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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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40 Comments
IEQp1 in international settings
A couple of our readers posted questions in this space asking for specific guidance on applying IEQp1 in international settings, dealing specifically with ASHRAE-62 issues. I apologize, but those comments were deleted due to "pilot error" on my part.
I've asked a couple of our esteemed experts to weigh in on this topic in general, and I also invite readers to post new comments, or re-post previous questions.
Thanks, and I apologize for the error.
Tristan Roberts replied Editor – LEEDuser, BuildingGreen, LLC Jan 29 2010
One of our consultants emailed me the following about doing this credit internationally:
The issues that can be problematic on international projects pertain primarily to natural ventilation strategies. Natural ventilation is not addressed adequately by ASHRAE 62 criteria (which establishes distance and window/area ratio requirements), particularly for projects that base substantive natural ventilation design on other criteria, such as "effective opening" area to floor area, using various (and often combined) types of ventilation, such as thermal chimneys, etc.
Also, it bears mentioning that many countries have higher volume ventilation requirements than ASHRAE 62, but equivalence comparisons are sometimes required since ASHRAE 62 can be unfamiliar to non-Americans.
Jean Marais replied b.i.g. Bechtold INGENIEURGESELLSCHAFT MBH Feb 11 2010
Putting in the 4% effective opening area to floor area also by no means garantees successful natural ventilation. That's why it is usually accompanied by the AM10 supporting documentation or a simulation: multi-zone nodal bulk air flow &/ CFD
required Upload for IEQ p1
Does anyone have a sample for the upload required for IEQ P1:
"Graphic and numeric summary of the airflow analysis performed. Include the boundary conditions used for the analysis, simulation algorithm, solution variables, temperatures, airflow volumes and mean age of air for the spaces modeled."
Josiah Ives replied Sustainable Design Consultant, KEMA Services, Inc Jan 18 2010
The prerequisite compliance should either be a calculation of the ventilation rates (as shown in IEQp1 Tables 1, 2 and 3 of the LEED Reference Guide) or it should be a table stating compliance with the prescriptive requirements of ASHRAE 62.1 Section 5.1 (as shown in IEQp1 Table 4). Your quoted text seems over the top for the Prerequisite; perhaps is it a review comment for an attempt at IEQc2 using natural ventilation?
High rise residential
I have a project that is a 8 story high residential high rise with no natural venilation and was built in the 70's and its located in Long Beach california so there was no HVAC system ever installed in any of the units or common areas. i am looking for any ideas to meet this prereq? :)
Tristan Roberts replied Editor – LEEDuser, BuildingGreen, LLC Feb 15 2010
Joseph, could you provide a bit more background and clarification? You say there's no natural ventilation, but also no HVAC? Maybe I'm missing something, but that sounds like a recipe for suffocation—definitely not ASHRAE-62 compliant! ;)
I assume this is a major renovation? Are there plans to use natural ventilation and/or HVAC going forward?
High Rise Residential
ok, we convinced them to use operable windows in all the units. but there is no HVAC that goes into the units. the HVAC only covers the common areas. and yes major renovations
Tristan Roberts replied Editor – LEEDuser, BuildingGreen, LLC Feb 22 2010
So have you reviewed ASHRAE 62.1-2007 section 5.1 to ascertain whether you might be compliant? Seems like you have a shot at it now—but only ASHRAE 62 and your credit calculations will tell you for sure.
David Posada replied Sustainability Manager, GBD Architects Mar 10 2010
You may have resolved this already, but for the record it may be useful to point out that residential projects with no mechanical ventilation in the units can meet ASHRAE 62 with operable window areas that meet the necesary percentage of floor area (4% in 62.1-2004 I believe).
One hurdle we've faced is that occupied areas must be within 25' of the operable windows. Local codes may accept a condition where part of a room is within that 25' distance, but in a previous 2.2 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 the USGBC ruled that all the occupied space must be within that 25' to comply as naturally ventilated.
