Entry Type ID Date Applicable Rating System Primary Credit Inquiry (LIs) Ruling (LIs) Related Addenda/LIs Related Resources Campus Applicable Internationally Applicable Country Applicability Reference Guide (Addenda) Page (Addenda) Location (Addenda) Description of Change (Addenda) "LEED Interpretation" "1948" "2007-12-19" "Schools - New Construction" "The stated intent of this prerequisite to ""Provide classrooms that are quiet and in which teachers can speak to the class without straining their voices and students can effectively communicate with each other and the teacher."" Per the prerequisite, this is accomplished by meeting prescriptive requirements for the building envelope and interior assemblies, with the goal of achieving a maximum background noise level in classrooms and other primary learning spaces of 45 dBA. The prerequisite has a prescriptive standard that would require a roof/ceiling assembly with an STC rating of 50. Our elementary school has been designed to meet a maximum background noise level in classrooms and other primary learning spaces of 45 dBA using careful selection of a planned development site that has low outdoor sound levels. The background noise level in classrooms and other primary learning spaces is calculated with windows maximized for daylighting and views, and a roof/ceiling assembly with an STC rating of 40. Will a roof/ceiling assembly that has an STC rating of 40 be acceptable to achieve EQp3 if the project can achieve the LEED goal of a maximum background noise level in classrooms and other core learning spaces of 45 dBA?" "The cost impact for increasing a roof assembly from STC 40 to STC 50 can be significant, and the STC 50 roof is over-designed for a quiet site. If the site Ldn (day-night average sound level) or peak Leq (hourly equivalent sound level) is verified to be lower than 60 dBA the STC 40 roof will be acceptable, with a qualification for mechanical noise as noted below. Rooftop mechanical equipment is frequently a significant source of interior noise, and this noise impact may be increased by a lighter weight roof assembly. The roof and mechanical system design must be adequate for providing the required interior noise level, regardless of the roof STC rating. Interior noise impacts from future increased noise levels will typically be controlled by window acoustical performance for most noise sources. Although designers are required to consider future noise levels, mitigation for future noise sources that result in interior levels above 45 dBA will probably require upgrades for windows and possibly for the roof, depending on the noise exposure. *Initially, an earlier version of this ruling was posted. It has been since amended by the EQ TAG.* Applicable Internationally. " "2040, 5111, 5308" "None" "X" "LEED Interpretation" "2204" "2008-08-05" "Schools - New Construction" "We are writing with a request for review of a question very similar to others already raised by other applicants, regarding the Prerequisite for Minimum Acoustical Performance in an elementary school, a question to which I hope you will give further consideration. We are planning and designing the substantial renovation of a Lower School, K-5, for a private girls\' school. The existing buildings were built in 1972 as an open-plan school, and have been used that way, with some modest alterations, ever since. For pedagogical, operational, and specific institutional cultural reasons, all thoroughly and painstakingly considered by the school and the design team, the school has determined that they will be best served by retaining a degree of visual connection and generous passage between teaching spaces, while for the first time dividing the individual classrooms from one another to reduce the potential for unhelpful acoustic distraction. As planned, this will involve building solid walls between classrooms, but with broad areas of fixed glass along the corridor walls, permitting view from an open library and circulation space at the core of the building, into and through the classrooms to the exterior. Plans also include solid sliding partitions, easily operable by a child, approximately 8 feet wide by door height, interconnecting some of the classrooms to permit the rather frequent multi-class meetings that are part of the school\'s daily routine. It appears unlikely, if not impossible, that the glass area and easily-operable sliding doors will meet the STC criteria required for separation of teaching spaces by the Minimum Acoustical Performance Prerequisite, and yet these design elements are of critical importance to the school\'s specific curricular and pedagogical needs. The building plans also include all-new energy-efficient mechanical and electrical systems, new higher-performance window systems, all-new interior finishes specified for LEED conformance, a much-increased full-building insulation system, re-roofing for solar-load reduction and amelioration of the heat-island effect, and many other environmentally responsible components. By our rough tabulations, the project should score somewhere near the boundary between Basic and