Living on 1kWh a day
From Mvca
Living on 1 kilowatt a day
A small 1 kilowatt solar PV system of only 6 panels provides an average of 4 kilowatt-hours a day.
A bit small for most! But it's a challenge. Could anyone live on that? The household can have:
.............................................................................................................Per year
An efficient new fridge.......................................................................405 kWh
A new dishwasher used on economy, every second day...................130 kWh
A 4-5-star top-loader washing machine (1/2the washes are cold).......170 kWh
Ten 11-Watt compact fluorescent globes x 4 hours a day..................161 kWh
A medium LCD TV, on 4 hours a day..................................................230 kWh
Vacuum cleaner 1800w x 52 hours a year............................................94 kWh
Laptop:18w, 4 hours a day, 200 days a year.........................................22 kWh
A 70w ceiling fan or standing fan, 4 hours every day in summer.........26 kWh
-200kWhs are left for a microwave, iron, electric fan on the gas heater,
perhaps an electric pump for solar hot water,
electric clocks, radios and music........................................................200kWh
Total...................................................................................................1440kWh a year
As you can see, it’s very tight but possible, especially for a single person or couple, to live on 1440 kilowatt hours (kWh) of electricity a year or 4 kWh a day, averaged over the year. This assumes they have gas or solar hot water and gas heating, as many Victorians do. In practice, the average Victorian home uses about 15.7kWhs a day, but many energy-conscious people use less.
How much solar energy would you need?
You would need a 4kW grid-connect system (about 22 panels) to provide 16kWhs a day on average. At time of writing (early 2011) this would cost about $14,000, but a 2kW system, supplying half the average Victorian home's electricity would cost less than $5000 (both after deducting solar credits). Obviously then, the first line of attack is to cut back electricity use as much as possible.
Beware of…Old appliances
– these can use a lot more electricity than newer ones.
E.g. A small old fridge....700kWh a year,
an old dishwasher (used daily) 350kWh,
a washing machine.......... 700kWh a year…
One pensioner was given an old electric heater: she accepted it gratefully, without questioning its electricity usage. Her consumption surged to 21kWh a day! She changed to compact fluorescent globes and an efficient new heater and reduced it to 7kWh a day. Don’t give inefficient appliances to the poor – give them to the recycling depot.
Electric hot water instead of gas or solar
An electric-boosted solar hot water system produces more greenhouse emissions than a gas hot water service (with no solar panels). Why? Victoria’s brown coal-powered electricity produces approximately four times more greenhouse emissions than natural gas, for the same heat output (depending on the efficiency of the equipment). The electric booster on a solar hot water system is the culprit.
Replacing an electric hot water service with gas-boosted solar can save up to 6 tonnes of greenhouse gas a year. If you have an electric hot water service running on cheap off-peak electricity, the dollar cost may be quite low, but it is still creating about 7.5 tonnes of greenhouse gas a year. But gas is non-renewable and could run out in a few decades. The MVCA convenor Richard Keech has come up with a solar hot water system boosted with a heat pump.
If you already have gas hot water, changing to gas-boosted solar saves only half a tonne of CO2 a year. Compare solar electricity: 1kW of solar electricity saves 1.9 tonnes of CO2 a year, assuming the solar electricity replaces coal-fired power. A now normal-sized 2kW system of 12 panels would save nearly 4 tonnes. There is a belief that the first thing every home should do is to install solar hot water: look at the detail of what's best for you. Solar power may save more money, and greenhouse gas.
Alternatively use 100% GreenPower.
The philosophical debate continues as to whether it's best to buy GreenPower or go solar in your own home. The argument has lost some of its bitterness since 1/1/2011, when the market for solar credits was separated from the market for large scale generator credits. This was done to prevent solar credits "flooding the market' and reducing support for large wind-power etc. There are 3 options:
1. Save as much power as possible by conservation
2. Produce your own solar electricity and/or solar hot water or
3. Buy Greenpower. General consensus is to do all three things if possible.
Beware Halogen down-lights
These are “low voltage” - not low Wattage! One halogen light is generally 50 Watts, as much as an old incandescent globe. Twenty halogen lights use 1000W (1kW – the output of a whole 6-panel solar system). They emit heat, increasing air-conditioning costs, the hole in the insulation lets out heat in winter, and they cause house fires. A solution is to ask your electrician to put a normal hanging light back in the room. Or, the 50W halogen globes can be exchanged for 20W IRC globes. These are halogen globes coated with infra-red reflective coating to concentrate the heat inwards, making them more efficient. This will save 60% of the power bill. There is less fire risk with IRC (coated) globes as they don’t emit as much heat. LED lights are a good but more expensive alternative.
