Calculate Average Price For Various Periods

Hi everyone, looking for a little guidance on my problem. Trying to calculate the lost revenue value for when a piece of machinary is offline for a period of time based on the hrly price during that particular period. The machines come on/off line at various times during the year so i am trying to make this a bit dynamic so i only need to add new info and not have to change the formula

Column F - Off date of machine
Column G - Restart date of machine
Column H - Hrly time
Column I - Hrly price

I thought this formula (an array) would work for me

=average(if((Column H>=Column F) * (Column H<= Column G), Column I)) but it only calculates that average price for the first period and not new average prices for other periods.

Any thoughts on what adjustments I can make to my formula or is there a better formula to use?

Thanks for any assistance.
Nish