Silver certification, and would almost certainly be LEED certified if not for its failure to satisfy the acoustic separation component of the Minimum Acoustical Performance Prerequisite. This means that this project may not be LEED certified, despite the fact that in many key respects_ not least of which is that it is a renovation of an existing building on an existing site_ it is exemplary in its approach to the prudent use of materials and to sustainable, environmentally responsible operation. This is not a case where inattentive design or sloppy construction may lead to degradation of the intended acoustic environment, but one where there has been thorough and thoughtful consideration of the relative merits of connection and separation in the context of this school\'s approach to teaching. The school has been enormously successful using the open-plan arrangement for over thirty years, and cannot now fully abandon that model for teaching. At the same time, they are wholeheartedly committed to being environmentally responsible. How, within the LEED Rating System for Schools, can we accomplish both goals, and recognize the school\'s environmental commitment with the appropriate LEED certification? Must we adhere to the specific acoustic separation criteria of the Prerequisite for Minimum Acoustical Performance, or are there other measures ensuring speech intelligibility and acoustic comfort that, in this set of circumstances, would be acceptable? Is the alternative compliance path for Indoor Environmental Quality, Prerequisite 3: Minimum Acoustical Performance, described in your recent bulletin, intended to permit an application based on such alternative criteria?" "The project is seeking guidance on how to meet the prerequisite requirements based on the specific design and programmatic considerations for the project and its classrooms. The project is noting challenges in meeting the STC criteria. It is unclear however if the project has evaluated compliance for the project based on the recently released LEED for Schools EQp3 Performance/Intent Equivalent Alternative Compliance Path (PIEACP), dated April 23, 2008. The alternative compliance methods noted in this PIEACP does provide other means to meeting the earlier established requirement for STC, while still meeting the intent of the prerequisite. This document can be downloaded from the USGCB website and should assist the project in meeting the prerequisite requirements. The intent of the PIEACP is to optimize the acoustical isolation for instructional spaces that employ teaching strategies or methods which inherently cannot meet specified STC ratings. The project will meet the prerequisite if all reasonable measures are employed to limit sound transmission within the circumstances of the project; application of these measures can be demonstrated by submission of a narrative as directed in the PIEACP. Compliance with the STC ratings specified in EQ P3 is not required under this alternative compliance path. Applicable Internationally. " "None" "None" "X" "LEED Interpretation" "2243" "2008-08-13" "Schools - New Construction" "This Credit Interpretation Request asks two questions. First, is there a possible exception to the STC requirement for exterior window glazing based on environmental noise level ? Second, are skylights included in the STC requirements? If so, is there a possible exception to the STC requirement for exterior skylight glazing based on environmental noise level? The project is an addition and renovation of an existing gymnasium building on a school campus in a quiet suburban area of Baltimore City, Maryland. The specific location of this building on the cjacent classrooms per se. The intent of the Dining Hall is that it be used primarily for food service with occasional use for special events for the campus and community. These events are intermittent, generally evening occurrences. Decibel levels, environmental noise, for the site are below 60 dB DNL. Glazing specified meets high energy and thermal efficiency goals and admits significant daylight into the building. The glazing does, however, not meet the STC of 35 required by EQ PR 3. Calculated STC for the glazing is STC 32. The Dining Hall is naturally lit by 21 skylights specially designed to work in combination with sloped skylight monitors to spread light evenly through the dining hall. The specified skylights succeed in meeting energy, thermal, and lighting goals. They do not however come with any performance information and do not appear to meet the STC 35 requirement. Reverberation requirements are met throughout the project as it was judged that the spaces would be moderately noisy. The required STC separation has also been provided between the Dining Hall and all other interior spaces anticipating the infrequent occasions when the space is used for events. Exterior wall and roof assemblies are all in compliance with the STC requirements. All mechanical and other building system equipment has been evaluated and designed to meet acoustic requirements for EQ Credit 9: Enhanced Acoustical Performance. Based on the condition described, is