Sustainability Report

Embodied carbon overview

• CplusC Architects + Builders conducted a Life Cycle Assessment (LCA) to evaluate the embodied carbon associated with the materials and construction of Holocene House. The study considered all primary building components, including external and internal walls, windows and doors, slabs, roofs, foundations, and building services, over a 50-year reference period (with an anticipated lifespan of at least 80 years). Global Warming Potential (GWP) is reported at 9.77 kgCO2e/m².
• Material selection was informed by this assessment. Corten steel, initially proposed for the exterior, was rejected due to its higher embodied carbon and maintenance requirements in a coastal environment. Instead, charred spotted gum hardwood was adopted as a lower-impact alternative. This shou sugi ban cladding, a traditional Japanese method of wood preservation, offers durability, minimal maintenance, and contributes to a Bushfire Attack Level (BAL) rating of 29.
• The LCA also highlights the project’s broader material strategy, with 97 percent recyclable content, 98 percent certified timber (FSC/PEFC), and 76 percent of products supported by Environmental Product Declarations (EPDs).

Operational emissions overview

• In 2023, the project became the first in Australia to achieve Active House Alliance certification, with a performance score of 1.64 across comfort, energy, and environmental criteria.
• Holocene House is designed as a self-sustaining, energy-positive home. Sixty-six rooftop photovoltaic panels generate 26.4 kilowatts of solar power, with energy stored in an on-site battery system, producing approximately 20 percent more energy than the household requires. Electric vehicle and bicycle charging infrastructure is also integrated.
• A hydronic heating and cooling system embedded in the concrete slab, supplemented by radiators, maintains year-round comfort, while an energy-efficient heat pump provides hot water and heats the swimming pool during cooler months. Passive strategies are also integrated, with the natural, chemical-free swimming pool and adjacent bio-filter pond contributing to thermal mass and helping to cool incoming air in summer.
• The house also functions as a water catchment and storage system. Rainwater is collected via an overhead canopy and stored in a 15-kilolitre underground tank, supplying water for showers, toilets, laundry, and the pool. Greywater from showers, sinks, and the washing machine is filtered and reused for irrigation, supporting a climate-resilient and largely self-sufficient water system. Additional elements, including a fruit and vegetable garden and a chicken coop, further contribute to the home’s self-sufficiency.
• Material reuse strategies also support the project’s overall resource efficiency. Excavated materials were repurposed across the landscaping, driveway, and rear yard, while elements from the original house, including joinery, bricks, timber, and planting, were salvaged, reused, or donated. Recycled hardwood was used to create a range of custom elements, including a 12-metre laminated kitchen island bench, flooring, joinery, and structural components.