Sustainability Report

Embodied carbon overview

• Greenview House has been assessed over a 60-year design life. The embodied carbon assessment was undertaken through a whole-building Life Cycle Assessment prepared in accordance with ISO 14040, ISO 14044, EN 15978, and the RICS Whole Life Carbon Assessment, 2nd Edition, methodology.
• The assessment was based on the as-built project and modelled the principal construction materials and quantities using the BIM model, construction drawings, and detailed quantity analysis. Particular attention was given to accurately quantifying the highest-impact materials, including the structural frame, concrete substructure, and external envelope.
• In accordance with EN 15978 guidance, cut-off criteria were applied to exclude individual materials and components contributing less than one percent of the total environmental impact, while ensuring that the combined impact of omitted items did not exceed five percent of the overall assessment.
• The upfront carbon impact, covering life cycle stages A1–A5, is 889.8 kgCO2e/m². This includes impacts associated with material extraction, manufacture, transport, and construction. 
• The whole embodied carbon impact across stages A–C is 1,622.5 kgCO2e/m², covering construction, maintenance, replacement, and end-of-life.
• Greenview House sought to reduce embodied carbon through efficient structural design, the careful selection of lower-carbon materials, and a focus on durability and longevity. These principles informed key decisions throughout the design and construction process.
• Below ground, the house was constructed alongside an adjoining new-build property, with both basements built simultaneously by the same groundworks contractor. This allowed for shared party structures and a simplified design, reducing the amount of concrete and steel reinforcement compared with constructing the basements independently.
• Above ground, the superstructure is formed from cross-laminated timber (CLT). The use of CLT was intended to reduce embodied carbon through lower manufacturing emissions, efficient material use, reduced waste, sustainable sourcing, and carbon storage within the timber itself.

Operational emissions overview

• Sustainability informed every stage of the design process, with the primary objective of creating a highly efficient, low-energy home on a constrained urban infill site. The net-to-gross efficiency of the 40-square-metre plot is 85 percent.
• Greenview House adopts a fabric-first approach, prioritising a highly insulated building envelope, airtight construction, reduced thermal bridging, and high-performance glazing to minimise operational energy demand before incorporating low-carbon building services and on-site renewable energy generation.
• Full Passivhaus certification was considered during the early design stages. However, analysis of the site’s orientation, constrained mid-terrace position, and relationship between a smaller existing dwelling and a larger proposed neighbouring development identified practical limitations that made formal certification difficult to achieve. Rather than pursuing certification, the design adopted Passivhaus principles wherever appropriate to maximise building performance.
• The building envelope combines internal and external wall insulation, with 75mm insulation internally and 150mm externally, helping to optimise wall thickness and thermal performance. The weighted average U-value for the walls, roof, and floor is 0.13 W/m²K.
• Airtightness was achieved through the careful detailing of all CLT panel joints, which were fully taped, and the installation of a continuous self-adhesive vapour control membrane. A preliminary airtightness test was carried out during the latter stages of construction, identifying areas of the building envelope that could be improved. The final airtightness test achieved a 25 percent improvement, reducing air permeability from 2.64 m³/h·m² to 1.99 m³/h·m².
• All windows are triple-glazed, providing high thermal resistance and minimising heat loss. The window frames were taped and fully sealed to prevent air leakage. Thermal bridging was also reduced through the use of an aluminium ‘helping hand’ bracket frame system with thermal isolator pads for the timber cladding installation.
• To complement the fabric-first approach, building services and renewable technologies suited to the scale of the project were incorporated, including solar PV, an air-source heat pump, and mechanical ventilation with heat recovery. The home is equipped with a balanced MVHR system with a thermal efficiency transfer rate of 75 percent.
• The predicted operational energy demand is 28.3 kWh/m²/year. Since completion, the building’s energy consumption has been monitored during occupation. Based on measured electricity use between 26 February and 9 November 2025, a period of 257 days, and adjusted to account for seasonal variation during the winter months, the estimated annual operational energy consumption is approximately 5,494 kWh/year, equivalent to 71.2 kWh/m²/year.
• The monitored figure represents the building’s total operational electricity consumption rather than regulated building energy alone, and therefore includes space heating, domestic hot water, ventilation, lighting, cooking, appliances, and other everyday plug loads. As a result, it provides a measure of real-world building performance alongside the design-stage energy prediction.
• To further reduce operational carbon emissions, the house incorporates a roof-mounted photovoltaic array, estimated to generate approximately 1,554 kWh of renewable electricity each year, offsetting a proportion of the building’s annual electricity demand. Together, the high-performance fabric, airtight construction, MVHR, air-source heat pump, and on-site renewable generation support the project’s operational efficiency.

Service/maintenance emissions overview

• The building has also been designed for efficiency and a long lifespan, prioritising durable, low-maintenance materials and detailing. Exposed polished concrete screed was specified as a floor finish at basement level for its robustness and ease of repair. 
• Externally, thermally stable cladding materials were selected to reduce degradation and minimise ongoing maintenance. 
• Robust construction detailing draws on tried-and-tested methods, carefully adapted to suit a contemporary new-build home, helping the building remain efficient, resilient, and low-maintenance throughout its lifespan.