Sunday, December 14, 2014

Intergenerational politics

There have been a number of articles recently about the increasing wealth disparity that exists between the baby boomer generation and subsequent generations. These take several forms:

  • The ABC had an article about the rapid accumulation of wealth in older Australians versus declining wealth in younger generations. LINK
  • This (slightly hyperbolic) ABC article was written about a Grattan report - LINK
  • Another article defended the record of baby boomers. LINK
  • Yet another article recounted a very personal debate about the vices of the baby boomers. LINK
I think that we need to step back from this. The risk in these kinds of articles is that we establish an intergenerational schism. People get defensive, or aggressive.

So, prior to any analysis I think I should observe that:

  • Cultural differences between baby boomers and subsequent generations are very minor (much less than between the boomers and earlier generations). At the individual level, we are no different and would have likely made the same choices (in aggregate) had we been in the same situation. (ie. while I think there is plenty to criticise in what the boomers have done, I think my generation will fare no better)
  • In any population or demographic analysis such as this, we are always talking about a distribution. There are many poor baby boomers, and many rich Millennials.
  • It is utterly useless to attribute blame anyway


From what I have seen, the Grattan report seems pretty good. It is not inflammatory (unlike some of the others), and is based on data. The most compelling data are shown in this figure:
Data showing welfare receipt in Australia by age. Source: Grattan
My view is that these data are unequivocal. There is a net transfer of wealth from young and relatively poorer Australians to older richer Australians. The critical thing to notice is the large increase in the right-most bar in the 65+ bracket. Also, the right-most two bars of the 25-34 bracket. 

From reading comments on a couple of online sites, there appears to be a lot of misunderstanding what this report is saying and what it means.

This report is not comparing baby boomers in their 30s against today's 30 year-olds.

Instead, it is looking at demographic changes that have occurred in Australia in the last 8 years. What they have found is that, in those 8 years, older Australians have got substantially richer, while younger Australians have become poorer [1]. Let's keep things simple: people who were in the 25 - 35 age group 8 years ago are now in the 35 - 45 age group. I don't think we can attribute these changes in wealth to big differences between these age groups. In other words, I don't think there are large differences between today's 30 year olds and today's 40 year olds in terms of frugality, sense-of-entitlement, work-ethic, etc. I don't think such differences can account for these systemic shifts. 

These are statistics that have been calculated across the entire population. They are not about individuals. This report highlights systemic problems that urgently need to be addressed. You do not want to be living in a country with a poor and disenfranchised youth -- see Libya, Egypt, Iran for what happens. 

[1] In other words, comments like "Well, I was poor when I was young too" do not apply, as what we are looking at here are rapid changes in the relative levels of wealth between different age groups.

Friday, November 28, 2014

Energy efficient behaviour pays


Investing in energy efficient buildings is a powerful way to save energy, but ultimately the occupants' behaviour is what determines power use. Without spending any additional money, you can reduce your consumption right now by changing your behaviour.


I work as an energy efficiency consultant. Generally, this involves finding investments that can be made (eg. LED lighting, better insulation, variable-speed-drives) that will result in decreased energy consumption. This works well, and there are generally good opportunities for people and organisations to make targeted investments in energy efficiency with good economic returns. However, it is easy to be blind to the most significant effect on energy consumption: human behaviour. Let me illustrate this by way of an example.

My family and I lived in Brisbane for almost three years, arriving in late 2010. We owned our home, and made some energy efficiency investments in it (solar PV, solar hot water, better lighting, blinds). Once these measures were completed, we were using about 5 - 6 kWh/day. When it came time for us to leave Brisbane, the real-estate market was poor, so we decided to rent out the house rather then sell it. We did this for a year and, because of the way the feed-in tariff (FiT) operates in Queensland, we kept control of the electricity supply and were reimbursed by our tenants (had we transferred the supply to them, they would have lost the solar PV FiT). Thus, we were able to see their consumption on a quarterly basis. What was immediately apparent was that their consumption was much higher than ours -- generally it was 2 - 3 times higher. Where we were using 5 - 6 kWh/day, they were using 14 to 18 kWh/day -- in the same house. Clearly, their appliances were different, which could account for part of this, but the majority of this difference I attribute to behavioural differences [1].

What this shows is that simple behavioural change can be hugely significant. Simple behaviours like these have a huge affect on household power consumption:

  • whether the oven is used in batches to cook a lot at once, or if it often turned on for only one small dish
  • whether appliances are turned off at the wall when not in use
  • whether there are many energy-hungry appliances (eg. large TVs)
  • when and how air-conditioning is used
  • whether lights are turned off
  • whether hot food is routinely put in the fridge without pre-cooling
  • how hot water is used
  • whether computers are left running when not used


This shows that energy efficient measures are important, but that the energy use of a building is determined in the end by its occupants. A positive way of seeing this is that you can save energy, without spending any money, merely by changing your behaviour.

[1] We were regularly washing nappies, and we also cook a lot. At that time, we had a relatively inefficient fridge -- thus we could have used a lot less also. Also, note that this house has one small through-window reverse cycle air conditioner, but is mostly not air-conditioned. Thus air-conditioning cannot account for this difference either.

This article was written by Angus Wallace, and first appeared at

Thursday, November 20, 2014

How fast do cars actually go?


I calculated the average speed that people achieve in cars, considering their actual average speed on the road, and the time they spend earning the money to maintain their cars. I found that, for an above-average income ($60000/year), a person driving 10000 km/year achieves an average speed of only 22.9 km/h. If you earn less than this, you must spend more time earning money to pay for your car, and your average speed is lower still.

How fast to cars go?

What I want to do in this article, is work out how fast people actually travel when they're driving cars. I want to consider actual average road speeds, and also consider the time they spend earning the money to pay for their car and its maintenance.

Traffic Speeds

Average speed of urban traffic in Australia, by time. Source:, page 104

This paper, has the 2005 statistics for vehicle speeds in Australia. From it I got this figure, showing that the average speed of cars in urban areas during the day time is about 42 km/h. Of course, congestion has got worse since then, and I would expect average speeds today to be lower, but I couldn't find those statistics.

Combine with time spent earning the money to pay for the car

Across Australia, once on the road, your average speed in the city is about 42 km/h (more like 37 km/h during peak periods). But what about the time you spend earning money to pay for your car? To work this out, I extended this spreadsheet (previously introduced in this article). It now also calculates the average speed of a motorist, based on the 42 km/h on-road speed and the time they spend earning money to pay for the car.

The average speed they attain depends on how much they drive -- as someone drives more, the marginal (time) cost of each extra kilometer decreases so their average speed increases. Here are some examples:
  • For a person on an above-average wage, driving 10000 km per year, they average just below 23 km/h
  • For a person on the same wage, driving 5000 km/year, they average just below 18 km/h
  • They won't reach an average of 30 km/h until they are driving 80000 km/year
  • For a person on $40000/year driving 10000 km/year, they average 18.5 km/h


  1. When you consider the time spent to pay for a car's maintenance, and the actual speed you achieve on the road, cars are not actually a quick way to get around. 
  2. The cost, to the taxpayer, of car infrastructure is huge -- I question whether it is good value for money.
This article was written by Angus Wallace and first appeared at

Thursday, November 13, 2014

What does it cost to own a car?

There have been a few good articles recently about the social cost of cars. Here is a good one -- it nicely summaries what many people are unaware of: vehicle registration does not pay for car infrastructure. Cars require a taxpayer subsidy.

People who ride bikes subsidise people who drive cars.

Here, I want to explore something different.

