20th International Passive House Conference in Darmstadt

About ten days ago, we took part to the 20th International Passive House Conference in Darmstadt, Germany.

Now at its 20th edition, this passive house-focused event brings together researchers, designers, experts and manufacturers from all around the world.


This is the third Conference we attend after the 2014 edition in Aachen, and the one in Leipzig, last year. We are now quite aware of the changes happening within the “passive” world: the most evident of all, the increasing number of Chinese participants, which shows a raising interest from China for the passive house standard.

An image of the exhibition at the Conference.

As for previous editions, the Conference was organised over two days, with three plenary sessions, and sixteen specific sessions with dozens of speakers from all continents.

It would be impossible to cover the entire program of the event, so we try and summarise in this article the highlights of the sessions we attended.


The main topic of the 2016 edition was durability: it was not a coincidence that the 20th Conference was organized in Darmstadt, for the 25th anniversary of the Kranichstein passive house. After pioneer projects in the 70s and 80s, which include the Rocky Mountain Institute, the Kranichstein building can in fact be considered the first “modern” passive house.

For the occasion, the Passivhaus Institut executed a variety of tests on the building, to evaluate the aging process of insulation materials as well as insulated glass; the mechanical ventilation system was thoroughly inspected and indoor air quality measured; air tightness of the building envelope was tested again, after twenty five years.

Built in 1991, the Passive House of Kranichstein allows today to study durability of insulation materials, air tightness, mechanical ventilation and so on.

Since these tests are so important, we’re going to cover them in a specific article to illustrate and comment the results.

An image from the inside of the mechanical ventilation system of the Kranichstein passive house: twenty five years on, if the filters are well maintained and cleaned, the ductwork remains clean too.

An important session of the Conference was dedicated to long term monitoring of passive buildings, both residential and non-residential.

The Energon in Ulm, Germany: this office building has been monitored for ten years. (Although its thermal envelope is of very high quality, this building is not certifiable as passive because of the high primary energy demand determined by the appliances used inside it).

Twenty five years after the completion of the Kranichstein passive house, thousands of passive buildings in different climates provide “field validation” to this construction standard.


Once we saw the brilliant presentation done by our fellow “southerners, our enthusiasm was so high that we wanted to title the whole article something like “Darmstadt shines of southern sun“. Then, after one week spent in the city (where we got rain, hale and snow in the mean time), the initial title seemed a bit overly optimistic in terms of local weather. The sun showed up only on the day of our arrival, and disappeared behind the clouds for the rest of our stay.

The value of the Warm Climates session (with Jurgen Schnieders, and Francesco Nesi as moderator) was to demonstrate the hard work done in countries such as Spain, Greece, Turkey and Cyprus, as well as Australia and Italy. In these countries, one of the main obstacles that the “passive movement” has to overcome is cultural. False myths and lack of knowledge abund among professionals, and become part of our daily fight.

Oliver Style presented the monitoring of a straw bale passive house near Barcelona, Spain, during a heat wave in summer.

Oliver Syle shows temperature anomalies in Europe, taking place during the monitoring period.

The high quality of the thermal envelope, provides the building with a higher time constant than normal buildings, so that a passive building can guarantee comfortable conditions even in case of extreme weather events, whether in summer or in winter.

Nasia Roditi and Stefanos Pallanzas presented “Passivistas, the house project“: the first case of deep energy retrofit in Greece, using the EnerPHit protocol.

A moment of the presentation of “Passivistas”

Partially funded with a crowd funding campaign, and with help of many Greek CEPHD designers, the Passivistas project shows the importance of deep energy retrofits in warm climates, in terms of quality of life, environmental impact and cost/benefit.

Esteban Pardo Calderòn reported on the diffusion of the passive house standard in public buildings in Northern Spain, with some remarkable examples.

Calderòn illustrates some examples of public buildings in Northern Spain, built according to the passive house standard.

Tugba Salman Gurcan, of Ekho, presented a public building in southern Turkey, certified both passive house and LEED platinum. She compared costs and benefits of both certification schemes, in terms of human health and comfort, and environmental sustainability of the building.

