Started scaling the stairs today

As I am conditioning for the Vertical Marathon in about 8 weeks from now, I started formal training earlier. Did some warm up exercises before taking lift down to the 1st floor and began climbing 18 storeys. Once done, more stretching was being carried before taking lift down and doing it one more time. I reckon it takes more energy to scale the stairs than running a short distance? My next target will be the block opposite mine: 30 storeys