Back due to popular demand, Silence of the Fans: Part 2 will talk about satisfying building loads with minimal noise. However, at times it can be too quiet!
Has anybody attended a musical, and just before the good part, there’s a giant mechanical rumble and a “whoosh!” from a fan that muffles up the performance? Or has anybody turned off the thermostat before a meeting starts so they’re not interrupted by the air handler midway through? These are examples of poorly designed forced air ventilation systems, but there are better solutions!
One solution for spaces with high cooling loads is displacement ventilation. This works well for large auditoriums and office buildings with ceilings over 10 feet high. Displacement ventilation provides a minimal amount of low velocity, cool air at floor level, and lets the return ducts at the ceiling slowly draw the warm air that has risen from heat sources (bodies) below. In a theater, this provides cool air directly to the occupants. Through stratification, the hot/warm air continues to rise above the occupants to the ceiling. No need to “push” and “mix” the air with high velocity air – the cooling goes where it’s needed!
Variable refrigerant flow (VRF) systems are another solution for spaces that have different heating or cooling loads. An exterior heat pump drives refrigerant through pipes spread throughout a building. Terminal units gently circulate air throughout the room to provide an occupant set space temperature – no more locked thermostats! Imagine that kind of power! These systems can even move heat from one room to the next, instead of burning fuel or rejecting heat outside, to save energy.
Last, there’s radiant heating. Radiant heating is kind of like a sharp knife: nobody realizes how great it truly is until they get one. Then it becomes a prized possession! Radiant heating doesn’t seem like a radical technology, but it’s so undervalued. It provides reliable heating that doesn’t make a peep while providing comfort directly to its occupants. However, architects can make it flashy by installing radiant heating AND cooling in the ceiling! The radiant cooling extracts the heat from the hot air stratified at the ceiling and promotes air circulation.
The Sound of Silence
If there was a disclaimer, this is what it would be: these systems might not make enough noise for occupants. As crazy as that sounds, people can go bonkers when they don’t get auditory feedback from their surroundings. When somebody places a call, they wait for a dial tone to let them know it worked. Cashiers swipe cartons of eggs past the scanner until it “bleeps”. One example of an auditory fail is watching a baby boomer start a Prius; they hold the key for 10 seconds because there’s no “vroom” to signify it started.
To prevent deafening silence, install a touch-tone thermostat and a white noise machine to fill the void instead.