  1. What does car ownership cost its owner?
  2. How much time must the average car owner work to pay for their car?
These questions aren't often asked, so I ran a few numbers in a simple spreadsheet, which can be viewed here.

The cost of car ownership:

A private citizen on a slightly above-average income will spend 2.75 hours per week working to pay for their car. This includes a very small mileage (less than 40 kms/week). As the weekly distance driven increases, so too does the cost, though the cost per distance decreases.

A private citizen on a slightly above-average income will spend 2.75 hours per week working to pay for their car.

I ran the "model" with a heap of [distance travelled] options to explore how much work was required. I estimated several things:
  1. work hours per week
  2. Cost in Australian dollars per kilometer driven
  3. time spent working, per distance. This is measured in hours per 100km per week. This is the time that is worked by the car owner, each week, for each 100/kms they drive.

What I found really interesting is that it is really expensive.

For a person who drives 10000 km per year (just under 200 km per week) they must work nearly 4 hours per week, which equates to more than 2 hours work per 100km per week, for a total cost of $0.44/km driven. Suddenly public transport is looking very cheap indeed. Remember, this is the private cost borne by the car owner, and does not include all of the public costs borne by the Australian taxpayer.

A total cost of $0.44/km driven -- a limo is cheaper!

As you drive less, owning a car makes even less sense. For someone who drives 3000 km per year, the cost is more than $1 per kilometer. You could catch a limo cheaper than that!


Owning a private car does not make economic sense, even with the strong public subsidies that currently exist. Of course, the bottom line is not the only consideration, so I understand that people will want to keep a car, just for security and convenience. However, if you are a household with more than one car, I would strongly encourage you to consider getting rid of one car and exploring other forms of transport. Your wallet, and your country will thank you!

This article was written by Angus Wallace and first appeared at

Monday, November 3, 2014

National gambling day

Today is Melbourne Cup day: a national celebration of gambling and excess.

I tend to steer clear of gambling, but I wanted to offer a tip of how to maximise the expected return of any bets you make.

My tip: don't bet on the horse you think most likely to win

This probably seems like silly advice, but what you need to consider is that the odds determine your winnings. If a horse is very likely to win, and you bet on it, and it wins, you will not win very much (because its odds of winning are good (say 2-to-1 or even 3-to-2). When horses are very likely to win it is even possible to receive less than you bet (when your horse wins)!

Instead, what you need to do is identify the horses whose odds are overestimated. For example, if a horse is listed as 40-to-1, but you think it's really a 30-to-1, then you should consider betting on it. What this means is that your potential winnings are higher than the risk of the horse not winning.

Of course, doing this is a lot harder than just trying to pick the winner! That's why I don't bother gambling: in my opinion, the race organisers have it all worked out -- the best way to maximise your money at the end of the day, is not to place any bets ;-)


This article was written by Angus Wallace and first appeared at

Sunday, November 2, 2014

Water at my house - part 2: hot water

Hot water

Please refer to this article that I wrote previously, which gives an introduction to the hot water system I've chosen.

At this point, only the main solar hot water system is connected. This supplies the whole house. It is located above the laundry and near to the bathroom, but is across the house from the kitchen (which is on the Eastern side of the house). Refer to Figure 1.

Figure 1: Schematic of the water connections at my house. Note the two hot water systems.
Having a hot water system a long way from where you want to use the hot water is a waste. This is because of two reasons:
  1. the hot water cools on its way to where you want it. This can be reduced by lagging (insulating) the pipe
  2. when you're finished with hot water, you're left with a pipe full of hot water. This is wasted.
This is bad for two reasons:
  1. we're running rainwater, and don't want to run out in summer. Hence we catch the water that's coming out of the tap before it gets hot. This is doable, but is a hassle.
  2. I want to run on pure solar hot water (without electric boosting), and anticipate that this will sometimes be marginal in winter. Any wasted hot water will make this harder.
Because of this, it is very beneficial to have hot water closer to where we actually want it. This is particularly true in the kitchen where solar heated hot water can regularly be used, if it's convenient (eg. fill the kettle with solar-heated hot water to save electricity).

For this reason, I've put a second, smaller, solar hot water heater on the roof right above the kitchen.It holds 30 L and cost AU$300 on ebay. Internally, this is different from the main heater in that there is no heat exchanger (refer to Figure 2 (b) in this article for a detail of the main solar hot water heater). The difficulty is that the unit can tolerate no more than about 5 psi, so can't be used in a normal fashion (ie. the supply fills and pressurises the tank, and a tap at the point-of-use controls the exit of water).

As far as I can see, there are two options to use this tank (which is not yet connected):
  1. set up a small header-tank, and use this hot water system as gravity fed. This is not ideal because it necessitates a float valve and a tank up on the roof that is higher than the hot water system
  2. use a tap that "pushes" water into the tank, causing its hot water to overflow down a pipe, and that water is what comes out of the faucet. This is not ideal because there will be quite a bit of latency between when one turns off the tap and when the water stops coming out. Also I can imagine that in summer the tap could drip if the tank boiled.
I haven't yet decided which of these arrangements to go for. At the moment I'm focusing on building a chicken house!

This article was written by Angus Wallace, and first appeared at

Water at my house - part 1: rainwater

This post will evolve, but the idea is that is summarises what we've done to manage the water at our place. It will contain links to other relevant posts I've written.


Our house was built in the 1950s, and is typical of houses from that era. It is mostly brick, with a tile roof on the main part of the house and a lean-to at the back with corrogated iron. There are four downpipes on the house, one in each corner. Those on the Northern side of the house drained to the back yard. The downpipe at the South-East corner drained to the street (that has possibly the largest flow of the four), and the pipe at the South-West drained to the neighbour's  front yard!
At the back, our garage had a gutter down the East and West side.

Some considerations for our rain water system:
  • We wanted to catch all the water that fell on our roofs, and not waste any
  • We didn't want big tanks in the front yard
  • We wanted to use the rainwater in the house
  • Where possible, we wanted to avoid pumping the water (gravity feed) (in keeping with low energy, as described in these posts)

Rainwater plan

Below is a schematic for our rainwater system
Figure 1: Schematic (not to scale) of the water systems as installed
We decided to install 5 rainwater tanks. We installed
  • 2 x 15 kL tanks in the NE corner of the block as bulk storage.
  • 1 x 5 kL tank near the pergola
  • 2 x 1 kL tanks at the front of the house
I have performed a detailed analysis (using historical meteorological data) of whether this will be sufficient rainwater storage in this article.

This leaves one downpipe without a tank attached in the NE corner of the house. For now, I've raised the pop (within the gutter), so that the water will preferentially drain to the West (the other downpipe that's being caught by the 5 kL tank) and will only go down the NE downpipe if the rain is exceptionally heavy and the gutter is in danger of overflowing (refer to Figure 2(a) for detail). I plan eventually to run a new gutter around the house-attached pergola on the northern side.
Figure 2: (a) cross-section of a gutter showing the raised pop that will only drain when the gutter is in danger of overflowing. (b) detail of the manner of connection of the main solar hot water system

The five rainwater tanks equilibrate via blue-line poly pipe. The 5 kL and 15 kL tanks are connected by 25 mm blue-line. This is low-pressure, and I've also included a gravity fed tap in the middle of the vegetable patch to allow gravity fed watering. The two 1 kL tanks are connected to the 15 kL tanks via 40 mm blue-line. Because of the front tanks' small capacity and distance to the rear tanks, I wanted to avoid a situation where heavy rain caused them to overflow despite there being storage space at the rear tanks. The larger diameter of the 40 mm blueline allows water to more-quickly move from the front to the back of the house.