In one case we were able to use a small booster/ transfer fan to circulate that air beyond that 25' distance, thus providing a combination of natural and (a little) mechanical ventilation.
Alex Wong replied May 10 2010
David,
Was the transfer fan runnign continuous?
David Posada replied Sustainability Manager, GBD Architects May 12 2010
No, they are controlled by the occupant with a switch. This was to be consistent with operable windows and mechanical ventilation having user control.
Ev (System Efficiency) for Constant Volume 100% Outdoor Air Syst
Dear All,
Looking at the LEED submittal form for this credit I am really confused. Having assumed that this will be very easy with a constant volume system that works only with 100% outdoor air (no recirculation), I see now that the form requires entering Ev (system efficiency) values for each zone???
First of all, isn't this meaningless? 62.1 standard uses Ev values for systems that are multiple-zone and recirculating. What is the point in entering an Ev value for each zone?
Second, since I am forced to enter this value (otherwise the form does not calculate), what do you suggest I enter? My system is constant volume and rates that are 30% higher than 62.1 requirements are ducted to each zone without recirculation. Slightly less airflow rates are achieved for exhaust, again ducted from each zone and exhausted directly to the outisde without any recirculation.
Thanks for any replies,
Roger Chang replied Principal, Director of Sustainability, Westlake Reed Leskosky Mar 31 2010
Omer,
With constant volume systems, Ev still needs to be determined from Table 6-3 in Standard 62.1. The value of Ev will be based on the highest Zp (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) ventilation rate / design supply airflow) value of zones connected to the system. You are correct that with a 100% outside air system, Ev doesn't affect the final result.
Omer Moltay replied Mar 31 2010
Yeah but when I follow the logic backwards, for Ev not to affect the final result it has to be equal to 1, meaning from Table 6.3 that max(Zp) has to be smaller than 0.15. How can this happen when I have a 100% outside air system?
Thanks,
Roger Chang replied Principal, Director of Sustainability, Westlake Reed Leskosky Mar 31 2010
Omer, I understand the confusion here. Please refer to 6.2.4 (Equation 6-4) to calculate Vot (assume Ev = 1). You input your actual design OA in the LEED letter template and the template determines whether you're 30% over 62.1 requirements by comparing to the calculated Vot value. You may want to attach a brief narrative describing that you have 100% OA units. It looks like the template could use a check box for 100% OA conditions.
Omer Moltay replied Apr 02 2010
Hi,
I think there's a catch here that I am seeing now. I did not tell you that my 100% outside air system works in parallel with fan coil units for zone conditioning. Looking at Appendix A, the calculations for Ev are necessary since there is secondary recirculation of outdoor air due to FCUs (not between zones but within zones). I did a quick calculation for one system and my Ev turned out to be 1.69.
Now I am trying to understand this. Does system ventilation efficiency really increase when there is secondary recirculation within zones?
Roger Chang replied Principal, Director of Sustainability, Westlake Reed Leskosky Apr 06 2010
Omer, for this type of system, Ev does not apply. The 100% outside air system simply needs to provide the appropriate 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) ventilation rate to each zone. Secondary recirculation applies more to fan-powered 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 systems.
Omer Moltay replied Apr 06 2010
Thanks for the comment. But if Ev does not apply, what's the point in asking for this in LEED submittal? I mean even if you enter "1" for Ev, this has a meaning which could mislead.
Applying ASHRAE 62.1 to an existing building
We are doing a major renovation on an existing building. The project is seeking LEED NC certification and we are having trouble interpreting how the ASHREAE 62.1 standard needs to be applied to existing spaces, the basement and the penthouse, where no improvements are being made to the ventilation system. The basement has both occupied and non occupied spaces, the penthouse is a non occupied, mechanical space.
