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Solution: A standard roof mounted Trane XL 1600 unit was installed and ducted to serve the classroom. ( Details:unit roof mounted on good quality spring curbs, supply air run horizontally through a 10ft.long lined duct on the roof before making a 90degree turn to penetrate the roof ( to avoid sending noisy, turbulent air straight down the HVAC unit) both ducts and registers in the ceiling plenum were generously sized to maintain low air speeds, double walled ducts were used on the roof )
RESULTS: The total background noise level was reduced more than 10dBA. Worst case post renovation classroom HVAC noise are now:
36.7dBA in Heat 2 ( Maximum)
35.4 dBA in Cool 2 ( Maximum)
Noise levels expected most of the time are:
31.3 dBA in Heat 1
31.1 dBA in Ventilation Mode
HVAC noise levels in Heat 1, Cool 1, and ventilation modes are well below the 35dBA limit specified for background noise(unoccupied) in ANSI S12.60-2002.
According to S12.60-2002, the 1 hour LEQ must not exceed 35dBA.
The classroom is within the ANSI noise requitement even with remaining outdoor to indoor noise transmission. Insulated window unit will be installed later for energy conservation and further noise control. The classroom teacher is delighted with the change.
COST: Total invoice for HVAC replacement was $15,000 , about $15 per square foot.(This was far less than anticipated by the school district.) The cost difference between an in kind replacement of the existing unit and the selected Trane instalation was about $5,000, or about $5/SF. Most of the extra cost will be recovered in less than 4 years by energy savings.(the Trane unit has a 16 SEER rating)
"The value of a more effective education for the 500 students who will use this classroom over the next 20 years is priceless." David Lubman
TEACHER TESTIMONIAL: " As mentioned by Shari, I have nothing to compare the noise level to as the class did not start until the renovation was complete. However, I do have a few comments...The heating and A/C system is amazingly quiet. I am frequently in classrooms where the teacher turns off the A/C or heater while lecturing and then turns it on as the students do independent work. They have to choose between comfort and quiet. That is far from the case in Room 2. REcently the janitor from the school came in to set my heater to come on a certain temperature. He said,"I am not sure it's working, I don't hear anything. I reached up and showed him how to feel the warm air coming from the vents. If you really strain to listen you can hear a small sound as the system starts but then there is no other sound. I know the acousitcs of this class has been helpful for my students with cochlear implants. Sincerely, Lynn Hill"
DETAILS: Paradise Canyon School, La Canada School District, Ca. Acoustical COnsultant, David Lubman, FASA, Westminster, Ca., Mechanical Design/Installation: Jim Fricke, Pacific Services, Newhall, Ca. desgin/installation, School Administration: Sherri Mudd, Foothill SELPA Director
CASE STUDY #2 Problem: A noisy wall mounted HVAC unit in a double-trailer classroom building at the Wildomar School in California's Riverside County was too noisy to accomodate children who have cochlear impants. The unoccupied room noise level was 45.3dBA with the wall unit in operation. The noise level with HVAC off was 38.7dBA. Riverside County school authorities sought to meet the 35 dBA requirement of ANSI standard S12.60-2002 on classroom acoustics.
Solution: The wall mounted Intertherm 939X heat pump was replaced with a standard 12-SEER Carrier model 38QRC. The unit installed on a concrete pad about 4' from the building and ducted to serve the classroom.
