This passive house in L’Ametlla del Vallès stems from a commission by a family with a slow-living philosophy, who enjoy spending time at home and are passionate about music.

Achieving a high quality of life within planetary boundaries, without exhausting the remaining carbon budget, in a fair and equitable way for all the inhabitants of the planet, is the only way to avoid a climate catastrophe.

This should be architecture’s only objective.

The first premise of sustainability is reducing consumption, and this also applies to architecture. What is the point of building with natural materials with a low ecological footprint if the per-capita ecological footprint soars with large housing developments where the square metres per person are disproportionate, and where unnecessary resource consumption in the form of extra m² drives up a construction project’s environmental impact calculations?

The start of an architectural project should begin by questioning how many square metres are needed to live comfortably, healthily, and happily, with the social and environmental awareness that the resources we consume cannot harm the health and wellbeing of the rest of the people who inhabit this planet, neither now nor in the future.

It is not acceptable to approach a project from a capitalist view of the planet in which carbon emissions are simply released into the atmosphere, hoping that someone in the future will bear them as environmental and life-related costs. Projects must be conceived from social and environmental responsibility, and from the conviction that it is possible to deliver an exceptional project with the minimum resources necessary to ensure a dignified and sufficient quality of life.

This was the starting point for this project for a family with three young children and an exceptional environmental awareness.

The clients for this home are a couple with two children and a third on the way, who came to our studio when they were expecting their first, with tremendous excitement to begin a life project and with a philosophy closely aligned with the studio’s values.

When we met, they had not yet purchased the plot, so our team supported them from the very first steps, reviewing the site from a technical and legal standpoint and accompanying them through every phase of design and construction.

They ultimately purchased a plot in L’Ametlla del Vallès, a small, quiet town in the northern area of Barcelona. The site is in a well-connected residential development and sits on a small south-facing hill. It also has a certain slope that allows us to achieve magnificent views and solar exposure, but it also increases the technical complexity of the siting, as we must overcome a significant level difference from the street to the area where the home’s main floor is located.

In addition to its steep slope, the plot has a several-metre embankment along the access street. Even so, we decided to place the house at a certain height relative to the street to improve solar gain and views, and together with the family we assessed on site the most suitable location for the home.

We decided to place the house in an intermediate area to avoid too many stairs while also finding the best position on a section of land with a smaller level change, which allows us to build a semi-buried house and resolve the entire programme on a single floor.

The project strategy begins by analysing all possible options and choosing the most favourable one. In this case, we are dealing with an elongated plot that extends longitudinally in the north–south direction, which requires us to find a solution to guarantee light and heat to all rooms. We therefore prioritised a compact, single-storey house to improve the overall thermal efficiency. To address solar exposure in the rear rooms, we added a central courtyard that acts as a thermal buffer in both summer and winter.

The house is therefore divided into two bands by a covered courtyard that functions like a greenhouse. On the south side, we located the living, dining, and kitchen areas, while the north band contains the bedrooms and bathrooms. The children’s bedrooms, which have a direct relationship with the courtyard, share a study area that also serves as a circulation zone, allowing one to move around the house.

The courtyard, protected with glass, functions like a greenhouse and helps us regulate the temperature of the entire home, while also creating cross-ventilation in the living areas and bedrooms.

In winter, the air inside the courtyard is warmed through the glass roof, via the greenhouse effect that traps the sun’s heat but does not let it escape. This preheated air is introduced into the home through micro-ventilation in doors and windows.

In summer, the courtyard is shaded with vegetation and the roof windows are opened, preventing direct solar exposure and generating ventilation. In addition, the natural adobe floor accumulates moisture from the air or introduced through direct water input; as it evaporates, it draws heat from the air, improving the sensation of coolness.

Photographs: Salva López