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The Journey to a Passive House

Read the August 2012 Update

In 2011 Ellen and Casper Valentin purchased a section in Raglan and decided to build a certified Passive House (PH). In this article we follow their journey as they take the project from conception to completion.

Concrete has just been poured

The Journey So Far (to July 2012)

Ellen & Casper


  • In July 2011 we bought the section

  • In Aug/Sept we decided we wanted to build a certified Passive House (PH); after doing lots of research on how we could build a quality home

  • MOAA Architects was keen to join in with the project. They completed the Passive House Designer course in November 2011. A tough 2 week full time course. He is now one of the few PH designers in NZ

  • The journey started to find the products we needed for to build a PH, performance for each product is quite important. Eg walls and windows need to have a certain minimal insulation value. You can't have any thermal bridges in a PH and a PH is airtight. Those criteria determine what products you can and can't use.

  • One major delay is getting certified climate data of our location. PH has a comprehensive calculation package that calculate how much energy your house will consume to maintain an internal temperature of 20degrees inside. Many parameters feed into this (number of people living in the house, all the specs of the materials used, etc), local climate data is one of them. Because PH is new to NZ, the International PH Institute didn't have any certified data available.

  • Once the design was ready we had to get it approved by a PH certifier. This happened oversees as there are no certifies in NZ yet. The certifier goes over the design in detail, checks all the calculations, requires test results from material used, etc. All to get an accurate calculation for the energy demand. MOAA had done a great job, as the house was nearly spot on with minimal changes.

  • We had to wait for the 'verdict' from the certifier to order certain products. This was in particular important for the window frames - these have to come from Germany as in NZ there is no product available (yet) that performs following PH standards. We wanted to be sure the certifier would accept our window frames chosen. The delivery time for windows is 15 weeks, so we wanted to get that order in asap to not cause delays in the built.

  • Maximum energy demand is 15kWh per m2 per year for heating (note, on top of this comes energy for electricity). After some changes and when the official climate data came in, our house only consumes 6kWh per m2 per year for heating the house.

  • The unique thing about a PH is that it is a proven method, you know in advance how much energy the house will use. There are criteria to be met and several tests to be done throughout the process: eg a blowerdoor test to test for airtightness for the house.

  • The build started the first week of July. We couldn't believe it was happening, it has been a long journey.

  • Estimated finished date is mid December this year.
  • 10cm high density slab and footing insulation

    Concrete slab

    Breaking the ground...

    Concept drawings and house plans

    Read the first part here...

    August 2012 Update

    The Walls

    The walls are up

    Working with ICF blocks went incredibly fast, the walls of the ground floor were up within 2 days And filled with concrete one day later. The mid floor had to be built before the walls of the first floor could go up. This is all done now and we're waiting for a few dry days to construct the roof.

    The walls of our Passive House are incredibly well insulated. The two layers of polystyrene and the concrete in the middle ensure good insulation and a solid structure. The construction also avoids thermal bridges; we don't want those in a Passive House as they are a major cause of heatloss. In the following video we show how the walls are constructed and what thermal bridges are.

    Inside the concrete

    Before pooring the concrete all piping for cables have been put in. Little holes had to be cut in the polystyrene, but filled after, as holes affect the insulation. Things are going smooth so far, hope we can keep that up.




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    Showing 1 Comment

    Posted by Nick Jarrett on 03/11/2015 03:02 PM

    Ellen and Casper's Passive house
    Congratulations to Casper and Ellen on getting your Passive house underway. Thank you for posting. It is interesting that there are now quite a few certified passive houses, zero/low energy and very low energy houses being built here in NZ. Although the passive house standard will probably never become the accepted common building standard for NZ it will certainly help to improve the level of thermal performance for future houses as improved building methods and quality building products become more readily available. Casper and Ellen, would you be willing to share more information on your build? What u values are your walls, roof, floor and windows? what ventilation system are you using. How are you going to achieve the airtightness level? Are proclima involved or some other method/product?

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