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Session highlights from the International Passive House Conference in Frankfurt, Germany, 19-21 April 2013:

  • There are 3 stresses in any design: Architecture (aesthetics), costs and energy efficiency. These are the common business concerns, but each needs equal consideration;
  • The ‘innovative’ approach of moving the airtightness barrier (to being external) is being investigated, with the main factor being the impact on condensation and moisture ingress. (Note: for those projects in climates with high humidity, we know that the moisture barrier and airtightness barrier should be combined and installed externally);
  • Retrofitting for Passive House: where insulation must be installed internally (e.g. because of street frontage), the minor loss of space is not an issue in reality. Experience shows that careful design negates the losses of space and good design can use this opportunity to optimise the use of space. This is particularly relevant for small terrace houses;
  • Typical airtightness in the UK approaches 15h-1 (hooray! The Australian experience is not unique). I believe this probably includes fireplaces;
  • The NZ contingent came to tell us of the experience in the land of the long white cloud. While those of us in Australia may already be aware of the Passive House movement in NZ, the European crowd were intrigued to hear about it. It was great to hear that they have rapidly advanced the implementation of the standard, and that there are a number of completed and certified projects. Much of the activity is from the demand of EU and North American expats, horrified at the poor efficiency of housing available in the country.
  • Not sure how prolific the use of radiant walls is in these colder climates, but I was intrigued to see it. With radiant floors and ceilings being used in Australia, perhaps the limitation in the use of the same technology is the preference for lightweight construction. Probably also the less demanding climates!
  • Hungarian delegates reported the proliferation of Passive House in Hungary is good. There are approximately 100 projects of which 50 are certified.
  • A clever way of expressing the net zero energy building: “PH + PV = 0”. Concise.
  • A project case study noted windows with Ug = 0.4 W/m2K!
  • Representatives from Portugal, the newest Passive House affiliate country, noted that monitoring is critical, both for proving performance and developing the standard in a new climate;
  • The Portuguese experience of developing Passive House noted that there are a number of key steps for introducing the concept to the market, and convincing people to take it up:
    • Successful examples, including evidence;
    • Demonstration of the concept as a winning business case;
    • Establishing funding partners, such as low-interest loans or subsidies on low-energy builds;
  • The use of PHPP for hot and humid climates, from Jessica Grove-Smith of the PHI:
    • Active cooling algorithms were including in the PHPP 2007 version;
    • PHPP will have many advancements in its calculation of sensible and latent loads;
    • Application in hot and humid climates has been advanced through experience in Mexico in particular, with the development of the “DEEVI” tool, a version of the PHPP simplified and modified;
    • Output will now include the breakdown of latent and sensible loads, and include a maximum load for both of these;
    • Diffusion of humidity through building elements has been neglected based on iterative research. The neglect of this load has less impact that including a calculations with many assumptions;
    • The heat generated from the dehumidification cycle is now taken into account (in PHPP 2013);
    • The ability to use the PHPP as a plant selection tool is enhanced with the inclusion of the sensible heat ratio;
    • More options on control strategies now included for energy recover in different modes (bypass on/off, enthalpy control or temp control);
    • Additional options on summer ventilation options, to include either temperature or enthalpy control;
    • Conclusions: the PHPP is a reliable and useful design tool for hot and humid climates; this is verified through both dynamic simulations and early monitoring of realised projects.
    • The furture provision of certified cooling devices for selection in the PHPP is envisaged, although there is no set timeline as there are no certified devices yet! It is expected that this will come about very soon. The PassREG program will likely set the certification criteria and product will follow from there;
    • Comfort criteria for hot and humid climates: 20˚C in heating and 25˚C in cooling. 12g/kg humidity (no change).
    • There are new climate data sets that have updated cooling load data, although the use of the old sets is fine for now and won’t result in error. Merely a ‘finessing’ of the inputs.
  • A study of the application of Passive House in Mexico:
    • Criteria for this climate: 45kWh/m2a for sensible loads, dehumidification at 25kWh/m2a (currently given as a total 69-70kh/m2.a, not separated until 2013 PHPP). Cooling load <= 10W/m2. 25˚C internal, 12g/kg humidity.
    • A number of fabric options were analysed: the best solution being  interior insulation and external airtightness/vapour tight layer.
    • In Mexico the buildings are painted dark colours, this was found to be quite a clever solution in terms of moisture control as the hot surface caused evaporation of moisture. Not sure of the effects on heat transfer though!
    • Insulation levels:  R2.5 in walls and roof, R2.0 in floors.
    • Casa Pasiva = Mexican certification for PH;
    • Refer PHI and Passipedia for free information on the Mexican experience;
  • A US presenter on the realisation of a project in Michigan (check): the variation between temperatures in the ground level and the upper level was just 0.25˚C! Note that there will be absolutely no stack effect on ventilation in this case (it was noted that the client wanted operable roof lights in the stairwell, which would have provided little air relief).
  • Lessons learned from the Belgian experience:
    • no matter what the problem, there was a solution. This applied to all types of projects, from new build to heritage restoration;
    • Results often exceeded expectations, often at reasonable costs and with high standards achieved;
    • There was strong lobbyist opposition to the strong efficiency directive from the local government. They threatened to withdraw investment, but were ignored and the government recorded much success;
  • The public sector role in energy efficiency (Finnish presentation, from Oulu):
    • Because every building must go through the permit process, this allows an opportunity for communications with the project team. This should be used to highlight the importance of efficiency measures;
    • Any target needs 3 years to be realised, especially in the slow-moving building sector;
    • Often it was found that the building permit stage was actually far too late, as building design was too far progressed. It was realised that the project team needed information at the stage of site purchase;
    • Achieving good airtightness is always possible (listen up people!!), although it requires excellent attention to detail and documentation in the design phase.
    • Attitude is one of the most important factors in achieving a good design (hear hear!).
  • Monitoring of the Bamburg and Lunen aquatic centre projects:
    • Increasing the air humidity in an aquatic centre environment resulted in less evaporation from the pools and thus less energy use in maintaining water and heat levels. This must be done to a manageable level to avoid oppressive air comfort for those not actually in the pools (where it felt ok).
    • In a Passive House building there is no condensation on the windows, as there is no temperature differential at the window surface. The internal window temperature is much closer to the internal air temperature, eliminating the likelihood of condensation.
    • Ongoing monitoring and testing allowed for the reduction of air quantities by 41% in one of the pool halls. This had to be communicated to staff and facility management, who would inexplicably change operational levels for often nonsensical reasons.

So now is the time for wrapping up from 2013 Conference in Frankfurt. The International Conference is most definitely the highlight in the annual calendar for Passive House professionals. Coming together with up to 1000 other experts from 45 countries was a great opportunity for developing knowledge and ideas. The flow of experiential information was truly invaluable. Here’s hoping we are able to return in 2014!