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What is 5-star?
‘5-star’ is a standard that rates the energy
efficiency of all houses and apartments in Victoria.
Since July 1st, 2004, all new residential developments
are required to meet the 5-star standard.
The energy efficiency of a home is determined by its
orientation, insulation, window design, internal design
and water saving fixtures and systems. ‘5-star’
takes into account all these factors and uses accredited
software programs to determine their combined energy
efficiency.
There are two basic parts to developing to meeting
5-star requirements: First, every home requires an approved
energy report, which is prepared by a qualified energy
rater. Secondly, all new homes must include either a
rainwater tank reticulated to toilets (ie water from
rain tanks to be used for flushing of toilets) or a
solar hot water system.
Energy Report
An energy report takes into account the different energy
efficient factors of a home and rates their combine
efficiency. They are produced by qualified energy raters
with the use of accredited software programs: FirstRate
(typically used in Victoria) and NatHERS. If the initial
design of the project does not meet the ‘5-star’
rating, energy raters will give suggestions to adjust
the design.
Some architects, or draftsman, are qualified energy
raters and are able to produce energy reports. Other
energy raters can be found in energy consulting firms
or work individually on a free-lance basis.
An energy rater’s report can have a significant
impact on the final cost of constructing your
project, as the rater determines what materials
(eg glazing, type of insulation and extent) are
required to be used to meet the 5 star energy
efficiency standard.
Our suggestion is to find an energy rater who
is aware of the cost implications of their decisions
and will find the most cost effective solution
to achieve the required efficiency standard. In
many instances our clients have saved thousands
of dollars by preparing new energy reports. |
Rainwater Tank Vs. Solar Hot Water System
Part of the requirement of the ‘5-star’
standard is that all homes include either a rainwater
tank (minimum 2000 litres) or a solar hot water system.
One system reduces water use while the other saves energy
consumption. Ultimately it is the client’s choice
on which system is to be installed, we have prepared
the following guide to aid your decision.
Make a decision on a system before consulting
your architect or draftsmen so that they reflect
your requirements in their drawings. If you do
not instruct them on a system, they will likely
choose one for you. |
Rainwater Tank
On average, about 20% of the water used in houses is
flushed away in toilets. The main purpose of the rainwater
tank, therefore, is to use rainwater in cisterns as
oppose to flushing away fresh water.
To meet the ‘5-star’ requirement, the rainwater
tank has to have a minimum capacity of 2000 litres to
store water to use in toilets. If rainwater is to be
used elsewhere, a larger tank is required, with 2000
litres of the water in that tank to be stored for toilets.
Advantages |
Disadvantages |
Generally less expensive to supply and install
relative to solar hot water systems. |
Usage is dependant on rainfall; on average,
Victoria experiences rainfall of more than 1mm
100 days per year – two-thirds of the year,
the tank does not collect water. |
Saves water used to flush toilets, as well
as other household uses if larger tanks are installed.
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Uses garden/courtyard space.However tanks are
available in different shapes, such as ‘Slimline’
to minimize this impact.
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Reduces water consumption and therefore costs. |
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Can have a low visual impact relative to installing
solar hot water units on the roof (depending on
dwelling design), as it can be placed in visually
less prominent locations or even under the dwelling
or within its support structure (depending on
construction of house and model of tank). |
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Variety of types, models and colours available
to suite different needs; can be constructed on
site and, therefore, designed to suite specific
requirements. |
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Solar Hot Water Systems
Heating water accounts for about 30% of the energy
used in households. Solar hot water systems use renewable
energy from the sun to heat water, reducing greenhouse
gas emissions and energy bills.
There are several different types of solar hot water
systems, the most common being the ‘closed-coupled
thermosiphon’ system and the ‘forced circulation’
system (also known as the pump, split or active system).
Advantages |
Disadvantages |
Saves energy used to heat water; provides at
least half of total hot water requirements –
with correct design, model and maintenance can
provide almost all of hot water requirements with
solar energy. |
Generally more expensive (even after rebate
provided by the Government), relative to rainwater
tanks. |
Reduces energy bills – arguably more
cost saving than rainwater tanks in the long run
– and greenhouse gas emissions |
Usage is dependant on amount of sunlight provided |
All systems have a gas or electric heating
system to heat water when solar energy is insufficient. |
Can have a high visual impact (depending on
dwelling design), especially with commonly used
closed-couple system where the tank is placed
above the solar panels on the roof. |
Does not require large spaces on ground, even
if forced circulation system is used as the tank
is comparatively small.
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