The location of the project, in Southern Turkey.

Marco Pietrobon, of the Politecnico of Milan, presented the results of a survey done on occupants of passive buildings in different regions of Europe. The survey was intended to understand actual comfort levels, and the influence of user behavior on the overall performance of highly efficient buildings.

Paris Fokaides showed the monitoring of a passive building in Cyprus, with a comparison between the recorded internal conditions in summer time with the most widespread standards of comfort.

Paris Fokaides presents the passive building monitored in Cyprus.

Our presentation covered the first building envelope system certified by PHI for passive houses in a warm climate.

A moment of our presentation

We feel that pre-designed envelope systems are going to play a major role for the diffusion of the passive house standard in the near future. We are going to illustrate the potential for the market of North America at the next NAPHN Conference, scheduled for June in New York.


Another important session we attended was the one on renewables. We had the chance to listen to several presentations on how the energy market is evolving in different parts of the world, with a combination of more efficient demand, and more sustainable supply of energy.

Tobias Loga of IWU showed how the “Net Zero” goal can be easily misleading, depending on the way the “demand – supply” is calculated. With the same building and the same system, the percentage of covered demand via renewables varies substantially depending on the fact that the calculation is done on an annual, monthly, daily or hourly basis. A building may “appear” net zero from a yearly calculation, by producing more energy it consumes over the course of the entire year. However, more accurate calculations (say, hourly), demonstrates that the actual coverage provided by renewables can be a lot lower than 100% – as far down as 50%.

Comparing calculations: yearly, monthly, daily, hourly. With the same building and system, the more precise the calculation, the less “net zero” the building.

Providing the building with electric batteries is going to improve the situation, but it is not going to make a substantial difference, as described later.

Rainer Vallentin moved a critique to the new calculation of primary energy renewable (PER), available from version 9 of PHPP. His considerations were mainly focused on CO2 emissions, and brought so some changes included in version 9.6 of PHPP, scheduled to be available in English in the summer.

Vallentin motivates his critique to the new PER method.

Marc Grossklos of IWU illustrated the monitoring of a multi-family passive house building in Frankfurt, including 17 dwellings. The building is provided with a cogenerative system, as well as PVs.

A photo of the building.

The goal of the monitoring was to understand the increase of electric autonomy of the building, with on-site production of energy, and electric storage (batteries) to increase self-consumption.

An illustration explaining the production of energy on-site: heating (left) and power (right).

The data show how the electric batteries allow for an increase in self-consumption of the energy produced on site. However, this increase remains confined to an average value of 8%.

The conclusion was that, even more than one renewable source is present in the project (cogeneration, PVs), at the moment it is not yet economically conventient to aim to an “electric autarchy” higher than 90%.

The results of the monitoring.



During the session dedicated to design tools, Harald Malzer showed a preview of the features included in the next version of DesignPH – the plug-in for SketchUp that allows to model and design passive buildings in 3D.

Malzer during the presentation of the incoming new features of DesignPH.

In our mind, the most important new feature of DesignPH is going to be the brand new way the software is going to calculate the shading. The assessment is going to be carried out for each single window, depending on the actual projection of the surrounding elements.

A preview of the new shading calculation in DesignPH.

Once the calculation is done, it is going to be possible to export the data to PHPP.

A release date for the new DesignPH was unfortunately not provided during the presentation.


After the 2014 edition in Aachen, and the 2015 one in Leipzig, this Conference leaves us once again satisfied (and exhausted).

The passive house standard is spreading to different regions of the world: first of all in China. The number of participants from this country alone is steadily increasing.

The Warm Climates session left us very proud of the work done by our fellow southerners. This demonstrates how quality of the built environment and energy efficiency guarantee an added value, and allow for cost efficient solutions also in milder climates than Mittel Europa.

Just like for earlier editions, the most interesting part of the Conference is meeting other people in person – people from other countries and other continents, who every day face the same problems and same myths as we do.

The location of the 2017 edition has not yet been announced – rumors claim it’s going to be in the city of “W”.




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