the United States? Could you provide a few examples of the kinds of spaces that are not referenced in Table 6-1 of ASHRAE 62.1?
No, our project is not located in the US.
Most of the rooms are rooms with clinical requirements.
We have a specifc guidelines for rooms with clinical requirments that we are following. The Ashrae 170, is not applicable on our project. the Requirments are in many cases to stringent regarding RH values.
We run into this all the time as well. We often have to apply a different default and explain why based on the building's use. An easy example, linear accelerators are modeled as medical procedure rooms. ASHRAE doesn't list the lin accs and this makes the most sense to all. Hope this helps.
Great Susan,
Are you referring to the Normative Appendix E? We have been thinking about following that one.
So in the states, there are hospitals that do not need to meet ASHRAE 170? I thought t´his was just a problem for hospitals outside the states.
IEQp1 Corridor
Hello,
I'm working on a project that the air exchange in the corridor is made by an adjacent open plan office. I would like to know if I still comply with the requirement of the standard and how should I calculate this area? Should I exclude the area from the corridor or Should I include this area in the office area?
Thanks!
You will want to include the corridor in your calculations. Is the corridor completely open to the office?
Yes. Its open to the office. There is no door interupting the way.
So, to include the corridor in the calculation I consider it as part of the office?
Thanks,
That is a reasonable approach.
Hi Roger,
I've checked the plant and I've noticed that there are some small corridor isolated (there are door in all adjacent rooms). To comply with ASHRAE standard, do the project really need to install outdoor air duct in those spaces (even knowing that the space is very small and the volume of outdoor air in the space will be very little)?
I'm confused, because the standard doesn't require outdoor air in the toilets, only exhausting fans, knowing that the air exchange will be doing by air pressure difference. If there are some exhauster in those space, do the project comply with the standard?
Multi-family residential - ASHRAE 62.1 2007 - ch. 5 Natural Vent
We have a mixed use retail - residential project with the residential units relying on natural ventilation with the required 4% operable window area to floor area ratioFloor Area Ratio (FAR) is the measure of the density of non-residential land use. It is the total non-residential building floor area divided by the total buildable land area available for non-residential uses. For example, on a site with 10,000 square feet of buildable land area, an FAR of 1.0 would be 10,000 square feet of built building floor area. On the same site, an FAR of 1.5 would be 15,000 square feet of built floor area; an FAR of 2.0 would be 20,000 built square feet and an FAR of 0.5 would be 5,000 built square feet..
The problem is that some of the open living-dining-kitchen spaces are more than 25 ft away from the window. We do have dedicated kitchen exhaust systems towards the back of these large spaces and are hoping they qualify for what ASHRAE 62.1 calls an 'engineered' ventilation system under the 'exception to the prescriptive' at section 5.1.
ASHRAE states this must be approved by a local authority.
Does anyone have experience with the USGBC interpretation of this exception and any specific calculations and calc method they would require? There are no 'precedent 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's' on the matter although I know that they have approved booster fans beyond 25 ft, etc.
Take the exhaust cfm and apply a zone air distribution ventilation effectiveness (Ez) of 0.8 as per Table 6-2 (Makeup supply drawin in on the opposite side of the room from the exhaust and/or return). See if this corrected value meets the breathing zoneThe breathing zone is the region within an occupied space between 3 and 6 feet above the floor and more than 2 feet from walls or fixed air-conditioning equipment. (AHSRAE 62.12007) rate calculated for the entire open living area.
Roger: we are facing a similar situation with a residential building (20% of the units have spaces more than 25' from an operable window). We have had to eliminate the proposed ventilation supply due to a structural engineering constraint. In addition to using continuous kitchen exhaust, as Michele has proposed above, we will be installing trickle vents to provide additional fresh air. Our window operable area: to floor area ratioFloor Area Ratio (FAR) is the measure of the density of non-residential land use. It is the total non-residential building floor area divided by the total buildable land area available for non-residential uses. For example, on a site with 10,000 square feet of buildable land area, an FAR of 1.0 would be 10,000 square feet of built building floor area. On the same site, an FAR of 1.5 would be 15,000 square feet of built floor area; an FAR of 2.0 would be 20,000 built square feet and an FAR of 0.5 would be 5,000 built square feet. already exceeds ASHRAE 62.1 requirements, per NYC code.
Given that this design change is not being mandated by the Department of Buildings or any other authority, but rather is a response to a structural design constraint and our desire to meet ASHRAE 62.1, we will not be receiving any formal approval or review from a local authority for this proposed design. We have already satisfied code through the window operable area: floor area utilized. How critical is it that a local authority review and approve the engineered natural ventilation design when it is being proposed as best practice to meet LEED requirements, as the 'standard' design already satisfies local standards?
Ventilation Rate Schedule sample
You should update this sample under your rescources section to one that includes an Ev rate. I submitted a Ventilation schedule with the same sections as your sample and it was not excepted because it did not include Ev rates. Might be useful to others!
Is there only one Ev rate for the whole system.
Thanks, Nena,
We'll look into this and see if there something better. Anyone on the forum have a sample they'd like to offer?
Naturally ventilated office rooms served by ductless split sys.
We have a project that is predominantly a parking garage structure. All of the enclosed circulation, storage and restroom areas are provided with natural ventilation via operable windows and no air conditioning systems. However, there are four small rooms (about 140sq.ft. each) used as offices and they are provided with ductless split systems and operable windows for natural ventilation as the ductless systems are not really equipped to take and condition outside air. I was wandering if somebody had a similar situation where the space is provided with a/c and is relaying on operable windows for natural ventilation. Would this be acceptable approach to meet the IEQp1and has anybody ran into an issue with the EAp2 and EAc1 by using this strategy? Would we need an interlock to shut down the a/c unit when the window is opened or do something special from energy consumption stand point?
Natural ventilation is acceptable, as long as the window area meets the area requirements of ASHRAE 62 (4% of net occupiable floor area). The latest version of ASHRAE 62 contains additional guidance that I recommend be followed Section 6.4).
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