The 25 mm blue-line from the 5 kL tank is connected to a Grundfos variable speed pump which supplies the house. To use this, we also installed a valve that allows us to turn off the water supply near the street. To save energy, we run our pump at a lower pressure than the main supply (~25 psi, versus 55 psi for the supply). I think that this makes our plumbing work better (our shower in particular works better at lower pressure).

System advantages

  1. Because the tanks are in equilibrium, and are scattered, we have low-pressure rainwater available around the yard. This is a very simple system, and lets us access water under its own pressure without using a pump. Simple, non-powered systems are cheap and resilient, as described in these posts.
  2. Little/no rainwater is wasted. It would have been possible to create a wet sump system, whereby the stormwater from the front of the house was routed to the tanks at the back underground. This would have allowed us to avoid having tanks in the front yard. The problem with this system is that any water left in the pipe between rains tends to go bad. To avoid this bad water entering the rainwater tanks, this needs to be drained. Apart from being a waste, it is very difficult on our block which is almost flat. Although there is water inside the blue-line pipe, this water is often moving: as we use water in the house, it causes all the tanks to re-equilibrate, which cycles water through the pipe and prevents it going bad. It would not have been possible to adjust our gutters to direct water out the back without extensive modifications.
  3. Because we have tanks (and not just piped water) all around the yard, the pressure we achieve by gravity feed is maximised [1]. This means that we can mostly avoid pumping water in the garden (saving electricity).

System disadvantages

  1. Digging the trenches and installing the pipe was a lot of work and the components were fairly expensive. A wet sump system would be cheaper overall (there would be fewer tanks, for example) though installing the piping would be more labour-intensive.
  2. Some might perceive the 2 x 1 kL tanks in the front yard as being an eyesore. I will write more about aesthetics in another post


Through a wide-gauge pipe, it is quite amazing how much water will flow even at very low pressure. Last summer, I would water the garden through a 25 mm hose with as little as 20 cm of water head (~ 0.2 psi), and found it very effective. It doesn't spray, but a lot of water still comes out if one holds the end of the hose near to the ground. Also, the water rate can be regulated by how high one holds the hose.

If I was building a house from scratch, setting up a similar system would be simpler because I would have all the gutters drain to one or two points.

A sizable expense has been the connectors for the blue-line. If I did this again, I would seek a solution that minimised the number of connectors and provide a significant saving.

[1] When water is moving through a pipe, there is a pressure loss that is related to the speed of the water and the diameter of the pipe. By having a column of water (ie. a tank) right next to  where we want to use it, there is less pipe and thus less pressure loss.

This article was written by Angus Wallace and first appeared at

Thursday, October 30, 2014


I often read articles about the bright future of electric cars. Here are a few.

The economics of electric vehicles

Part of the reason for moving to electric vehicles is the increasing difficulty of sustaining our oil consumption [1].The problem is that to replace the existing vehicle fleet with new electric vehicles will, I think, be prohibitively expensive. Consider that in Australia a petrol car can be bought for less than $1000, whereas the cheapest electric vehicle is more like $45000.

Because of this, I think that in general electric cars will be for rich people only, even in developed countries, and that middle-income and lower people will not own a car at all.

The electric-vehicle you will use will probably be an ebike. Consider this table:

ebikeelectric car
initial cost$500 - $4000$40000 - $100000
range50 km160 km
carrying capacity1 - 3 people4 - 5 people
energy to recharge0.3 - 0.5 kWh10 - 20 kWh
battery replacement cost$500 - $800$15000
top speed30 km/h150 km/h

Clearly, cars and bikes are very different vehicles and there are many things cars can do that bikes can't. This is irrelevant, though, if the cost of the car is out of reach of many people -- as it is. I bet that this won't change either.

Using an ebike

My family's ebike was build from an old mountain bike, and a retrofit kit that I bought from gloworm bicycles [2]. I installed it myself, though mechanically challenged people could get it installed at a bicycle shop, or buy a complete ebike off-the-shelf. This kit was $1500 -- there are much cheaper kits available (starting form about $400) but we wanted a quality kit that would last.

There are a few scenarios when we use the ebike:
  • we're ill, and not up to riding our other pushbikes
  • we're going a long way or up a big hill, and taking the kids or other cargo (say, 30 kg) in the bike trailer 
  • we're coming home last at night, and know we won't feel like cycling
  • just feeling lazy that day
If we didn't have the ebike, these are all scenarios where we would drive instead of cycle, so having the ebike has meant that we drive a lot less.


The performance of the ebike is amazing. Much better than I thought. It has a 200 W motor, which doubles the power of a reasonably fit cyclist. A couple of things I have done with the ebike that I would never have imagined:
  • took the two kids, lots of food/water, bike locks, trailer, etc up a steep 400m climb to go bushwalking (overtaking lycra-clad road-bikers on the way)
  • accelerated myself up to about 30 km/h without pedaling at all
  • Visited the hardware store and bought up, used the trailer to get it home
The power and range of this unit has exceeded my expectations. It has a nominal range of about 50 km, though after three years' heavy use its range is about 1/2 that -- and less if I'm using the motor heavily (ie. the above examples).


If you would like to cycle, but think you lack the fitness, or if you already cycle, but would like to decrease your dependence on your car, an ebike could be a good option.


[1] The capital expenditure of oil majors is soaring, while their production is flat or decreasing
[2] I have no affiliation of any kind with glo-worm bikes -- I'm just a happy customer

Monday, October 27, 2014

Storing renewable energy

Once you are producing renewable energy, there is a strong financial incentive to use as much of it as possible rather than drawing power from the grid. This is for the simple reason that (in Australia) the compensation for exporting power to the grid is as low as 8 c/kWh, whereas it can cost more than 35 c/kWh to draw power from the grid.

The optimal way to use your renewable energy is: use as much of it as possible, and draw as little from the grid as possible.

That's all very well, but the sun only shines in the daytime -- how do you use your home-generated "free" energy at nighttime? The obvious idea is to use batteries: charge them when the sun shines, and use the power later. The problem is that they're too expensive for this to make economic sense (though their price is rapidly decreasing). Is there any way around this? Here are some ideas:

Use a delay timer so that appliances run in the day time, when you are producing energy.

  • Many appliances these days have timers (for example, my washing machine has a "delay" function that let's me delay a cycle's completion by up to 12 hours. I try to always run the machine in the middle of the day.
  • If it's a hot day, and you think you'll be using air-conditioning, then run it during the day to pre-cool the house (this will only work well if your house is well-insulated).
  • It is possible to cook during the day too, even if you're not at home, using a slow cooker, or something similar. Cooking when not there can be a fire hazard, so be careful.

Design your systems so that power consumption occurs during the day, when you are producing

  • There are fridges and freezers that will create and store "coldness" when power is available (eg. these -- I have not used them though). I think it would be similar to do something similar with a conventional fridge/freezer -- this is something I plan to experiment with.
  • If you run pumps, etc, then run them during the day. If you need pressurised water at night, it may be possible to use a header-tank.
  • If you need electricity to heat your hot water, time it to occur during the day.

