Sustainability Report

The strategy for reducing embodied carbon was holistic and heavily focused on reuse and material substitution:

• Retention of Existing Structure: The design avoided demolition by retaining $70\%$ of the existing 19th-century timber balloon frame and masonry fabric, conserving its original embodied carbon.

• Selective Deconstruction & Reuse: Structural timber elements from temporary protection during demolitions were carefully dismantled, re-dimensioned, and reinstalled into the new truss system, demonstrating a circular construction logic.

• Low-Carbon Material Choices: The new extension relies on glulam beams and simple platform-frame infills with a large amount of timber (40% of new timber elements were sourced locally or reused).

• Surface Economy: The use of exposed OSB panels for interior walls, ceilings, and built-in furniture is a "low-tech" approach that eliminates the need for secondary, carbon-intensive finishes (like plaster and paint).

• Efficient Foundations: By working entirely above the existing masonry base, the project eliminated the need for new concrete slabs or deep foundations, which are major contributors to embodied carbon.

Operational emissions were minimized through enhanced passive design and optimization for future renewable energy:

• Passive Envelope: The existing structure was upgraded with compact insulation layers and meticulous airtight detailing to drastically reduce heating demand.

• Natural Ventilation: The layout and fenestration are optimized for natural cross-ventilation, minimizing the need for mechanical cooling.

• Controlled Solar Gains: The building manages solar heat gain effectively to maintain internal temperatures.

• PV-Ready Design: The monolithic southern façade and roof were designed to be optimised for future photovoltaic (PV) integration (up to 8 kWp generation capacity).

The design focused on low-maintenance, high-durability materials and future-proof design for repair and replacement:

• Durable Cladding: The use of corrugated fibre-cement cladding on the exterior offers high durability and acoustic protection, thus lowering long-term maintenance needs and extending the service life of the envelope.

• Reversible Finishes: Interior finishes were conceived with a low-tech and reversible logic (e.g., exposed OSB panels are screwed, not glued), simplifying future repairs, replacements, or changes.