this post was submitted on 24 Jun 2024
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Building HVAC engineering (equipment sizing, ducting design, etc.) has been largely handwavy bullshit for a very long time and only recently has moved towards any sort of precision. Not uncommon to find boiler plants that are 3-4 times the maximum heating load in the winter, or fans running at 100% 24/7 when code only requires half of that.
Costs just get passed on to tenants so there was never much motivation to do better, the only reason building owners are moving now is because of government regulation and incentive programs.
I used to work in HVAC. I remember we had a small cold room that was struggling to maintain temperature, as in, design was supposed to be 0°F but it couldn't get below 36°F. There was a large hole in the box that was undoubtedly the cause of the problem, so I asked the installer how they accounted for that. "Oh, I doubled the infiltration value." When I tried calculating the actual losses it was way, way higher than the infiltration value. Like, the room needed someting like 3-4 times its total refrigeration capacity to reach target with a giant fucking hole in the box.
No idea who thought putting a giant hole in the box was a good idea.
"Sealed" is also a vague suggestion with HVAC. Every ducting join, every piece of equipment, all of it leaks. I shudder to think how much heating/cooling is wasted that way.