House MM by Alventosa Morell Arquitectes: A Sustainable Expansion in Valldoreix, Spain

A Thoughtful Approach to Residential Growth

Located in Valldoreix, Spain, House MM by Alventosa Morell Arquitectes is a carefully designed extension of an existing 1947 residence. The project reimagines the site’s spatial potential, introducing a new independent volume for the homeowner’s daughters and grandchildren. Balancing regulatory constraints, environmental factors, and architectural harmony, the expansion integrates seamlessly with the original home and its surroundings.

Adapting to Site Conditions

The 800m² plot features a notable 1.5m level difference between the swimming pool and the northern garden. Regulations restricted the ground floor of the new structure to 65m², necessitating a compact yet functional design. To optimize space and maintain a strong connection with the existing home, the architects opted for a semi-buried configuration, leveraging the natural topography to enhance thermal efficiency.

A Dual-Material Strategy for Comfort and Sustainability

The extension employs a two-tiered material approach that enhances energy efficiency and structural performance:

• The lower floor, built in exposed concrete, is designed to retain soil and minimize heat loss. This robust structure benefits from the thermal inertia of concrete, ensuring passive climate control throughout the year.
• The upper floor, in contrast, embraces lightweight construction with large openings to maximize natural light and cross-ventilation, fostering a strong relationship with the outdoors.

This strategic material use allows the house to maintain a low energy demand of just 12.5 kWh/m² per year, significantly reducing its environmental footprint.

Harmonizing Architecture with Nature

To comply with zoning laws and enhance site usability, an auxiliary structure used as a parking area was demolished, creating space for the expansion. The preserved swimming pool remains an integral feature of the landscape, reinforcing the project’s commitment to maintaining the site’s original character.

With a focus on sustainability, spatial efficiency, and family living, House MM exemplifies how thoughtful architectural interventions can adapt historic homes to contemporary needs without compromising their essence.

All Photographs are works of Adrià Goula