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.

Homes will become our universe

Some time ago, Orange has launched in Romania, right at EFdeN house, Orange Home for housing through the “You can travel anywhere without leaving home” campaign, which made me wonder a little about how we live in the future. These predictions by Ray Kurzweil (Google’s futurologist) give us a picture of a possible scenario.

I think the time we spend at home in 2030 will be around 80%

This future that we will spend almost all the time in our homes is not one that I like, but I think it is an inevitable future. Today we spend 50% of our time in houses and the rest of the time we spend on:

  • work – will be moved home via VR (Virtual Reality)
  • transport – will be drastically reduced due to the efficiency and decrease of the need of mobility, but will remain for meetings with friends, family or new experiences
  • shopping – will move online, see Amazon’s purchase of Whole Foods
  • education – all online, MOOC are the future of education and robots who will do home-schooling are already a reality
  • entertainment –  meaning parks, clubs, pools, restaurants, things you can’t do at home
  • tourism –  we will travel more due to cheaper transportation, that’s the good part

Just as social media has taken over our universe, attention and time, is already considered a dependency, VR (Virtual Reality) will be an even more dangerous trend, to which we will become even more addicted to. We will be able to be the masters of the worlds we can create, and we will not want to get out of this ideal and easy world that we can control.

How will this trend influence how we design, build and live

What we can do in terms of the built environment is to design and build suitable housing for such user behavior, which, in one way or another, will bring communities closer. This means that besides a co-working space, a home should become a friendships space.

At least 2 families, adults + children, must be able to spend time together and this will be translated into larger livingroom+ diningroom + entertainment areas, and the bedrooms surfaces will be reduced to an usable and comfortable minimum.

Larger spaces mean higher costs, and inside cities, this would be very expensive. In big cities, the cost of living is already exorbitant. The consequence of the fact that we no longer have to get out of the house to work is that we no longer need to live inside the city, and that opens up a potential new urbanization stage of the planet. At this moment, half of the planet’s population lives in cities, taking up only 2% of the planet’s dry surface.

Today there are 7.4 billion people on the planet, and by 2030 there will be another 1.2 billion, which means almost double the size of Europe’s population today.

Due to climate change and global warming, a walk to the park will become a walk to the mall, where climatic conditions are optimal. At the mall you have access to almost anything you want, it is a place for all ages and needs, and this behavior can already be noticed. Even if it is sad to imagine a world that is shared between home and mall, it is currently the most likely future.

#FutureHomes: Creating the next generation of homes

In the last 8 years, I have been part of some amazing teams where we designed and built 3 different award-winning homes, but I still have a lot to learn and explore in order to achieve my dream: to create the next generation of homes.

I always tried to imagine the perfect home and after two pre-certified homes and working with Living Building Challenge, BREAM and Green Homes standard, I felt there’s a lot of room for improvment. Today this type of certification only tackles the product, missing anything else.

From my point of view the perfect living / the perfect home should incorporate the following 3 dimensions and this is how I end up creating the CIP Diagram, with more details to follow.



This is where I have the most experience and where sustainability standards (BREEAM, LEED, WELLBEING INSTITUTE) are doing a great job of getting the bigger picture.

To do: In the next 3 years, I want to design 3 homes in 3 different extreme and harsh environments. I cannot say what is the level of details I am going to achieve and when, but the plan is to go as far as possible and one day to actually build each one of them. In the last edition of Solar Decathlon, I learnt once again that there is so much knowledge across the world in creating homes, related to climate, to culture & heritage, to the economy, lessons we did not yet learn.

3 different homes in 3 very different places

  • one in the extremely hot (let’s say Sahara)
  • one in the extreme cold (let’s say Nord Pole)
  • the last one, most difficult, on Mars (waiting for other smart people to decide the place of the colony).

Read more on Medium…

Visit 15 green homes @ Solar Decathlon Middle East in Dubai

The international competition for solar houses called Solar Decathlon, Middle East edition is the reason why 15 teams from 11 countries came here with 15 solar homes are now open to visits in Solar Innovation Center in Dubai.

Until 29th you can visit us in Solar Innovation Center (60km from Burj Kalifa into the desert) between 9.00 – 12.00 from Sunday to Wednesday and 9.00 – 18.00 from Thursday to Saturday. Plan your visit here.

During the 10 days period, all the participating houses are monitored and tested on 10 different contests, 6 with international jurors and 4 with sensors installed in every house. In the same period the houses are open for visits, offering guided tours to everyone interested.

Solar Decathlon was created by the US Department of Energy in 2001 and it now takes place on more than 5 continents becoming a worldwide phenomenon. In the last 8 years I have participated in 2012 edition in Madrid, 2014 edition in Versailles, and now in Dubai.

This is also the reason why EFdeN home and I are here.

In the last two years, we had to design and build an amazing 100% electric home, solar powered and sustainable. We built it in Romania this summer, and then we had to disassemble and transport it to Dubai where we reassembled in just 14 days.


Here you can see how monitoring looks like for all the houses on our shared platform. We are 3 days away from the end of the competition and everything is looking great for us.

EFdeN @ Solar Decathlon Middle East so far:

  • 1st place: Communication Contest
  • 2nd place: Engineering and Construction Contest
  • 3rd place: Sustainability Contest

Btw, if you like our project, you can vote for us here for the People’s Choice Award, this is extra competition. This is how EFdeN came to life.

10 Recommendation for better buildings


In the last weeks we have travelled over 4000 km, organised 10 session of public consultation in Cluj, Iași, Galați, Brașov, Craiova, Timișoara and Bucharest, where we met and discussed with over 400 people from different ages, social and professionals categories in order to co-create and support Romania’s National Renovation Strategy. The goal of this consultation was to facilitate the dialogues and responsabilisation of the interested parties in order to transform the existent buildings, both public and private, to be more energy efficient and sustainable.

Context: Almost 80% of our time in spent in buildings: being home, working, shopping or visiting public institution. The safety and healty of this buildings having an incredible impact on population. Romania, as a member of United Nation and European Union, has to work towards limiting the global warming under 2°C until the end of this century, according to COP21 treaty in Paris. Buildings are held responsible for 40% of the energy consumption and 36% of CO2 emission in European Union.

Read the document here: 10-recommendation-better-buildings