there an exception/reduction to the STC requirements for exterior glazing in the Dining Hall? Second, are the skylights described considered in the STC requirements and if so then do they qualify for an exception/reduction of STC requirements? The project team feels that the spirit of \'EQ Prerequisite 3: Minimal Acoustical Performance\' has been met and is committed to providing school environments that are designed with the comfort and performance of the student in mind." "In this case, since the dining hall is not a core learning space it can be excluded from the requirements of EQp3. Applicable Internationally. " "None" "None" "X" "LEED Interpretation" "2264" "2008-08-13" "Schools - New Construction" "Part 1 The project is a corporate day-care facility for children that range in age from infants to four years of age. The project has voluntarily selected the LEED for Schools rating system and is seeking USGBC\'s approval on the proposed classification of space as ""classroom"" further defined as ""core learning spaces"" for the purpose of providing the required sound insulation. Per EQ Prerequisite 3; Minimum Acoustical Performance and EQ Credit 9; Enhanced Acoustical Performance. Currently, the project program has spaces for younger children (e.g., infants and toddlers through the age of three) where the primary role of the employees at the facility will be caregiver providing for the basic needs of the children. There are also three preschool spaces for children the age of four. In addition to providing for the basic needs of the children, the employees will engage in more of a teaching role. The ANSI S.12 sound isolation requirements for school spaces are predicated on providing adequate acoustical separation between core learning spaces. Based on this, we intend to only treat the preschool spaces as classrooms, or core learning spaces as these are the only spaces where there will be teachers teaching children. Part 2 In addition, the project would like to get a clarification on the composite sound isolation (STC) requirement for corridor walls. The project corridor walls will have areas of operable glazing assemblies that are necessary for both daylighting and outdoor fresh air intake. Firstly, the ANSI S.12 requirement for corridor walls (Table 3 in Section 4.5.2) states that the composite STC for corridor walls (excluding entry doors) should be a minimum of 45. In addition, classroom entry doors are required in Section 4.5.5 to achieve at least STC 30. Lastly, the updated LEED for Schools alternative compliance paths promulgated in the USGBC\'s 23 April 2008 PIEACP document state that windows ""must meet an STC rating of at least 35."" The PIEACP document does not specify that these requirements are for both exterior and interior windows. The project would like the USGBC\'s response to the following proposed corridor wall assembly: 1) entry doors that achieve at least STC 30; 2) partition assemblies (non-window) that meet the ANSI requirement of STC 45 or higher; and 3) interior window assemblies that achieve STC 35 or higher." "The first question is whether the project team can apply the requirements of EQp3 and EQc9 to preschool spaces as core learning spaces and exempt other care giving spaces from the requirements for EQp3 and EQc9 in a daycare facility. This approach is acceptable as long as the project team provides clear documentation of the teaching and/or care giving spaces excluded and the reason why the project team does not consider them core learning areas. The second question is whether the prerequisite STC requirements for windows apply to interior window assemblies as well. The project team must use a window assembly that can achieve an STC of 35 or higher for interior and exterior window assemblies. The assembly ratings of the proposed corridor wall are acceptable as described above. Applicable Internationally. " "None" "None" "X" "LEED Interpretation" "2309" "2008-09-25" "Schools - New Construction" "The School Board of this Florida County has elected to design and build its first school to be certified under the LEED-S program. The design for this facility is based directly on the two most recent schools that have been built in the county, one of which has received a LEED-NC Silver Certification while the other is currently under USGBC LEED-NC Review. This school will be comprised of 7 buildings totaling approximately 81,000 square feet. Buildings 3,4,5 & 6 are devoted entirely to classroom space while buildings 1,2 & 7 accommodate the cafeteria, music room, library, offices, and mechanical, etc. Classroom spaces have been designed in accordance with the District School Board\'s Continuous Progress Curriculum System, briefly outlined here: ""When new facilities are designed and built, it is with the intention of providing an optimal, learner-focused environment for students and staff to participate in a Continuous Progress Curriculum System within a caring environment and culture. A significant feature of Continuous Progress is the ""blurring"" of ages across grades. The extended placement of children in a multi-age or non-graded