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Week Seven - Winter Heating

Average Canberra household = 310 to 643 kilograms CO2e per person per year

· Weekly experiments

Me

- If you're cold, put on a jumper.

My preschooler

- Princess Ponies don't wear jumpers! Turn up the heater.

The rule in Canberra is that you don't turn on your heater until after Anzac Day. My daughter thinks this means thousands of soldiers sacrificed their lives so she can play dress-ups in comfort.

Down south, most of us heat our houses from April until October. That's a lot of carbon dioxide and equivalent emissions (CO2e). While a hothouse climate might fix winter for good, I'd prefer to cut carbon before we get there.

How much CO2e?

The climate change wars often focus on energy use, because it accounts for a big chunk of our collective CO2e. It's also easy to cut back without hardship.

The average three person household in the ACT generates around 6 tonnes of CO2e from electricity and another 2.7 tonnes from gas each year. Around 3 to 5 tonnes of that is in winter - a whopping 4 to 7.5% for the household's entire carbon footprint for the year.

Not all of that CO2e and energy is used to heat the house. We also cook, have hot showers, watch TV and enjoy all of the other power-hungry pursuits of modern life. Subtracting spring usage from winter usage gives a crude estimate of how much power is used for heating. It's not perfect, because in Canberra and elsewhere, many people still use heaters during spring, particularly when there's a cold snap. But on this estimate, the average three person household generates around 600 kilograms of CO2e from natural gas and another 400 kilograms OR 1.4 tonnes of CO2e from electricity. The difference between the low estimate and the high one is from underfloor heating. Warm tiles might feel nice, but they'll double or triple your winter electricity use.

My three person household differs from these averages. We generate just over 1 tonne of CO2e for natural gas and around 800 kilograms CO2e for electricity to heat the house in winter. That's a good chunk for me to reduce. The numbers are artificially high on this estimate as our spring usage is so low. Basically, we turn our heaters off early in the season, which means that when I subtract our spring usage from our winter usage, I don't get much of a discount. But I'll stick to this data set and method throughout the project for consistency.

What are the options for winter heating?

CHOICE gives a good overview of home heating options. There's electricity, gas, wood-burning, ethanol and hydronic heating. Retrofits can help efficiency and installing good insulation is particularly important.

Those who are building or choosing a home have many other choices. They can consider the thermal mass of their building material, with a higher thermal mass retaining more heat in winter and more coolness in summer. They can orient their house so that the kitchen and living areas face north. They can also set up passive heating and cooling systems.

Concrete, brick and stone textures

In Canberra, you want a house with high thermal mass built from brick or stone, but you often get an
asthma-inducing ex-Government shack that's so cold, the air mists when you breathe.

 

Those of us who aren't house-hunting can still make improvements. I'm not planning on moving my family for the sake of this project, so we'll stick with what we have. My house has natural gas central heating and an electric space heater for the kid's room. My family has refused to overwinter by sewing themselves into their underwear and huddling up with the chickens and dogs, so we've agreed to try the following experiments instead.

Week One - Drop the temperature.

Apparently, each degree you add to the thermostat adds up to 10% to the energy you use. I'll drop our heat as low as I can go without mutiny and measure what happens. We have good snow gear so I'm not expecting hypothermia. Princess Pony will have to wear a beanie over her crown.

Week Two - Efficiency retrofits

Ideally, I'd shift our house brick-by-brick to maximise passive solar heating, then replace the lot with eco-friendly rammed earth. But instead, I'll test out the best and cheapest retrofits and use past data to show what happened when we installed insulation. I'll also try to decide if double glazing is worth it and test out some low-cost amateur options.

Week Three - Energy choices

By week three, my house should be using the least energy needed to stay comfortable. But what type of energy is best for the planet? Natural gas or wood? Grid, off-peak or solar? I'll run the numbers and see.

If you're interested in gauging your household energy use and seeing how you track on the averages, look at your past power bills or note down the readings on your gas and electricity meters outside. You can then compare your home electricity use with averages on Energy Made Easy. If you're way higher than the norm, it's time to rethink your indoor temperatures and make some other retrofits.

Spreadsheet calculations, data sources and references in 'Notes' section, Week Seven.

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