In this video ( <a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=aJ4TJ4-kkDw" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=aJ4TJ4-kkDw</a> ) they talk about the usage for underground buildings. It could be for underground buildings what the lift is for high buildings (eg make it practical).<p>This was on Product Hunt a while ago: <a href="https:&#x2F;&#x2F;www.producthunt.com&#x2F;tech&#x2F;coelux" rel="nofollow">https:&#x2F;&#x2F;www.producthunt.com&#x2F;tech&#x2F;coelux</a>