On weekends, try to perform energy-intensive activities during the day

  • vacuuming the house
  • cooking, especially the oven
Doing some of these will help you to use more of the power that you produce, and will increase the benefit of your renewable energy system. Note that, if you want to go off-grid, tricks like these can allow you to use a smaller off-grid system (which is cheaper!)

this article was written by Angus Wallace, and first appeared at

Monday, October 20, 2014

Consumption as status symbol

In our society, what we own expresses and defines who we are to others. This is common in most societies: although the status symbols may change (feathers or beads in some traditional societies, cars in ours), the presence of status signalling possessions is common. This is probably partly because humans don't have seniority symbols as part of their bodies (eg, silver-back gorillas). That kind of social hierarchy is just as ingrained in us though (we are primates, after all), and I believe that any attempt to ignore or deprecate humans' deep need for hierarchy will lead to societal dysfunction (as new hierarchies are established, generally based on dominance and/or aggression instead of leadership and experience [1]). Because of this, humans will always have need of status symbols -- this cannot be trivialised or ignored -- they are a vital part of what makes us human.

Despite this, there are plenty [2] of relatively affluent people who voluntarily choose to consume less (this is part of the project of this blog) and thus renounce those status symbols. This doesn't make sense -- if status symbols are so important, why are some people renouncing them?

The reason is that there is more than one kind of status symbol.

Not all status symbols involve consumption and material goods.

The British aristocracy [3]

In centuries gone by, the British aristocracy controlled the majority of the wealth in Britain: they owned the land, controlled the trade, owned the weapons and soldiers, dominated the intellectual life. As the British Empire declined, and the welfare state distributed wealth more widely, the traditional aristocracy were greatly impoverished, and lost the majority of their wealth. Many of them still retain their country houses, but they cannot really afford to maintain them. This is why many of them are now (at least partially) open to the public -- the aristocracy need that tourist income. Nowadays, they often wear relatively shabby clothing too. Nonetheless, they are clearly still aristocratic. Consider:

  • They wear tweed, and other clothing symbols that, although shabby, are status symbols
  • They are highly educated, and speak in a distinctive manner that displays they have been to the "right" schools
  • They preserve their family heritage, and demonstrate their "blue blood" wherever possible (eg. coats of arms, customs, etc)
  • They are often fluent/native standard in multiple high-status European languages (eg. French, German)

Thus, they cultivate status symbols that are not based on consumption. Despite this, do not think that you can just talk your way into the British aristocracy -- despite its (sometimes) poverty, this is a very elite club.

Values, knowledge and skills as status symbols

Given that people will always need status symbols, I'd like to encourage an open movement that considers values, knowledge and skills as status symbols and as being "higher status" than mere possessions. What would this look like? Here are a few ideas:

  • Being skilled at a musical instrument would confer status. Here I imagine a Jane Austin society, where the ability to play (eg) piano and sing was highly regarded
  • Being well-read and abreast of international politics and its historical context would be highly regarded
  • Being a skilled cook would be highly regarded (this is more a working class status symbol than aristocratic, but is very important!)
  • Piety could become a status symbol
  • Being athletic would continue to be a status symbol

Problems I can see

I can't think of examples where people (en masse) have voluntarily reduced their material consumption while maintaining status. The British aristocracy were forced, by diminished circumstance, to cut their consumption (perhaps this happened during WW2? Frugality as patriotism?). Still, I think it is plausible that society could "learn to love" non-consumption-based status symbols, given the right leadership.

It will be difficult to reduce the status of the motor car. This is because of the power (size, speed) controlled by a car-driver as compared with someone not in a car. For many motoring enthusiasts a request that they replace their cars with a game of intellectual elitism will be a tough sell. I will think more about how this could be addressed.

(possible) Solution

The only way I can see this working is by appealing, as in WW2, to patriotism. If consumption can be cast as making Australia weaker (a very good case can be made here), then thrift and frugality can be shown to be patriotic. I think this needs to be the approach. Perhaps Martin Luther, the Renaissance thesis-nailer and initiator of the Protestant Reformation (not the American civil-rights leader) could be a good example of someone who made a strong case that material excess represents a weakening and distraction from what is truly important.

Consumption makes Australia weaker -- frugality is patriotic!

This article was written by Angus Wallace, and first appeared at

[1] Refer to almost every political revolution ever
[2] As a proportion of the population they are few, but in absolute numbers there are many
[3] This subject necessarily dredges up ideas of class, elitism, etc. I want to put it on record that I'm not a believer in these things -- I believe in the egalitarian project, in theory. I just can't see it working in practise because of the deep-seated need for hierarchy that humans posses. I think it would be nice if people were less hierarchical, but we need to work with people as we are, rather than try to idealise ourselves into something we're not (an approach I don't think will be successful in reshaping our society).

Sunday, October 19, 2014

Consider the push mower

People spend a lot of energy on their lawn. Whether it's energy to supply the copious water they require, energy for fertilizing, aerating, pesticides or mowing -- lawns use a lot more energy than a comparably-sized native garden.

We have a small lawn at our place. It's about 1/6th the size it was when we moved in and we kept some for the kids to play on. It's probably 20 - 25 square meters. We needed a lawn mower, and since I'm a strong believer in 1950s approaches, I was keen to investigate a push mower.

I was hesitant though: I've never known anyone to use a push mower -- there must be a really good reason why no one uses them. Perhaps they're really hard work? Maybe they don't work well?

Test run of a push mower

Then, one day as I was riding off on my bike, I discovered that our neighbour uses a push mower. I asked him if I could borrow it to try it out and he was very happy to loan it (thanks, Peter!), so I tried it on our back lawn.

It was so easy! It is no harder to push a push mower than a "normal" petrol mower. I think it's because a petrol mower is so much heavier that the advantage of the motor is completely lost.

My push mower

I went and bought one almost immediately. The push mower I bought is a Flymo H40 (new ~$140, I bought second hand for $50) and it uses a scissor-like action to cut the grass, which is very efficient.

Here are some great things about it compared to a petrol mower:
  • Small and light (I can easily pick it up with one hand)
  • Simple
  • Cheap to buy, no maintenance costs
  • Easy to use
  • quiet
  • no fumes, no fuel

Why aren't push mowers the norm

Given this big list of advantages, why are push mowers not ubiquitous? I've been thinking about this since I bought one. This is complete speculation, but here goes:

In the mid 20th century, when push mowers were the norm, internal combustion engines (ICEs, the kinds of motors that burn petrol, diesel, etc) were relatively uncommon. Cars were rare and hence ICEs themselves were rather foreign. As cars started to penetrate the suburbs, ICEs would have been associated with a certain amount of prestige and I suspect it was this perception that drove the uptake of petrol mowers -- they were a status symbol.

Since I've been thinking about this kind of thing more (ie. "where do opportunities exist for us to cause less destruction to the natural systems that support us?") I've come to realise that, oftentimes there are huge opportunities for improvement that exist from doing things in a completely different way (outside common thinking boundaries -- eg. don't just get a more efficient ICE lawn mower -- dispense with the motor altogether!) -- often these are methods that our ancestors discovered, but subsequent generations had abandoned (often for reasons that were questionable at best).

Wednesday, October 15, 2014

If you want to be wealthy

People who want to be wealthy have many attitudes. One very important one is that they are prepared to defer pleasures to build more wealth. In this article, I want to talk about this.

But first, I want to clarify what I mean by wealth. I'm not envisaging some Scrooge character sitting on a pile of gold,  or wealthy plutocrats lighting their cigars with wads of $100 notes. I am thinking about financial independence. The ability to make your own path, and make decisions about the course of your life that aren't controlled by financial considerations. If you are not a believer in wealth, do not write off this article. Hear me out.

Up front cost, long term benefit

If you want to become wealthy, all you need to do is maximise the difference between what you earn and what you spend (where income is greater than expenditure), and invest that difference. Do this for a long time, and you will be wealthy.
Where people struggle is that they want expensive pleasures now, not later. Because of this, their spending creeps up towards (or even exceeds) their income. Thus, they never save money and will never be wealthy. Wealthy people (those who built their wealth) do not do this. They control their spending, keeping it low, while they create capital with their savings -- capital that continues to generate more income for them.

