Wis. Stat. § 704.27
If a tenant remains in possession without consent of the tenant's landlord after expiration of a lease or termination of a tenancy by notice given by either the landlord or the tenant, or after termination by valid agreement of the parties, the landlord shall, at the landlord's discretion, recover from the tenant damages suffered by the landlord because of the failure of the tenant to vacate within the time required. In absence of proof of greater damages, the landlord shall recover as minimum damages twice the rental value apportioned on a daily basis for the time the tenant remains in possession. As used in this section, rental value means the amount for which the premises might reasonably have been rented, but not less than the amount actually paid or payable by the tenant for the prior rental period, and includes the money equivalent of any obligations undertaken by the tenant as part of the rental agreement, such as payment of taxes, insurance and repairs. Nothing in this section prevents a landlord from seeking and recovering any other damages to which the landlord may be entitled.
Wis. Stat. § 704.27
This section requires a minimum award of double rent when greater damages have not been proved. Vincenti v. Stewart, 107 Wis. 2d 651, 321 N.W.2d 340 (Ct. App. 1982). "Rental value" includes only those obligations that the tenant is required to pay during a holdover period regardless of whether or not the tenant uses the premises. Univest Corp. v. General Split Corp. 148 Wis. 2d 29, 435 N.W.2d 234 (1989).