Sustainability Report

Archello: Were any sustainability certifications or performance standards part of the process, formally or informally?

Satish Jassal: The project was designed to meet and exceed the London Plan and Haringey Council’s net zero operational carbon objectives, achieving a 104 percent reduction in regulated CO2 emissions compared with Part L 2013 (England’s baseline energy-efficiency standard for new homes). Although no formal certification such as Passivhaus or BREEAM was pursued, the scheme followed Passivhaus principles informally, with an emphasis on thermal continuity, airtightness, and high-performance building fabric. Standard Assessment Procedure (SAP) calculations confirm that the homes exceed the Council’s ‘Be Lean, Be Clean, Be Green’ hierarchy, with residual emissions addressed through on-site renewables.

Embodied carbon overview

• Estimated embodied carbon is approximately 600 kg CO₂e/m² (GIA), around 20 percent below the RIBA 2030 Target Benchmarks for small residential projects.
• The project uses traditional construction, with brick and low-cement blockwork external walls and open webbed timber joists for the floors.
• Brick envelope: Wienerberger Morado Red Multi bricks with BES 6001 Responsible Sourcing certification. Technical lifespan of 150 years, 95 percent recyclable or reusable at end of life, and approximately 2.0 kg CO2e per kilogram cradle-to-grave.
• Insulation: materials include Kingspan K108 Thermawall and K107 Thermaroof boards (lambda 0.019 W/mK), BBA certified with zero-ozone-depleting blowing agents.
• Green roof system: Optigreen extensive wildflower mat on Rhepanol® fk single-ply waterproofing, contributing to biodiversity and rainwater attenuation.
• Windows: Rationel AURA double-glazed timber/aluminium composite units (Uw ≤ 0.8 W/m²K)
• Waste minimisation strategies were implemented during construction.

Operational emissions overview

• Operational carbon performance is modelled at approximately –1 kg CO₂e/m²/yr, delivering effective net zero operation due to the all-electric specification and PV array.
• The development achieves a 104.6 percent reduction in CO2 emissions compared with the Part L 2013 baseline using the GLA Energy Hierarchy.
• Be Lean (energy efficiency) delivers a 15.3 percent reduction, and Be Green (renewables) provides an additional 89.4 percent reduction, resulting in a cumulative 104.6 percent reduction without reliance on carbon-offset payments — this exceeds net zero.
• The combined use of air-source heat pumps (ASHPs) and photovoltaic panels generates a 104 percent reduction in predicted CO2 emissions when accounting for carbon factors and scaling from six sampled dwellings to all eight homes.
• ASHPs deliver almost a 50 percent reduction in total regulated energy demand compared with gas boilers. Regulated energy includes space heating, water heating, lighting, and auxiliary loads, as defined by Part L of the Building Regulations.
• Electricity generated by the photovoltaic array is 16,137.64 kWh per year, exceeding Be Green regulated demand.
• The all-electric strategy includes ASHPs and mechanical ventilation with heat recovery (MVHR), with no gas infrastructure.
• A fabric-first approach underpins performance, with external wall U-values of 0.12 W/m²K, floors 0.10 W/m²K, roofs 0.10 W/m²K, and airtightness below 2 m³/hr/m².
• Brise-soleil reduce overheating risk while allowing winter solar gain.
• A long-life/loose-fit principle is supported by robust materials and natural ventilation through dual and triple aspect layouts, reducing reliance on technology over the building’s lifespan.

With the project’s durability-first strategy, brick and metal-clad facades are designed for a service life of more than sixty years with minimal maintenance.