What is a Passive House and why it matters, easy explained

At the end of May, I attended the “Certified Professionals in execution for Passive House” course, organized by URBAN-INCERC under the Train-to-NZEB program. From now on, I am a Certified Passive House Tradesperson, attested by Passivhaus Institut (PHI) in Darmstadt, Germany, as a result of the exam passed. Das cool!

For the wide audience, passive, active, nZEB or NZEB, eco or green are often confused and there is enormous or unnecessarily complicated information online, so I decided to write summarily about these concepts. If you want to learn more about this subject, there will be several courses for learning and certification at URBAN INCERC, details at the end of the article.

In short: If you want to have lower priced bills, a smaller negative impact on the environment and a healthier indoor environment, Passive House Certification gives you the following: the confidence that design and execution are  qualitative and according to the requirements of the standard.

Why is it called passive? Because it refers to how the building is heated, namely passive, meaning it can be done only through the ventilation system with heat recovery, the temperature of the people inside and the solar input, due to very good insulation that reduces almost complete heat loss.

So the Passive House is a voluntary certificate given by an institute and comes with a diploma that looks like this, either you can put it on the front of the house for everybody to see, or keep it in the drawer as a guarantor of the house quality.

The principles of a passive house

  1. Continuous thermal insulation, sufficiently thick and of good quality
  2. Effectively oriented windows, doors and openings to maximize the solar intake in the winter time, and minimize it during summer
  3. The watertight building envelope, to prevent air and water infiltrations.
  4. Reducing heat bridges to the minimum to prevent heat loss
  5. Mechanized ventilation, with heat and humidity recovery

The 5 Passive House Criteria

  1. Heat demand for heating max 15 kWh/m2/year or heat load for heating max 10 W/m2
  2. Annual cooling demand max 15 kWh/m2/year
  3. Annual primary energy consumption max 60 kWh/m2
  4. High air sealing n50 ≤ 0.6 shifts/hour
  5. Frequency of overheating max 10%

Advantages of a passive house

  • Uniformity of temperatures resulting in higher comfort
  • There are no direct cold air streams, meaning a healthier and more enjoyable environment
  • you have no dampness because the design and execution have been well done
  • you pay less monthly money for the entire time you will stay in the house, the cheapest energy is the one you don’t consume
  • You will spend 50% of your time in a healthier air
  • You will be ready for legislative changes
  • You will be part of pollution reducement and indirectly reduce your CO2 footprint
  • Devalues harder but you want to resell or rent it
  • EU Directive 2010/31 / EU will enter in effect on 31 December 2018, all new public buildings will have to be nearly zero energy buildings (nZEB), and from 31 December 2020 it will be mandatory for all new buildings to be nZEB.
  • The European Union has a very high consumption per habitant, compared to the global average and takes steps to promote inefficient buildings and subsequently to ‘fine’ them.

Mythbusters about passive houses

  • passive houses don’t have windows -> they do and even many and larger, efficiency matters
  • a passive house cannot be built of any material -> yes it can, it only counts efficiency, there are certifications for materials, which gives you confidence, it is recommended, but not mandatory for the process
  • it is only for new homes -> already built houses can be certified too
  • there are many passive houses -> a home is certainly passive only if it has certification
  • you cannot open the windows in a passive house -> you can, but only if you want, not because you have to
  • the air is frowst -> only if there’s something wrong with the house
  • passive houses are ugly -> many of them are, but this is a problem with the architect/beneficiary
  • only houses can be certified as passive -> certification is not only for homes but also for office buildings, schools, covered swimming pools, etc.

Costs for passive house

  • Initial investment costs are only 10-20% higher
  • Operating costs are 80% of the total cost of a home
  • A passive house, even if it has a slightly higher initial cost, it pays off quickly: 5-10 years
  • There are also indirect costs that cannot be quantified in as far as the benefits of a passive house for health, productivity and preservation of value over time
  • can reduce heating costs by up to 75%

Minuses and pluses to other certifications

Pluses: Certified with seniority, trustworthy, financially accessible, you can easily find resources, materials, technologies and certifiers. Compared to other certifications, the construction is assessed also, not just the design part.

Minuses: It doesn’t consider the water or material side, the CO2 footprint of the materials or their toxicity, the level of indoor lighting or the amount of natural light, etc.

What other certifications still exist for buildings

  1. The Energy Efficiency Certificate (Slab) issued by authorized energy certifiers
  2. LEED, developed by the US Green Building Council, the best known and spread
  3. BREAM, the property of Building Research Establishment in the UK, and 8 years older than LEED, more widespread in Europe
  4. LBC, developed by the Living Building Institute, is the most severe building sustainability certification system

Ok, and what is nZEB, NZEB, eco, sustainable and green, energy independent or renewable house?

  • nZEB and NZEB are not certifications, but they are described at the national level and means nearly Zero Energy Building and Net Zero Energy Buildings = they need to produce locally and from renewable sources as much energy as they consume annually
  • active, eco, sustainable and green are vague terms, abusively used by everyone for everything, hence the necessity for BREAM, LEED, LBC, etc certifications.
  • energy independent means you can produce by yourself the energy you need, all year long, you are supposed to not be connected to the network and have a storage system.
  • the renewable house doesn’t exist yet and I heard this said about the EFdeN house. It would mean that in the event of a malfunction, it can fix itself. But there are already such materials (even in the EFdeN house, the kitchen counter), but today there is nothing at such a complex level as a home. The confusion comes from the fact that energy is produced from renewable sources.


Passive House is a certification standard issued by an institution based on measurements made on a building.

There are 5 criteria that must be followed for insulation, openings, building envelope (outer closure), heat bridges and ventilation system.

Passive House is a certification that measures energy efficiency only, even if there are many positive health and comfort consequences in such a building.

BREAM, LEED and LBC are other certifications that monitor many things,  and they also take into account the materials used, their toxicity for the environment and habitat, the CO2 footprint of materials and types of equipment, the indoor comfort and health parameters, the level of lighting, etc. are.

Thank you Horia Petran and INCD Urban-Incerc Bucharest to support EFdeN project! Courses are not only for designers or consultants but also for future beneficiaries who want it. If you are interested, send email to train-to-nzeb@incd.ro and learn more about the 2 modules: I) Building Envelope and II) Installations.

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