An eTool LCA was conducted on Wylie Place in Leederville, Perth. Alex Bruce, our Business Development Manager and in-house renewable energy engineer, wasn\’t exactly sure what he should do first to get the biggest reduction in carbon whilst keeping the project under budget. At that stage, Alex used eTool LCA to quantify and compare results to support his decisions. A financial analysis for retrofitting Alex’s house was conducted at the same time as using eTool LCA. All investments were made to ensure a return under 6 years. The previous owner used 22 units of energy per day which is Perth’s household average. Alex not only reduced his usage down to 6 units a day for two occupants, but also generates $1,400 a year by feeding energy back into the grid.
- Date: August 2012
- Client: Alex Bruce
- Location: Leederville, Perth
|Total CO2e / Year / occupant (kg CO2e)||% Saved Against Benchmark||eTool |
|Embodied Carbon||523.9||53 %|
|Operational Carbon||– 618.5||118 %|
|Total Carbon||– 618.5||118 %|
Extended due to density. The 100m2 townhouse is two stories with 3 bedrooms on a 110 m2 block. Considering it is located in Leederville, an inner city area of Perth, this house has a lower redevelopment potential with high occupancy levels. The high occupancy has also reduced the environmental footprint, when we calculate functional units of kgCO2 per year per occupant. In other words, the impact caused by the materials, construction and operation benefits more people.
Improvements like ceiling insulation and an external shading devices helped to reduce heating and cooling loads, therefore reducing energy demand. The ceiling insulation is reused batts thrifted from a friend’s house which was being demolished around the same time. The west facing external wall was covered with shade cloth in the summer, reducing the wall temperature from 65 to 35 degrees at the hottest times of the day.
With a 2.6 kW solar PV system, takes advantage of Alex’s north facing roof. Solar PV has a high embodied carbon component and without it the design would have achieved a better “Embodied Energy” rating. However, the substantially reduced “Operational Impact” due to the renewable energy input offsets this increased “Embodied Impact” many times over during its design life.
The solar PV system produces more energy than the house needs, so the excess power is fed back into the grid, offsetting even more carbon and generating extra money for Alex. The main advantage of a solar system is that it offsets carbon intensive grid electricity.
Including exposed brick walls. The recurring maintenance of painting walls and replacing carpets across the 70 year design life is considerable in both cost and carbon impact. By choosing more natural finishes, Alex has greatly improved the recurring carbon impact of the house.
Heat Pump Hot Water
System was an ideal solution for Alex’s house as it is 2 stories. The main advantage of a heat pump system is that it extracts heat from the environment to heat water using only about one third of the energy of a standard electric storage system. A 280 litre heat pump system was put in place.
System allowed occupants to understand what appliances and devices were demanding the most energy and adjust their behaviour accordingly. This was a big factor in reducing operational energy on a daily basis when compared to a benchmark.
This assessment was conducted by Henrique Mendonca.