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Electrical systems

The predominant conventional electrical systems including domestic appliances in Australia operate at single phase 240V AC. The conventional electrical service is delivered from 3 phase public supply, with this transformed from 11,000V at local area transformers and leaving the power station at 312kV. Buildings are usually reticulated exclusively in 240V AC.

Renewable energy

often generates electricity at direct current (DC); conventional wisdom is that this energy needs to be stored and inverted to 240V AC suitable for reticulation.
The rationale is that voltage drop across distance transmission in small diameter core cables is low in alternating current (AC), while in DC both voltage drop and arc spark distances are large.
Yet during the same period of evolution, DC electricity has been developed to operate successfully in:-
  • marine applications
  • caravan and houseboats
  • electric fencing and pumping bores
  • electronic appliance internal operation.

This architectural practice

starts with the philosophy, that a low energy demand building will meet peak effectiveness if the best fuel for each use is supplied; and that losses during inversion from DC to AC and return are avoided.

A number of the projects developed in this office therefore integrate mixed electrical distributions; notably 12V DC, 24V DC and 240V AC.
The 'natural' electrical fuel from a renewable energy system depends on the system size, usually 12, 24 or 48V DC.
The higher the base voltage, the less stress on the storage system in inversion to 240V AC.
Some appliances can operate on any of the natural voltages, notably pumps and lighting.
In projects from this office then:-

  • the natural system voltage is used for specific functions, notably water distribution and pressurisation pumps, lighting : usually of low wattage efficient types including fluorescent for general space lighting and halogen for spot and task lighting.
  • specific DC voltage is delivered to specific individual appliances, notably appliances from marine or caravan industries including tape recorder, television, radio, small refrigerators; and to individual electronic appliances normally 240V AC powered which have been retro-fitted including computers and gas boost ignition to hot water systems.
  • 240V AC is reticulated primarily to heavy draw appliances, particularly washing machines; and to refrigerators and electronic appliances which are in use as manufactured.

Integral to low energy demand is the strict avoidance of some appliances , notably electric element heating including space heating, water heating boost elements, even electric kettles.
"But it's only a small kettle" probably has a 2.5kW element in it whereas a low energy demand building may have a 1kW system for the total building.
Convenience appliances too are frowned upon - electric toothbrushes, single use gadgets, and so on.

Energy efficiency

is maintained by building-in larger diameter cabling to DC circuits. Operational effectiveness is maintained by fitting all switches with indicator lights which are 'on' when the zone circuit is live.
The system also includes main and sub-boards with extensive zoning of the building to ensure unused portions can be easily shut down and spurious energy losses (base load keeping VCR LED's glowing, etc.) avoided.

Energy demand is contained by minimising the demand from electric appliances.
A vented pantry will contain much which by convenience is put into refrigerators.
A small front load washing machine may require 2 or 3 loads but will draw 25% peak demand of large top load washing machines when the unit is full of clothes and water.

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