Biggest bang for the $ - reduce electical/cooling demand
We are considering several options for trying to reduce our electrical bill. Living in central Texas, the focus is on cooling costs in the summer. I realize there are several variables so looking at general thoughts on the options below. Last year was a scorcher, temperature wise, and we had our daughter's family living with us which added to the electrical/cooling demand. We are probably looking at staying in the house about 7 years.
Two story home, 3700 sq ft built in 1992. Original A/C's (Trane Seer 9) are 3 ton (downstairs) and 4 ton (upstairs). I am assuming they are now probably operating less efficiently given their age. The upstairs unit evaporator coils have been replaced twice (HSA home warranty covers the cost) and usually end up with 3 calls/summer for freon leaks. Current initial quotes are around $11,500 to replace both units or about $6,500 to replace just the upstairs unit (runs much more than the lower unit.
Need several windows replaced (fogging/moisture due to leaky seals) in front entry way (open two story foyer) facing South and gets lots of afternoon sun. The two main ones are a 4' x 6' and a 3' x 6' above entry door. Considering good low-E windows. Current quote is about $4,000 and includes several other smaller windows.
Additional insulation in attic. R-36 (blown cellulose) when built. About $1,300 to go to R-49.
Considering radiant barrier (foil attached to ceiling of attic, not spray) in attic. About $2,000.
Add solar film to inside of windows. About $1,500.
Solar screens on windows are original and need replacing. less than $1,000.
One local company states a "good efficient home" should result in highest electrical bill about .07 * sq ft or $259 for our house. Our Jan-Mar and Oct-Dec electric averages about $215 and Apr-Oct average $421 with the max $520.
We can't do it all at once so we are looking at either replacing the upstairs a/c or doing some of the other items this year.
Any thoughts are appreciated.