Because these spaces are existing and no changes are being made to the ventilation systems in these areas can they be excluded from the scope of the prerequisite? If they do need to be included and improved to meet the ASHRAE standard, do both occupied and non occupied spaces (specifically the mechanical, electrical utility and elevator equipment rooms) need to be improved to the standard?
Roger Chang replied Principal, Director of Sustainability, Westlake Reed Leskosky Apr 09 2010
On a recent major renovation project, our USGBC reviewer commented that we did need to apply ASHRAE 62.1 to all spaces, including electrical, mechanical, and elevator machine rooms. These spaces are considered non-regularly occupied spacesRegularly occupied spaces are areas where workers are seated or standing as they work inside a building. In residential applications, these areas are all spaces except bathrooms, utility areas, and closets or other storage rooms. In schools, they are areas where students, teachers, or administrators are seated or standing as they work or study inside a building., but they are NOT un-occupiable spaces (like a crawl space, for example). I think the only way to get around this is to go with LEED-CI and exclude non-renovated spaces. I encourage others to share their experience with this!
Dealing with Basement Spaces in ASHRAE 62.1-2007
This question is similar to the one above. On a new construction project (70+ unit residential with first-floor commercial and parking garage) we have three spaces in the basement that we were not intending to ventilate, as it is not required by NYC building code since they are not regularly-occupied areas. We will ventilate a basement storage area, super's office, and elevator equipment room per ASHRAE 62.1. We did not intend to ventilate the electrical and water meter rooms and a small unclassified space (closet? 5'x4.5') at the end of the corridor, unless absolutely required. These rooms do not contain mechanical equipment (beyond the meters) and will only be occupied during meter inspection and reading. They were designed as separate rooms due to load-bearing walls making this an easy design solution. My questions are a) do we need to ventilate these spaces? and b) if so, what would they be classified as per ASHRAE? The tables in section 6 of the ASHRAE manual do not contain space classifications that seem well-suited to these spaces. If a closet is not being used to store janitor supplies and other potentially hazardous materials (requiring exhaust), is it considered a storage room and thus needs to be ventilated?
Any insight is appreciated.
Roger Chang replied Principal, Director of Sustainability, Westlake Reed Leskosky Apr 19 2010
There is an ASHRAE 62.1-2007 space category for electrical rooms (0.06 cfm/sf) and storage rooms (0.12 cfm/sf), which indicates they should be ventilated, even if they are not regularly occupied spacesRegularly occupied spaces are areas where workers are seated or standing as they work inside a building. In residential applications, these areas are all spaces except bathrooms, utility areas, and closets or other storage rooms. In schools, they are areas where students, teachers, or administrators are seated or standing as they work or study inside a building.. It would be good to get feedback from others on this forum also.
Mark Benson replied Apr 19 2010
Interpretation IC 62.1-2007-17 of ASHRAE 62.1-2007 clarifies that electrical rooms, storage rooms, telecommunication/data, telephone/data entry, and elevator equipment rooms don't require the per square foot ventilation rate if they are unoccupied the majority of the time. Addendum 'd' or 62.1-2007, which will be included in 62.1-2010, incorporates this interpretation.
If you want to double-check me, go to http://www.ashrae.org/technology/page/1412 and see for yourself.
30% Increased ventilation issues
The 30% increase in ventilation above ASHRAE 62.1-2007 is a good idea in dry climates. Our issuse is that we have several projects that are seeking LEED Silver with client (GSA) demanding the increased ventilation credit be applied. Since most of these projects are located in southeastern humid climates we are concerned that even with ERVs our system loads will demand too much additional tonnage and dehumidification to be prevent mold concerns. Has anyone addressed these concerns and is there a reference in the LEED V3 manual where this is noted so we may reflect such to our owner?
