a/c question

i live with two other housemates, and we have central air conditioning. we're in texas, where it's still hot (in the 90s), so the a/c is on, but we keep the thermostat near 80 degrees. the thing is it gets cold here at night (in the lower 60s), which means it's cooler inside than outside. so i've recently started opening my window at night to keep cool. does that affect how often our a/c switches on? i don't think it does because by opening my window, i'm making my room cooler, so the a/c won't switch on if it's set to 80 degrees. but one of my housemates thinks it'll make the electricity bill more expensive. yes/no/maybe/askmelater?

It really shouldn't.

Your main problem in terms of money would be running fans extra hard at night to keep air circulating, since the a/c isn't doing it then.

If the humidity is relatively low, it won't affect things, but if it's high, the AC will have to work to remove the extra moisture when it does kick back on.

Trudat.

99% of all A/C is regulated by exactly ONE thing: The thermostat. You've implied that the house has one thermostat (the usual situation; landlords don't want to own multiple coolers).

I doubt that the extra dehumidification work would offset the real temperature lowering caused by opening the window, in terms of energy expenditures. However, when humidity is introduced, people feel warmer, which might 'cause folks to feel warmer in the morning.

The thing to keep in mind here, however, is the 2nd law of thermodynamics: Yr home seeks thermodynamical entropy. You can't "lose" cool air out yr window when the air out the window is already cooler.

i hadn't considered the humidity issue--it has felt a little more humid in the mornings, but it's still cooler in my room than the rest of the house in the morning, so i doubt humidity is affecting the a/c.

(btw, they don't open their windows because they don't have screens and would feel weird with the window wide open, ya know? just in case you were wonderin'...)