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Hi, just joined because I was reading all the posts about MHRV. I have the basic design of my proposed 110 sq M house: 3br, 2 disability bathrooms, superinsulated, Off centre roof pitch with the long side facing N (S hemisphere!). wrt the MVHR, it seems the most economical solution for me is a Mitsubishi Lossnay ceiling mounted. After doing some research, I have found a Chinese Co that supplies 90mm round Semiflex duct & accessories. Yet to create a manifest, but providing the freight is reasonable, should be economical. The Co is: https://www.erviguicoo.com/fresh-air-abs-distributor-with-high-quality-abs-materials-product/. So far I have a catalogue, but will need drawings, etc. The Lossnay will be locally sourced for warranty. btw, the Steib-Eltron tool is great for designing the MVHR system. Some details of the build: light construction because there are no snow loads! The Wall frames will be Pine, with the top & bottom plates screwed as well as nailed (due to Cyclone uplift). Studs 90x45, on 600 centres. The roof trusses will be at 900 centres. The roofing is Trimdek corrugated iron, but I will use 0.48mm as I will use S5 mounts for the solar PV that are rail-less (just screw to the ridges, hence the thicker steel). Hempcrete: 270mm thick walls with 10mm lime based render each side. One thing I will do differently is to raise the truss bearing point so I can have 300mm of insulation across the ceiling with no step down, The Hempcrete walls will go to the top of the outside edge of the trusses, & will return into the ceiling, sitting on a ledger. Then I can seal & attach my OSB airtight layer directly under the trusses. The OSB also gives wind bracing. (all joints sealed & taped). 300mm Fibreglass insulation above OSB. This will be built on a slab foundation, using Cupolex domes. The edge rebate will have stainless ant barrier/dampcourse. Air sealing: all transitions taped after walls are rendered. Slab is to be polished, so the concrete will be edge primed before taping . Blower Door test: I will DIY a blower door using a s/h Automotive 12v radiator fan. I already own a digital manometer, & after reading the MVHR threads will buy a Testo 425 Digital Hot Wire Anemometer (the computer connected one), & control the fan with a DC speed control to vary output. The Air volume can be easily measured with a cone over the fan, & something like a piece of 150mm plastic stormwater pipe, with a hole to insert the Anemometer probe. This anemometer is apparently sensitive enough to check for leaks around windows, etc. The Automotive fan will easily blow/suck 50 pascals. My build is also in a bushfire zone. No gaps bigger than 2mm in the outer sheath & roofing: I do not use Soffits or barges: I use a product called G&G gutter brackets that screw to the metal roofing overlap. I use 150mm half round gutter that I can easily clean (with a moon section on a pole). The gutter ends are sloped so I can sweep the leaves out. In Australia, the roof space must be ventilated, which is accomplished with about 75mm wide folded perforated aluminium sheet that runs on top of the hempcrete, to the underside of the roofing. I have designed a system that stops the embers. The vent at the ridge is a product called Vent-a-Ridge. This allows air to pass under the (raised) ridgecap, exiting through the corrugations. There will be the usual smart membrane & counter battens for air flow. Hopefully I can build this for less than a ´normal´ builders build (aiming for $au2500 per M sq) regards, Doug