April • 2013
Considering Noise During Design
For many different types of commercial and private buildings, effective management of noise and vibration is critical. Meeting rooms, office buildings, classrooms, laboratories and residences are just some of the interior spaces that require aggressive noise abatement measures for the comfort and enjoyment of the people who use them.
One of the biggest contributors of distracting noise and vibrations in most buildings is the HVAC system. When designing a new building, it is vital that you carefully plan the design and location of the HVAC system at the start of the project. Integrating HVAC considerations into an acoustical plan at the beginning of a building plan will avoid the need for costly and time-consuming redesigns later.
There are a number of issues to consider when designing a building that has specific acoustic or noise canceling needs. Each of these issues should be dealt with up front so that the HVAC system can be designed for maximum efficiency and minimal noise.
Some buildings are almost entirely noise-sensitive, such as performance halls or schools. Others may have certain areas where control of noise and vibration are important, such as a floor of offices in a larger warehouse. The purpose of the structure should greatly influence the location and type of the HVAC system to be installed.
The actual location and use of rooms that must be kept quiet also influences HVAC design. A laboratory may have different acoustic needs than a rehearsal room, for example.
Many HVAC systems cause vibrations from blowing air, mechanical motors and other processes. These vibrations can be as distracting or disrupting as noise.
Addressing acoustic issues at the start of the design process will make HVAC placement easier, less costly and most effective.
The farther away noisy HVAC equipment is located from noise-sensitive areas, the less intrusive it will be. Some HVAC equipment will have to be in a completely separate structure to avoid noise issues. It is best to locate HVAC systems or rooms in basements, below grade, and/or next to rooms that are not noise sensitive, such as bathrooms, cafeterias, stairwells and storage closets. Keep in mind that noise and vibration can also travel from floors and ceilings, so consider what is above and below the HVAC unit.
The use of devices to lessen noise and vibration transfer is also important. The walls and masonry surrounding an HVAC room might have to be designed thicker than usual. To reduce vibration, use isolators that are designed to absorb vibrations and distribute them evenly. Two popular types are neoprene pads placed under equipment and spring-type isolators that absorb vibrations.
While quieter HVAC equipment may be more expensive than pre-packaged rooftop units, it is also likely to have a longer life and need repairs and replacement less frequently. More energy-efficient and newer technologies such as solar panels, chilled beams or displacement ventilation can provide comfortable interiors without nearly as much noise or vibration as older types of HVAC units. Sound-absorbing ductwork, efficient supply and return fans and silencers can also help with acoustic needs.