Roger Chang replied Principal, Director of Sustainability, Westlake Reed Leskosky Apr 29 2010
I think the best way to tackle this one is to do some energy modeling comparing a case with 30% increased ventilation to one without. You'll typically find a hit with energy performance, which can then be presented to the GSA. They're much more interested in energy, than ventilation, given the stringent energy targets that need to be met. New construction will typically need to hit 30% better than ASHRAE 90.1-2007. With an ERV, you can still get by with a high outside air fraction in the SE US, as long as equipment is properly matched to the load. ASHRAE 62.1-2007 provides some good guidance on conditions to assume for dehumidification calculations.
LEED MURB Canada Issues
We've got a 5 storey wood frame building pursuing LEED Silver. Our current dilemma is we have large and long units. Approximately 80% of the suite can be natuarlly ventilated to ASHRAE 62.1-2004. Our problem is the 25' rule within the same space, which in our cases are dens and kitchens. The dens have no door and have a permanent opening as required by ashrae but the farthest wall is not within 25'. I'm sure some people have run into this problem, I see some people have put transfer fans in their units, how exactly was this designed?
Currently our design incorporates a geothermal water to air heat pumpA type of heating and/or cooling equipment that draws heat into a building from outside and, during the cooling season, ejects heat from the building to the outside. Heat pumps are vapor-compression refrigeration systems whose indoor/outdoor coils are used reversibly as condensers or evaporators, depending on the need for heating or cooling. In the 2003 CBECS, specific information was collected on whether the heat pump system was a packaged unit, residential-type split system, or individual room heat pump, and whether the heat pump was air source, ground source, or water source. c/w with a 4" round outside air duct ducted to the return air duct of the heat pump. We also have a continuously running HRV exhausting from each suite and supplying fresh air to the corridiors. I realize this is a hard thing to input on the energy models (so i've been told) and we may incur an energy penalty for reheating outside air for each unit, the project energy modeler is in the midst of modeling this to ensure we still get our requried energy points.
Has anyone been successful with the proposed system above or have an example of something that has been successful?
Thanks,
Alex
Alex Wong replied May 10 2010
Sorry i forgot to add that the HRV will only supply approx 70% of the required O/A. The rest of the portion is by fresh air duct to the heat pumpA type of heating and/or cooling equipment that draws heat into a building from outside and, during the cooling season, ejects heat from the building to the outside. Heat pumps are vapor-compression refrigeration systems whose indoor/outdoor coils are used reversibly as condensers or evaporators, depending on the need for heating or cooling. In the 2003 CBECS, specific information was collected on whether the heat pump system was a packaged unit, residential-type split system, or individual room heat pump, and whether the heat pump was air source, ground source, or water source. and/or openable windows. Is this too complicated? Can we pass with just openable windows and make-up from the corridor?
Roger Chang replied Principal, Director of Sustainability, Westlake Reed Leskosky May 12 2010
Alex, I have some experience using transfer air to meet 62.1 requirements. You have to look carefully at the classification of air (1, 2, 3, 4). 62.1 allows you to transfer air, as long as classification of air stays the same or goes from lower to higher (cleaner to dirtier). You may be able to use the OA from the HRV to ventilate the 20% that is not covered by natural ventilation.
Alex Wong replied May 14 2010
Thanks for your reply Roger,
I think the confusion we are having is there is no prescriptive method to prove you are meeting ASHRAE 62 by means of partial ventilation and natural ventilation. It seems on the diagram at the top of the page if you have a mixed system you must meet 100% of the mechanical ventilation (VRP). But even if you have 95% of the openable window area required by section 5, we are still required to meet the rates required by the ventilation rate procedure. Does this seem a bit over kill?
IEQ Prereq 1 - Template/Form Issues
The template requires data be entered for both Ez and Ev. From what I read in ASHRAE 62.1-2007 Ez is not related to your Vot if you have a multi-zone system. In additional unless your population density varies then Vot is basically the sum of Vbz (Vou) divided by Ev so you end up with Vou/Ev.