classroom assumes a variable rate of skill attainment and removes the issue of grade level advancement within a two to three year period. Teachers place students in multi-age settings, which increase opportunities for them to be exposed to and to emulate higher language and communication skills modeled by more advanced and chronologically older students. Elementary schools are organized into houses or teams to accommodate children in flexible, multi-age groups. Primary houses are generally for children five to eight years old; intermediate houses are generally for children eight to eleven years old. Groups of students are assigned to teams of teachers over a three-year time period. While participating in either a primary or intermediate house, children may be placed in a number of multi-age groups over time. Such groups may be organized by subject/content area, by developmental need, by specific skill need, or by interest. These groups are frequently and intentionally changed to accommodate the individual and rapid cognitive, physical, and emotional growth of elementary age children."" As with the county\'s most recent LEED-NC Silver certified school, integrating these Continuous Progress Curriculum System goals into the architectural design of the project necessitated the design of classroom ""pods"". Each ""pod"" consists of a group of 4 classrooms that are designated as primary or intermediate and are connected via a shared corridor and small, open entryways in each classroom. These pods serve as the multi-age ""house"" or ""team"" unit requested by the School Board. We have learned through a report generated by our acoustical consultant that this new school is in compliance with all of the IEQp3 requirements provided that each ""pod"" may carry the designation of a single multi-age core learning space, as STC 52 wall assemblies will be constructed between each ""pod"". Demising wall constructions, interior glazing assemblies, and door constructions will be addressed in a narrative to be included with our application. Other measures taken to limit sound transmission include: STC 50 exterior wall assembly, STC 53 wall in bathrooms adjacent to learning spaces, and STC 35 exterior windows. Thus our project team is requesting a USGBC ruling that will directly address our compliance with the ""Alternative Compliance Path for meeting the Sound Transmission Requirement: For sound transmission between core learning spaces and adjacent interior spaces""." "Each ""pod"" can be considered a core learning space and, according the PIEACP, the description above satisfies the prerequisite requirements. Applicable Internationally. " "None" "None" "X" "LEED Interpretation" "2361" "2009-01-14" "Schools - New Construction" "We are seeking relief from the reverberation time (RT) requirements of EQ Pr3. Our project is the renovation of a historic academic building originally constructed in 1932 for an independent school in New England. The classrooms are a bit unique, and that is proving to be a challenge for meeting the acoustics prerequisite, even with the new PIECAP. Each classroom is about 350 s.f., and is both the instructor\'s office as well as the teaching area. In the center of the room is a large oval table where 13 students and one instructor sit, facing one another during instruction time. The specific ""Harkness"" tables used in the classrooms, the number of students in a class, and the principle of teacher ""ownership"" of classrooms has been a tradition at the school for over 100 years and there is no plan to change this. The ceilings are existing to remain plaster, the floors are hardwood, with the occasional area rug in some classrooms. The window wall is plaster - other walls in the room have a mix of slate blackboard, plaster, bookcases and wood paneling - all hard surfaces. The classrooms have a large amount of historic wood paneling and moldings that would inhibit acoustical modifications. (We can provide pictures if that would be helpful.) The project acoustical consultant tells us that the classrooms, as presently set up, will not meet the RT requirements set forth in LEED. For the size of these rooms (less than 10,000 cf of volume) the reverberation time requirement is to be less than 0.60 seconds. This is the average of the 500, 1K and 2K octave bands. Measurements show that, for the rooms without carpet on the floor, the reverberation times are generally 1.0 or 1.1 seconds, with one result being 0.90 seconds and one result being 1.2 seconds. For a medium size classroom with a large area rug the reverberation time is 0.80 seconds. The building renovation includes replacement of the HVAC system and windows, but the work in the classroom areas will be largely cosmetic - we\'re not replacing ceilings, walls or floors in most of these rooms. The school is not interested in making significant changes to these spaces such as acoustic tile ceilings, or other treatment - after all they have served their purposes just fine for 76 years. If the intent of the prerequisite is to provide spaces where ""students can effectively communicate with each other and the