Turning invasive trees into sustainable housing

Introduced to the islands over a century ago to help reforest the local landscape, albizia is one of the fastest-growing tree species in the world. Now for the bad news—this magnificent but highly invasive tree has caused a vast amount of damage to houses, roads and public infrastructure in Hawai‘i, shading out native species and posing a major threat to Hawai‘i’s forest ecosystems.

But not all is lost, says UH Mänoa School of Architecture alumnus Joseph Valenti, who is positioning the albizia tree to be a source of useful, abundant and high-value building material. Over the last year, Valenti has been hard at work developing the prototype for a functional structure made almost entirely out of albizia wood, giving the unwanted material new life as a sustainable dwelling in answer to Hawai‘i’s housing crisis.

Valenti and his team have found promising results in structural testing and started building the kit-of-parts for the prototype as part of an architecture course led by Valenti and 3D lab director Steven Hill in the summer of 2017. “The material is perceived to be structurally weak,” says Matthew Lynch, system sustainability coordinator for the University of Hawai‘i. “But according to some of the preliminary testing that has been done, we’ve actually found quite the opposite.”

The project not only challenges existing construction methods and subverts Hawai‘i’s model of import-dependent infrastructure, but it also incentivizes invasive species removal by delivering a tangible return on the significant cost of containing Hawai‘i’s albizia population. Conceived as a locally sourced solution to the diverse design challenges of our island community, Valenti’s customizable wooden dwelling is easily assembled and disassembled for use as transitional housing. Its arched skeletal structure and louvered walls complement Hawai‘i’s tropical climate by employing passive design strategies inspired by indigenous Pacific Island architecture.

The Albizia Project is now in its second year of research and development. Construction of the first full-size prototype is currently underway with funding from the UH Office of Sustainability, the UH Mänoa School of Architecture and the Hawai‘i Housing Finance and Development Corporation. Slated for completion in April 2018, the prototype will be exhibited for one year at the UH Mänoa campus adjacent to the School of Architecture at University Avenue and Campus Road.

The goal of The Albizia Project is to ultimately pave the way for an array of new design solutions that utilize Hawai‘i-grown wood and promote ecological and socioeconomic sustainability. “Every time we save a tree from the chipper, we are sequestering carbon,” Valenti says. “As we incentivize removal, we can begin to restore ecosystems with Hawaiian hardwoods and other high-value native species. We are creating an enterprise that is regenerative, closed loop and local.”