January 24, 2016
A recent post in the influential blog inhabitat has a showcase of “Solar-powered Bush House exemplifies chic eco-friendly living in the Australian outback.”
Designed by archterra architects in Western Australia, (not built by us) it is great to see their simple but contemporary design gain international attention for their sustainable approach. They have used a long east west axis, good cross ventilation and appropriate shading devices.
“Two rammed earth walls and a concrete floor slab help retain thermal mass” which is an excellent approach. I think its thermal performance can be improved a little by replacing the south facing rammed earth walls a more insulated walls system. This would reduce the winter heat loss through these southern walls that never receive solar gain. You could then utilise more rammed earth internally.
Internally positioned rammed earth is the best performing position as it is thermally isolated from the outside climate. This then gives you options in summer to cross ventilated during the cooler night and isolated it from the hot day time temperature. In winter the walls will absorb the winter solar gain from the great solar passive design and also any additional warmth introduced from the fireplace. These internal walls are great for regulating the diurnal (day vs night) temperature and are more efficient at regulating the humidity.
archterra architects also have a good focus on the environmental impact of each material “Life cycle cost analysis carried out by etool can provide an in-depth analysis of your buildings carbon footprint and comparison agains an ‘average’ equivalent building with respect to materials and energy input/output.”