New tests by nk Architects show that it cuts the noise in half.
When Passive House started in the 90s, it was all about energy, and that is what the basic standard regulates. But saving energy is a hard sell these days when fossil fuels are so cheap, so Passive House people are pivoting to other virtues of Passive House design that are byproducts of super-insulated walls and high quality windows: Comfort, that comes from having a wall surface and window that is close to room temperature, and Resilience or security, because Passive House designs stay warm when the heat goes out.
But there is another feature that comes with thick insulated walls and triple-glazed windows: Quiet. It really cuts down the noise inside. A few years ago I was in Jane Sanders' Passive House renovation of a Brooklyn townhouse and noted in my post on it:
For someone living in New York City, perhaps the biggest benefit of building to Passive House standards is that it is incredibly quiet inside. Bergen is a busy street, with buses and trucks going by at all hours. However the high quality triple glazed windows plus the thick blanket of insulation really cut the noise; you could see buses go by and really could not hear a thing.
But how much quieter is it? Zack Semke of nk Architects looked at the question and writes:
We asked the acoustic engineers at SSA Acoustics to evaluate just how significant the noise reduction in Passive House buildings is. They studied the design of a 12’ by 9’ section of exterior wall from a typical multifamily unit, comparing two versions of the wall: one using conventional construction and double-paned windows, the other employing Passive House thickness, insulation, airtightness, and triple-paned glazing.
Thanks mainly to the greater thickness of both wall and windows, the Passive House wall reduced exterior noise penetration by roughly 10 decibels. And that's before making materials selections that could further reduce sound penetration, like insulating with mineral wool, a naturally soundproof product. The exact reduction will vary depending on site conditions and design choices.
The decibel scale is logarithmic, with every ten dB meaning a doubling of noise and vice versa, so a reduction of ten dB means it is reducing the noise level by 50 percent. That is a serious turning down of the volume.
It's one of the reasons that I have become so fond of the Passive House concept; you come for the energy and carbon but stay for the comfort, security and quiet.