Should I pay for utilities (like heat and electricity) in my home office with my business or personal bank account?

Is your home office a separate structure or how would you even know how much to pay for that part from your bill?  And if you are filling Schedule C for your business it doesn't matter which bank account or credit card you use to pay expenses.  It all goes on your personal 1040 tax return.

Personal ... it is a personal expense of which some may be taken on the Sch C thru the OIH expense form 8829.