Studio AE

About passive houses

The history of passive houses. Brief

The history of passive houses begins in 1991 in Darmstadt-Kranichstein, Germany, with the building of the first passive house. Therefore, the institution that accredits houses is based in Germany and it is called the Passive House Institute.

Germany is the country with the most houses with such certificates, followed by Austria and the Scandinavian countries. In certain countries, this type of building has long been encouraged. For example, in Austria, the Federal Ministry of Transport, Innovation, and Technology has been promoting and supporting the development of passive building solutions since 1999. As a result, approximately 1,400 passive buildings were constructed in Austria between 2004 and 2006.

Romania & passive houses

In Romania, passive houses are a niche domain, a field that is still in its infancy. So far, only a few passive houses have been certified. The country has a more conservative attitude towards significant changes.

Studio ae aims to change this attitude and promote new architectural trends that will help the field evolve and change people's lives and communities for the better.

Growth in each sub-sector: as a field still in its infancy, the use of passive houses will increase not only in respect of homes but also offices and public buildings.

In 2010, the Directive on the Energy Performance of Buildings (Directive 2010/EU of the European Parliament) stipulated that starting with 2018, all new public buildings were to have a reduced energy consumption level (Near Zero Energy Buildings - NZEB).

The NZEB standard, mandatory in the EU: Starting with the end of 2020, this standard has become mandatory for all buildings in Europe. This means that, regardless of their function, buildings must be built with near-zero energy consumption. Thus far, initiatives for passive construction are only present in the private sector and absent from the public building sector.

Passive house/building definition

Corbeanca Residence

Passive houses are buildings defined by low energy consumption and high comfort. The consumption of such a house is less than 15 kw*h/m²*year.
The most important factors that influence this result are good thermal insulation, optimally sized and positioned windows, airtightness, condensation and dampness prevention, and a constant and controlled supply of fresh air. During winter, the air is brought inside through a ventilation system with heat recovery. Together, these principles significantly reduce the energy needed for heating and cooling the building.

The term passive comes from the principle that a large part of the required energy is obtained from passive sources, for example, solar radiation, heat given off by users, or technical equipment (household appliances that give off heat - oven, cooker, etc.).

Compared to an existing house, a passive house consumes about 90% less energy for heating, which translates into significantly lower energy bills.

Passive house | eco house | green house

To be classified as passive, a house needs to comply with the Passive House (PH) Standard briefly described above.

The eco house or green house concepts are not as clearly defined and can be open to interpretation.

Passive house design stages

Corbeanca Residence

First of all, the goal to build a passive house needs to be defined early on, from the architectural concept phase, as well as during the project goal definition phase.  

If this request is expressed once the project phase is complete, or at the start of the construction phase, the entire approach will need to be readjusted.

Compared to a normal project, a design team that has energy efficiency skills and expertise is needed for this type of project.

Building a passive house is an iterative, multi-stage process that involves research and innovation.

To achieve this goal, the team will need to precisely align all the elements of the building: from architecture to structure and installations.

The design phase is longer, approximately 6-9 months. Each element is verified in terms of its performance to temperature variations. Any vulnerable points, or "thermal bridges" where condensation can occur, are identified and solutions are proposed in each case.

Patience and planning are essential to achieve the desired result.

In our team, architect Andrei Ștefănescu, co-founder of the studio, has a master's degree in sustainable development & energy audit and proven experience in these types of projects.

Certification | House Diploma!

PThe Passive House Institute (PHI), the international accreditation institute for passive buildings is located in Germany, Darmstadt.

Several PHI certified experts operate in Romania.

It is advisable to work with the consultant team as early as the concept stage, as problems identified during this phase are easier to remedy.

Two major steps

As a general rule, there are two major stages in the certification of passive houses (auditing): during the design stage and at upon the completion of the building phase.

During the first phase, the technical documentation is analyzed and approved before the start of the construction. Once the building phase is complete, an inspection takes place to certify that the construction includes all the project requirements (if any) and that the final on-site tests take place: the moisture-proof test, air change limit per hour, the constructor’s declaration of conformity and technical agreements. Several verifications are also made during the build-up phase for certification.

Essentially, the certification is the written document that testifies to the performance of the house. For long-term purposes, it is written proof of the building's performance, and it contributes to a higher property value.

Advantages and disadvantages of passive houses

As far as the disadvantages are concerned, we can include a higher initial investment, a longer waiting time, and a lack of specialists in the field (both in terms of design and execution).

However, the long-term perspective of the project allows us to weigh in on the goal of the building, and, from this perspective, the advantages are even greater and include efficient resources usage, a smaller household carbon footprint, improved quality of life, thermal comfort irrespective of the season, lower bills, lower maintenance costs. According to the standard, the maximum consumption of a passive house is 15 kWh/m²/year.

In certain specific cases, under optimal conditions, off-grid buildings can also be built, which are completely independent of the centralized energy system.

Associated costs

The benefits are greater, and the costs are clearly higher as there are more aspects to integrate, the chosen materials have a superior quality, there are significantly more design hours, and increased labor during the execution phase.
The estimated costs can be 15-25% higher compared to typical constructions. Of course, a lot depends on the types of finishes desired by each beneficiary.

The costs can vary on a case-to-case basis, depending on the complexity of the design, the type of foundation, etc.


The future means reducing consumption. In the building sector this means that, from the very beginning, buildings will be designed for the purpose of making them more energy efficient, reducing wasted space, etc. This is not only true for individual housing, but also other types of buildings such as offices, schools, supermarkets, or logistics centers.
The aim is to build efficiently today for a sustainable future.

Energy-efficient buildings will be increasingly present. This does not have to do with a certain trend, but with the desire to build with the awareness of the importance and limitation of the resources needed for that said building, as well as the needed construction time.
Presently, we are surrounded by many factors that contribute to a state of uncertainty: from pandemics to war on our doorstep, to increasing electricity and gas prices that make us question the “traditional” solutions.

The whole process of building for a better future needs to be reexamined and passive houses are an excellent starting point.

< >

Stay in the know. Straight to the point.

I have read and agree to the terms and conditions of use