Participants should secure accommodation by themselves. The internet booking services as well as Airbnb have good selection for the Helsinki region
Google Hotel Search: https://www.google.com/travel/hotels
Scandic Hotels offers 10 % discount with the booking code FIARB. Click “Booking code, Bonus Cheque or Reward night” and add the code FIARB to the textbox “Add booking code”.
https://www.scandichotels.com/hotels/finland/helsinki
Some recommended hotels nearby the meeting venue: