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Overview | Achieve Better Buildings! Passive House Conference Heidelberg - May 2019

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The Passive House standard was defined and put into practice for the first time in Darmstadt in 1991 almost three decades ago. Next October 2019, the 23rd International Passive House Conference will take place for the first time outside Europe, in Gaobeidian, China. Before that, in May this year the passive-house pioneering city of Heidelberg hosted the Better Building! Passive House Conference.


The event housed at the late historicist German Renaissance-style Kongresshaus (1903) gathered over 350 participants. Amongst German enthusiasts and attendants from USA, Australia and New Zealand, important delegations came from Eastern Europe and Canada and also from Chile where the national “Passive House Institute Foundation” has just been created. Finland’s association was likewise formalised at this occasion.


With these late additions the number of member organizations of the International Passive House Association (iPHA) has reached 23, representing 19 countries.


Keynote introductions were led by Franz Untersteller, Minister for Environment, Climate and Energy of the State of Baden-Württemberg, by Prof. Dr. Eckart Würzner Lord Mayor of the City of Heidelberg and by the founder of the PHI Dr Wolfgang Feist, who stated that “decisions needed can be taken without disrupting the economy now; If action is taken at later time the situation would be very different”; “Business as usual does not work; full hitting the brakes neither! Additional positive measures are needed! (…) measures that will enable the shift to a sustainable economy over a period of around 30 to 50 years worldwide”.




During the two days of the conference there were plenary sessions covering a rich array of topics. These topics went from the technical and detailed aspects of highly efficient construction, dealing for instance with Summer comfort in Passive House or Airtightness, to the district scale approach as seen at the Municipal implementation and Passive House districts session, or at the workshop Climate protection at district level - planning and evaluation with district PH.


In the topical Cooling and Dehumidification session, cases of the growing body of Passive House certified buildings in hot climates were presented. Jürgen Schnieders and Marco Filippi covered cooling parameters and monitoring feedback, while Dragoş Arnăutu described the successful deep retrofit of a textile factory in Sri Lanka.


Embracing social welfare and an international co-operation context, Elena Reyes and Javier Flores presented the summer comfort strategies of a large low-income housing project in Mexico, funded under EU Latin American Investment Fund (LAIF) through the Ecocasa programme. The first series of the 600 dwellings have been built and blower-door tested, proving cost-effectiveness, substantial CO2 emissions savings and high comfort quality. The non-renewable Primary Energy (PE) demand can be lowered from the more than 500 kWh/(m²a) of a build as usual configuration to conditions of around 120 kWh/(m²a)


Context, market and policy trends were considered in sessions such as Delivering NZEB: PH Buildings in Europe, Sustainability and Renewable Energy Supply, Passive House: A great concept – but where‘s the demand? and Passive House – it‘s worth it! How do I explain that to my builder? That was also the case at the panel discussion:  How can high energy-efficiency and building culture be combined, where renowned architects shared experiences, hurdles and up to date PH design potential.




Aside from the conference sessions, there were over 30 stands of the Passive House Exhibition inhabiting the venue and showcasing to the participants a number of certified building components, products and technical devices, along specialised associations and firms stands – from contractors to energy consultants, architects, engineers and quality assurers.


Another complementary aspect of the event was the arrangement of visits and excursions proposed in and around Heidelberg the day after the conference. Guided tours were organised to visit educational, office, and residential PH buildings that had been built recently or retrofitted.


This included the central and impressive Bahnstadt development, one of the largest Passive House district in the world, falling behind the Bahnstadt-inspired colossal 100.000-dwellings Gaobeidian PH district. The municipal visionary commitment and multifunctional new quarter of the city equipped with quality public spaces aiming to provide by 2022 home for 6500 inhabitants and 6000 jobs.


As a novelty, this year’s conference held two (spoken word competitions) Passive House Slam sessions. Michael Meyer-Olbersleben won the German edition going about his Kazakhstan experience having to set up Blower-Door material from scratch and with the help of the e-cigarette from a walking by smoker for leak detection.


Romanian structural engineer that became a building physics specialist and a PH construction enthusiast pedagogical communicator, Marius Şoflete, won the English version Slam award with amusing stories from construction sites. He also presented the experience of the Buhnici House in Bucharest in the Delivering NZEB session.




In terms of software and applications for conception and simulation, several presentations exposed very specific tools, some of which have been developed under the AZEB project.


For instance, PHI Senior Scientist Benjamin Krick presented a set of tools and explained how precise window choices/performances are being evaluated in detail according to climate setting and to pre-existing building conditions and parameters, aiming to prevent mould and condensation and to determine the most cost-effective options.


Concerning general modelisation tools, three workshops were organised:


-Get to know the new features of design PH The Design PH Sketch-up plug-in 2.0 was officially released with improved functionality and user interface. This version displays new 3D raytracing shading analysis allowing the user to obtain summer and winter precise factors, although prior calculation methodologies remain nonetheless valid. Comparison of results utility, thermal bridge assessment and ventilation inputs are also part of the new features.


-BIM and PHPP The workshop covered methodologies for incorporation of energy efficiency parameters into BIM models, and the current functionalities of BIM2PH, to the new interface concept allowing BIM software to export data to PHPP.


-What’s new in PHPP? This workshop on the PHPP aimed to anticipate PHPP 10 features and novelties, such as cooling units and heat pumps input options, and stress tests for extreme weather. There would also be integrated methods for comparison with monitoring or consumption data for quality assurance.




The renovation challenge and the application of the EnerPHit standard were topics addressed along two dedicated sessions: Future-proof retrofits (DE) and Deep retrofits (EN). Schools, public and residential building cases were discussed as well as the Ventilation-Envelope tandem strategy and the PFEFFER (PreFabricated Elements For Fast Energetic Renovation) systems.


Several outcomes and cases from the Sinfonia project (funded by the EU’s 7th Framework Programme for Research) were presented, such as the retrofit cases of Austrian elementary schools from the late 1950’s.


Feedback from the work on these schools and from the ongoing monitoring underline the importance of shading and daylight redirection for comfort and energy savings.


It highlighted the positive experience of simplified ventilation schemes for ease of flow control, including a draft-free air supply via perforated textile diffusers and the overflow concept through acoustic door devices (and active overflow if listed-building).


The integration of (future) district heating systems within a Danish (Bjerg architecture) social housing PH retrofit was also explained.


Two other remarkable and recently completed residential retrofits discussed in this session are the Neue Heimat Tirol (NHT) Innsbruck EnerPHit renovation of an ensemble of three to four storey housing blocks, and the (3 towers pilots) case of the 14 storey Torri Madonna Bianca in Trento, part of the Stardust project (EU Horizon 2020 Smart Cities).


For both, works were conducted with inhabited homes, achieving optimal energy performance levels after renovation, and in both cases, simplified ventilation schemes were applied.


In the NHT Innsbruck neighbourhood, conventional heat-recovery ventilation with central groups installed in the roof of each of the blocks and dense pipeline network embedded in the insulated façades, were 3D-planned in detail with the help of the designPH plugin. Within the apartments, it was an extended-cascade ventilation scheme that was implemented.


For Trento’s case it was identified as a far more optimal renovation choice to retain an only-extraction mechanical ventilation system with natural air supply instead of a centralised double flux option. The costs of the only-extraction retrofit are four times lower that those of the fully centralised option and still have slightly better Final Energy Demand results and slightly lower operational costs. The 90% reduction in energy consumption is achieved thanks to a heat recovery system via a heat pump connected to the exhaust air. Comfort aspects (also acoustics, wind currents, etc.) were considered, as well as social aspects and architectural value of the buildings. The operation included upgrade of the entrance lobbies and addition of a 15th floor for common rooms.


Other sessions of the conference dealt with more specific topics or building typologies such as the Curtain Façades workshop and the Non-residential buildings with special requirements slot where hospitals, swimming pools, or childcare/community centre cases were addressed.


Besides these sessions and topics, other outcomes worth highlighting are:


- The importance of the evolution of the renewable energy industry and the interaction and association with the building sector and with the urban planning scale. General objectives are set, evolution is ongoing and yet uncertainties remain ahead. In this field Benjamin Krick, in his accurately named presentation PER and Passive House:  The PERfect team, pointed out how “heating with electricity was a no-go in the past, this is changing”


- One session was dedicated to Quality assurance, handover, and monitoring. While the performance gap may be quite variable and should be reduced with experience gained, “commissioning and monitoring remain keys to success” as Wolfgang Hasper entitled his slot. In this sense, Dr Kati Jagnow insisted on simplicity, “less is more”, building upon her detailed feedback from the operation of St Francis in Halle PH school.


-Presentations in AZEB project sessions addressed, off course, long term costs and affordability ( A step by step guide; Only numbers count –lifecycle costs in social housing), and often also monitoring feedback (Brunck-Quarter: Successful energy efficiency modernization with long-term monitoring results; Lessons learned from quality assurance in Heidelberg-Bahnstadt).


Additionally, another whole session focused on Cost-effective supply solutions considering building services optimisation (Split units experience in Kranichstein; Compact heat pumps; Reducing domestic hot water demand).


The Optimisation of investment and lifecycle costs were also addressed during Dr Feist presentation. He has explained how “investing in a well-planned Passive House isn’t much more expensive than investing in an ordinary house” which is reinforced by the fact that up-front cost premiums for achieving Passive construction have lowered over time. Furthermore, Dr Feist stressed how the additional 29 kg/m² of CO2 eq. required to reach PH standard compared to the current regulatory – German NEH – standard level, are amortised in 1.45 year while offering a 2.6 factor of increased efficiency.


These considerations support the principle by which the way to achieve NZEB construction is to first confirm that optimal context-driven passive construction measures are ensured before investment goes into renewable and/or active measures. Often this may be failing to happen effectively, as illustrated by the case study of Piero Russo Engineering, comparing Passive House design to regulatory NZEB requirements in southern Italy, demonstrating the technical and economic benefits of the PH approach and the risks of invoking a reference building principle.


As a conclusion, cost-effectiveness and technical optimisation are key drivers for construction projects. The market uptake of (energy efficient and environmental friendly) effective measures for new construction and for retrofit of the building stock, require public and private funding and investment on a large scale. In these areas capital and mortgage markets are called to play an active role in the transition to an energy efficient, fossil-free, circular and sustainable building sector.


Evolution and development in these fields is underway and bound to integrate sessions of future editions of Passive House Conferences.


Succeeding the Chinese edition of 2019, it will be the turn to the city of Berlin to host the 24th international Passive House Conference in the autumn of 2020.