tom wrote in message
om...
Can not convince wife about two things. Just want to bring it here for
a serious judgement:

1. Use Air conditioner for home at night:
Temperature outside = 69F, Temp in home = 81F,
Air conditioner trigger set to 75F

method A. With windows being open - My way
method B. With windows being closed - Wife's way

Question: which one make house temp drop faster and which one costs
less electricity?

If there is no wind (or no fan blowing the cool air into your house), then
neither method A nor method B will cool the house down more quickly. This
is because the air return to the AC system is inside the house. The hot air
will not get 'blown out' of the house. And there will be minimal air
exchange through the windows.

As the wind increases, eventually method A will cool the house down more
quickly. However, it will take a good sized wind or big windows to beat the
AC. AC units typically cool the air about 20 degrees F. So the air coming
out of the AC will be at 61 F (starting with 81 F), regardless of where the
thermostat is set.

(Let your wife win on this one.)

If you want to save electricity, buy a window fan.


2. Use AC for car in a hot summer day
Temperature outside = 80F,
Temp of a car parked in sun for one hour = very hot, don't know
exact temp

After getting into the car
Method A: open windows, drive for a moment then close the windows
and start AC. - mine
Method B: Start AC right away without opening windows. - wife's

Question: which one make car temp drop faster and which one costs
less electricity?

Method A here will cool the air inside the car faster. But the main source
of heat in the car is not the air, but the roof, seats, floor, windows and
dashboard. They've all been heated to uncomfortable levels, and the heat
capacity of the air is minimal, compared to the rest.

Once the air has been blown out (which will take about 2 seconds), you can
safely close the windows.

There is no electricity in a car AC system (except in an electric car)...
the AC compressor runs off of an engine belt.

--
greywolf42
ubi dubium ibi libertas
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