Im in a PhD program at MIT where I mainly build embedded systems and its not something I would recommend unless you are passionate about it. Hardware is "hard" and frustrating to debug since you are navigating both the hardware, embedded software, and sometimes the external software the device talks to. Many of my peers just do software-focused projects and can iterate much quicker. On the flip side, showing people physical artifacts that I've built is rewarding. Having the skillset to build a physical product from the ground up is nice and I would argue there are less people around that can do that. I get at least one person a week that comes to me to help them debug a hardware project since they mainly learned through Arduino sketches but when shit hits the fan, its a daunting task to debug beyond the sketch.
The other thing to note is if trying to spin out, finding VCs to fund a hardware startup is also tricky since the time horizon is much longer than a software startup. That being said, I've worked at a hardware startup before and if you have a compelling enough story, you can raise money without needing an initial prototype. In fact, I would recommend this since I also know of a lot of engineers who've spent a lot of time building something first and then there is no market/funding for it.
Now getting back to me not recommending this route, especially on the PhD level. Stable jobs for this line of work are hard to come by and are often underpaid for reasons I don't entirely understand besides that pure software deployments can reach larger audiences in a shorter amount of time which equals more ROI. The space is a bit fragmented and the level of skill varies. Many undergrads aren't really taught embedded-c either and often gravitate to higher level languages which are more domain flexible. Unless you land a job at a tech company building rapid internal prototypes which pays fairly well, the more common route I see in this space is for highly skilled people working contract jobs which can be too unstable for some. If you really wanted to go this route, I would recommend coupling embedded engineering with another domain (e.g., edge machine learning, technology applied for conservation/ecology). I did this about 2 years ago in my PhD and I can say that it has brought me significantly more attention and interest from funders and potential employers.
Depends if you live in a climate where just regulating humidity is enough to guarantee thermal comfort, something that is dependent on humidity, operative temperature, clothing level, metabolic rate, and air flow rate. And people are general only comfortable in environments that are 30-60% relatively humid so that’s a pretty small window.
A lot of that is due to structures not having a proper vapor barrier, therefor allowing vapor exchange from the outside world which decreases in-wall condensation.
I think you can only separate them in radiative systems. But otherwise, a modern commercial HVAC system has a degree of mixing the air from the outside world to reduce gas and particulate concentrations. So in some systems, the HVAC is the ventilation system but when only ventilating, the flow rate is stepped down and the conditioning system is inactive.
This depends on the climate zone you’re in. In drier climates, some HVAC systems are actually humidifiers which blow the outside dry/hot air through a wet membrane (ex., desiccant) and blow out wetter/cold air.
I would disagree with new houses not considering ventilation. There are set building standards (ASHRAE 62.1, 62.2, and ISO standards) that have been around for a while that specify how ventilated spaces should be for given use cases. There’s a more recent trend to evolve these standards to take into consideration non-hazardous levels of particulate matter and gases that still show cognitive impairment—-I’m currently exploring this topic area for my PhD work.
What we’re seeing, though, are tighter building envelopes so that the structure is thermally efficient. However, with a tighter envelope, active/natural ventilation systems becomes even more important than in older structures where there is some rate of natural air exchange with the exterior through building cracks and terrible (by todays standards) windows.
There are companies coming up that are looking at “Personal Comfort Systems” and there is a fair amount of active research in this area (ex., https://cbe.berkeley.edu/research/personal-comfort-system/). It’s an interesting space since you have essentially two knobs to play with: (1) a persons actual heat exchange with the environment and (2) a persons perceived heat exchange.
Modern building codes do carefully consider ventilation, but I think a lot of knowledge and tradecraft have been lost.
If you're lucky and live in an older house of the correct design from just before A/C, (most of the oldest two-story single family homes in Berkeley, FWIW) you might notice that some of the internal walls stay well below room temperature during the summer.
The buildings typically have pier and beam foundations, and the cooling walls have passive draft ways that pull cool air over the ground under the house and up against those walls. This is great in the summer, but not so much in the winter. I don't know how they use convection to pull cold air up, or how they prevent moldy foundation dirt air from permeating the house. I've heard there are some pretty clever designs, but (of course) they're hidden behind walls.
Anyway, our modern house is one story, and has an intentionally-uninsulated concrete slab on grade foundation, so we get a similar effect. (Passive solar heat keeps it toasty in the winter.)
We usually have our windows open, but we also over-insulated the walls (for noise and efficiency), and have a tight building envelope, so the heating/cooling bill is tiny.
(Edit: I bet they vented the walls into the attic and under the floor. That'd create a strong updraft in the summer (out the attic vents), but (if the attic is well insulated against the rest of the house) not in the winter.
