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1 April 22, 2009 GP #6 Build Green Schools Click on this link for more information. Virginia Beach Middle School- Registered LEED for Schools 2.0 Sold by Robert W. Hayes Co., Inc. Norfolk, VA (2) EVAPCO UT Cooling Towers with Super Low Sound Fans and Water Silencers This issue of Green Piece will address the LEED for Schools 2009 Indoor Environmental Quality credit categories regarding acoustics. The Super Low Sound Fan can assist with obtaining these credits. First, consider the following about Green Schools: On average, one green school project is registered in the LEED for Schools rating category every day. See the file registeredschools.xls sent with this Green Piece containing a current list of LEED school projects in design. 1, 2 Six (6) states have adopted legislation requiring green schools as standard. Ohio has adopted LEED Silver as the minimum rating and will have a projected 250 schools undergoing construction in the next two years. 2 Classrooms with improved acoustics create a more productive learning environment for children and allow teachers to be heard without straining their voices. 3 According to the Institute for Enhanced Classroom Learning, children in today s classrooms have difficulty understanding 20 to 30 percent of what their teacher said because of excessive ambient background noise, reverberation, and a poor signal to noise ratio. 4 Listen to the podcast interview of Ms. Rachel Gutter, Senior Manager LEED for Schools discussing this topic and the NEW credit categories for Acoustics. 1

2 LEED Credits for Schools with the Super Low Sound Fan! LEED for Schools focuses on K-12 educational spaces, universities and interpretive centers. The acoustical credit categories of LEED for Schools 2009 are: (IEQ) Prerequisite 3: Minimum Acoustic Performance (IEQ) Credit 9: Enhanced Acoustical Performance IEQ Prerequisite 3: Minimum Acoustical Performance Required Intent: To provide classrooms that are quiet so that teachers can speak to the class without straining their voices and students can effectively communicate with each other and the teacher. Requirements: Design classrooms and other core learning spaces to include sufficient sound-absorptive finishes for compliance with reverberation time requirements as specified in ANSI Standard S , Acoustical Performance Criteria, Design Requirements and Guidelines for Schools. Achieve a maximum background noise level 1 from heating, ventilating and air conditioning (HVAC) systems in classrooms and other core learning spaces of 45 dba. Potential Technologies & Strategies Commercially-available software may be used to perform the calculations for core learning space noise levels, provided calculations are based on 2007 HVAC Applications ASHRAE Handbook, Chapter 47 (with errata but without addenda 1 )Control of classroom HVAC noise involves all potential noise sources and paths, including duct-borne, structure-borne, and equipment radiated noise. Factors specific to the project site are also very important; examples include classroom/mechanical room adjacencies, equipment located in ceilings above or near classrooms, and noise transmission via return air plenums when classroom walls do not extend to structure. 1) Recommended methodologies and best practices for mechanical system noise control are described in Annex B of ANSI Standard S , and the 2007 ASHRAE Handbook - HVAC Applications, Chapter 47 on Sound and Vibration Control(with Errata but without addenda). 2

3 IEQ Credit 9: Enhanced Acoustical Performance 1 Point Intent To provide classrooms that facilitates better teacher-to-student and student-to-student communications through effective acoustical design. Requirements Sound Transmission Design the building shell, classroom partitions and other core learning space partitions to meet the Sound Transmission Class (STC) requirements of ANSI Standard S , Acoustical Performance Criteria, Design Requirements and Guidelines for Schools, except windows, which must meet an STC rating of at least 35. AND Background Noise Reduce background noise level 1 to 40 dba or less from heating, ventilating and air conditioning (HVAC) systems in classrooms and other core learning spaces. Potential Technologies & Strategies Design considerations include reducing noise from exterior to interior spaces, between spaces within the building, and within the classroom space. External to internal noise transmission can be reduced by orienting classrooms away from external noise sources and using thick and/or massive materials in walls and roofs. Also, windows should be well sealed and have adequate air gaps between sheets of glass. See IEQ Prerequisite 3 for more potential technologies and strategies. 1) Recommended methodologies and best practices for mechanical system noise control are described in Annex B of ANSI Standard S , and the 2007 ASHRAE Handbook - HVAC Applications, Chapter 47 on Sound and Vibration Control(with Errata but without addenda). In order to assist in meeting the prerequisite and credit requirements of 45 and 40 dba background noise in the classroom, low octave band exterior noise transmission must be reduced prior to entering the classroom. Jim Perry, an Acoustical Consultant with Cerami and Associates, NYC, performed a sound analysis on our Super Low Sound Fan. After the test was completed we interviewed Jim, and he stated that the most dramatic improvement occurred in the low octave bands which carry through buildings, the EVAPCO Super Low Sound Fan really addresses these critical low octave band frequencies. In addition, large noise reductions in the low octave bands is critically important, low octave rumble is the most difficult to attenuate. To see Jim s complete interview click on this link to the Super Low Sound Fan video 3