teacher"", these rooms certainly meet that intent. It\'s just that the prerequisite does not seem to anticipate this sort of space. This issue has been discussed at length with the school, and they have committed to having sizable area rugs in the rooms so that the excess reverberation would be only a modest amount over the requirement. Typically this would reduce RT to around 0.80 seconds. Given the teaching method (face to face, around a table), the fact that these are existing conditions in a historic building, and that we are committing to improving the worst situations by adding area rugs, we ask if our proposed actions meet the intent of the prerequisite? The outcome of this issue will have an impact on the school\'s ultimate decision to pursue LEED Certification for the project." "The project as described meets the intent of acoustics prerequisite, and is compliant with the prerequisite. The primary reasons for acceptability are the face-to-face teaching style with teacher and students seated at a central table, and the reasonable level of acoustical control provided by the proposed large area rugs. Use of the large area rugs is a requirement for compliance with the prerequisite. If the teaching style changes to a lecture format or other significant change from the current face-to-face format , additional acoustical modifications must be implemented to meet the reverberation time as stated in the acoustics prerequisite." "None" "None" "LEED Interpretation" "2398" "2009-01-14" "Schools - New Construction" "Per the Guidelines for CIR Customers document, we first contacted LEED Customer Service to present our difficulty with meeting the requirements of EQp3 for the design of an open plan high school in a rural town in Kansas. They were unable to help us and directed us to submit this CIR. Teachers in the current school use a Project Based Learning (PBL) approach to instruction. The new school building has been designed to facilitate the multidisciplinary projects and high degree of student interaction that makes PBL successful. This is, however, a very different school design than the developers of LEED for Schools 2007 had in mind when they created this rating system. As minimum acoustical performance is a prerequisite it is imperative that we gain direction from USGBC; however, we are attempting to avoid compromising the educational program of the school or adding extraneous items (like operable or glass partitions) in order to meet the LEED requirements. Our project is currently at 50% Construction Documents with a plan to complete CDs in December. We have hired an experienced acoustical consultant to assist us. After review of the prerequisite\'s requirements and the Performance/Intent Equivalent Alternative Compliance Path (PIEACP) dated April 23, 2008, we decided to follow: Reverberation Time (RT): Alternative Compliance Path 2 Sound Transmission Class (STC): Alternate Compliance Path Background Noise: Alternative Compliance Path However, while we believe we can meet the requirements for RT and Background Noise, we realized that we cannot meet STC - specifically between a few adjacent core learning spaces. We have recently reviewed the LEED for Schools v2009 version and noted the changes to this prerequisite, namely the exclusion of the minimum STC requirement. The LEED 2009 Schools 1st PC Comments & Responses.xls states in Cell E93 that: ""The STC requirements were removed from the prerequisite for several reasons. By mandating STC requirements be met, the cost of a project grew significantly. Additionally, an STC requirement would prohibit open-plan classrooms from achieving LEED for School certification. While the Acoustics working group believes that open plan style classrooms are not as effective, it is not the intent of the USGBC to dictate design."" In the past USGBC has developed credit substitution matrices for new ratings systems, which allow users of previous versions to utilize the new compliance paths - although the release of these often lag the release of the rating system by several months. While we recognize that LEED for Schools 2009 has not been balloted and that this change is more substantive than in the past due to credit weightings, we are asking that you grant us direction to use the LEED for Schools v2009 version of the EQp3. Alternatively we request to be exempt from the STC requirement of LEED for Schools v2007, either throughout the school, or just between the few spaces that cannot meet it. Either of these paths will ensure that we may continue on our quest for LEED certification for this project under LEED for Schools v2007. As indicated above, we are well down the road in our design and waiting to change to the entire LEED for Schools v2009 is not an option." "The applicant is requesting approval for achievement of EQp3 for a design that does not satisfy the minimum STC requirements outlined in either the LEED for Schools Reference Guide or the Performance/Intent Equivalent Alternative Compliance Path (PIEACP) dated April 23, 2008. The project team has also requested to satisfy the requirements for EQp3 in LEED for