The first of its kind, and nothing to measure it against
Bale Bio is an 84-square-meter pavilion on Mertasari Beach in Sanur, built for the ReBuilt initiative. Eco-Mantra was engaged to carry out its life cycle assessment. Its design was inspired by the bale banjar, the open meeting hall at the center of Balinese village life, which was once built from timber and local materials and is now almost always concrete. The pavilion is the first building in Bali to use structural laminated bamboo, and that was the problem: nobody could say what the material’s carbon actually was, because the emission data for Indonesian bamboo did not exist.
Project Details Summary
- Location : Mertasari Beach, Sanur, Bali
- Size : 84 m², 8.5 m at its highest point
- Built : September 2024 – February 2025
- Initiative : Bauhaus Earth, ReBuilt
- Project Team : Kota Kita, Indobamboo, Atelier One, Bamboo Village Trust, Warmadewa University, Cave Urban
- Eco-Mantra’s Role : Life cycle assessment, cradle-to-gate (Stage A)
- Status : Built and open
Measuring the carbon footprint of a new material
Building the missing data
Peer-reviewed emissions figures for Indonesian bamboo barely exist, and the assessment platform we work in had no entries at all for Indonesian bamboo building products, so the team made its own inputs. We combined data from a published LCA of tali bamboo products with field research on carbon storage in Balinese bamboo strands to generate the embodied emissions for bamboo culms and shingles. Laminated bamboo has no Environmental Product Declaration in Indonesia yet, so we used the EPD of a comparable product made by similar production techniques. Where no Indonesian emission factor existed at all, we drew on countries with a similar energy mix and production profile, then ran a comparative review to check how much that substitution moved the answer. It moved it very little.
Running it before the choices were locked
The assessment ran before and during construction rather than after it, so the carbon numbers arrived while the material choices were still open. The structural bamboo was grown by smallholder cooperatives in Flores, split and treated near the point of harvest, then laminated in Bali by Indobamboo. The rest of the structure is round poles, splits and pelupuh cladding, and those simplest components turned out to perform best of anything on the building, because they need almost no processing. Concrete foundations stayed. We judged them essential for Bali’s climate, and the assessment says what they cost in carbon.
The result
A 104% reduction in cradle-to-gate emissions. 51,336 kgCO2e for a baseline building of the same size and function, against −2,062 kgCO2e for Bale Bio. The pavilion stores more carbon than its construction released.
All figures are Stage A: extraction, production, transport and assembly. Biogenic carbon storage is included and no end-of-life scenario is assumed. Stages B, C and D are under ongoing assessment, supported by a maintenance manual developed after construction. The findings appear in IOP Conference Series: Earth and Environmental Science, from the Sustainable Built Environment Conference in Tokyo.
The biggest emitter was in the roof
The single largest emissions contributor in the whole building turned out to be the carpet rubber waterproofing membrane in the roof. On Bale Bio the membrane is in place, so the finding went into the maintenance plan: reroofing with the same product would add emissions the building has otherwise avoided.
On the next building, the same finding can change the specification. Swapping a product on paper is far cheaper than fixing it after the building is up, which is why the real value of an LCA is having carbon data on hand while the key material choices are still being made.
