Trane TRG-TRC007-EN Manuale Utente

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TRG-TRC007-EN

period three

The first step of an acoustical design is to quantify the goal. Period Two 
introduced several single-number descriptors that designers commonly use 
to define the acoustical design goal for a space. Each descriptor has its 
advantages its and drawbacks.

In general, when defining the acoustical design goal for an interior space, either 
an NC value or an RC value is used. To aid HVAC system designers, the 
American Society of Heating, Refrigerating, and Air-Conditioning Engineers 
(ASHRAE) recommends target RC ratings for various types of spaces, and 
encourages the use of the RC rating method whenever the space requires a 
neutral, unobtrusive background sound. Figure 34 includes an excerpt from the 
ASHRAE Handbook—Applications (Table 43 in Chapter 46 of the 1999 edition).

As mentioned earlier, A-weighting is also used in many hearing-protection 
safety standards for industrial environments. These standards generally take 
the form of a maximum A-weighted sound-pressure level at a specified 
distance from the piece of machinery.

room type
hotels/motels

guest rooms

banquet rooms

libraries
office buildings

open plan offices

public lobbies

performing arts

theaters

practice rooms

schools

small classrooms

large classrooms

room type
hotels/motels

guest rooms

banquet rooms

libraries
office buildings

open plan offices

public lobbies

performing arts

theaters

practice rooms

schools

small classrooms

large classrooms

25 to 35

25 to 35 
30 to 40 

30 to 40

40 to 45

25 max

35 max

40 max

35 max

25 to 35

25 to 35 
30 to 40 

30 to 40

40 to 45

25 max

35 max

40 max

35 max