Sustainability Report

The project did not follow a formal certification scheme such as LEED or BREEAM, but it applied sustainability criteria throughout, supported by Life Cycle Assessment (LCA) methodologies to evaluate the material impact of steel, glass, and natural pavements. 

The project also aligned informally with United Nations Sustainable Development Goals (SDGs) through its focus on reuse, renewable energy, and reduced environmental impact. These included SDG 11 (Sustainable Cities and Communities), SDG 12 (Responsible Consumption and Production), and SDG 7 (Affordable and Clean Energy).

Key strategies to reduce embodied carbon included:

• Full reuse of the existing stone walls, thereby avoiding emissions associated with new masonry manufacturing and transport.
• Structural optimisation of metal profiles to minimise steel quantities.
• Local sourcing of sand and fine gravel to limit transport distances and support regional circular practices.
• Use of natural hydraulic lime mortars (Saint-Astier), which provide compatibility with historic masonry and have significantly lower embodied carbon than cement-based products.

Indicative embodied carbon values used by the design team included:

• Structural steel: 1.7–2.5 kg CO2e/kg
• Technical glass: 25–35 kg CO2e/m²
• Existing stone: near-zero new emissions
• Natural pavements (sand and fine gravel): 3–5 kg CO2e/m²

The photovoltaic installation has a moderate embodied carbon profile of approximately 600–900 kg CO2e per 1 kWp installed; this is typically offset within 2–4 years of energy production.

Operational emissions were reduced through a combination of passive and active measures:

• The new internal glass roof functions as a daylight collector, significantly reducing the need for artificial lighting.
• LED lighting with intelligent controls was integrated to optimise energy use.
• A discreet photovoltaic system was installed on the adjacent cemetery roof, supplying renewable energy without affecting the church’s heritage character.

Based on the project’s low energy demand and the combination of daylighting, LED lighting, and photovoltaic self-generation, operational energy consumption can potentially be reduced by 100 percent, depending on final usage patterns.

The restoration emphasises durable materials and low-maintenance systems:

• Natural hydraulic lime mortars support long-term performance and moisture regulation within the historic masonry.
• Galvanised steel profiles and photovoltaic panels offer a service life of 25–30 years with minimal upkeep.
• The natural pavements (sand and fine gravel) require only periodic levelling and remain fully reusable.
• Heritage preservation contributed to reduced maintenance needs, with the existing stone structure retained intact.