Where to invest?

Investing wisely is critical, and I will not try and advise you. I will suggest, though, that you could consider investing in renewable energy and energy efficiency. These are not investments that yield a dividend in the normal sense, but they will reduce your expenses. In a way, this is better because a reduction in expenses is not taxable. As I've said previously, I estimate the investments I've made at my house to have a ROI of 17.5% -- a rate that may actually increase with time (as the cost of power increases) -- I challenge you to find a similarly-yielding investment with this level of security.


In the same way as a wealthy individual will invest for the future, so too do societies. I would argue that the preservation of environmental capital is prudent for a society that values its future. I hope it's obvious that an individual or society that is spending its capital cannot expect to be wealthy in the future. (I hope that Australians realise this and don't yoke ourselves to fossil fuels.)

Renewable energy

This idea of investing now to generate future wealth is a powerful reason to invest in renewable energy, which has higher upfront costs, but much cheaper lifecycle and whole-system costs. If we, as a society, can increase our investments in this sector, it will help ensure our continued wealth.

Your investment

If you want to be wealthy, I recommend you do not put your money into a flashy car or a new kitchen or bathroom. I recommend you invest in energy efficiency and solar PV. Unlike fancy renovations, energy efficiency and solar PV will give you more money in your pocket, every month, ever after.

This article was written by Angus Wallace, and first appeared at

Tuesday, October 14, 2014

Focus your energy, reap the rewards

There are only so many hours in the day

A common saying. I think it means that we need to focus our energies on the activities that further our goals. We need to recognise that we can't achieve everything and that if we try, we will merely dissipate our energy and achieve little.

This is also true when it comes to energy use. If you want to save power and money (we all have better things to do with our money than waste it) then you need to focus your consumption to achieve the outcomes you want, and avoid using it where it gives little or no benefit.

This article goes part-way to explaining how I have reduced my power consumption to $1/day ($90 consumption per bill).

Heating and cooling

Heating and cooling are probably the biggest users of energy in Australia (even though the climate is fairly benign here). What is the outcome are we trying to achieve with heating and cooling?: Personal comfort. This is fine, but is it really necessary to heat/cool an entire house to achieve this?

Heat/cool just the room

Instead of trying to heat/cool your entire house, why not close some doors, and just focus on the room you occupy. This will save you a large amount of money.

Heat/cool your personal space

This will save you even more, since it is only your immediate environment that you're affecting. For example:
  • Use a pedestal fan to gently move air over you in summer -- the room feels much cooler when there's air movement
  • Put on a jumper in winter
  • We use an electric rug (eg. these) when sitting on the couch or at the computer. They use as much energy as a light bulb, but feel very warm (a typical reverse-cycle air-conditioner might use 3 - 5 kW that's between 60 - 100 times more power than a heated throw)
  • Have a warm or cool drink (depending on the season)
  • If your room is unbearably hot, try evaporative cooling (in hot-dry climates) instead of reverse-cycle -- your wallet will love you. An typical portable evaporative cooler uses 50 - 300 W, less than 1/10th what a reverse-cycle system uses.


Cooking can add a lot of heat to your house. This might be welcome in winter (though it's probably not the best way), but in summer it's a clear negative. Try to cook in ways that release less heat into your house:
  • avoid the oven where possible 
  • use insulated cooking to keep the heat in the food 
    • put lids on pots/pans (and turn the heat down)
    • use the microwave, rice cooker, electric frypan, slow cooker -- insulated where possible, to focus the heat in the food (they're more efficient than a pot on the stove and much more efficient than an oven). Use a haybox cooker to achieve even more
    • Then off the heat early, and cover the food with a couple of tea-towels (beware of fire risk -- take off the stove first) the food can finish cooking with the heat it already contains, and stop heating your house
    • cook outside -- particularly in summer. You might consider a solar cooker and save energy at the same time
  • cook for shorter periods -- a pressure cooker is good here
  • substitute cook methods. For example, I've found that a pasta bake cooks well in the microwave, and then can be quickly browned under the grill. This avoids using the oven: it saves energy and keeps the house cooler.
A lot more information on the relative efficiency of different cooking methods can be found here.

Money savings

The money you save from using less energy can be used to further your other goals. Energy efficiency makes you richer! Right now, many Australians feel under pressure from their power bills. It does not have to be that way. If you are unhappily paying more than $300/quarter -- you are doing it wrong and have huge opportunities to save money.

Sunday, October 12, 2014

Cycling with two kids

I believe that driving cars is very unsustainable, and am a keen cyclist. Generally, where possible, I ride my bicycle in preference to driving a car. I have done many cycle-camping trips, and am comfortable riding with a lot of luggage or a trailer. I've spent a lot of time thinking about the "best" way to cycle with kids.

Options (each has advantages and disadvantages):

Child seat

On an ordinary bike, it is not easy to carry more than one child. I have ridden a 10-speed, steel-framed racer with my four-year-old in a rear seat, and my 1-year-old in a front seat (that attaches to the cross bar) -- riding the bike is fine, but it is very difficult to get on and off the bike. A Ladies'- or mixte- frame, with a seat that mounted on the handle bars would be easier to mount, but heavier to steer. Particularly with front panniers as one needs with a rear-mounted seat.

My solution, which I think works well, was to buy an xtracycle kit, and convert my bike into a long-bike. Then there is room at the back for two seats.
The advantage of this is that there are still only two wheels on the road, and it rides similarly to a normal bike with little extra weight and no extra rolling resistance.
The disadvantage is that weight near the back of the xtracycle (behind the rear hub) tends to unbalance the bike. This can be compensated for by riding without shaking the bike, and I haven't found it to be a problem (my now-two-year-old weighs 15 kg, and I regularly ride with them both on the back plus lots of luggage and it is fine).

More detail of my setup is provided in this article.


This option gets the weight of one's bike at the price of an extra tyre on the road. It makes the bike much longer, and the child can't be too tired. On the plus side, when the tag-a-long is remove the bike is an ordinary bike.
UPDATE: I recently saw a tandem tag-a-long that has one wheel on the road, and carries two kids -- one behind the other. It looked nice, and I think it was by weeride, and was about AU$450. Because the kids are in a line, it's no wider than the bike, and so gets around the width problem of a trailer (below), and only has one extra wheel on the road. Had this option been available previously, I might have done this instead of the xtracycle.


This is perhaps safest for the kids, though its width is often a problem. It also adds lots of weight, rolling resistance and wind resistance -- riding is much heavier work. The advantage is that no modification to the bike is needed and the trailer can be shared between bikes.


On the whole, I feel that the xtracycle is a great option. It rides like a normal bike (unlike, for example, a bakfiets), weighs only marginally more than an ordinary bike, but can carry two kids plus lots of luggage. I've happily ridden 25 kms with my two young kids plus luggage.

I should note that my xtracycle is based-on a recycled bicycle that I bought from the nice guys at the bicycle revolution in Brisbane. It has a Rohloff hub, velocity rims, and some Magura hydraulic rim brakes that I salvaged from an old bike. I love my xtracycle!

This article was written by Angus Wallace, and first appeared on

My xtracycle

In this article I detail how I modified my xtracycle to cheaply carry two children. For the context of my decision to do it this way, please read my other article, cycling with two kids.


This article is for information only. If you decide to proceed with doing this, you take full responsibility for ensuring your arrangement is safe. Think carefully about what would happen if a child-seat detached from your bike with your child in it, and only proceed if you are confident you can install it safely! Off-the-shelf options are available! I accept no responsibility.

