[Greenbuilding] Looking for a whole-house fan thermostat

[Nick Pine]

> We might go further than that, with a $99 eway TU PC loaded with
> ubuntu and a USB one-wire adapter and a USB X10 adapter and 2
> $44 Aagelectronica AG 8540A temp/RH sensors to measure indoor
> and outdoor temperature and humidity. That way, we could also heat
> the house on a spring day when outdoor air is warmer than indoor air
> and dry enough that there's no danger of condensation on cold surfaces
> indoors (with a dew point calc.)

Td = (460+Ta)/(1-(Ta+460)ln(RH/100))/9621)-460, approximately.
Ta = 70 F at 50% RH = 0.5 makes Td = 530-(1-530ln(0.5)/9621)
= 50.5 F, so we wouldn't want to warm a 50.5 F house with 70 F
50% outdoor air.

We might also use X10 to turn off the AC when the fan cools and turn
off the heater when the fan heats. And cool a basement below the room
temp setpoint at night and turn on a circulating fan between the 
basement
and the house to cool the house with the basement mass during the day.
And dehumidify inexpensively on cool dry days in summertime and
warm dry days in wintertime.

In a hot arid climate, we might turn off an AC and turn on an indoor
portable swamp cooler when the indoor temp rises to 80 F and run
a small exhaust fan when the indoor RH rises to 56%, if outdoor air
is dry and cool enough for evaporative cooling to work well.

Nick