I have been the curator/manager of a small historic building for 10 years and a change in management now requires that I document my working hours and processes, presumably to determine a change in my salary. 
Specifically I am asked "from when to when do you work?"
I have never been required to document my processes before, and this place has been generally neglected until I brought significant changes to its bottom line.

I live on site (my workplace is also my home) and my basic duties have been to look after it and handle visitors or anyone who wants to use the venue for other purposes like events. 

Firstly, visitor inquiries (and visits) could happen at any time during the day and all other duties around maintenance and care for the building happen ad hoc around the clock - from when I wake up to when I go to sleep.

Beyond that, I was able to build major partnerships and bring more visitors, groups, events, etc. than all its lifetime put together. Also by attending conferences, traveling, etc. I significantly boosted the visibility, image and quality of the place.

The former owner of the place knows this but my achievements were never reflected in any formal review; I enjoyed full ownership and independence in how I worked and developed the place until it was noticed and is being taken over.

As someone who looked after the place almost like its owner and was dedicated virtually the entire day, I am not sure how to quantify my working hours, or how I could explain that I work based on "business needs" like an entrepreneur/owner would do.

Any advice appreciated!