pchwalek · HackerTrans

hace 4 añosdiscuss

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.

pchwalek

hace 4 añosdiscuss

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.

pchwalek

hace 4 añosdiscuss

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.

pchwalek

hace 4 añosdiscuss

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.

pchwalek

hace 4 añosdiscuss

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.

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