Buyers compare floor areas because floor areas are easy to compare. Orientation is the number that decides whether you actually use the space.

The afternoon test

Visit at four in the afternoon. If the main living room needs a lamp on in summer, no amount of extra metres will fix it.

South is not always right

In a warm climate a south-facing glass wall is a cooling bill. South-south-west with a deep overhang gives you the light and not the heat.

What it is worth

Across our last forty completions, dual-aspect units sold for six to nine per cent more per square metre than single-aspect units in the same block.