4 The dominant noise source of a standard cooling tower fan is in the lower octave bands- 63 to 250 Hz. The Super Low Sound Fan provides considerable reductions in this range, especially in the 250 hz band, as shown in the unit comparison in Table 1: Table 1 Model: AT Motor: 25 HP (18.5 kw) Top Standard Fan Top Super Low Sound Fan In addition to the low octave reduction capability of the Super Low Sound Fan in the 63 to 250 Hz range, the Super Low Sound Fan eliminates discrete blade passing frequency tone harmonics providing an overall better sound quality. It is known that discrete tones are more objectionable resulting in the most complaints. See the Narrow Band Spectrum Analysis in Figure 1 showing the blade pass tones of the standard fan rising above the smooth broadband of the Super Low Sound Fan. Figure 1 In the 2007 HVAC Applications ASHRAE Handbook, Chapter 47 5, various sound rating methods are presented to develop background noise calculations in the classroom. One method includes a sound quality evaluation called the RC or Room Criteria Method which addresses low frequency ranges. With the superior sound levels of EVAPCO s Super Low Sound fan in the low frequency range and smooth broadband sound spectrum, it provides a clear benefit to the acoustical consultant to specify Super Low Sound Fan pressure levels. 4

5 Furthermore, Chapter 47 of the 2007 ASHRAE HVAC Applications Handbook, page 47.2, recommends to select a fan that generates the lowest possible noise at required design conditions. And on page 47.3 Table 1 it recommends to select quiet equipment for towers and condensers: Sound Source Table 1 Path No. Cooling towers, air-cooled condensers 4,5,6,7 No. Transmission Paths Noise Reduction Method 7 Noise radiated to outside enters room windows Locate equipment away from critical areas, use barriers and covers to interrupt noise paths; select quiet equipment. In order to meet the low interior classroom sound requirements required in these categories, the design engineer should consider specifying EVAPCO equipment with the Super Low Sound Fan to provide low sound levels and low energy consumption. Note that most of the sound reduction solutions in LEED for Schools recommend thicker walls and insulating materials. While these construction methods will work to reduce sound levels, it will also increase building costs not a green building design solution. Specify the Super Low Sound Fan to help meet the background noise levels in the classroom the real Innovation in Design! EVAPCO s Super Low Sound Fan, when applied to cooling towers, closed circuit coolers or condensers is the reasonable solution to assist in achieving background noise levels of dba within the classroom. Go for the Green! Daryn S. Cline Daryn S. Cline, LEED AP Senior Manager, Environmental Technologies References: 1) Source: USGBC Registered Project List 2) Source: Rachel Gutter, Senior Manager, LEED for Schools. 3) Source: USGBC s LEED for Schools- 4) Source: School Planning and Management, October 2008 Breaking the Sound Barrier for Enhanced Classroom Learning 5) Source: 2007 ASHRAE Handbook HVAC Applications, Chapter 47 Sound and Vibration Control. 6) ANSI Standard S Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools Application of Low Noise Technology for Evaporative Cooling Equipment, CTI Journal, Vol. 26, No. 1 7) Application of Low Noise Technology for Evaporative Cooling Equipment, CTI Journal, Vol. 26, No.1 by Trevor Hegg and Will Nuckolls, Evapco. 5