Front loader washing machines that heat water with electricity.
Front loader washing machines use less water than top loaders, but may heat up their own water with electricity, even if you have a solar or gas hot water system. Ensure the front loader has two inlet pipes, (one for hot, one for cold) and attach the hot to your gas/solar hot water system. Or use the front loader on cold wash with Cold Power washing powder or liquid.
Dishwashers
- also heat up their own hot water. If you have an electric hot water service, connect the intake pipe to cold water, or all your rinse water will be too hot. There is a belief that dishwashers create less greenhouse gas than hand washing. Not necessarily true, especially if you hand wash in water heated by solar or gas power. Check the star label and energy usage of the dishwasher.
Desk-top computers
A desk-top computer can use 70W of electricity. A laptop uses 18W.
Wide screen TVs
Ultra big ones guzzle power, especially earlier plasma TVs (LED TVs are not so bad).
Ducted air conditioning and heating – electrically-heated outdoor spa pools – swimming pool pumps…
Small bar fridges and drink coolers
can be wildly inefficient. Check the energy star labels when you have ducted heating or cooling installed. People tend not to notice stars when the unit is in the ceiling or under the floor. The supplier may give you a 1-star unit. Ask if you can close down the ducts to rooms which are not in use before buying. Avoid bar fridges.
Air-conditioning
A 550 Watt air conditioner in just one room, used for 8 hours a day all summer uses 400kWh (depending on the temperature selected). Ducted air-conditioning for a whole house uses a lot more. A heat pump to the air (or geo-exchange heat pump under the ground) can bring in 3 to 5 times as much energy as it takes to run it but these are not cheap. Consider roof fans, cool roofing etc.
Tips for saving energy and greenhouse gas
- Kitchen: electric jug for one cup of tea - just cover the element. Do not fill it up more than necessary.
- Put a lid on cooking pots. Keep the flames below the pot, not licking up the sides.
- Rinse cereal bowls in cold water to remove cereal before it hardens. The bowls will dry in the drainer. Use the dishwasher every 2 or 3 days, not every day.
- Bathroom: hang towels up to dry, don’t leave them scrunched up on the floor. They will not need washing as often.
- Showers were only introduced about 50 years ago. Previously, people bathed occasionally but usually just washed with a flannel each morning, then washed the flannel. Daily showers feel great, but they aren’t essential for hygiene.
- Laundry: preferably wash in cold water. Soak greasy items in a bucket of hot water with detergent first, rather than filling the whole machine with hot water.
- Iron once a week, not daily. Don’t heat up the iron just for one shirt.
- Lighting: A 100 watt incandescent globe (on all the time) uses 876 kWh a year, more than half the output of a 1kW solar power system. Don’t forget to change over all the incandescent lights, even outdoor lights.
- Insulate well, and stick weather stripping (from a hardware store) under doors, around windows, anywhere a draft gets in.
- Curtains should touch the floor, to prevent warm air circulating up to the glass in winter and getting cold.
- Use external blinds (cheaply available from Bunnings or Spotlight, or get some made) on the north and west-facing side of your house to keep the heat out.
- Cool roofing paint is one way to keep the house cool without turning on air conditioning. Astec and Insultec are two good Australian brands (see separate section).
- Avoid electric heaters, cookers and hot water services unless they run on 100% GreenPower.
- Beware GreenPower based on hydro power. This is renewable, but hydro dams emit a lot of methane and nitrous oxide from rotting vegetation: both potent greenhouse gases. Choose GreenPower that is based on solar, wind power, geothermal/wave power, bagasse or landfill gas, not hydro.
- Barbara Hutton 20.1.2011 version
