A report published by Edge Environment sustainability consultancy firm proposes that the most sustainable buildings in the future will have a stronger focus on minimising the embodied emissions of materials used in construction.
'Energy-efficient dwellings – Can embodied energy spoil the story?' used life cycle assessments (LCA) to document the energy and emissions performance of a typical Australian freestanding home compared with the 2013-built sustainable residential project home called "CSR House".
The LCA compared the energy and environmental performance of CSR House across 23 climate zones in Australia, and benchmarked it against the Housing Industry of Australia's (HIA) reference building of similar size.
Their conclusions were that lowering a residential building's operational energy, via energy efficient building products, remains key to lowering its overall emissions.
However, as operational emissions are falling rapidly, due to better thermal design, more efficient HVAC appliances and growing consumer awareness about energy and carbon, the source and emissions-intensity of building materials are becoming increasingly significant at the domestic level.
Key findings of the report, courtesy of EDGE Environment:
Investments to reduce operational energy, including sustainable design using emissions-intensive materials, remain well worth it.
Investing in an energy-efficient home pays off environmentally and financially. The energy drawn for the home's typical domestic use (operational energy) still dominates total lifecycle energy use. Each of the occupier's behavioural choices can dramatically reduce it, by smart and efficient appliances, and by sustainable design and choices of building materials. These savings comfortably outweigh additional emissions, if any, embodied in the materials used in sustainable design. As the cost premiums of non-'standard' materials continue to fall and energy prices continue to rise, sustainable design will also continue to be financially attractive.
However, more attention should be paid to embodied emissions, as they are already significant and are becoming more so.
Even so, embodied emissions cannot be ignored. While most lifecycle emissions are due to the building's use, the building's materials account for at least 10-20%. As the buildings become more energy-efficient, that proportion is rising and embodied energy is almost matching operational energy in the most efficient designs. Moreover, as designers can influence but not control occupant behaviour, their choice of building material may account for up to half of the lifecycle emissions that they can control.
These findings have clear implications for home users, for design and construction businesses, and for their material suppliers.
Designers and builders should continue to focus on the designs and materials that will reduce operational energy, including by influencing low-emission appliances and behaviour, but start to demand materials that minimise lifecycle emissions. Suppliers should continue to meet that demand with resource-efficient and low-emission production, both to reduce their operating costs and to maximise their market access and sales. Homeowners and users should seek out sustainably designed homes: with it, their own appliance and behavioural choices will save much in energy costs; without it, those choices will reward them less.