Sustainability Report

Embodied carbon strategies

La Balma reduces embodied carbon through a combination of structural decisions and regulatory shifts. 

• The five upper floors are constructed in CLT and the building eliminates a parking garage — a major source of concrete and excavation. This outcome followed a multi-year advocacy effort by Lacol that began during the studio’s previous La Borda project — the objective was to remove the obligation for parking in Barcelona’s public housing. The team designed La Balma in parallel with and without parking to maintain project schedules while the regulation was under review. In 2020, during construction, a metropolitan regulation change was approved allowing public housing with an A energy rating to be exempt from parking requirements. With a lighter timber superstructure and no requirement for parking, La Balma’s foundations and ground-floor structure required significantly less concrete. 
• The dry construction system — based on timber and clay — reduces the use of wet-process materials, lowers embodied emissions, and generates minimal site waste. 
• Structural research from La Borda, comparing embodied carbon in concrete, CLT, and recycled steel systems, informed La Balma’s approach. A regular structural grid with load-bearing facades and a central H-shaped core limits structural mass while supporting long-term adaptability.

Operational emissions strategies 

• The environmental strategy prioritises low energy demand and climatic comfort within a limited budget. A changeable building section manages solar exposure: the lower floors optimise winter solar capture, while the fourth and fifth floors are protected from excess exposure to the sun. Air-conditioned areas are compact and highly insulated, with cross-ventilation, south-facing shading, and passive measures supporting summer performance.
• A geothermal system provides heating, cooling, and domestic hot water, including “free-cooling” via the circulation of naturally cooled groundwater. 
• The building’s interior climate is supported by radiant clay wall panels placed on the inside face of the facade. These panels operate at low temperature to maximise geothermal efficiency and, importantly, provide thermal inertia that the CLT structure lacks. The clay panels absorb and dissipate heat, radiating warmth when required, and contributing to cooling during free-cooling cycles. Together with the exposed timber ceilings, the clay layer also helps regulate indoor humidity.
• Utilities are centralised to improve performance and reduce costs. Although photovoltaics and grey water recovery could not be installed during construction, the building contained all pre-installations — both systems have now been added, four years after completion. 
• Lacol simulates every building they design and monitors them over time, using this data to refine management. Residents receive training to optimise the use of passive systems, as user behaviour is considered essential to achieving low operational energy use.