I've dealt with a number of older whole house fans (10 years and older) and the one thing they all had in common was a ton of noise.
Are the new "low noise" fans actually that much quieter than the old fans, and should one expect a premium price for a quiet whole house fan?
Are there installation tricks/techniques that will help reduce noise even further?
Noise should be a main concern when shopping for a whole house fan, because the hours while you are sleeping offer the coolest temperatures of the day. More important than simply exchanging the air, the cooling of the thermal mass of the structure down to the core simply takes time. Unfortunately, you can not wring all of the heat out of the thermal mass like a sponge - it just takes time - and a bit of stady, constant airflow. In this way, Running a fan overnight while you are sleeping will take advantage of these cooler temperatures, making your fan more effective on more days of the year, and reducing your need for A/C to a minimum.
Some manufacturers have incorporated ECM (electronically commutated motor) technology into whole house fans. This not only delivers AMAZING efficiency numbers, but the brushless motor design also offers extremely low noise levels.
With older, brushed motors, turning them down to a lower speed using a rheostat can reduce the noise level slightly, but you will notice that the power consumption stays roughly the same. On the other hand, ECM technology allows you to not have to trade efficiency for noise level, and you can actually maximize efficiency while minimizing noise level.
Whole house fans + ECM motors = A perfect combination for quiet, effective, efficient natural cooling.
They may cost a bit more, but considering the outstanding efficiency numbers and low noise levels, a modern whole house fan (especially those using an ECM motor) is definitely a worthwhile investment.
Cheaper whole house fans are too noisy that they in many cases go unused, or they are turned off too early in the evening, before it has really cooled off outside.
In the ~7 years since this was asked, an obvious-but-new concept emerged that has made whole-house-fans even quieter. The ECM motors from greenhead's answer are getting more common, but now companies are offering mounts that suspend the actual motor and fan a bit away from the intake like shown:
This not only moves the fan several feet away from the intake below, but also reduces much of the vibration to near zero because it's suspended.
So yes, new fans have gotten much more efficient and much quieter.
I finally installed one, and following a tip on a review left on Amazon.com, I built a box larger than the fan, then put pipe insulation around the bottom edge of the fan. Slipping the fan into the box I built causes the fan to rest on the pipe insulation, reducing the vibration transmitted from the fan to the rafters to a minimum. It doesn't reduce the noise of the air flow, but I'm getting 80dB directly below the fan, and 50dB in the bedrooms, which is fantastic compared to other house fans I've known.
Still too loud to comfortably talk beneath for extended periods of time, but not a jet engine roar either.
If I wanted to reduce the sound further I'd probably use ductwork to move the fan further away in the attic, but I'm satisfied with this. The house is normally 40-45dB during the day, so 50dB in the rest of the house is fine.
If you choose to follow this technique, make sure you leave room for your shutters to open when you build your box. I didn't do a fit test before moving everything to the ceiling, and it's significantly harder to rework the box in the ceiling than it would have been on the ground.
Also, I highly recommend installing a timer switch for the fan. It was easy to install, and now we don't have to think about turning the fan off, just press one of the buttons for the length of time desired and forget about it.
I can't speak to how much better the "low noise" fans are than the old ones, but I have an old one and really don't notice the noise much.
The location of the installation is key here. In my case, the fan is on the second floor at the end of a hallway where all the bedrooms are. While it is loud if you are in that hallway, you can really barely hear it through the rest of the house. So as long as you tuck it into an out-of-the-way corner of the house, the noise isn't really that much of a concern.
