The short answer is that they provided the science behind the building. The passive house consultants used the Passive House Planning Package to understand the building physics. They assessed and modelled our plans, proposed materials, construction method and windows and doors to determine whether we could achieve the passive house standard in our climate. There are various passive house standards that we could have worked towards.
For reference, the house is made of lightweight timber stud walls and mostly timber cladding, on a concrete slab which is coupled to the ground. There is a small section of brick veneer. The roof is a timber skillion roof that is covered with corrugated Colorbond. The windows and doors are double-glazed, timber with 3 seals incorporated into the frames.
The passive house consultants did a WUFI analysis to assess moisture in the house under various circumstances and with various climatic conditions. This is known as hygrothermic analysis and models how water vapour will travel through the house. It’s done to prevent moisture building up in the house and damaging the fabric of the house and our health over the long term. I have noticed increasing attention being paid to this as builders become more aware of airtightness and after the months of recent rain and major flooding in NSW.
They also modelled the thermal bridging risk in the junctions between the internal and external surfaces of the house. This includes things like the connection between concrete slab and walls, corners, balconies, connection between walls and roof, etc. The construction method for these junctions was defined with drawings to guide the builder.
We received all of the above as a detailed package of drawings and reports. Our consultant scheduled some time with us and went through it all. I don’t have a technical background, but we were able to use this information to make decisions about heating, cooling and de-humidification options.
Once the initial analysis and reporting was done, we were able to start the process of selecting a builder. From there, the consultant had an ongoing role in liaising with the builder. This included site visits for supervision at different stages throughout the build and collecting the information required for passive house accreditation at the end.
We are aiming for passive house certification. It is an extra expense, but I think it is worth it. Certification will provide reassurance that the house performs as it was intended when we started. We contracted the passive house certifiers and the consultant is liaising directly with them.
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