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Introduction
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. The 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.
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 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-mode spaces (with both mechanical and natural...
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47 Comments
Particulate Matter Removal
Hi to all of you,
as per Standard 62.1-2007, in Section 5.9, one of the minimum requirements for mechanically ventilated spaces, a MERVMinimum efficiency reporting value. 6 filter shall be provided upstream of all cooling coils. ...,
How strict is this situation if the units are VRF evaporators?, since they have very little pressure available and the filters would cause a big drop of it.
thank you
We have run into this on a number of projects. As this is a pre-req we have not pushed back on this requirement and always included at least MERVMinimum efficiency reporting value. 6, but usually MERV 8 filters.
Consider:
Oversizing the ductwork (if there is any) will help reduce pressure drop,
creating an oversized plenum filter box to reduce the FPM across the filter, or
select a higher static VRF unit.
Thank you Dylan, it´s been very helpful,
FTE vs ASHRAE 62.1 occupancy
Hi All
For a C&S project there are default FTEFull-time equivalent (FTE) represents a regular building occupant who spends 8 hours a day (40 hours a week) in the project building. Part-time or overtime occupants have FTE values based on their hours per day divided by 8 (or hours per week divided by 40). Transient Occupants can be reported as either daily totals or as part of the FTE. Residential occupancy should be estimated based on the number and size of units. Core and Shell projects should refer to the default occupancy table in the Reference Guide appendix. All occupant assumptions must be consistent across all credits in all categories. occupancy figures that shoudl be used for water calcs, bicycle racks etc where the final occupancy is not known. These are I believe average occupancy figures that represent an average number of occupants on a typical day and are less than what we would expet to be the peak occupancy. While FTE are ok for the average usage and water/bicycle number types of calcs I don't belive they should be used for the ASHRAE 62.1 fresh air calculations.
ASHRAE 62.1 has another set of default occupancy which are what I would descibe as the peak occupancy and the MEP designer will use these numbers in the MEP calcualtions NOT the FTE numbers.
Has anyone encountered this issue and dealt with the fact all the online forms are trying to use the same occupancy for Fresh air calcs as the FTE?
I think we should be able to use different occupancy in this case (as would the MEP designer) and that FTE should not be used fo this credit.
Regards
Julian
Air Extraction System
We are working on a natural ventilated CS office building. The entire building is going to be natural ventilated with no AC. The bathrooms are the only areas with an air extraction system, but we haven´t been able to understand if this system belongs to a mechanical ventilation system?
The air extraction system simply take out the air from the bathrooms and transports it to the outside of the building.
Could anyone help us with this?
Thank You!
Regarding my question above, maybe some details will shed some light in our inquiry:
As I stated above, the only mechanical ventilation in the project will be an exhaust ventilation system in the bathrooms. The LEED online form's Table "Ventilation Rate Procedure" doesn't seem to be designed for exhaust systems, since it asks for information such as Rp, Ra, Ez and Ev that is not included in ASHRAE's Table 6-4 (the table to be followed by air exhaust systems, according to ASHRAE 62.1 paragraph 6.2.8).
The form doesn't seem to include a table specifically for exhaust systems. So, any idea on how should we proceed? Should we exclude this exhaust system from our calculations? Should we mark the Special Circumstances Box and upload our own table, using Table 6-4's information?
Once again, thanks for your help.
Luis,
You do not need to include the exhaust system in your calculations for this pre-req. Having an exhaust system does not count as Mechanical Ventilation for LEED purposes.
As a naturally ventilated building you must comply with ASHRAE Standard 62.1-2007, paragraph 5.1.
Thanks for the answer Dylan, it's been really helpful.
Naturally ventilated spaces
I appreciate your interpretations on the ASHRAE 62.1 regarding the requirement for naturally ventilated spaces:
5.1.1 Location and Size of Openings: Naturally ventilated
spaces shall be permanently open to and within 8 m
(25 ft) of operable wall or roof openings to the outdoors...
Does that mean that a residential studio (with no partitions) that is 30 feet long with an operable opening at one end would, would not, or would partially meet the distance requirement? My dillema is this: Technically, The studio is one big open space that is within 25 feet from an opening - then, it is compliant as per the ASHRAE wording. However, the last 5 feet of the studio are over 25 foot away form the opening- then, the area limited by the 5 feet length and the width of the studio may not qualify. Any thoughts on this?
Technically, I think you're correct, but this may not be a good idea for good air quality. Note that ASHRAE 62.1-2010 now has more restrictive guidance on the location of openings in section 6.4. For example, with a single opening, the maximum distance coverage is 2H, where H is the ceiling height.
Garage and technical rooms
We are dealing with project with underground garage, where adjacent spaces are technical rooms. Can we transfer the air from the garage to the technical rooms to ventilate them? Do we need to keep positive pressure in these rooms if they are not 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.?
Thanks for help
Could you provide clarification on what you mean by technical rooms? Parking garage is classified as Class 2 air, so you can't transfer to Class 1 spaces, which includes data rooms.
