In the case of a workplace (which includes access to and from, also any areas his/her employees have access), the employer is the RP. Under Art 5(1) as RP he/she is responsible for articles 8 to 22 with a possible get out clause if the RP does not have control, art 33.
Under art 5(3) any other person who has to any extent, control of premises and this would include the owner/managing agents if they have control of, say the fabric of the building, providing the RP has brought it to their attention, they would be responsible.
I would imagine the tenant?s agreement would show who has control of different items, who pays and I would think in most cases the fabric of the building would be under the control of the owner/managing agent, other items would depend on any legal agreements.