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PROPOSAL TO REVISE ENERGY EFFICIENCY REQUIREMENTS OF THE BUILDING CODE OF AUSTRALIA FOR COMMERCIAL BUILDINGS 155
• any reduction in operating costs due to BCA induced reduction in total
consumption;
• any reduction or delay in capacity due to this effect; and
• any reduction in hedging or other costs due to BCA induced changes in
the load profile.
These effects will take place in an environment in which the CPRS,
renewable energy targets and potential climate change will be driving
large scale investment in both energy generation and distribution
investment, as discussion below illustrates.
Potential effects on the generation sector
Peak load effects on the capital costs of the electricity sector stem from
the need to have back up capacity and/or additional interconnection
network capacity to supply extreme demand levels that typically prevail for
less than 1 per cent of the year. Systems which operate with a typical load
factor of 60 per cent, involving peak, intermediate and base loads may
have base load factors as high as 90 per cent and peak load plant with
load factors of 10 per cent or lower. Reserve capacity set as a buffer over
and above estimated maximum demand can amount to 10 per cent or
more of the total capacity. Average peak loads are typically at least
50 per cent above average loads. (Critical peaks on extreme (hot) days
can be much higher than this.)
Residential use currently contributes disproportionately to peak demand,
and the need for peak load capacity, particularly through the impact of
summer loads driven by home air conditioning, whose penetration is
increasing. The commercial sector, in contrast, while contributing to mid
afternoon strength of demand, tends to be out of phase with the overall
late afternoon – early evening peak coinciding with the switch on of
residential cooling (or heating). While accounting for 28 per cent of total
consumption, residential use could more reasonably be considered to
underpin 35 per cent of maximum demand — when peak influences are
added to the commercial, industrial and mining demands. 39 Any
39 In this review no direct estimate has been obtained as to the share of peak demand
attributable to the residential sector. However, if, in the extreme case residential
demand is responsible for most of the 50 per cent difference between peak loads and
average load, then, rather than approximating households ‘capacity share’ on the
basis of their share of total consumption driving 28 per cent of the capacity needs
Australia- wide, this capacity share is better approximated as 35 per cent. (This
assumes 28 per cent of the average load with a weight of .67 and 50 per cent of the
peak load with a weight of .33, giving 0.35). Data for the regulated residential sector
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