ASHRAE 62.1 excludes equipment rooms and storage rooms from the definition of occupiable spaces. If your technical rooms are within this definition, they don't need to be ventilated.
uncondtioned space and natural ventilation
Hello
We are working on a office building applying for LEED CS. The building is going to be naturally ventilated. we haven't been able to understand if naturally ventilated spaces are considered conditioned or unconditioned, or somewhere in between. Regrettably, ASHRAE is not very clear with info and definitions regarding natural ventilation. Could anyone help us with this?
Thank you all
Luis, could you clarify how you're using the definition of conditioned versus unconditioned in your LEED submission?
Well, we haven't designated any space yet, but since the ASHRAE defines a conditioned space as "a cooled space,heated space, or indirectly conditioned space" and our building is naturally ventilated as a whole (and therefore there aren't any cooling or heating system), we think that everyone of the building spaces are considered unconditioned. What do you think Roger?
Applicability of ASHRAE62.1 in Major Renovation
Dear all,
This covers more than just ventilation but as this is the most important I put all facts and questions down here.
An existing building from the 1970s is undergoing construction works. The client would like to certify the building and is seeking our advice. The works will mainly comprise a complete facade replacement and some work on none load-bearing walls. All HVAC systems and plants, distribution and so on will remain unchanged as far as possible.
According to the definitions in the Rating System Selection Guidance June 2011 this is a major renovation and the project would certify under CS Major Renovations.
Probably some of the systems are not compliant to ASHRAE 90.1-2007, but in most sections there are exceptions for existing systems that are not replaced or altered. So there seems to be no problem here, correct me please if I'm wrong.
We are sure that the ventilation rates are not compliant to ASHRAE 62.1-2007 in some places. There will most probably be no space to upgrade the system to ASHRAE 62.1, especially in the case of 5 underground parking decks. I can't find an exception similar to 90.1 in the 62.1.
Does anybody know of exceptions especially to ASHRAE 62.1 or a USGBC document / policy that allow the certification of this building (assuming all MPR and other prerequisites plus enough credits are met)? Or is this a project that just cannot be certified at all?
Jens, there are no exceptions. All prerequisites need to be met.
Tenant Layout
For our LEED CSv2.0 project, we have been asked to provide a proposed tenant layout for approximately 6 office spaces. There are (2) office spaces and (1) corridor space for each of (3) Roof Top Air Handling Units. As the programming of each office has not been decided as they will be individual and seperate office spaces, we are unable to provide a realistic expected program for each office. Fortunately the OA design for these units are large enough to accomodate the office spaces in a worst case scenario for an office (100% conference / meeting space has the highest occupancy values and OA rate requirements per person). Has anyone had any experience or have any comments on instead of providing an office specific programming layout to provide a narrative and associated ASHRAE 62 calculators showing that the RTU's are capable of handling the office space in these conditions?
Even if programming hasn't been completed, it should be possible to present a tenant layout plan that would be one of several possible options. The goal here is to show what might reasonably be built, and how the systems would perform for such a potential layout. It's mainly a test fit of a generic space plan to show the system meets the requirements with that case.
All we know about the spaces is that they will be office spaces, so if we show that we are able to exceed our OA requirement in the worst case scenario with the most OA required, shouldn't this be an acceptable method instead of pretending we know what the future layout could be, and as a result possibly undersizing the OA required for the space?
Grouping of spaces
I am working on a project with similar spaces repeating on each floor. I know LEED allows one to group spaces in some credits. However, the LEED online template says "Complete the following table for each mechanically ventilated space in the project building." The key word being "each". The reference manual doesn't seem to suggest that spaces can be grouped and the ventilation rates be added for simplifying documentation. Typically, do you group such repetitive spaces then?
Some time ago but this still might help. I have a project where floors 3 to 33 are essentially the same. I wrote a narrative explaining this fact and filled the table with one examplary floor and all non standard floors. This approach was accepted in Desing Review.
Operable Windows
We are working on a natural ventilated CS office building. The Leedonline form asks to fill in a table with the operable window area, in order to calculate ratio of window to occupiable area.
This building's natural ventilation system consist in ceiling duct system with openings to the outside thus creating a windflow that ventilates the offices. This offices have operable openings to regulate the inflow of air. Do you thinks we should include these operable openings' areas in the window area of the table?
Thanks for your help
instead of a window area, you probably need to use the area of the openings on the outside of the building, since this is the "inlet" area that is delivering the outside air. That open area needs to be at least 4% of the floor area it serves.
C&S scope
We are working on a C&S project but in the middle of the design phase we learned that a gym will lease three floors.
Air handling units will be installed on all floors except in the gym.
The gym will install their own AHU´s.
Do we need to include the ASHRAE ventilation requirements in the lease agreement?
ASHRAE 62.1 compliance is required for any space in the building. So yes, if the owner is not installing the ventilation system as part of the C&S than the lease agreement needs to require the gym to comply with ASHRAE.
