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BASIX® & Hot Water

The first section within the Energy portion of the BASIX® Certificate refers to the hot water system intended for your home.

The importance of this is because in NSW, depending on the system used, heating hot water is responsible for up to 50% of the households average energy bill.

BASIX® allows for the choice of the following systems:

  • Solar (Gas boosted)

  • Solar (Electric boosted + timer)

  • Solar (Electric boosted)

  • Electric Heat Pump

  • Gas Instantaneous

  • Gas Storage

  • Wood Combustion

  • Electric Instantaneous

  • Electric Storage

Images of hot water systems are:


Solar Hot Water Process

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Basically, BASIX® has rated these units in order of “most” to “least” efficient, with solar gas boosted being the most efficient, and it would be highly unlikely that either of the two electric systems would ever be accepted in the BASIX® Certificate, because they are the least efficient systems.

There are two  main types of systems used in NSW and they are storage or instantaneous heaters (also referred to as continuous flow). 

Whichever system is used could depend on the following:

  • Amount of people in the house

  • Energy efficiency

  • Price of the unit

  • Available space

  • Adequate sunlight

  • Availability of gas

Energy efficient units will produce less Greenhouse gas emissions, and this is one of the main objectives of BASIX®.  As shown on the graph, gas boosted solar units will produce approximately 0.3 tonnes, whereas electric storage will produce around 4.0 tonnes.  It should be noted that most homes before the introduction of BASIX® would have installed an electric storage unit.

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BASIX® also requires grades the solar and heat pump systems with a REC’s score and the gas units with a Star rating.  Basically, the higher the REC or Star rating, the more efficient the unit should be.

Types of systems are:


Solar hot water systems are generally the cheapest systems to run, however they are also one of the most expensive systems to supply & install.  They do have the advantage that on average they will “pay for themselves” in around 5 to 10 years, depending on the system purchases and location of your property.  They will also be connected to either gas or electricity, to supplement the period when the sun is not available for generation.

Solar systems can either be installed with the tank on the roof with the collections or on the ground (lo-line system).

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Heat Pump

Heat pump systems are generally new to the market, and although not as efficient as the solar units, they will use up to 70% less electricity than the existing electric heaters.

Basically the system works by extracting heat from the surrounding air using a refrigerant gas and a compressor, which is then used to heat the water in the storage tank.   Because the unit works this way, you will get the similar sound for the compressor of an air-conditioning unit.

These systems in some cases have similar supply & installation costs as the solar units, and like the solar units government rebates are available through the REC scheme.

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Gas hot water systems can be either storage or instantaneous styles.

BASIX® allows more Energy points for the instantaneous or continuous flow units, and these are Star rated, so the higher the Star rating, the better the unit.

These units are mainly installed externally, but with the correct flue or ventilation systems, they can be installed internally.

Generally gas storage tanks are smaller than the older style electric systems, because unlike electric, the water can be heated anytime of the day.  So it the tank becomes entry, it will reheat straight away.

Whereas with the continuos flow systems, these are heated as required, so you will see only a small unit on the wall, and these systems can also have controllers installed within the house to vary the temperature as required.

Both of the systems can be run on natural gas or LPG and LPG is only chosen if natural gas is not available, because of price and refuelling issues.

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Wood Combustion

This system heats the water using a ‘wet-back’ attached to a slow combustion or solid fuel wood heater.  It can also be a wood burner solely for heating the water. 

These systems can only be connected to mains pressure water if they have a heat exchanger.

You should check with council before installing a solid fuel heater and also consider the cost of the fuel.

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Electric heating of water will give you the lowest point in the BASIX® energy score for hot water systems, and it is unlikely that one will give the required pass for this section.

These systems are either storage or instantaneous.  Storage tanks can be as large as 400 litres and as little as 25 litres.

In storage systems, water is generally heated over night and the unit can be connected to off-peak power tariff.

Peak electricity is used for continuous or instantaneous systems and is more was expensive then the off peak rates.

What is REC

REC or Renewable Energy Certificates were introduced as a form of electronic currency, with the intention of promoting renewable energy generation. The rebate for solar and heat pump systems is based on the amount of greenhouse gas emissions saved, and the manufacture will be able to provide the REC value for their units.

To obtain more information on REC’s and the rebate system, go to:

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