Steps on a carbon-neutral journey

How will I know that my home is carbon neutral? How will others believe me? The first steps are working out what to measure, and how to measure it. This post explains how that’s done.  It’s a little bit dry, so to keep you interested, here’s a snapshot of the next step which was the waste audit, described by the household 13yo as ‘totally gross’.

Myrle pouring rubbish for waste audit

The National Carbon Off-set Standard (NCOS) tells us to do a life cycle analysis (LCA) of the greenhouse gas emissions associated with home. That means working out a ‘cradle to grave’ assessment of all greenhouse gas emissions involved in running a household. The NCOS points us to the International Standard for Environmental Management – Life cycle assessment – Principles and Framework IS014040 identifies four phases for an LCA. Here’s how it looks for my house.

flow diagram for carbon LCA

There are some general standards, and some choices about the scope of a greenhouse gas inventory. These are well established for businesses and products, and they can also be applied to a home. For instance, the Scope 1 emissions from my diagram are really a must. Those are the direct emissions from gas heating and fires, and anything else burned or decomposing at a site. Strangely, human breathing is not included in inventories, even though animal farts may be.

pre-winter solstice bonfire 2015

Emissions from electricity used in a building are also a must in the inventory. But you don’t have to include the full fuel cycle emissions from electricity, like transmission losses from the poles, wires, and the times when high voltage loads are transformed to lower voltages. I’ve chosen to include the full fuel cycle. The interpretation stage gives me a chance to change my mind about this if it’s not working out. Similarly, I’d love to include the emissions associated with the stuff we buy for my home. I would, but the data gathering and calculations are way too complex.

The reason that we can exclude these ‘scope 3’ emissions is that they are all included in the inventories being done by other people or businesses. For instance, I’ll be counting emissions from air travel, even though airlines are required to record and report all of those emissions under Australia’s National Greenhouse and Energy Reporting Scheme.

Keep your eye out for the next post, on my home waste audit. That’s when we’ll start to see how my emissions stack up, and what I can do to reduce them.

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