[..]The treerooms have no sewage system and eco-friendly products are used when cleaning. Each has a modern, environmentally-friendly and completely odorless co

[..]The treerooms have no sewage system and eco-friendly products are used when cleaning. Each has a modern, environmentally-friendly and completely odorless combustion toilet where everything is incinerated at 600°C using electricity. The Mirrorcube treeroom, on the other hand, has an electrically-powered, odorless freezing toilet. Bathrooms feature water-efficient sinks with enough running water for washing hands and face and brushing teeth. All wastewater is collected in a container that is emptied daily, while showers are located in a separate building. No drains are placed affecting nature adversely.[..] This is the bit that I found interesting and ended up at this forum: https://forum.susana.org/141-other-types-of-toilets-and-sanitation-systems/13360-are-so-called-freezing-toilets-common-in-finland-does-anyone-know-anything-about-them https://forum.susana.org/141-other-types-of-toilets-and-sani... The amount of water used for flushing human waste(around 10k liters a year) that can be saved with freezing toilets is enormous. Energy cost isn’t much compared to our current sewage systems. Composting is important.