Reviews are a great way to gather more detailed feedback on an idea. You can define review metrics to rate ideas on attributes related to the challenge e.g, environmental impact, social impact or cost effectiveness.
This provides a more nuanced evaluation of an idea than a binary thumbs up/down vote allowing people to review the idea against the criteria provided.
Reviews metrics are configured in the Challenge creation wizard. The metrics are attached to the challenge, so this means you can have create relevant review metrics for each challenge.