The life & times of an HVAC Engineer

One thing I have to take into account as an HVAC engineer is how noisy the air distribution is going to be. You can’t usually see or feel air, but if it’s got some force behind it you can sometimes hear it – think about the sound of the wind howling around tall buildings, the squeal you can get out of a deflating balloon, the background noise around the car on the motorway (it’s not all from the tyres & engine!) or even the beautiful noise you can get from flutes, clarinets & the like.

Well since my job is often to make rooms more comfortable, by providing them with fresh air and keeping them at a nice temperature, it would somewhat defeat the object if I then made them really noisy. So to avoid the whoosh & hum of fast moving air it’s important for me to design the ducts to be big enough to keep the velocity low, and to avoid obstructions & corners (much like in my earlier post: Die Hard School of Ductwork Design). The lower the air speed, and the smoother the ductwork, the quieter the air will be…but the ductwork will take up more space – so there is a balance to be had. I also need to make sure there are attenuators before and after the fan to make sure the noise generated by the fan isn’t passed into the rooms. On top of this if there are quiet/private meeting rooms I need to consider installing ‘cross-talk’ attenuators to stop conversations from travelling from one room to another via the ventilation. If there is noisy equipment in the plantroom (the room that contains all the boilers, air handling units & other equipment to keep the facility working) then I might also need to consider acoustic louvres to make sure air can get in, but not much sound can get out.

But where else in engineering is sound critical? There’s some relatively obvious roles like sound engineer or telecommunications engineer…but have you thought about the impact of acoustics on car design? Many automotive engineering companies now employ NVH (noise, vibration & harshness) engineers to make sure cars give good feedback and a safe, enjoyable experience to their drivers and passengers.

But what if your car makes no noise? There is a lot of debate at the moment about what noise electric vehicles ought to make. There are concerns that if cars are silent they’re a far greater risk to pedestrians, especially blind & partially sighted pedestrians, who may not be aware that the vehicle is there. Also, many drivers actively enjoy the sound of their engines, so may not wish to drive silent electric vehicle. Not to worry, Elvin from Warwick University has come to our rescue. “Who is Elvin?”, I hear you ask. Elvin is and ELectric Vehicle with Interactive Noise, and he looks like this:

image credit: Warwick University

He’s a bit of a test project to gauge opinion on the acoustics (whether artificially added, or left ‘silent’) of electric vehicles and he lives on the campus of Warwick University. If you’d like, you can go and listen to Elvin and give Warwick your feedback on what you think he should sound like. As electric vehicles are likely to be the transport of tomorrow I think this is a brilliant opportunity to be involved in a little bit of engineering design. I’ll certainly be taking part!


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