Recently I dipped my toe into the controversial pond containing the often competing imperatives of Canberra’s garden city character and people’s right to do whatever they want on their aspirational quarter acre … or in modern parlance 0.6177 hectares. I mentioned the difficulties in dealing with regulated trees which are certainly wild cards and potential black holes the normal punter should watch out for when approaching development possibilities. I recently designed a house for a senior public servant who had bought a plot of land with seven regulated trees on it. It took many months resolve whether they preferred design would be achievable or not. Caveat emptor!
Other than the issue of regulated trees what other ‘tricks for new players’ should one seek to avoid when ‘eeny minny mo’…ing blocks for potential development? Probably the first and most important one is what is the orientation? The most suitable blocks to redevelop to ensure a sustainable outcome are ones in a landscape format, those whose long axis faces north. Look for a shape akin to the shape of a single bed in plan form. It is not vital to have the block facing precisely true North, anything in the ‘solar slot’ is acceptable. The ‘slot’ is any situation where the long side of the block address any angle between 20° west of North and 30° east of it. A rectangular house facing following the geometry of the block can be simple in plan form and easily take advantage of just about all of the available winter sun.
Canberra is a heating rather that a cooling dominated climate by a factor of about 8. By this I mean that if you were to heat and cool house to normal temperatures throughout the year one would use eight times as much on your heating as your cooling. If you’re going to utilise the free energy from the sun getting the simple orientation equation right is a vital first step. Selecting the correctly block makes all the subsequent design decisions snap into place like lids on a biro. This is level 101 of lessons for passive solar design in our climate. Perhaps ignoring this simple principle was excusable in a less energy conscious age but it seems unforgivable to see how the precious ball continues to be dropped.
With a good block selected in considering the first decision in deciding to lay out the house was block for your correctly oriented block is to it means getting the key living areas area facing north and relating well to private outdoor spaces and for the building not to overshadow itself. I also think a good principle is to try to achieve a one-room thick allowing you to have alternative outdoor spaces both winter and summer. Windows on the north side only often cause glare. Small well insulated openings in the south can promote good cross ventilation and an improved feeling of connectedness to key outdoor areas.
Combine these simple principles with good levels of insulation in wall and and ceiling, high-performance Windows and you have a simple starting recipe for good sustainable design. It is important to remember that a house is more than a machine for collecting heat it needs to be home too. I haven’t touched on the mysterious matter of thermal mass in this short piece but will return to it later. The subject is slightly less complicated than dark matter or dark energy but often equally misunderstood.