I was curious about the 35 degree outside temperature. I found a site with weather data for Jerusalem and I'm not seeing anything close to 35 degrees so you must be using Celsius; yes, 35 C is very hot. Your temperatures in Jerusalem are similar to where I live in Savannah, Georgia.
http://www.timeanddate.com/wea...
Plants in the bank:
My experience with live plants indoors at a business office or bank is this:
You will need to do all the work to care for the plants; watering, pinching off dead leaves and flowers, checking for insects, etc.
You will need to have at least two sets of plants as you will need to constantly rotate the plants...take the plants out and put in new plants probably about once a month. The employees of the bank will not care for the plants and will expect the plants to always look perfect. Also, you will need to use some sterile planting medium so there will be no insects introduced into the bank building. Bank employees and customers would most likely enjoy seeing plants in bloom or at least plants with interesting foliage. It will be a very big job for you.
I have found that Pothos are very forgiving plants, meaning that they can adapt to indoor environment better than some other plants. The Golden Pothos/Epipremnum aureum is very pretty.
There are many other good choices for indoor plants in a bank (depending on the available light and watering schedule) but I don't know if you can grow the plants from seed. It might be better to buy plants, take cuttings to increase the number of plants.