This shows the xtracycle, when it had only one seat attached


I bought two second-hand rear bike seats (topeak, I think they were). On their underside, they had two large metal bolts embedded in them, which attached to in-built suspension which attached to the carrier. I sawed off the legs of the seats with a hand saw, and then the bolts with a hacksaw. The seat around these bolts is very strong, so I drilled a hole through the centre of each bolt-stub, and used these to screw the seat through the xtracycle "flight-deck" (the top of its rack) and into the aluminium tubing that holds the flight-deck. I did this because otherwise the flight deck could easily detach from the tubing. I put a few other screws through the flight-deck and into the tubing to make sure it is secure. I put three other bolts through the seat, attached only to the now-firmly-attached flight-deck, and included large washers to spread the strain on the seat.
A detail of the underside of the seat. The legs protruded at the bottom and were sawn off. The two metal circles at the top are the remains of the "captured" bolts, which were sawn off flush with the bottom of the seat and then drilled through so that the seat could be screwed through the "flight deck" and into the aluminium tubing beneath it, anchored through the bolts themselves. Also visible are several holes through the base of the seat. I tried a couple of locations for these, and didn't use the first ones (I can't remember why). They were attached to the flight-deck using bolts and large washers to distribute the force across the seat's plastic so it didn't tear.

The benefit of this system:

  • cheaper (total cost of the two seats: $100, plus a few screws/bolts that I had anyway and will reuse when finished with)
  • the weight is lower to the ground than the off-the-shelf-xtracycle-seats', and so the bike is much better balanced (the off-the-shelf seats are at least 100 mm higher -- this would make a big difference to handling)

My kids on the back of the double-seater (faces smudged to preserve their privacy)

The down side is that the seats can't be easily detached -- they stay on the bike all the time. I have now removed the front seat and put some handlebars for my elder son to hold on (they are attached to my seat post)

On my xtracycle I now have two seats. For rear one has been there for about 18 months (since my youngest son was about 12 months old), and the front has been there for about 3.5 years. I had one nut come off one of the bolts on one seat, but because each seat has 5 bolts/screws it was still safe. I check them regularly to make sure they are safe, and feel that they are stronger, more rigid, better balanced and safer than the off-the-shelf child-seat-and-carrier-combo I use on my steel-frame racer.

Now that he's older, my four-year-old doesn't need a seat any more, and can hold onto the handlebars I've installed for him


It's not just kids that I can carry -- the carrying-capacity of the xtracycle is huge.
I've had 80 kg of wheat in sacks, plus my two-year-old on the back, plus my normal daily luggage (nappies, change of clothes, etc) on it and rode home in the rain. It was very heavy but still stable. Amazing.

I should note that my xtracycle is based-on a recycled bicycle that I bought from the nice guys at the bicycle revolution in Brisbane. It has a Rohloff hub, velocity rims, and some Magura hydraulic rim brakes that I salvaged from an old bike I broke. I love my xtracycle!

This article was written by Angus Wallace, and first appeared on

How much do we use?

One of the things that is hard to communicate to people, in the context of reducing energy or water use, is just how much we use, and just how little we really need to use. Using less has many benefits -- mainly that we save money, and cause less destruction to the natural systems that support us.

I want to convince you that when people talk about reducing consumption, they're not talking about hardship or being a neo-Luddite. They're talking about being a little bit less wasteful and profligate.


A typical Australian household uses more than 25 kWh/day. This is an extraordinary amount of power, and is an average consumption of more than 1 kW continuous. To put it in perspective, it is equivalent to one-and-a-half draught horses working for you -- all the time, day and night, without rest. If people had to do this work, it would take five to eight energy slaves [1], working contstantly, to provide it.

The other thing to appreciate is that, for every 1 kWh of electricity you use in your home, 3 - 10 kWh of energy have been used in mining, processing, transporting, generating, distributing and transmitting that electricity to you. This is another reason to avoid electricity use where possible [2] and use lower grade sources of energy.


This is brought into sharper focus when we consider cars. 1 L of petrol contains about 10 kWh of energy. If you drive 8 - 12 km, you will probably use about 1 L of fuel, which is the equivalent of a draft horse working for about 12 hours. When a moderately fit adult can comfortably cycle that same distance in about 40 minutes, it becomes clear what a waste of energy cars are!


The average Australian household uses more than 300 L of water per day. When you consider that a four-person household would drink about 20 L per day, that is a lot of water! Also reflect that Australia is the driest continent in the world. I think that this kind of water use will not be sustained, because the cost to provide the water will become too great.


When people talk about reducing consumption, they're not talking about hardship or being a neo-Luddite. They're talking about being a little bit less wasteful and profligate.



This article was written by Angus Wallace, and first appeared at

Wednesday, October 8, 2014

Power consumption at my house


We have a normal house, and have not invested greatly in energy efficiency, but we are very careful with our power use. We have spent about $2500 installing a solar hot water heater, and have bought some energy saving LED light bulbs, and are very aware when we use power. All of our appliances are at least reasonable when it comes to power use, and we have installed a small (2 kW) solar PV system (we paid $5000 for a good one, but similar systems are available for $2000). We are now in a situation where we are exporting (selling) about 3x the power we are importing (using), and I expect to have negative power bills (ie. the utility pays us). I have estimated our ROI for this investment to be about 17.5%. We do not have a generous tariff on our solar PV (we get 24 c/kWh when we sell, and are charged 35 c/kWh for what we buy). We buy 100% GreenPower. I think this makes the case that high electricity bills aren't a necessity, and that you have the power to do something about it.

Our power consumption

This is a short post which shows graphs of the power consumption at my house. There is nothing fancy about it -- I just take regular meter readings myself so that I can monitor the system's performance. These graphs should stay up-to-date as I add new data. I show these data so that you can see what is possible in a very normal Australian house. We don't have fancy passive-house design or lots of expensive modifications. We just don't use a lot of power because we're careful. Our house was built in 1955 and is unassuming. We do not use gas at all (well, we have a gas bottle on the BBQ which we use a handful of times each year).

We have a standard grid-tied solar PV system. This means that any power it produces, that we are not using then-and-there, is exported to the grid. The amount of power exported is measured. If we are using power (eg. electricity in the house) while the system is producing, then only the excess power is exported (ie. the difference between what's generated at the panels and what we consume). If our consumption exceeds what we're generating, then we're importing power.

The first graph shows daily consumption (get power from grid, red) and solar PV export (send power to grid, green). I don't take a meter reading every day, so where I don't take a reading the graph shows an average since the previous meter reading. Notice the sharp change at the beginning of September where the electric storage hot water system was switched off. This reduced our daily power consumption by about two thirds (from to 3 kWh/day). Note that I live in Australia -- winter is from June to August!

The second graph shows our cumulative consumption and solar PV export. Seasonal variation in exported solar PV production is very evident (green line, from May to August). The production decrease in winter looks worse than it actually is because this shows not the generated power, but the exported power (which has our instantaneous use subtracted from it, which is higher in winter). Also note that the angle of power consumption changes at the beginning of September, when the electric storage hot water system was switched off. Our 2 kW solar PV system is mounted flat on a tiled roof. I don't know the exact angle, but it would be less than about 30 degrees, which is sub-optimal for winter production (because of the angle of the sun in winter, they would produce more power if they were at a steeper angle -- 60 degrees in Adelaide). They do and are unshaded all day.

This article was written by Angus Wallace and first appeared on

Tuesday, October 7, 2014

What does "sustainable" mean?