Schools 2009 in lieu of satisfying the requirements of the current LEED for Schools requirements. The project team must demonstrate compliance with either the STC requirements specified in the LEED for Schools Reference Guide or the PIEACP dated April 23, 3008. The PIEACP intent is to optimize sound isolation between spaces, but it does not include quantified STC requirements. The design team can comply with the PIEACP by including sound isolation design to the extent possible within the program and building limitations, but compliance with specific STC ratings is not required. Per the PIEACP, the team must submit a narrative describing measures taken for sound control, but if sound isolation is limited or even non-existent, this does not preclude compliance with the prerequisite. Submission of the narrative stating the sound isolation conditions between relevant spaces constitutes compliance with the PIEACP. Applicable Internationally. " "None" "None" "X" "LEED Interpretation" "5131" "2008-10-08" "Schools - New Construction" "We are currently designing Phase 1 of an Educational Campus for our client in Dubailand United Arab Emirates. This phase consists of an Early Childhood Centre (Cr" "The project as described meets the intent of the acoustics prerequisite, and is therefore in compliance. Specific responses to items 1 through 4 are as follows: 1. Acoustical performance estimates for the composite wall assembly and exterior noise levels confirm that background noise levels will be below 40 dBA. The exterior wall/window assembly is therefore in compliance with the prerequisite. 2. As a flexible, supervisory space with no lecture type of instruction, the space is exempt from the STC requirements. 3. The composite performance of the exterior wall and door supports interior noise levels below 40 dBA and is therefore in compliance with the prerequisite. 4. The Library and additional rooms as described in the CIR are not core instructional spaces, and are therefore exempt from the STC requirements. Applicable Internationally; UAE." "None" "None" "X" "LEED Interpretation" "5204" "2009-04-21" "Schools - New Construction" "Duval County Public Schools (DCPS) requested the design team locate one single toilet room in each of the classrooms for their new Kindergarten through Eighth grade school. This is intended to eliminate potential vandalism and the noise associated with gathering in group toilets. Additionally, the single toilet rooms allow better supervision of the students and are designed for their safety and to minimize disruption in the classroom. In the Kindergarten through Third grade classrooms on the first floor, there is a direct access into the toilet room and it will be unisex. In the Fourth through Eighth grade classrooms on the second floor, there will be a vestibule for entrance into the female and male toilet rooms. The single toilet rooms located in the classrooms are private spaces and are not intended for common or public use. They are to only be used by the occupants in the respective classroom. The single toilet rooms are placed along the corridor wall, in the corner of each room to minimize sharing of multiple walls with the classrooms. One wall shares 8"" CMU wall assembly with the corridor (STC rating of 48) on both floors while another shares a double wall with another toilet room on the first floor and on the second floor, the other wall is adjacent with the vestibule room. The other two toilet room walls will have a direct adjacency to the classrooms and have an STC rating of 50. These walls have limited penetrations to help minimize sound transmission. The insulated steel door leading into the single toilet rooms and at the vestibules meets the requirements of ANSI A250.8 for level and ANSI A250.4 for physical-endurance. The Ceco Door Product specified is a 1-3/4"" Medallion (MS) full flush door with fiberglass insulation to help limit sound transmission. The door assembly itself provides an STC rating of 41. As single occupant toilets, noise created within the toilets will be limited to that which only one individual from the classroom space can make. Mechanical exhaust from the toilets is also minimal, with only 50 cfm requirement, in lieu of the larger exhaust requirement from group toilets. The dual flush toilets will further help to reduce sound. ANSI S12.60-2002, Table 2, indicates the minimum STC ratings required between classrooms and adjacent spaces. ANSI refers to ""common use and public use toilet room and bathing room"" and that the required assemblies have a rating of 53. DCPS and the design team respectfully request that the individual toilet rooms in this project be considered private, not common or public use, and that the 50 STC rating be considered acceptable for this use as the restrooms are not for public use but for the private use of the occupants in the classroom." "The project complies with EQp3 through the provisions of the LEED for Schools Performance/Intent Equivalent Alternative Compliance Path (PIEACP), dated April 23, 2008. This is acceptable as compliance with the PIEACP is demonstrated by submission of a