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Cake day: May 29th, 2024

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  • Yes, thermal mass only serves to even out fluctuations in temperature. If the outside environment swings between hot and cold then a building with high thermal mass will tend to have a temperature in the middle of those two extremes. Like how a heavier ship is tossed about on the waves much less than a small boat.

    But if a place is consistently hot or cold for a long time thermal mass doesn’t really do anything. At most you can use it as a battery, so you can, for example, run a heat pump while electricity is the cheapest and use the thermal mass to maintain the temperature you established over the costly period.

    So many people think that its a substitute for insulation though, which slows down the rate of heat transfer in or out, and does actually let you use less energy to maintain a given temperature.





  • For awhile now I’ve been thinking about how nice it would be to have a something like a modern version of the Poqet PC.

    The Poqet PC had a much nicer keyboard than the laptop in the article, and between the simplicity of its software and a very aggressive power management strategy (it actually paused the CPU between keystrokes) it could last for weeks to months on two AA batteries.

    Imagine a modern device with the same design sensibilities. Instead of an LCD screen you could use e-ink. For both power efficiency, and because the e-ink wouldn’t be well suited to full motion video, the user interface could be text/keyboard based (though you could still have it display static images). Instead of the 8088 CPU you could use something like an ARM Cortex M0+, which would give you roughly the same amount of power as a 486 for less than 1/100th the wattage of the 8088. Instead of the AAs you could use sodium ion or lithium titanate cells for their wide temperature range and high cycle life (and although these chemistries have a lower energy density than lithium ion, they’d probably still give you more capacity than the AAs, especially if you used prismatic cells). With such a miniscule power consumption you could keep a device like that charged with a solar panel built into the case.

    Such a device would have very little computing power compared to even a smartphone, but it could still be useful for a lot of things. Besides things like text editors or spreadsheets, you could replicate the functionality of the Wiki Reader and the Cybiko (imagine something like the Cybiko with LoRaWAN). You could maybe even keep a copy of Open Street Map on there, though I don’t know how computationally expensive parsing its data format and displaying a map segment is.