Trane TRG-TRC007-EN manual Setting a Design Goal

period three

Acoustical Analysis

notes

Setting a Design Goal

room type	RC(N) criteria
hotels/motels	25 to 35
guest rooms
banquet rooms	25 to 35
libraries	30 to 40
office buildings	30 to 40
open plan offices
public lobbies	40 to 45
performing arts	25 max
theaters
practice rooms	35 max
schools	40 max
small classrooms
large classrooms	35 max	Figure 34

Setting a Design Goal

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.

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