The most suitable blocks to redevelop are those in landscape formation.

The most suitable blocks to redevelop are those in landscape formation. Photo: Melissa Adams

RECENTLY I dipped my toe into controversial waters containing the competing imperatives of Canberra's garden city character and people's right to do as they see fit on their quarter-acre block. I mentioned the difficulties in dealing with regulated trees, wild cards or potential black holes the punter should watch out for when imagining their own Grand Designs. I recently designed a house for a public servant whose plot had seven regulated trees on it. It took many months to battle through the system for a workable solution. So caveat emptor where the garden bit is concerned.

What are the other ''tricks for new players'' one should be conscious of when considering blocks for potential development? Other than the normal ''location, location, location'', probably the first cab off the rank would be the block's basic orientation. To ensure a sustainable outcome, the most suitable blocks to redevelop are those in landscape format, those with a long axis facing north. Look for a shape akin to that of a single bed in plan form and facing a specific direction. It is not vital to have the long side of the block facing precisely true north; anything in the ''solar slot'' is acceptable. The slot is an angle between 20 degrees west of north and 30 degrees east. A rectangular house following the geometry of this block can be simple in plan form, cheaper to design and build, and will be able to take advantage of all the available winter sun.

Canberra is a heating rather than cooling-dominated climate by a factor of about eight. If you were to heat and cool a house to normal temperatures throughout the year, you would use eight times more energy on heating than cooling. If you're going to utilise the sun's energy, getting the simple orientation right is a vital first step. Selecting the correct block makes all subsequent design decisions click into place. This is 101 in the school of passive solar design. Perhaps ignoring this principle was excusable in a previous age. But it seems unforgivable now.

With a good block, the next thing is to get the most important parts of the house in the right spot. This should be obvious; it means locating the key living areas (probably the family-meals-kitchen zone) facing north. These, too, should have their long axis facing the sun and relate well to private outdoor spaces. A long rectangular house on a rectangular block has the added bonus in that it is less likely to overshadow itself. In thinking about these key living areas, one trick is to try to achieve a one-room-thick space with the benefit of allowing one to have alternative outdoor spaces both winter and summer on either side of the house. As long as the net energy balance works out, this is a good way of avoiding glare. The passively designed houses of the 1970s often had windows only on the north side and combined them with dark floor and wall finishes, resulting in uncomfortable glare. Small double glazed openings on the south have the advantage of promoting good cross-ventilation and that lovely indoor-outdoor feeling to key outdoor areas.

Combine these simple principles with high-performance windows, good levels of insulation for walls, floors and ceilings, and you have a simple recipe for good sustainable design. It is important to remember that a house is more than a machine for collecting heat, it needs also to be home.

I haven't touched on the mysterious matter of thermal mass, but will return to it some other time. It is definitely less complicated than cosmic dark matter or mysterious dark energy, but is often equally misunderstood.

Tony Trobe is a Canberra-based architect