What is a passive house?

A passive house is a dwelling designed to consume very little energy and offer optimal thermal comfort throughout the year without resorting to conventional air conditioning systems. The term comes from the Passivhaus standard, created in Germany at the end of the 20th century, and has become one of the global benchmarks in sustainable construction and energy efficiency.

This type of housing works on a basic principle: making the most of natural resources, such as sunlight and ventilation, and minimizing heat or cold loss through efficient design, high-performance materials, and precise execution. Unlike other systems, a passive house does not require large investments in technology to consume less; it achieves this from the very root of its architectural design.

A passive house is a home built to consume a minimum amount of energy, maintain thermal comfort throughout the year without conventional heating or air conditioning, and minimize environmental impact through ultra-efficient design.

1. What distinguishes a passive house from a conventional house?

While traditional homes rely on heating or air conditioning systems to maintain comfortable conditions, a passive house reduces that need to almost zero. It achieves this thanks to:

• An exceptionally well-insulated thermal envelope.

• Almost complete absence of thermal bridges.

• High-performance triple-glazed windows.

• Controlled mechanical ventilation with heat recovery.

• A compact design and proper orientation toward the sun.

In other words, the house is so well protected from the outside and so well designed internally that the temperature remains stable throughout the year, regardless of whether it is 5°C or 35°C outside.

2. Origin of the Passivhaus standard

The Passivhaus concept was developed in 1991 by German physicist Wolfgang Feist and Swedish professor Bo Adamson. Their goal was to find a way to build homes that required very little heating or cooling. To this end, they established a certification system with strict technical criteria, including:

• Heating demand less than 15 kWh/m² per year.

• Air tightness of maximum 0.6 air changes per hour.

• Total primary energy demand below 120 kWh/m² per year.

• Virtually no thermal bridges.

This standard has been replicated in thousands of buildings across Europe and America, and has been adapted to different climates, proving that it is not just a fad, but a viable, long-term, cost-effective, and efficient solution.

3. How a passive house works

The secret of a passive house lies in its natural thermal balance system. Through reinforced insulation, controlled ventilation, and solar optimization, the home generates its own comfort without using much energy.

For example, during winter, the house retains the heat generated internally (cooking, people, appliances) and supplements it with solar radiation. Ventilation with heat recovery keeps the air clean without losing temperature. In summer, thanks to sun protection, orientation, and insulation, the house stays cool, preventing overheating.

In addition, the mechanical ventilation system not only controls the temperature, but also ensures excellent air quality by filtering out dust, allergens, and pollution.

4. Advantages of living in a passive house

The benefits of this type of housing are numerous, and not just financial. Among them are:

4.1 Energy savings

A passive house consumes up to 90% less energy than a traditional house. This translates into lower bills, greater independence from fossil fuels, and a home that is prepared for a future with rising energy costs.

4.2 Continuous comfort

The interior temperature remains stable throughout the year, with no drafts, no cold spots, and no need to turn air conditioning systems on and off. Even on the most extreme days, the home feels comfortable with minimal intervention.

4.3 Health and air quality

Thanks to mechanical ventilation with filters, the indoor air is clean, free of particles, without excessive humidity, and constantly renewed. This significantly improves quality of life, especially for people with allergies, asthma, or respiratory problems.

4.4 Sustainability and CO₂ reduction

Passive houses help reduce the carbon footprint of the residential sector, one of the most polluting on the planet. According to the International Energy Agency, buildings account for more than 30% of global energy consumption and 28% of CO₂ emissions. Building according to Passivhaus criteria is part of the solution.

5. How much does it cost to build a passive house?

One of the most frequently asked questions is whether a passive house is more expensive. The answer is that, in terms of initial investment, it can cost 5% to 15% more than a conventional house. However, this additional cost is recouped in just a few years thanks to energy savings.

In addition, many countries and autonomous communities offer subsidies, tax deductions, and grants for the construction of energy-efficient homes, further reducing the gap.

6. Can passive houses be built in Spain?

Yes, and increasingly so. The Passivhaus standard is suitable for warm climates such as the Mediterranean or continental climates, provided that the design is adapted to local conditions. In Spain, there are already hundreds of certified homes, and every year there are more and more projects that follow these principles.

In fact, the new Technical Building Code (CTE 2019) requires all newly constructed homes to be Nearly Zero Energy Buildings (NZEB), a step very close to the Passivhaus standard.

In addition, several architecture firms and specialized construction companies already offer customized solutions for building passive houses anywhere on the peninsula. (passivhaus.es)

7. Can renovations be carried out to convert a house into a passive house?

Although more complex, it is possible. This is known as "EnerPHit, " a variant of the Passivhaus standard applied to major renovations. This type of renovation requires:

• Reinforced exterior and interior insulation.

• Replacement of woodwork.

• Improvements in thermal bridges.

• Mechanical ventilation system.

• Air infiltration control.

It is not always possible to meet all the requirements of the original Passivhaus standard, but reductions in energy consumption of between 60 and 80% are achieved.

8. Who certifies that a house is passive?

Official Passivhaus certification can only be issued by the Passivhaus Institut in Germany or accredited technicians. To obtain it, the project must meet all technical requirements, pass airtightness tests (blower door test), and demonstrate that energy demand is truly low.

However, many non-certified homes apply passive design principles with very similar results, albeit without the official seal. The key is that the design is carried out from the outset with efficiency criteria in mind.

9. How do I know if a passive house is right for me?

If you are looking for a comfortable, efficient, healthy, and future-proof home, a passive house is an excellent option. Although it requires planning, the result is a home that promotes well-being from the design stage, without relying on the intensive use of mechanical systems and with a much longer than average lifespan.

Especially if you are concerned about the environment, energy costs, or the indoor health of your home, this type of construction offers real and proven advantages.