Predicted climate change is often reported as the mean seasonal change between climate variables averaged over a given period, while thermal and other energy engineering simulations often require hourly representation of climate variables (elements). This paper describes a method of combining seasonal increments being developed by Australia’s Bureau of Meteorology with hourly data representing the present climate. The resulting ersatz hourly data will be representative of future climate estimates and can accordingly be used for energy engineering purposes – particularly for the design of long-lived assets like solar power stations and energy efficient buildings.

The paper will also discuss the Bureau's multi-year project to establish a database to manage and provide these predicted average data. It will also reflect the uncertainties associated with these estimates of future climate. Some of the causes of uncertainties in projections are limitations associated with:
• Spread in model projections due to basic model physics
• Cloud physics (response/feedback)
• Carbon cycle
• Biosphere response (currently a CO2 sink but could become a CO2 source)
• Lower confidence in the smaller scale
• More confidence in some parameters than others (eg. temperature better than rainfall)
• More confidence in mean values than in variability
• Some aspects of the oceans not well understood like: the southern hemisphere thermohaline circulation, the ocean thermal response and sea ice