Sustainable is a word we often hear. What does it mean?

Maybe when you hear the word "sustainable" you think about hippies, solar panels, or Priuses. I want to convince you that none of these, or any other value-judgements, are part of it.

Merriam-Webster defines sustainable as "able to last or continue for a long time".

Simply put , if an action (something we do) is sustainable, then we will be able to keep doing it indefinitely. If an action is not sustainable, then we will not be able to keep doing it.


An example that is easy to understand is budgeting money:

"Annual income twenty pounds, annual expenditure nineteen six, result happiness. Annual income twenty pounds, annual expenditure twenty pound ought and six, result misery."
Charles Dickens, "David Copperfield"

In other words, it is not sustainable to spend more than we earn. If we try, we will probably be ok for a while (as we draw down our savings, sell things, etc), but eventually our actions will catch up with us and our spending will be reduced (by forces beyond our control). Also, think about the likely suffering that will occur in this process: as we owe money to our friends (debt), get evicted from our house, etc.

This seems so simple: spend less than you earn. How is it that so many people get into deep financial trouble by breaking this simple rule?

The reason is that life is complex. It is not always obvious that we are in the process of spending our capital to prop up an unsustainable lifestyle, or accumulating debts that can't be repaid. When it does become clear, people can feel that they are committed to that lifestyle and cannot reduce their spending. This is how people can end up with nothing*.


A very similar process can be observed with fishing. If we wanted to summarize the history of fishing, it would go something like:

  • Find a new fish to catch (eg. North-West Atlantic Cod)
  • Fish it until the fishery collapses and the fish can no longer be caught (not quite to extinction, perhaps, but until the system is destroyed)
  • Find a new fish to catch
  • Repeat

It's clearly against the everyone's interests for this to happen, but it has happened time and time again: unsustainable fishing has destroyed people's livelihoods. It wasn't always apparent that the industry was unsustainable and when it became apparent, people felt they had no choice but to continue. I should emphasise that the consequence of unsustainable fishing can be very similar to the consequences of unsustainable spending: poverty in the communities in which they occur.

It can also happen that the point of no return occurs before people notice. Also, even when there is a regulatory body charged with preventing overfishing, it is still very easy for damage to occur.

Environmental Sustainability

Hopefully these two examples show that this is a general principle that can be applied broadly. It certainly applies in general to our relationship with the environment in which we live. Things that we do that are unsustainable will not be sustained. I'm not saying we oughtn't or mustn't continue to do it. I'm saying we won't continue to do it, and that events beyond our control will stop us from doing it -- in the same way as a bankrupt, debt-ridden person will not maintain their high-spending lifestyle, no matter how hard they try.


* this is clearly an extremely simple sketch of a very complex thing, but I think it covers it in broad strokes.

This article was written by Angus Wallace, and first appeared on

Monday, October 6, 2014

Detail: a solar hot water system

Solar hot water is such a good idea that it amazes me that there are houses in Australia without it!
A solar hot water system (HWS) is so cheap and easy that it can be built DIY as my friends Roman and Jana Spur have done in Brisbane (I don't think they've documented theirs, so I've included a link to another).
Solar hot water encapsulates some of the good things I've discussed in recent posts, such as:
  • It is extremely simple, and is thus cheap, robust, repairable, low-energy
  • It uses the sun's energy directly, without any conversions, and so is using low-grade energy that would otherwise be wasted. This energy that is falling on your roof anyway, and using it liberates high-grade energy for high-grade applications (eg. computers). It also shades the roof, and so helps keep the house cooler in summer.
Despite this, paying to have a solar hot water system installed in Australia costs a lot of money -- typically it is nearly $5000. In days gone by, most solar HWSs had a tank on the roof, coupled directly to the solar collector, through which the water flows by thermosiphon -- there is no pump required. These days, installers are less keen to install tanks on roofs because of the weight, so the tank typically sits on the ground and the water circulates with a pump. I view the pump as just another thing to break (and use power), and was not keen to get such a system. It's also possible to just install a larger solar PV system, and use that extra electricity to heat the water, but I didn't want to do that because it would be using high-grade energy (electricity) to produce heat, which is wasteful.

This article goes part-way to explaining how I have reduced my power consumption to $1/day.

After a bit of searching, I became aware of some Chinese designed and built systems that are available in Australia for around $1000 (depending on size). For some, it's possible to add collectors to a standard electric storage unit, but I decided to buy an integrated system, which is shown in the photo.

The solar hot water system, installed on my roof and plumbed in. This system cost me ~$1300, not including installation costs.

This system is differs from typical Australian systems in a few ways:


The biggest difference, is that the tank is at atmospheric pressure (not mains pressure). The water is just sitting there, and the evacuated tubes are filled with water. Thus, the sun's heat directly heats the water, which sits in the tank. The small header tank you can see on top contains a float valve which de-pressurises the supply and ensures that the tank is always full. This has some advantages -- as water heats, it expands (some systems are known to dump all their water when it boils on sunny days). Because this system is open (note the upside-down U copper pipe at the top -- that's a vent), it can just vent steam if it boils. A downside of this I can see is that if I ever need to replace an evacuated tube, I'll have to drain the tank first.

Heat exchanger

So, if the system is low pressure, how do I use the water?
Separate to the supply to keep the tank topped up via the header tank, is a pressurised supply that passes through a heat exchanger within the tank. The cold enters, goes through a 30m copper coil within the tank, and by the time it comes out it has been heated by the hot water in the tank. The water in the tank acts as a heat reservoir -- that water never comes out the tap. The water that comes out the tap is instantaneously heated by the heat exchanger. A big benefit of this is that the hot water has no taste, since it hasn't been sitting in a hot tank, so I often use it to fill the kettle so it boils more quickly and uses less power.

The installation

This wasn't very easy, largely because I wanted the system to be on the steepest angle practicable. This is because in Adelaide, the optimal angle for a solar HWS is determined by the angle of the sun on the shortest day of the year. In Adelaide, this means a collector at 60° from horizontal (very steep!), so I had to "jack-up" the angle of the tank. I didn't get it as steep as 60° -- it's more like 45°, but trigonometry (performance = cos(15)) tells me that this should be about 96% performance at the winter solstice (vs a 60° tank). I made a big deal of getting this detail right, because I want to avoid using electric boosting as much as possible. The collectors face due North, which is also very important, and in winter it won't be shaded between 10am and 5pm.
I installed a heavy aluminium post horizontally on the roof to bear the weight. There is a wall directly beneath it, so the weight passes straight through the roof, through the rafters, and is borne by the wall. I've also put some tensioned wires to increase the strength of the frame when it is windy.


The system does not, to my knowledge, qualify for any rebates of this kind.

Total cost

I think the total cost, including getting it plumbed in, was about $2500 (about 1/2 the cost of a typical installation). This doesn't include the time I spent messing around. I estimate it's saving us about 6 kWh/day (that's what our old electric storage unit was using), which equates to about $2.10/day power saved [3]. This has a naive payback of 3.2 years at current power prices.


It works well. It was installed on September 21 (equinox), and has been boiling regularly since then. I will put shadecloth over the collectors in summer to reduce water wastage..

Future plans

I have a second smaller tank mounted on the roof nearer to the kitchen (to reduce the amount of hot water wasted in the pipes) that will be plumbed in soon. I will talk about this more in a future post.

[3] Our electric storage was not connected to off-peak power, which would have been much cheaper to run and would have made the economics less favourable

This article was written by Angus Wallace and first appeared at

Friday, October 3, 2014

Principle: lighter, simpler, less work

This post is part of a series on the principles of energy reduction.

