We had a lovely three day visit in the heat of August. The pay as you go air conditioning worked perfectly and cost around 4 euros a day for the amount we used it. It probably did change our behavior and reduce the energy used a bit. Simon provided a dedicated web link with all the details of the apartment. Self check in and check out were super easy. The apartment is extremely spacious with the exception of the bathroom which is a bit cramped. There is a steep walk home from the waterfront. We got a ride once but got quite a work out the other times.