Sustainability Report

Explanation of Calculation Methodology

The carbon emissions and potential carbon capture associated with the Casa D project were estimated using a manual material-based approach grounded in publicly available European LCA (Life Cycle Assessment) data. No software tools were used in this preliminary estimation.

Carbon Emissions

Material-specific emission factors were sourced from recognized European environmental product declarations (EPDs), the ICE Database v3.0 (University of Bath), and the ÖKOBAUDAT database (Germany). Emissions are calculated using cradle-to-gate values (A1–A3 stages), covering raw material extraction, transport, and production.

For each material or system, the approximate quantity was multiplied by its respective emission factor. The following key materials were considered:

• Reused reinforced concrete (structure): assigned negative emissions due to avoided production
• New steel structure and composite slab (extension)
• Aluminium window and door systems
• Thermal insulation and building envelope
• Interior finishes (flooring, plaster, paint, etc.)
• Technical systems: aerothermal heat pump, radiant floors, photovoltaic panels, and solar collectors

No emissions were included for landscaping or furniture.

Carbon Capture

Since the project does not employ significant quantities of carbon-storing materials (e.g., mass timber, straw, cork, or bio-based insulation), the estimated biogenic carbon storage is negligible (0–300 kg CO₂e). Non-organic materials like steel, concrete, and aluminium do not capture carbon.

Scope and Limitations

The estimation covers the entire building envelope and technical systems over a gross floor area of 187 m². It excludes site works, landscaping, operational energy, and transport or construction stage emissions (A4–A5).

This is not a formal LCA or software-generated carbon report but a preliminary approximation to contextualize the project's embodied carbon impact. 

EDesign Strategies That Reduce Operational Emissions

The Casa D project integrates a series of passive and active design strategies aimed at minimizing operational energy demand and associated carbon emissions:

1. High-Performance Building Envelope

The use of a compact, monolithic volume with limited openings on privacy-exposed façades reduces heat loss and gain.

High-quality thermal insulation and airtight detailing minimize thermal bridging and enhance energy retention.

2. Orientation and Passive Solar Design

Openings and the double-height void are strategically placed to optimize natural daylighting while avoiding overheating.

A skylight over the stair core floods the interior with morning light, reducing the need for artificial lighting during peak hours.

3. Zoned Layout and Thermal Efficiency

The spatial configuration allows for zoned heating and cooling, ensuring energy is only used where and when necessary.

The internal thermal mass of retained concrete elements helps regulate temperature fluctuations.

4. Low-Carbon HVAC System

A high-efficiency aerothermal heat pump provides both heating and cooling through a radiant floor system, which operates at low temperatures and is highly efficient.

The system also provides domestic hot water, reducing reliance on fossil fuels.

5. Renewable Energy Integration

The flat roof hosts photovoltaic panels and solar thermal collectors, which cover a significant portion of the building’s energy needs.

The system is designed to self-consume generated electricity, reducing reliance on the carbon-intensive national grid.

6. Natural Ventilation and Vegetation

The garden’s Mediterranean vegetation contributes to passive cooling and improved microclimate conditions.

Operable windows and cross-ventilation strategies reduce the need for mechanical cooling during shoulder seasons.

Design Strategies That Reduce Service and Maintenance Emissions

The Casa D project employs long-term durability strategies and low-maintenance technologies that reduce the building’s service-related carbon footprint throughout its lifespan. Key decisions include:

1. Structural Reuse and Longevity

The project retains the existing 1960s reinforced concrete structure, a material known for its longevity and low maintenance. This minimizes the need for structural intervention over time.

The new steel and composite structure was designed with seismic resilience in mind, ensuring performance without premature repair or reinforcement cycles.

2. Durable, Low-Maintenance Exterior Materials

The monolithic envelope, with minimal openings and solid surfaces, reduces exposure to weathering and material fatigue.

Aluminium window frames and cladding elements were selected for their high durability and resistance to corrosion, minimizing the frequency of replacement or repair.

3. Passive Cooling Through Landscaping

Mediterranean vegetation in the tiered garden contributes to passive cooling, reducing wear on mechanical systems and extending the lifespan of HVAC components.

4. Integrated, Efficient HVAC System

A centralized aerothermal heat pump system with radiant floors reduces the number of moving parts compared to split or ducted systems, lowering maintenance needs.

Radiant systems are embedded and operate at low temperature ranges, reducing thermal stress and extending their life.

5. Roof-Integrated Renewables with Known Lifespan

The photovoltaic and solar thermal systems are installed on a flat, accessible roof for ease of inspection and maintenance.

These systems are modular and replaceable on a 25-year cycle, with minimal disruption to the building envelope or interiors.

6. Minimalist Interior Finishes

Interior finishes are sober, robust, and chosen for longevity — with minimal reliance on high-turnover materials such as laminates or synthetic floorings.

The absence of high-maintenance decorative elements reduces renovation needs over time.