RESULTS:
Post renovation classroom HVAC noise ( corrected for ambient) are now: 32.0 dBA in Heat mode,31.0 dBA in Cool mode, 30.0dBA in Ventilation Mode. HVAC NOISE LEVELS IN HEAT, COOL, AND VENTILATION MODES ARE WELL BELOW THE 35 dBA limit specified for background noise in ANSI S12.60-2002.COST: Total cost for HVAC replacement and improved ducting was $15,000, about $15 per square foot.) Cost would have been lower in new construction, and might vary according to region)
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CASE STUDY BY ARCHITECT MICAELINA CAMPOS
Armstrong World Industries and Architect Micaelina Campos illustrated the effect of acoustical treatment in an existing classroom. Teachers were complaining about the vocal effort required to teach. Reverberation times went from 2.6 to 0.6 and background noise went from 66 dBA to 38dBA during peak street hours with three steps: installation of suspended ceiling tiles with NRC of 0.70, application of a wall treatment across the top portion of the back wall, and a reduction in the size of windows followed by installation of a second pane of glazing. After treatment 80% of teachers reported an increase in satisfaction with fewer voice problems being one of the most common reasons. School officials noted that before acoustical treatments 57.5% of teacher absences were due to voice or throat problems, and after only 34.7% were due to the same problem. Parents then had more rooms treated acoustically after moving their own weekly meetings to the treated rooms.
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Four University Law Lecture Audtoria Renovated for Improved Acoustics, Knight, Sarah, Evans,Jack B. (JEA Acoustics, Austin, TX, 2003)Includes before and after acoustical measurements, the complete list of recommendations, photographs, drawings, data charts. "http://www.jeacoustics.com/library/pdf/nc03 051.pdf"
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UNDERWOOD SCHOOL DISTRICT #550, John Hamann, Principal. Acoustical Surfaces placed acoustical sound panels in the band room. "Prior to remodeling and placing the acoustical panels in the band room, the sound was terrible, and the sound production that our band produced was below our standards. Since our project we have seen an immediate difference. They like the sound they are making, they rehearse with more enthusiasm, and becasue of that, the band's performances are up to our high expectations.Students are enjoying music more than ever before. I would recommend these panels to all schools. They have made a difference at Underwood." John Hammann, Principal."
RESULTS:
Post renovation classroom HVAC noise ( corrected for ambient) are now: 32.0 dBA in Heat mode,31.0 dBA in Cool mode, 30.0dBA in Ventilation Mode. HVAC NOISE LEVELS IN HEAT, COOL, AND VENTILATION MODES ARE WELL BELOW THE 35 dBA limit specified for background noise in ANSI S12.60-2002.COST: Total cost for HVAC replacement and improved ducting was $15,000, about $15 per square foot.) Cost would have been lower in new construction, and might vary according to region)
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CASE STUDY BY ARCHITECT MICAELINA CAMPOS
Armstrong World Industries and Architect Micaelina Campos illustrated the effect of acoustical treatment in an existing classroom. Teachers were complaining about the vocal effort required to teach. Reverberation times went from 2.6 to 0.6 and background noise went from 66 dBA to 38dBA during peak street hours with three steps: installation of suspended ceiling tiles with NRC of 0.70, application of a wall treatment across the top portion of the back wall, and a reduction in the size of windows followed by installation of a second pane of glazing. After treatment 80% of teachers reported an increase in satisfaction with fewer voice problems being one of the most common reasons. School officials noted that before acoustical treatments 57.5% of teacher absences were due to voice or throat problems, and after only 34.7% were due to the same problem. Parents then had more rooms treated acoustically after moving their own weekly meetings to the treated rooms.
_________________________________________________________
Four University Law Lecture Audtoria Renovated for Improved Acoustics, Knight, Sarah, Evans,Jack B. (JEA Acoustics, Austin, TX, 2003)Includes before and after acoustical measurements, the complete list of recommendations, photographs, drawings, data charts. "http://www.jeacoustics.com/library/pdf/nc03 051.pdf"
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UNDERWOOD SCHOOL DISTRICT #550, John Hamann, Principal. Acoustical Surfaces placed acoustical sound panels in the band room. "Prior to remodeling and placing the acoustical panels in the band room, the sound was terrible, and the sound production that our band produced was below our standards. Since our project we have seen an immediate difference. They like the sound they are making, they rehearse with more enthusiasm, and becasue of that, the band's performances are up to our high expectations.Students are enjoying music more than ever before. I would recommend these panels to all schools. They have made a difference at Underwood." John Hammann, Principal."
