Griesser AG

This project is distinguished not only by being the first Passive House renovation in Spain but also by the complexity involved in renovating a single apartment within an entire building. To achieve the Passive House standard, efficient sun protection is essential. This Passive House apartment features an interior wall cladding with thermo-acoustic insulation, highly efficient windows, and, most importantly, airtightness.

Griesser’s sun protection solution plays a key role in achieving the desired energy efficiency. It prevents overheating of the rooms and allows control over how much daylight enters the space.

Natural light in nearly zero-energy buildings promotes the health and positive energy of the residents.

Architect Miren Rivas, specializing in sustainability and Passive House design, is responsible for the first Passive House-certified renovation in Spain and the fourth worldwide. The project: an apartment in a residential building in the Las Arenas district of Getxo, Bilbao, with a magnificent view of the Bilbao estuary and the Biscay Bridge.

Rivas has extensive experience as an executive technician at the Passive House Institute and explains the project design, in which light is intended to bring joy, energy, and positive thoughts, as well as the entire renovation process of the apartment.

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Interview with Architect Miren Rivas: The First Passive House Renovation in Spain
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How did this renovation project come about, and what requirements had to be met?

The space in question is my new apartment. It was previously an office, and since a complete renovation was necessary, I decided on a Passive House project to experience it firsthand.

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Renovating only one apartment in a conventional building is far more complex than a complete renovation. What challenges did you face in designing a new energy-efficient apartment?

In an existing residential building, there are numerous conditions that cannot be changed, such as the facade, structure, and installations. The renovation focused exclusively on the interiors, except for the windows. I had to build a model of the building to have all the data at hand for studies on the new apartment.

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How do you plan a redesign that maintains balance and energy optimization after identifying the apartment’s requirements and structural obstacles?

Energy optimization primarily takes place inside. Key factors include the inner wall insulation with sound and thermal insulation, highly efficient windows, and, most importantly, airtightness. The apartment is sealed like a balloon, preventing uncontrolled air infiltration. Internal ventilation with a heat exchanger is also fundamental.

The design was primarily guided by light, positioning the living areas towards the sun and scenic views. Light brings joy, energy, and positive thoughts. A positive living space makes for happier residents.

In this regard, window placement and Griesser’s sun protection systems played an essential role in preventing overheating and managing natural light for greater well-being and energy for the whole family.

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What processes were necessary, and what solutions were implemented once the design was approved?

Following the complete demolition of the interiors, the first step was laying the insulation layer, consisting of gypsum on the walls and ceilings and insulation film on the floors. Next, highly efficient windows with sun protection were installed and perfectly sealed with the insulation layer. Then, the inner wall insulation with thermal and acoustic protection was added to the ceilings, floors, and around the entire apartment.

Once this was completed, the internal layout and installations followed a typical construction process, except for the ventilation system, which features a mechanical ventilation system with a heat exchanger and ducting running through the false ceiling.

Today, significant technological advances define the starting point of the so-called Industry 4.0. To what extent have these technological advancements contributed to the success of the renovation?

Materials and equipment continue to evolve, allowing us to adapt them to new requirements. We now have insulation with low thermal conductivity and reduced thickness, highly efficient heat exchangers, window profiles with low thermal conductivity, and low-emissivity glazing. Everything used in this renovation was carefully selected to achieve the best possible result.

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The choice of suitable materials is key to any energy optimization. Which materials were best suited for this renovation in Getxo? How does the climate zone of a project affect material selection?

I largely opted for natural and sustainable materials with a low CO2 footprint, such as wood for the windows, rock wool insulation, gypsum for the walls, and wood for the floors.

Material selection does not depend on the climate zone. What changes is only the thickness of the insulation. In colder climates, more thickness is required. Everything else (insulation layer, ventilation system, sun protection) can be used in the same way in any climate.

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One of the challenges in this region is humidity due to the cold climate and rainfall. Achieving a fully weather-insulated interior was crucial. What solutions were implemented to optimize insulation and floor permeability?

Airtightness was meticulously ensured, from the gypsum insulation layer on the walls and ceilings to the insulation film on the floors. A Blower Door Test was conducted to detect infiltration, and the results were excellent for a renovation. With airtightness and controlled mechanical ventilation, we were able to manage humidity in bathrooms and the kitchen, maintaining the apartment’s relative humidity between 45% and 55%, ensuring a very healthy living space while preventing allergies, mold, and other issues.

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What role does sun protection play in the energy efficiency of this building?

In a Passive House, overheating can cause serious problems. It is essential to prevent direct sunlight from entering in summer. This was perfectly achieved with the Lamisol 70 sun protection system from Griesser—motorized louver blinds that adapt precisely to the existing openings and prevent direct sunlight while still allowing natural light in and preserving the breathtaking view of the Biscay Bridge and Portugalete.

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The Biscay Bridge in Getxo is the world’s first transporter bridge made of metal and a symbol of the Industrial Revolution. It also demonstrates that the Basque Country has always been ahead in innovation, just as it is today with sustainable construction. What makes the Basque Country an ideal place for innovation?

An open mind and a respectful approach to the environment are key to development. We must face new challenges while always keeping our natural, industrial, and cultural heritage in mind.

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Although the Passive House standard is gaining international recognition in architecture, Spain is just beginning to adopt it. Is this renovation a crucial step in promoting Passive House construction in Spain?

Absolutely. People need to see that sustainable living is possible, even in an old building without insulation. A Passive House renovation can start from within, and the cost is only about 10% higher than a conventional renovation, which pays for itself in about eight years.

However, what truly matters in such renovations is indoor comfort. It cannot be measured, but it is immediately noticeable. Living in a healthier environment, free of humidity, with a constant winter temperature above 21°C and near-zero energy consumption, provides unparalleled comfort. In my new apartment, I removed 9 out of 11 radiators and still maintain temperatures above 21°C in winter.

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Besides private homes, sustainable architecture is also being implemented in social housing projects in Navarra. How can this help combat energy poverty?

A Passive House has near-zero energy consumption. With minimal energy input (one or two radiators for an entire apartment), a 100 m² home can be heated efficiently. Since these homes are well-insulated and airtight, there is no heat loss, ensuring a consistent temperature throughout the day and night. In winter, mornings are not cold, even without heating. The less energy is consumed, the lower the likelihood of energy poverty in a household.