narrative describing sound control assemblies, measures taken to limit sound paths, and special circumstances or considerations regarding the project. The paragraphs above describing the building assemblies and circumstances should be submitted as a narrative for compliance with EQp3 via the PIEACP. Applicable Internationally. " "None" "None" "X" "LEED Interpretation" "5212" "2009-04-21" "Schools - New Construction" "The Ursuline Academy Music Hall is a small addition to the school\'s Performing Arts building. We are seeking approval for this prerequisite through an alternative compliance approach due to the special nature of this project. This 3,480 square foot addition, while attached to the Performing Arts building, is not connected through corridors. To enter the new Music Hall, the students have to exit the existing building to enter the new one. LEED requires, through compliance with ANSI standard S12.60-2002, that a rating of STC-60 must be maintained through a composite wall and door construction between music and core learning spaces (which assumes that the adjacent spaces are both occupied). We submit that we have an adequate sound isolation wall between music to core learning spaces. This sound isolation wall consists of floor to deck partitions sealed at the perimeter with sound sealant, with two layers of 5/8"" thick gypsum wallboard on both sides of a 3 5/8"" metal stud, with acoustical insulation in the stud cavity. This partition is rated at STC-54 to 55 (laboratory testing). The doors to these spaces are rated at STC 40 with sound seals and fully mortised automatic door bottoms seals. These ratings exceed the norms for classroom spaces (usually STC-47 to 49 for walls and STC-20 or less for unsealed doors). The wall construction between the Office and Library to the Rehearsal Room will have floor to deck partitions sealed at the perimeter with sound sealant with one layer of 5/8"" gypsum wallboard on both sides of a 3 5/8"" metal stud, with acoustical insulation in the stud cavity. This partition is rated at STC-47 to 49 (laboratory testing). This partition type, even though it has a lower sound isolation rating, is considered acceptable due to the fact that when the teacher is teaching no one will be in either of these rooms; therefore an STC rating of 60 not relevant. It is because of the special way in which Ursuline plans on using these spaces that we feel that it is not necessary to achieve an STC- 60. Due to the special nature in which the school will be using this building will this be an acceptable solution to complying with this prerequisite?" "The project complies with EQp3 through the provisions of the LEED for Schools Performance/Intent Equivalent Alternative Compliance Path (PIEACP), dated April 23, 2008. This is acceptable as compliance with the PIEACP is demonstrated by submission of a narrative describing sound control assemblies, measures taken to limit sound paths, and special circumstances or considerations regarding the project. The paragraphs above describing the building assemblies and circumstances should be submitted as a narrative for compliance with EQp3 via the PIEACP. Applicable Internationally. " "None" "None" "X" "LEED Interpretation" "5238" "2009-08-04" "Schools - New Construction" "Question #1 The current prerequisite identifies the minimum STC rating that is needed, but not the minimum F-STC rating that is needed. In relying on ANSI Standard S12.60-2002, the credit accepts F-STC testing, but does not give the requirement for it. Without the requirement for F-STC, are we to assume that the requirement for STC and F-STC are the same even though the test methods and industry standard practice always presents different requirements for these two different test methods - ASTM E413 and E336, respectively? For example, the 2009 International Building Code Section 1207, ""areas shall have a sound transmission class (STC) of not less than 50 (45 if field tested)."" The ""F"" on F-STC represents the F in Field for the field sound transmission class. What is LEED\'s requirement for the F-STC? Question #2 - (dependant on answer to #1) With the current acoustical language in this credit, our project is left with the following dilemma. There is an official field test on an assembly similar to our project. It contains a 1/2"" less wood mass and a 1/2"" less Maxxon Gypsum Based Underlayment mass than what we will be doing. The rating achieved in that test is an F-STC 47 (Twin City Testing #02 31573-6). While this meets the industry standard practice of F-STC rating of 45 if a 50 STC was requested, at this point it may not meet the LEED credit. There are thousands of ways buildings are constructed. Only the most commonly constructed assemblies are tested for STC ratings. When a test does not exist for an exact assembly, most code bodies accept estimations or calculations based on solid data, experience, or historical performance. In our case there is a practical ways to accurately estimate the STC of an assembly. One of the laws of physics is expressed as follows: TL = 20 log (f * m) -34 where TL = transmission loss (dB) f = frequency