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Sustainability Victoria recently collaborated with SJD Homes to deliver what could only be described as a modern-day eco-ranch, with a twist. At first glance, you’ll never know just how energy-efficient and sustainable the home really is. It’s only when you take a moment to look beyond what appears to be a very typical four-bedroom, single-story display, that you can appreciate its 7.6-star NatHERS rating and its zero net carbon achievement.
The key take-out from this home is simple. New homes can successfully be energy-efficient, comfortable and affordable, without compromising on style.
Builder: SJD Homes
Estate: Cape Patterson
Address: 2 Sunlight Avenue, Cape Patterson
Design: Custom built
NatHERS energy rating: 7.6 stars
Whole-of-home assessment: The home achieves high efficiency with a modelled 'Zero Net Carbon' footprint in its operational phase.
Other features: Fully electric; recycled material (bricks)
Retail cost: $258,900 (does not include land price)
From the moment you enter 2 Sunlight Avenue it becomes clear why it performs in a class of its own. In fact, when looking at this home’s thermal envelope, less than one percent of homes built in Victoria last year performed as well as, or better than it does. The design is intended to feel comfortable all year round, with minimal reliance on heating and cooling.
In addition to its superior thermal envelope, this home is also equipped with enough solar PV to produce more energy than it uses over the year. It has also been fitted with all electric appliances (no gas connection) and is designed to produce no net greenhouse gas emissions.
Most impressive is that the purchase price of this home, including its energy efficiency package, falls in line with average costings for homes in Victoria. The average cost of a 6-star home of the same size is $284,418*, whereas 2 Sunlight Avenue, Cape Patterson is $258,900 including the efficiency package. Without the energy efficiency package, the cost of 2 Sunlight Avenue comes in at $229,900. Please note: the land price is not included in these figures.
*Source: Australian Bureau of Statistics – based on a square meter cost of $1,374.
Comfort aside, the home also shines when it comes to annual energy and cost savings. The estimated greenhouse gas savings is 6.2 tCO2-e and the estimated annual dollar savings total approximately $1,389.
This is based on 4 occupants in the home all day.
Table 1: Predicted annual energy costs, including supply charge, and carbon emissions of 2 Sunlight Avenue.
The current National Construction Code requires that new homes achieve a minimum of 6.0 stars under the NatHERS rating system. When it comes to design, 2 Sunlight Avenue has achieved well above the baseline, with an impressive rating of 7.6 stars.
“We wanted to create a home that was really comfortable for the occupant to live in, without the high price tag, so we paid really good attention to the orientation of the home.” Simon Dunstan, Owner SJD homes.
Orientation of the home with respect to the rise and fall of sun is crucial in maintaining comfortable internal temperatures. This home’s living areas all face north, making the most of available sunlight throughout the day. The addition of clerestory windows in the main living areas enables the home to further maximise on the benefits of its northern orientation. The design also factored in 900mm wide eaves on the north facing façade, protecting the home from the sun without compromising on light in summer and warmth in winter. View the floor plan.
Whilst orientation is key, it’s not the only design consideration for achieving a more energy efficient home. Other key considerations featured in this home include above standard insulation, windows and glazing, lighting, good air tightness, and energy-efficient appliance choices. From a sustainability perspective, the design also includes the use of recycled brick.
In addition to these considerations, 2 Sunlight Avenue also offsets any residual greenhouse gas emissions with an appropriately sized solar PV array. The 5 kW system installed on the roof offsets all emissions and further reduces the home’s energy use, significantly lowering the home’s energy bills.
As the thermal envelope of homes gets more efficient, attention to the appliances can make a substantial difference to the annual energy use of a home. Key energy-efficient design choices, including appliances, are listed in this table.
The home’s design is essential in achieving a cost-effective, energy-efficient home; however once that has been completed, it is crucial that the home is built and tested to meet the intended design outcomes.
The construction process at 2 Sunlight Avenue included:
During the construction phase, 2 Sunlight Avenue was subject to an as-built verification test. The test provided quality assurance, guaranteeing that the home’s thermal envelope had been built in line with the design spec.
Sustainability Victoria engaged an independent as-built verification assessor to ensure that the home was built to meet its intended energy efficiency targets. The verification check included a blower door test to measure air leakage and a thermography test to check insulation coverage.
The home was blower-door tested to determine the air leakage rate. The home passed the blower door test with an air-permeability of 4.4 m3/m2.hr, which is well below the requirements of the National Construction Code.
This test uses a specialised camera that can ‘see’ heat transfer, enabling the assessor to inspect the installation of insulation, by looking for hot spots and cold spots in the ceilings and walls. The inspection is passed if no more than 5% of insulation is missing.
The home passed with only 3.7% deficit in ceiling insulation coverage and an impressive 0% deficit in the walls.