Tree houses are an unusual undertaking. Generally those who embark on building a home in the trees cite the closeness to nature and the minimal impacts on the ground surface as evidence of an eco friendly and sustainable lifestyle. However, the sheer human cost of lifting all building materials up a 30 foot ladder is probably the primary reason that minimal and long-lasting durable materials are used.
Just as with the ancient Anasazi cliff dwellers of the American Southwest, the requirements to personally haul every item up a ladder will result in a personal cost-benefit ratio calculation of every item necessary for life. The end result is that the size of the residential structure is greatly reduced as well as the resources needed to live in such a structure.
A truly sustainable tree house is one that uses the natural environment to its advantage rather than trying to conform the environment to fit the plans of the structure. They integrate the concepts of permaculture and long-term sustainability with the practicalities of the landscape and the local climate.
Use of sustainable practices is almost mandated by the uniqueness of the placement of the house within the trees. It is relatively difficult to tap into the local utility system, if one even exists, so more inventive systems need to be incorporated to provide cooling, heating, water, and power. Solar power can certainly be used but placement of the solar panels is dependent upon the shade of the tree. Mini hydro power is also an option as well as wind or small-scale geothermal power.
Saving rainwater through the use of rain barrel systems is the most common method of saving and using water for everyday household use; but use of local resources such as springs and rivers may also be used.
One of the key problems to building a tree house is that trees tend to grow taller and into different shapes. A sustainable tree house must be able to adapt to the changing geometry of the surrounding trees without adversely affecting the trees. One method is to suspend the house from the trees while another is to use immature trees as a foundation of the house and utilize the growth potential to maximize the strength of the tree house foundation.
Without proper consideration of the potential tree growth nature will overtake the structure ad the tree house will eventually fail. This is an epic reminder about living in harmony with nature rather than trying to overtake it.