m = mass The known mass of each component in an assembly can be added up and the total inserted into this equation. From the data obtained from the equation, an STC can be calculated. By adding more mass to the current assembly of this project, an STC of over 50 can be calculated. This calculation is not an actual lab or field test. Will this calculation be acceptable for LEED?" "It should be noted that as an alternative to addressing the submitted questions, the EQp3 STC requirements can be met by submitting a narrative as specified in the LEED for Schools Performance/Intent Equivalent Alternative Compliance Path (PIEACP), ""Indoor Environmental Quality, Prerequisite 3: Minimum Acoustical Performance"", dated April 23, 2008. The PIEACP requires a narrative describing measures taken to limit sound transmission between core learning spaces, but does not require specific STC ratings for demising walls or other sound isolation elements. This enables design teams to meet the STC prerequisites by employing and describing sound control measures, without meeting or documenting specific STC performance requirements. Submitting a narrative per the PIEACP is a straightforward approach for compliance, and will eliminate the need to consider Questions 1 and 2. The rulings below apply if the primary compliance path for STC performance per LEED for Schools 2007 is pursued. Question #1: The LEED requirement for compliance with STC ratings is based on laboratory ratings. Post-construction measurement to confirm compliance is not required, but STC performance must be clearly documented in the design phase with reliable test data confirming that STC ratings will be met. The supporting test data must be conducted in accordance with appropriate ASTM standards, and provided by a NVLAP- accredited test lab or other reliable source such as an acoustical consulting firm that is a member of the National Council of Acoustical Consultants (NCAC), or the Institute of Noise Control Engineering (INCE). Question #2: It is widely recognized that field measurements are typically lower than laboratory ratings, with a 5 point difference allowed per building codes and many municipalities. The FSTC 47 assembly can be considered compliant with the STC 50 requirement, particularly considering that the design assembly has higher mass than the tested assembly. Applicable Internationally. " "None" "None" "X" "LEED Interpretation" "5308" "2008-03-21" "Schools - New Construction" "The project is a school located in a quiet suburban area in California where the environmental noise level is below 60 dB DNL. The proposed window assemblies have STC ratings up to 34. Interior environmental noise levels have been calculated to be below 30 dBA with the proposed assemblies. Please confirm that at ""quieter"" sites like the subject projects, window assemblies that have STC ratings less than 35 are acceptable. The window assemblies have been selected to achieve energy and thermal efficiency goals. A one-STC point reduction in performance is not considered to be acoustically significant. In addition, the roof-ceiling assembly at the project is calculated to have an STC that is modestly below 40, due to skylights and other daylighting components. In the CIR dated 19 October 2007, roof-ceiling assemblies that are less than STC 50 (i.e., STC 40) are acceptable, provided that the site DNL is below 60 dB and that rooftop mechanical noise is controlled to meet the prerequisite\'s requirements. We have calculated rooftop equipment noise through our roof assembly and have designed noise reduction measures for the equipment (through quiet equipment selections and acoustical barriers surrounding the rooftop equipment), and also added mass to the roof assembly in a targeted way to meet the background noise requirement in classrooms of 45 dBA. Thirdly, certain core learning spaces will be science lab/classrooms with fume hoods. We assume that the requirement for a maximum background noise level in classrooms of 45 dBA does not apply to fume hoods. The hoods will be on during experiments, but will be either turned off or covered during instructional times. While fume hood noise will be mitigated to the ASHRAE Chapter 47 NC 35 - 45 standard, it will exceed 45 dBA. Supply and return ventilation system noise will be designed to meet the required 45 dBA." "There are three questions posed in this CIR - one relating to the STC value for window assemblies, the second pertaining to the roof-ceiling assembly STC value, and the third pertaining to fume hoods. In regard to the window assemblies, an STC of 34 is acceptable under the described circumstances as the interior environmental noise levels have been calculated to be below 30 dBA, and the environmental noise level is below 60 dB DNL. Similarly, the roof-ceiling assembly is acceptable under the specific conditions as the design achieves a background noise level of 45 dBA. Lastly, fume hoods can be excluded from the requirement for background noise levels, and as noted, should be turned off during instructional periods. Applicable Internationally. " "1948, 2040, 5111" "None" "X"