The concept design

After sending a detailed response to the 10-page questionnaire that Luc provided us, we met him and certified building designer Steve Oke at Luc’s home office in Beechworth on 21st March 2019. We spent some time talking over what we were hoping to achieve and even more time with Scott and the designers talking nitty gritty Passive House concepts. It was reassuring that they recalled our preferences from the questionnaire and definitively seemed to be on the same wavelength. I thinks I managed to ask the odd intelligent question, and with Scott’s up to date knowledge being reinforced, it definitely seemed to be a meeting of like minds.

There was no need to consult with any other designers as we knew we had found a good fit.

Fortunately, Steve was on his way to Gippsland the next day and was able to drop by for a site visit. Then we just had to hold onto our enthusiasm and wait 4 weeks for the concept design to come back.

On the 15th April we received the first concept design within the stated time-frame. There was a more developed option and one alternative rough concept. Steve managed to keep the floor area low to suit our budget – our best approach to keeping the costs down as we understood that the Passive House requirements would add about 10% to a regular custom build.

The concept plan offered some new ideas to the many that we had already scribbled on various bits of paper and site plans and after some creative time over the Easter weekend, Scott sent Steve an edited plan that merged the most important of those together with the best aspects of the designs. We was thrilled when Steve thought the combined result was “actually pretty well resolved” and so the cast was set.

The concept plan wasn’t actually wrapped up in late July though, what with a trip to Bali for me and Scott jumping through hoops to get his TAE up to date, the process took longer than if left completely to the designer. However, it meant that we were much happier with the outcome and had given plenty of thought to how everything would be integrated in this new home.

The next task was to do a preliminary analysis using the Passive House Planning Package (PHPP). Luc set up input parameters describing our building (insulation R values, areas of windows facing each direction, roof colour etc etc etc) and then fed the model with a local climatic data-set. The analysis forecasts how much energy it takes to keep the building at a comfortable temperature (20 to 25 degrees C); describes what level of performance the windows need to achieve (double or tripled glazed, solar heat gain coefficients etc); and determines whether any design changes are needed. Fortunately, our concept design passed the analysis with all measures coming in well within Passive House requirements. Subsequently, Luc also had to provide the NatHERS certificate required for building approval and we were pleased to see that the design rating was 8.6 stars – not a bad result at all.

The final step was the detailed design – this is where it would have been great to have an experienced builder on the team! At this early stage of building Passive Houses in the Australian context, it seems like there are any number of different ways builders can achieve the goals, however, there is not a lot of data on the most cost effective way to get there. Following a bit of toing and froing and lots of research, our detailed plans were wrapped up and finally ready to submit to council just before Christmas.