Typically, you test a business model by first talking to customers. You need to validate that your service invention actually solves a meaningful and painful problem for your target customers. The least risky way to begin testing it is to actually talk to them.
I'd recommend a few simple steps.
First, create a "business model canvas
", or something like it. Make sure you list out all the possible customer segments, problem statements, channels where you can reach them, and then a cost and revenue structure (a strawman, usually. You'll refine it later).
Next, mock up a quick "persona
" of your target customer. This is a way of stating in advance what your assumptions are about the customer's demographics, behaviors, and problems.
Next, conduct problem interviews.
Do it in person. You can probably find customers by hanging around the shops and cafes near high-rise apartments. I have done this before for other consumer product ideas. You simply approach people, validate that they live in the towers, and ask if they want to be interviewed. Easy.
Once you have validated that you have a real problem that your service can solve, it's possible to start designing a very rough MVP of the service for further testing.
That is how I would approach it. I do lots of these projects as part of a structured MVP-testing process
. Let me know if you need help.
EDIT: It is neither hard nor expensive to interview enough people to validate your idea is worth taking further. It just take time, effort, and a thick skin. It's best with a note-taker with you, so you can interview and he/she can take notes. You'll get better insights if you don't have to do both. A great resource on interviewing customers is Talking to Humans
, by Giff Constable.