Cardinal rules for passive design

Go East, Young Plan

Fig 1. Thermal discomfort in SEQ Western Corridor

Despite strong current demand on the coast, the South East Queensland Regional Plan inexplicably projects major future population growth into the western corridor. This inland zone is up to 4°C hotter in summer and 4°C colder in winter than the coast (Fig.1). Energy conservation guidelines suggest an extra 1°C of cooling or heating could equate to a 10% increase in energy use. Westward growth would inevitably increase overall cooling and heating use, currently 27% of household energy consumption. Heavy air-conditioning use on the hottest summer afternoon generates peak electricity demand, and hence has a disproportionate impact on overall power network provision. Of greatest impact is the ‘tipping point’ decision to install air-conditioning. Air-conditioning of homes doubled from 32% in 1994 to 68% in 2008. Conversely though, almost a third of Queensland residences are currently un-conditioned and consequently consume very little energy for cooling or heating. Government agencies recommend summer thermostat settings of 24°- 28°, however, along the coastal zone, mean January maxima are only 28°- 29° with significant further cooling effects from reliable breezes. Focussing population growth in this salubrious region would significantly reduce energy demand for air-conditioning and heating.

Utilise the north/south spine

Recent Queensland masterplan analysed for lot

Currently, a 225 km transport corridor connects 70 rail stations from Cooran to Robina, all within 15 km of the coast. 14,000 hectares of land lie within ten-minute walking circles of these underutilised stations, and the line runs through hundreds of square kilometres of low quality state-owned pine plantations. Responsible urban planning would focus future population growth along this major public asset. Fast-tracking planned rail links to northern and southern beaches would dramatically improve amenity and equity for all intermediate stations.

Insist on east/west residential streets

In small-lot suburban houses, only front or rear windows now reliably admit summer ventilation or winter solar gain, as side windows are typically closed for privacy. The orientation of residential lots is thus crucial to the potential for passive housing design. Only on east/west streets, will front and rear gardens have optimal orientation to north and south. On north/south streets either the front or rear wall will face directly into the western sun. Diagonal street alignments (nw/se or ne/sw) are little better, as every building face is exposed to low-angle summer sun that is difficult to shield without also reducing ventilation. Some recent urban projects achieve less than 30% of well-oriented lots and an equal number of worst-case orientations (Fig 2). Energy-conscious subdivision design should produce long east/west residential blocks to give ideal orientation to every house. A passive future requires action now.