Simple systems, that do less, and cause fewer changes from their natural state, use less energy.


This is another argument against motor cars. Cars are
  • large and heavy: compare the weight of the car with the typical weight of their occupants and cargo,
  • complicated: these days, cars are not really serviceable or fixable -- replacement parts are ordered from the manufacturer and the original is thrown away
Similarly, air-conditioning is so expensive because it is artificially maintaining a space at a temperature different from its environment, which requires a lot of work.

Another way of expressing this idea is that human-built systems should work with, instead of against, natural systems as much as possible.

This post was written by Angus Wallace, and first appeared on

Principle: use the lowest form of energy possible

This post is part of a series on the principles of energy reduction.

Some kinds of energy are harder to get/make than others. High-grade energy, such as electricity and petrol, are very hard to produce and thus have great effects on the natural systems that support us. Thus, it's beneficial to use low-grade energy where possible, and avoid high-grade energy.

An approximate heirarchy is, from lowest (on the left) to highest (on the right) grade:
Heat << Fuel << Movement << Electricity
This means that it takes a lot of heat energy to make movement energy [1], and a lot of movement energy to make electricity (ie. a lot of energy is wasted at each stage. Generally speaking, a lot of heat energy has been use to make the electricity we have in our homes. If we then use that electricity to produce heat, we have wasted a lot of energy.

How to optimise this

We can use heat energy to heat. An excellent example of this is solar hot water which uses heat from the sun to directly heat water (a process that otherwise uses considerable amounts of fuel or electricity). Similarly, heat from the sun can be used to heat our houses (using either passive-solar [2] or active solar space heaters [3]) -- this saves a lot of fuel and/or energy. Solar heat can also be used directly for cooking via a solar oven [4].

A more subtle point is that if you have solar-heated hot water, and want a cup of tea, put solar hot water in the kettle and boil that.

[1] For example, the internal combustion engine in our car uses fuel to create movement. It does this at about 25% efficiency [5]. This means that it takes for units of fuel energy to produce one unit of movement energy.

This post was written by Angus Wallace, and first appeared on

Principle: avoid using energy where possible

This post is part of a series on the principles of energy reduction.

Energy* that is not used is the best saving. Whether the energy is renewable or not, whether it is efficiently-used or not, if you can avoid using it then you have just taken the most effective action to reduce your impact on the natural systems that support us. Thus, working out what energy doesn't need to be used at all is very important.

Heating and cooling

Space heating and cooling of dwellings uses a lot of energy. Think carefully about whether you need to perform this action, and if so how much. If you must, then minimise how much energy you use by maintaining the smallest temperature difference between inside and outside your dwelling (the greater the difference in temperature, the more energy is used). In practice, this means allowing your house to stay cool in winter and hot in summer. You can wear more clothes in winter, and fans in summer.


Cars use an extraordinary amount of energy. Any reduction in driving has a huge effect on your energy consumption. Many journeys are less than a few kilometers -- consider walking or cycling for these shorter trips.


Boil only the amount of water you need, since any surplus is wasted.


Of course, everything that we buy requires energy for manufacture, packaging, distribution, marketing, etc. Thus, part of reducing energy use is a reduction in consumption. The energy used in the creation of stuff is called embodied energy.

* clearly, using the sun's heat for heating still means using energy. Here, I refer to human generated energy (eg. electricity, petrol, etc)

This post was written by Angus Wallace, and first appeared on

Reduce energy consumption principles

In this post, I discussed the importance of using less energy. I have skimmed over what is an enormous subject. The motivations are something I would like to discuss more, but here I will say merely that if you believe in action on climate change, the only current effective action is to use less. Humans are in the process of destroying the natural systems that sustain us. 75% of our wealth is estimated to be provided, for free, by natural systems -- if we destroy those systems we will be (at best) impoverished.

Every proposed political mechanism is a means to use market forces (or other economic coercion) to encourage people to use less. We can use less right now! Not only will you save money, you can get a great return on investment and prepare yourself for a future where we use less energy -- a future that is well on its way to becoming reality.

In subsequent posts, I will detail some principles of using less energy.

This sequence of posts will then inform (and provide a reference point for) a series of posts detailing some of the design choices I have made at my house.

This post was written by Angus Wallace, and first appeared on

Bike to work day

Cycling organisations like bikeSA often promote initiatives like bike to work day. I think this is a good way of encouraging people to view cycling as a means of transport instead of just something fun to do.

I think that bikeSA should also consider running a drive to work day -- where everyone who would normally cycle, drives instead (with the consequent traffic chaos). Perhaps this would help motorists to appreciate the service that cyclists are providing and discredit the idea that cyclists are freeloading.

This post was written by Angus Wallace, and first appeared on

Wednesday, October 1, 2014

I want to go back to the 1950s

About a decade ago, I read an essay that made the thought-experiment: "what if we decided to live with a 1950s standard-of-living, but with modern medicine?" and concluded that this could be achieved with  two days' work per week. I can't find the essay now (will keep looking), but I think it's a great thought. Let's think a little about life in the 1950s (in Australia, anyway -- this was not the case in other countries):
  • One income could house and sustain a family
  • Cars were rarer
  • People generally ate fresh, home-cooked food
  • Community was very important
  • Most people grew at least some of their own food
  • Public transport and cycling was common
  • Lives were simpler and less hectic
  • Our per-capita footprint on the environment was much lower (we weren't destroying our ecological support-systems so quickly)
  • Electricity consumption was much lower, fuel consumption was much lower
  • Most food was organically grown
  • Market gardens and small-holder farms surrounded cities and provided much of the food
  • People ate less meat and fish
  • People owned less stuff, and produced less waste
  • Australia had a manufacturing base, because people were prepared to pay a living wage to people who made things
I could go on.

The point, though, is that in the 1950s the average Australian lived a simple life like that advocated by many environmentalists in response to the current crises that are plaguing our society.

I think that, in many respects, we have regressed from the 50s. Yes, we currently live a much more sophisticated (and more consumptive/wasteful) lifestyle than people did then but I suggest that this will not be sustained. I think that if we keep over-reaching in this way we will end up greatly impoverished and will not even be able to sustain a lifestyle of the 1890s let alone the 1950s. If, however, we can control our consumption now, a 1950s lifestyle could be sustainable.

Why is this so rarely discussed?

I think a big reason this is not mentioned is because of the social issues prevalent in the 1950s. Yes, the 50s were relatively sexist, classist, racist and bigoted. I am in no way advocating a return to those values. But, I think we can maintain modern egalitarian* values with 1950s levels of consumption in a sustainable way.
I think another reason is that we are so obsessed with the idea of Progress, and that we are somehow better than people back then.

My vision

My goal and vision is to live, essentially, with consumption levels of people in the 1950s. I am yet to renounce many modern luxuries (eg. I have a hand-me-down mobile phone, and an old computer with broadband -- and myriad others, of course -- this is an experiment and work-in-progress!). My family owns a car, but I want to act (as much as possible) as though the car is not there. As part of this, I want to embrace the 50s aesthetic. This is not novel (the retro/vintage movement is in, ahem, full swing), but forms a component.

My challenge

Lots of people like to talk about "traditional values" -- I challenge you to embrace the traditional values of thrift, low-consumption, lack-of-pretension and simple living.

The post "I want to go back to the 1950s" was written by Angus Wallace and first appeared at

* an interesting note is that Australian society was actually more egalitarian in the 1950s than today. Today the difference between the wealthy and the poor in Australia is much greater. Like in so many areas, we are better at talking about egalitarian values today -- in the 1950s, people just got on.
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