The problem I'm having is that the template is calculating Voz by dividing Vbz by Ez (Vbz/Ez = Voz) and then calculating Voz by dividing Voz by Ev (Voz/Ev = Vot) to obtain Vot for the zone. From what I read in ASHRAE 62.1-2007 and calculated using the 62MzCalc.xls spreadsheet, the second equation is not correct.
Has anyone else had this issue? I've tried contacting the USGBC, but have not been able to talk with anyone that understands the actual equations from ASHRAE 62.1-2007.
Roger Chang replied Principal, Director of Sustainability, Westlake Reed Leskosky May 27 2010
We recently ran into this issue also and had difficulty getting anyone at USGBC to understand this. Ez does still factor into the equation at the zone level. I would fill out the template the best you can and then include a note describing the issues with consistent terminology for this letter template. The second equation you mentioned isn't completely incorrect, unless you are claiming some sort of credit for diversity or short-term conditions.
Kimberly Walton replied Sustainability Project Engineer, PBS&J Jul 22 2010
I just discovered this issue also and sent a feedback request to GBCI asking if there is a way for us to provide our ASHRAE 62MZ Calc spreadsheets instead of filling in their jumbled template calculator. I'll post if I get a relevant response.
IEQP1 Natural Ventilation- Outdoor air quality
I am doning a new project, and using natural ventilation for one of the rooms. I do read carefully the requirements of IEQP1, but the LEED Guide does not require outdoor air quality test if using natural ventilation. But my colleague thinks that IEQP1 shall meet with the requirements of sections 4 through 7 of ASHRAE 62.1-2007, so outdoor air quality needs to meet with requirements of Table 4-1 (ASHRAE 62.1-2007), and need to take outdoor air quality test. Is Any one clear about whether needs to do outdoor air quality test if using natrual ventilation?
Tristan Roberts replied Editor – LEEDuser, BuildingGreen, LLC Jul 01 2010
For a naturally ventilated space, you don't have to meet sections 4–7, as discussed in the credit language for IEQp1.
Carrie Lai replied Jul 01 2010
Hi Tristan, Thanks.
After talking with my colleague, for the next project we will ask for local air quality first, If the air quality is poorer than Table 4-1 (ASHRAE 62.1-2007), then suggesting using mechanical ventilation with filters for the comfort and well-being of occpants. If the air quality is good, then it is good way to use natural ventilation.
Should I consider in this Prerequisite also the Restrooms?
Hi everybody,
from the precedent thread I understood that when I have a 100% OA system and multizone, I have to use Ev=1.
Now, let´s go to the question, I have a single AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. that serves more than one zone (Offices, Meeting rooms, Corridors and Restrooms). The restrooms are not considered in the Table 6-1 (Standard 62.1-2007), should I consider them? If yes, which values should I assume for Rp and Ra? In the italian norm, it´s considered that the restrooms may have only exhaust air and not supply air. (They must be underpressure, so the bad smells don´t arrive to the offices) How can I do?
Thank you very much in advanced.
Claudia.
Carrie Lai replied Jul 13 2010
Hi Claudia, for restroom needs to comply with Table 4-Minimum Exhaust Rates. That means the exguast rate of restroom will be no less the rates in Table 4.
Claudia Rieger replied Jul 13 2010
Hi Carrie,
thank you for the answer. But how it is possible to take that in consideration in the on-line Template for IEQ-pr.1? This Prerequisite refers to the "Ventilation Rate Procedure". It calculates "the design outdoor air intake flow (Vot)" and that has nothing to do with the exhaust air, isn´t it?
So, I think that in this Prerequisite you should take in consideration only the supply air, isn´t it?
Thank you very much.
Carrie Lai replied Jul 22 2010
Hi Claudia,
For some rooms, as showed in ASHRAE 62.1-2007 Table 6-4, the designer should consider the exhaust rates. The Prerequisite not only requires the supply air, but also the exhaust air for some spaces, e.g. toilets. You could find some help in the following website: http://green.harvard.edu/theresource/leed-submit/nc/
Hope this will help.
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