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design criteria. Unoccupied background noise level is one

' of the LEED design criteria. In previous versions of LEED

L . ’ for building design and construction, the prerequisite

j

1’ ___ -L background noise level was 45 dB(A), and a distinction
j_———u ' : credit was awarded to schools that met a background noise

'‘ _ 1. I ‘l level of 40 dB(A) or lower. These levels are noticeably louder

5 ‘ \ _'. _. J ‘ than the 35 dB(A) recommended by ANSI S12.60. Although
— , ‘i _ " Tel, ‘ 3‘ ' l. T 45 dB(A) is quieter than some of the unoccupied noise floors
5% - ' _ . in classrooms observed in our study, it does not necessarily

' ' .‘ ' . meet the needs of its occupants. In the most recent revision

of LEED (V4), the prerequisite background noise level was

- ’ ‘ ‘ adjusted to 40 dB (A), and the unoccupied background noise

‘* ' level requirement for the credit was adjusted to 35 dB(A)

_ . (USGBC, 2013), the level recommended in ANSI S12.60.
‘Hiiii ('iiii,,.i LEED is one of the only programs in the United States

that provides a means of incentivizing the achievement

5l"I""l of acceptable background noise levels in classrooms, but

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. _ l.n contrast, the United Kingdom has implemented

\' enforceable building regulations for classrooms to guide the

design and construction of classrooms, published inBuilding

’_ - i ' _ i_, Bulletin 93 (BB93) that was first issued in 2003 and last
T ' _ A, -"H revise in nite 'n om e artment or ucation

“ _w i ii‘ i d2015U dK1gCl Dp {Ed

V ‘,5 i ‘'§.'ifi. ‘ i A J "W _ and Skills, 2015). The requirements of BB93 for unoccupied

-If "i I,» i;:__—:_i> noise levels are similar to those recommended by ANSI

’ r’ I! _.'._ Vi ‘ S. ‘ S12.60. Maximum limits for the indoor ambient noise levels
" - ‘““%'» -- >‘ _._ ~ ‘ V i ,7 (IANLs) are set to 35 dB(A) for new primary and secondary
$ ' . iv '7 school classrooms designed as core learning spaces that are

, :6 v ' _' not open plan and to 40 dB(A) for refurbished classrooms

< " , _-’ __ redesigned for the same purposes. l.ANLs are A-weighted

. /

V ’ ‘ . ' V / ' ‘ _. equivalent levels measured over 30 minutes during normal
Figure 3. Typical (top) and unique (aamiin) features charur:te1is— F°“‘}““$ h°“"‘_ ""‘°1“d‘“g _ “°“° _°°“‘"b'f“_°_“‘ f’°_"‘
tic ofthe 220 classmoms measured in the central midwestem United “‘5"“_‘“°_““l 9‘1“‘P‘“”_'‘‘ “*5 “‘5““‘“°““l ““‘’‘_““A N‘““
States. Top: Manyelassmains in the United States use ucoustiealeeil— contributions from 84180611‘ Classrooms 319 Considered and
ing tile tD add ubsorptiim tD elassriwms tD limit reverberation time as mitigated with appropriately substantial wall construction
wellasto create easyuecess points to builalingsystems almve the tiles. between deeemomei deemed apprepn-ate by me type of
Bottom: Some classrooms have unique features like thuse shown. miviiies iiiiii iiiiise seiisiiiviiies iiiiiie iiiimiiiiiiiiiiii
Alrhaugh this roum’s ceiling is more sound reflective than acoustical
ceiling tile, the brick walls are more dimesive and less reflective than The requirements of BB93 for reverberation time are also
gypsum wall lmard. These consiiieratiims eumlrined withurelutively similar (0 those recommended by ANS} 312_50_ There
small volume meant that this classrooms reverberation time met the are however differeni requirements for school
ANSI $12.50 guidelines. ch’ ’ .

ssrooms and secondary school classrooms. Reverberatlon

times in general classrooms must not exceed 0.6 second in

that a building meets certain qualifications for sustainability. new primary schools and 0.8 second in refurbished primary

A building must meet prerequisite design criteria to obtain schools. For secondary schools, the upper limits are slightly

LEED certification but can add levels of distinction through higher: 0.8 second for new construction and 1.0 second for

earning credits associated with meeting more stringent refurbished. The stricter requirement for primary school
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