Environmental Assessment of Plant Fibre-Based Architecture
Abstract
The use of plant fibre-based (PFB) building materials has been recognised as a promising way to reduce consumption of scarce resources and carbon footprint in the construction industry. Previous research has demonstrated the large potential of fast-growing biogenic building materials to store atmospheric carbon and therefore compensate for a building’s greenhouse gas emissions from its initial construction. This thesis aims to investigate the environmental benefits of PFB construction based on real, already built projects. A selection of five buildings, awarded with the Fibra Award (an international architectural award for contemporary PFB architecture), are compared. Two main types of analysis are used to examine the chosen projects. First, a life cycle analysis is conducted to evaluate the global warming potential (GWP) of each project – this analysis considers the production of construction materials and their transport, as well as the building’s operational energy demand. Additionally, the positive effect of carbon storage by biogenic materials is quantified. Second, an “embodied land” indicator is calculated, using thermodynamic principles of both “Emergy” and “MAXergy” analysis. This indicator assesses the required land to directly regrow biogenic materials, and to indirectly restore not re-growable materials. The specific embodied land was calculated for each construction material, in order to enable a quantitative comparison between bio-based materials and non-regrowable materials and to assess renewability and sustainable use of resources more comprehensively. The results show that PFB construction materials may be used to lower a building’s total GWP effectively, due to their lower impact compared to other conventional materials and their storage capability. Two buildings with a wooden structure and straw insulation are even shown to have net- negative GWP balances of -22.8 and -26.1 kg CO2-eq per m2 of floor area; when the emissions due to building operation are not considered. It was demonstrated that the replacement of high impact construction materials with biogenic alternatives is drastically needed in order to achieve more sustainable buildings. The embodied land of a conventional wood construction with a straw insulation, for example, is shown to be more than 6 times smaller compared to a conventional steel building.