Mindblown: a blog about philosophy.
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Space Planning
The main acoustical goal should be to locate the major noise sources, mechanical equipment rooms (housing the AHU), cooling towers, chiller rooms and roof top and other package units as far as possible from noise‐sensitive areas in the building. In large buildings it is often necessary to locate the mechanical room in the core of…
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Fan Noise
It should be noted that the selection of a fan is based primarily not on its acoustical characteristics but rather on its ability to move a required amount of air against the installed static pressure created by the downstream system elements. The first cost of the fan, its size, and maintenance costs are of primary…
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General Features of a Ventilation System
In many countries, HVAC systems have come into widespread use in residential and commercial buildings (small houses, apartments, shops, stores, warehouses, hotels, and large office buildings, etc.). The energy sources for the systems include gas, oil, and electricity. In residential housing the heating or cooling medium can be air, water, steam, or refrigerant requiring ducting,…
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Interior Noise Level Design Criteria
When specifying interior noise level objectives for different areas of a building, many factors have to be considered. In general, the ventilation system noise should be low enough so as not to interfere with speech or other communicative sounds. In determining the acceptability of the air‐conditioning system noise, it is necessary not only to aim…
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Introduction
There is widespread use of heating ventilation and air‐conditioning (HVAC) systems in a variety of small and large buildings. The main consideration facing the designer of such systems is to ensure that the plant provides the required amount of heated or cooled air throughout the building and does not create objectionable noise or vibration either in the…
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12.9.4 Control of Vibration of Buildings Caused by Strong Wind
Structures such as buildings immersed in a moving fluid experience fluid loading forces. These forces are caused by several physical phenomena. The phenomena may be divided into three main categories: (i) steady incoming flow that impinges on the structure, (ii) unsteady incoming flow, and (iii) eddies (vortices) that form in the fluctuating wake flowing past…
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Impact Sound Transmission
Impact noise is other major sound transmission problem in buildings. Although transmission of airborne sound is probably the major problem, the secondary problem of sound transmission from impacts such as footsteps, doors slamming, hammering and other forms of construction, etc. has concerned acousticians for many years. Footsteps are the main source. There are two main…
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Single‐Number Ratings for Partitions
When comparing different wall constructions, it is often convenient to use a single‐number rating instead of the complicated transmission loss (or normalized NR) which varies with frequency. Early single‐number ratings were obtained by simply averaging the TL (or normalized NR) in the frequency range of interest. Although such a system may be useful in rating walls, it…
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12.7.2 Measurements of Transmission Loss in the Field
It is difficult to obtain the idealized conditions of random incidence, diffuse sound fields, and absence of flanking transmission in laboratory situations. In real buildings (field conditions), such conditions are impossible to obtain in practice. However, as discussed before, it is sometimes necessary to determine the TL of a partition in the field where flanking transmission is present.…
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Sound Transmission Measurement Techniques
There are several reasons for making sound transmission measurements, including: (i) to make tests under standardized laboratory conditions which should give repeatable comparisons of the performance of different partition structures and materials, (ii) to conduct laboratory tests in development work on partitions to indicate changes in sound TL which are caused by small design changes, (iii) to decide…
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