Energy efficient behaviour pays

Summary

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.

Background

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

Conclusion

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.

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[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 guesstimatedapproximations.blogspot.com.au

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 guesstimatedapproximations.blogspot.com.au

Reducing electricity consumption to affect political change

Many people are concerned about the negative effects that humans are having on the Earth's ecosystems, and with good reason: those systems support us, and without them we would not survive. It is estimated that for every dollar of GDP produced, the natural world contributes .75c -- these are services that nature provides for free and, without which, our quality of life would drop by 75%.

A big cause of human destruction of natural systems is in the provision and delivery of energy. The main culprits are fossil fuels which are starting to alter the world's climate -- a change that, if unchecked, will wreak great destruction on both the natural and human systems that support us. There are now technologies (solar PV and wind turbines) that can produce energy with much  less damage to the environment, and it is imperative that we transition to these as soon as possible. Unfortunately, there are entrenched interests that are heavily committed to fossil fuels and use their influence to slow the adoption of newer, less harmful, methods of energy production.
What is clear is that majority political support for serious action on climate change is currently lacking.

There are huge forces at work here. In the absence of a government with the ability and disposition for serious action, what can an individual do to help this process?

Number one: Use Less

When it comes to reducing one's impact on the systems that support us, there is simply no substitute for using less. Even "green" energy sources have impacts (albeit much more minor). Using less frees money and resources that can be better deployed by helping other, less fortunate, people adapt.

Number two: Avoid electricity or fuel where possible

Electricity is hard to produce, and there are always wastes and damage to the environment -- even when using solar PV or wind turbines. This is because the manufacture, installation and maintenance of these generally result in carbon emissions and other forms of pollution.
Therefore, if a task can be performed without using electricity at all, it is preferable to do so. A great example of this is hot water, which can be heated directly from the sun without need for electricity at all. By doing this, your electricity consumption will be much lower.
Similarly, a solar cooker can cook food without fuel or electricity, using only heat directly from the sun. These are simple and cheap to build.

Number three: buy carbon-emission-free ("green") power, and/or install solar panels

Here is where your large reductions in consumption will help -- because you're now using a lot less power, you will not need many solar panels to offset your electricity consumption (cheaper!).
At my house, we have reduced our power consumption to about 3 kWh/day for a family of four without significant lifestyle sacrifices. I think it can go lower still. We have a 2 kW solar PV system, which produces an average of about 6 - 8 kWh/day (averaged over the year) -- more power than we consume. We do draw power from the grid though, as we do use power at night (when the PV panels aren't producing), which is why we also buy carbon-emission-free power. By doing this, we ensure that we're not directly supporting the use of coal for electricity generation and because our power consumption is so low, the additional cost is very small. This also supports the businesses that are producing renewable carbon-free energy in Australia.

Dirty companies only have as much money as we give them

Using less means less revenue for the large energy generation, distribution and retail companies that, generally, are slowing the adoption of renewable energy technologies, and affecting public policy in negative ways. Make no mistake -- the combined actions of individuals is very powerful. The uptake of domestic solar PV has already had a huge effect on the energy generators and retailers in Australia.
This is because solar PV is usually producing power at precisely the times that energy is most expensive (energy retailers pay a fluctuating ("spot-") price for electricity,  and the times when the spot price is highest are the most profitable for the generators. Domestic solar PV is taking the edge from this demand, which is having a significant affect on the profitability of some of the big dirty producers. These kinds of commercial disincentives work to the advantage of renewable energy technologies.

If Australians continue to reduce their consumption and simultaneously install distributed generation (like solar panels, solar hot water, etc) and buy carbon-emission-free power, this will help to encourage the necessary changes. This will have a concrete effect on Australia's carbon emissions and reduce the likelihood of catastrophic climate change.

Remember, a carbon tax only has benefits because it causes people to use less -- we as concerned citizens can use less all by ourselves.

This post was written by Angus Wallace and first appeared at guesstimatedapproximations.blogspot.com.au

Energy efficiency at home

I am running a half-day workshop this coming Saturday at Northey Street City Farm on how to save energy at home. It covers

• how to estimate how much power devices are using
• how to find the best places to invest in energy efficiency at your place
• how to use the garden to reduce cooling costs
• some technical understanding of electricity and its supply
• how to examine behaviours seeking simple changes to save energy and money
• how to cook to reduce energy use

Here is a link to the manual I have developed. I will refine this in the future and keep this site up-to-date. It is covered by a CC license (details in the pdf). Any comments or suggestions are welcome and will be considered for incorporation.

This post was written by Angus Wallace and first appeared at guesstimatedapproximations.blogspot.com.au