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Week 10: Heating, Cooling, and Ventilation

Sides covering both lectures are here.

Lecture 1: HVAC for Small Buildings

Integrated Project Delivery -- sounds kind of like agile for building development.

MacLeamy Curve -- also reminiscent of concepts that come up in software development frequently.

What was the first heater? Fire.

Fire works as a heater because it radiates. All the convection goes straight up. Once you put it in an enclosed space you get some convection, but typically you don't want to breath this heated air. Improvement -- add a chimney. Now you are back to radiation only.

Bigger improvement -- self enclosed fireplace with dedicated intake and exhaust.

Next improvement -- central heating with a distribution system. Source energy + Heating System + Distribution System. e.g. Wood + Furnace + Air, or Electricity + Heat Pump + Water.

Lecture 2: HVAC for Large Buildings

Air Handling Unit - the primary devices which take outside air, condition it, and distribute it throughout a building. These come up at work a lot.

It strikes me that this course is just now in week 10 discussion the kind of "sustainable building tech" that I work with. But the real sustainability is to just not need an AHU, lighting controls, etc. via daylighting, natural ventilation, shading systems, and so on.

How much duct space do we need? 10 L/s of fresh air per person that needs to be conditioned. Two main concerns: number of people and overall load. Pick the larger of the two.

Air speed is typically assumed to be 1.5 m/s.

Air ducts need to be suprisingly big. Overall its really inefficient to condition with air.

Again we can simulate this calculations with the software.

The prof suggests architects might be better at laying out the ductwork than HVAC engineers. A really complicated puzzle. This is how you end up with a giant plenum or absurd ductwork. About a third of the volume of your building is just for these purposes.

Air terminal boxes (ATUs) - recieve air from an AHU and control airflow and sometimes temperature to maintain the desired space temperature.

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