Entire home expenses could be: Electric, gas, security alarm, telephone, water, sewer, garbage, cleaning service, mortgage interest, property tax, lawn service, etc.
If the office is in your home it would be unusual to have just office expenses but you could have:
New carpet/flooring, plaster, paint, or other repairs in just that designated room. You may also have a designated telephone line for just the office.
Hope this helps. Good luck.