[time-nuts] Room temperature control (was: Holdover, RTC for Pi as NTP GPS source)

Poul-Henning Kamp phk at phk.freebsd.dk
Wed Nov 1 15:32:25 EDT 2017

In message <20171101190841.366058d77e544d256b86248c at kinali.ch>, Attila Kinali w

>The best we can do today is to have a well insulated room (no windows
>with whith unknown power flows) and measure the temperature at a few
>strategically choosen points. Then control the heat influx and
>outflux using an approriate control loop. This will still result
>in deviations of 1-2°C when somone walks in.

It is a matter of energy balance.

Humans emit heat on the order of a hundred watts and the only way
to have that not affect the room temperture, is to "wash" it away
in airflow with much higher energy content, as is typically done
in clean-rooms.

That still leaves you with the thermal radiation imbalance from the
higher temperature of the human skin, which is why "nano" laboratories
sometimes are kept at an uncomfortably warm temperatures.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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