Yes you could do that... presumably you mean to alter IV ?
If IV1 holds start date and IV2 end date then:
IV9
=TIME(0,SUM(INDEX($D9:$IU9,MATCH(MIN(MAX($D$4,$IV$1),$IU$4),$D$4:$IU$4,0)):INDEX($D9:$IU9,MATCH(MAX($D$4,MIN($IU$4,$IV$2)),$D$4:$IU$4,0))),0)
Rather than double evaluating the formula to return Null for 0 use a Custom Format on the IV9:IV125 range of: [hh]:mm:ss;;
(this will display a blank for 0)
The use of MAX/MIN is to cater for possibility of dates being selected that aren't listed in row 4 (as per your example of Jan 09)
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