Authority having Jurisdiction
We are working on a CS naturally ventilated office Building. In the leed online form for this credit there is an option: "The space is an engineered natural ventilation system approved by the authority having jurisdiction(....)
The project site is located in Colombia, and this country does not have any authority with jurisdiction over ventilation standards or codes. In this case, does someone else can be considered an authority having jurisdiction? Who could this be?
Thanks for your help
Is there any kind of building official or code official who could approve the plans?
I don't know—this is not anticipated by LEED, clearly!
The interpretation 62.1-2004-20 has a comment that says "The authority having jurisdiction is not limited to the local governing body/municipality”. There may be others.
http://www.ashrae.org/technology/page/127
The 62.1 User´s manual on the natural ventilation chapter explains that for exceptions to the prescriptive requirements, the burden is on the design professional
to engineer a naturally ventilated system that works.
I believe that in those cases the natural ventilation designer will be the authority, and to demonstrate it a graphic and numeric summary of the airflow analysis performed, including boundary conditions used for the analysis, simulation algorithm, solution variables, temperatures, airflow volumes and mean age of air for the spaces modeled must be uploaded as requested in the template.
Biagio,
thank you very much for your comment, it was very useful.
Occupant diversity
Im working on a C&S building and we have two space types: office and meting rooms. I would like to know if I can use occupant diversity (D) for the outdoor air calculations. The ventilation table on the LEED ONLINE form doesn´t take the diversity into account, should I upload my calculations under special circumstances?
Ruben, you may account for occupant diversity in your calculations. Upload your calculations and assumptions demonstrating the relevant ASHRAE 62.1 equations used.
Tenant space without provision of HVAC system
For our LEED-CS project, there is no central HVAC system within the buidling. The tenant of the retail area will have to install their own equipment such as split-type A/C, fresh air fan, kitchen equipment etc. How can we achieve the minimum IAQIndoor air quality: The quality and attributes of indoor air affecting the health and comfort building occupants. IAQ encompasses available fresh air, contaminant levels, acoustics and noise levels, lighting quality, and other factors. performance requirement? Is it possible to achieve by means of natural ventilation by providing an opening according to ASHRAE 62.1 section 5.1?
Wei, you can achieve this through the natural ventilation path, although for a commercial project, usually you'll want to have some provision for ventilation air paths, at minimum, even if the actual HVAC systems are not provided.
Thanks Roger. Do we need to write the ASHRAE ventilation rate requirements into tenant lease if the tenants will install mechanical ventilation in the future?
Growth and Erosion
We have an HVAC system configured with ceiling plenum return. Is this plenum required to meet item (§ 5.5.1) Resistance to Mold Growth and (§ 5.5.2) Resistance to Erosion of ASHRAE 62.1?
I'm not an expert on ASHRAE 62. But based on the credit requirements, I don't see why you would be able to skip these requirements. What was your thought?
There are one big
There are one big manufacturing space in my project for which I have to determine mechanically ventilation levels/
No rates for industrial zones I've found in ASHRAE standard 62.1-2007.
Where I can find this data?
Armen, please reference the manuals by the ACGIH. http://www.acgih.org/home.htm
Thank you for answer,
I don't clearly understand what manuals should I look for? Since there are a lot of information on this site.
Please reference this set of books: http://www.acgih.org/store/ProductDetail.cfm?id=1913
Meeting 62.1 requirements
According to 5.10.1 you should have a relative humidity of no more than 65%. And you have to analyze this with outdoor air at humidification design conditions (design dew point and mean coincident dry bulb) with the space interior loads both sensible and latent, and space solar loads at zero. Although this make sense, how can you document compliance with this article???? Is there a computer program that can do this?? I've been trying to find an answer with Carrier HAP, without luck.
Any guidance in regards.
Thanks.
This should be analyzed using a psychrometric analysis program, where you can plot state points on an electronic psychrometric chart. Alternatively, you can use a traditional graphical approach on a paper copy of a psychrometric chart. This analysis is difficult to achieve with either Carrier HAP or Trane Trace. I believe you meant the dehumidification condition, rather than the humidification condition in your message?
Thanks Roger. Yes it is possible to do it with HAP, I contacted them and they explained to me how to do it. Yes, my bad, I meant DH.
Using default occupancy v/s estimated occupancy
Appendix 1 of the BD+C Reference guide states that "if the buildings and circumstances are not covered in this appendix, provide documentation for comparable buildings demonstrating average gross square foot per occupant..."
Something similar appears on the PI Form 3: "Actual Building occupancy is unknown and the defaultoccupancy counts do not adress the LEED building type. The project team will base occupancy on an alternative methodology"
For a C&S building in Mexico city, 250 gross sf per occupant seems to be a very low occupant density. Of course, this depends on (and here is my first question) what is the definition of gross area? Does it includes below grade parking and all other enclosed spaces? and, what alternative methodologies are acceptable for using a different occupant density?
Jana, one of our contacts from the USGBC just answered this question over in the forum on SSc4.2.
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