Sunday, March 29, 2015

National Construction Code

I see all sorts of advice online about how to do this, or what the regulations are on that. It's terribly frustrating when you find contradictory sets of information, or not quite enough detail to replicate the process yourself. So I try and go straight to the rules themselves whenever I can as otherwise it's madness.

Which is why I have been particularly excited that the National Construction Code is now available free online. Yay! Previously it cost around $400, though I did get access to a copy through the local university library (I work at the Uni, so that's not as dishonest as it sounds). An open, online source of information makes it much easier for the owner builder to work out the requirements cheaply.

Now we just have to hope one day that Standards Australia does the same.

Sunday, March 8, 2015

Rainfall

There are some inherent difficulties in how we've chosen to plan and build our house. A lot of the planning stage is taking place before we've actually bought land, meaning that we can't get truly accurate data on the specific climate of wherever our little patch of paradise will end up being. Makes planning for all manner of things a little difficult. But we have a rough estimate of where we'd like to be, and are reasonably confident that's the region we'll end up in, so I can proceed from there.

One of the most important things we need to plan for is water. This is the aspect of the build that most concerns me. Maybe that's surprising - I'm entirely confident we can build the structure of the house, and we've more or less decided gas for water heating and cooking is probably the easiest, and whilst I don't currently know terribly much about electronics and solar panels I'm sure I can learn. However, the rain does worry me as there's no manner of learning more about it that will make it rain more, and we are unlikely to have a mains water connection as a backup.

So off I go to the Bureau of Meteorology site to look for historic rainfall data. As you do!


For a rough first estimate the areas we're looking at properties fall solidly on the 1000-1500mm borderline. But I'm particularly interested in seasonal variation - winter is the wet season in this part of the world, which leads to a long dry summer. Into the future I can't imagine this will improve considerably.

Through my subsequent search I found the most amazing tool - Tankulator. You can enter in your likely postcode, find the nearest weather station, enter values for the size of the collection area, how much water you use (we'll have a composting toilet and recycle our grey water for use on the garden), the size of your tank, and it will draw you a graph of the predicted tank water level over 5 years. You can then make adjustments and go back and forth until you find the most stable configuration.


The Tankulator lets you select whether you'll start from an empty tank, or fill it initially to either 50% capacity or full, which we'll probably end up doing. I've struggled to find price estimates for water cartage, but there are several companies that offer this service in the area we are looking so this will likely be our safety net if we get our maths wrong.

It makes sense that a larger collection area will be better, and a larger tank capacity also. As we'll be completely off grid for water it's important that even during the driest years the tank is unlikely to empty entirely. I would also tend to see tank overflow as a failure - all that water that could have been captured and stored, if only the tank was bigger. Ideally I'd like the water level to hover between half and three quarters full, so I had to do a bit of fiddling around with my (entirely imaginary at this point) consumption, collection area, and tank size numbers.

The process of successively changing these numbers and seeing the effect they had on the amount of water stored (and whether it was trending up or down) was quite enlightening. It also highlighted the importance of the exact location in determining what size tank to get - the weather station shown above leads to a fairly stable water level, but the next one over trended way down over time with the same numbers.

Saturday, March 7, 2015

Planning for bushfires

Kyle and I are both well aware that bushfires in rural NSW are a case of 'when' rather than 'if', and that our safety will likely one day depend on having planned effectively for what to do when bushfires inevitably come our way. This seems particularly relevant when bushfire season is in full swing over summer.

So, at some stage in early January I started hunting for information on preparing rural properties far in advance of a fire risk.

Since it came up first on all my searches I started with the variety of widely publicised, government sponsored, bushfire safety fact sheets, figuring I could work backwards from there towards something more substantial (they always have that bit at the bottom that goes "for more information..."). However, I was a little disappointed.

I'm not particularly keen to simply take the advice from government factsheets at face value. It is reasonably likely that at some point in the next 20-30 years Kyle and I will be trusting our lives to these preparations so in my search for information I was after something more substantial than 30 pages worth of "that sounds like good advice to me". Given that the majority of this advice is aimed at more conventionally built houses (complete with ceiling cavities and wooden panelling, none of which we'll have) I was looking for some of the evidence underlying this advice so I could make an informed judgement about how it would apply to our rather different situation.

Now, don't get me wrong, I fully appreciate that the factsheets and bushfire plans and so on from the government and the RFS are probably responsible for saving many lives. I'm just not convinced that they're the best source of information available. The deeper I dug the more I found that any evidence that was actually available to me contradicted the advice in the official factsheets. However, the evidence also made me more confident of our ability to successfully design a property to be defendable - there's nothing like stories of people surviving firestorms in weatherboard houses to make you feel better about your earthen home's fire resistance.

Amidst my searches, I found a book by David Holmgren (unsurprising really, he seems to pop up whenever I have a question no one else has solved yet complete with a publication date sufficiently far in the past to make everyone else embarassed at not having figured it out themselves yet).
I bought a copy, and was suitably relieved when reading it. This was exactly what I was looking for - the book lays out an example of a property design that emerges as a consequence of good permaculture design and covers all aspects of the property that can act as structures and processes to seasonally prepare and defend the house itself. This makes a lot of sense to me, and is consistent with the stories I found of people experiences in defending their properties during bushfires.