Suppose you are looking for key indicators in the cleaning. So you are going to search the internet. The results will be advertisements of books on key figures. Cleaning companies who explain that they have key indicators in their business and do something with it. A cleaning consultant does not want to give you key figures because that is their trade. That means you get nothing to work with.
Maybe you should not want to have those commercial key indicators. They have nothing to offer other than general references to production experiences which are not measured in a scientific way. In a tender you can also see key figures. However, these are not usually tested in practice but are more in line with the market.
Get the key figures yourself! Take a license InPRC (www.inprc.nl)
Give any room and space in your building a unique barcode and let the cleaners scan the area prior to cleaning.
After several months you have the key figures for cleaning for your building applied in any area and space. No consultancy needed. You yourself have become expert and knows more about the cleanliness of your building than any cleaning company or cleaning advisor.
The license fee you will recoup within one, at most two years, apart from the superfluity to make costs of hiring a cleaning consultant.