Cross Laminated Timber (CLT) or Massive Wood is the answer.
While that may seem a ridiculous thing to say, in construction terms it’s not far from the truth. The CLT Fenster & Panel uses is 100% sustainable and origin identifiable. It removes the need for concrete and steel throughout much of the build process and can be used as easily in a domestic house construction as a multi residential unit construction.
CLT is used extensively across Europe, and is only available in completely fabricated packages, meaning that onsite construction takes only a fraction of the time of a conventional build.
For further information on CLT please see the attached factsheets.