Noise Attenuation in Distributed Energy Systems

Prime office space takes noise control in new directions.

Cogeneration, CHP, Combined heat & power

Editor’s note: This article first appeared in the November/December 2015 issue of Distributed Energy.

The commercial building sector has seen a steady rise in the use of distributed energy. Whether the need is for energy security, participation in a demand-response program, or as a strategy for sustainability, distributed energy projects are playing a role. But the noise of a generator makes special demands upon architects and designers.

Distributed energy fits well with some major trends in office designs, according to Ethan Salter, PE, LEED AP, a principal acoustical consultant at Charles M. Salter Associates Inc., San Francisco, CA. “We do see a lot more engine generators and emergency generators in buildings and even in residential areas,” says Salter. “With office buildings and intelligent buildings and 24/7 server rooms, they’ve got to have power, and whether they’re in the basement or on the roof, engineers have to make sure that noises and vibrations are controlled. Some options are springs or rubber isolators.”

And it’s not just mechanical generators. With solar PV, inverters can buzz and cause problems. Also, the equipment’s location in the building has to be considered. If you have generators on the roof, you can avoid putting them above quiet office space. Salter notes that his firm gets hired by customers or landlords to make sure the landlord is providing a building that people want to rent.

As firms, such as Google, redefine office environments, it’s not unusual to offices with TV stations, studios, music practice rooms, gyms, or sensitive conferencing facilities. “Some companies desire to have 100% uptime,” says Salter. “Or they may be working with locations in China, so you have an office going round the clock, and they need a generator. But landlords don’t know if a tenant plans on putting in a kitchen or conference room, yet they need to have a baseline so they can charge higher rents. For example, customers based here in California demand high-quality, and the landlord needs to meet all kinds of city and state requirements.”

With more companies adopting open office floor plans, Salter explains that a new problem arises, and actually requires the addition of noise. “It’s called sound masking or white noise, and it has become more important, because now offices are almost too quiet. Thanks to passive ventilation and an open plan and energy-efficient buildings, we’re seeing situations where there are distractions from things such as the clicking of keyboards. Also, video conferencing can be quite distracting, and there are issues of speech privacy. White noise can minimize those distractions.”

In such cases, designers have found that generic, undefined background noises, such as those from a generator, are not as distracting as conversations or other specific noises that workers can understand.


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