How green is my household?

Spring 2007 power bill

Hi, Bruce here, I've been comparing our power bills for spring 2007 and 2006, and found that in both years, our electricity use dropped by 15%, as did our bill. So, we're continuing the decline in household energy use. However, it isn't quite a fair comparison, because we didn't start our first carbon neutral year until part way through spring 2006. By last summer we were working hard to reduce our energy use, so it will be interesting to see if we can make further reductions this summer. I suspect we might, but only by a few percentage points, certainly not by another 15%.

As the spring bill is the last for the calendar year, I've now got all the figures for 2007, so have created a graph comparing our annual electricity use and cost for the past five years:

Click on image to enlarge

You can clearly see the effect of installing a solar hot water system in April 2004. Overall, we reduced our electricity use by 60% between 2003 and 2007, with daily use going from 25.7 kWh in 2003 to 10.8 in 2007.

The costs are harder to analyse because, since 2005, we've paid a premium to be on 100% green power; also, electricity prices have risen. Despite this, our annual bill has dropped by more than 30%, saving us about $400.

Climate scientists have warned that the world needs to reduce greenhouse gas emissions by at least 60% of 1990 levels by 2050. As far as stationary energy use is concerned, one house has already achieved that goal, and it only took 5 years, not 60!

Electricity bill - winter

Hi, Bruce here again. Our power bill for winter, the biggest of the four seasons, arrived this week. At first glance it seemed disappointing because our daily consumption, at 14.71 units/day, had hardly dropped from last winter. However, I realised that last year we spent four weeks in the UK for Hilary’s dad’s 80th birthday, whereas this year, only Hilary and Becky did the annual family visit.

I continued weekly monitoring the electricity use during the four weeks on my own, and used 237 kWh of electricity over that time. About 2 kWh per day is needed for the fridge, fish tank, etc, even if the house is vacant, so the use that could be attributed to my activities came to about 181 kWh. For a fair comparison between the two winters, I simply subtracted that figure from this year’s account, and ended up with a daily usage of 12.7 kWh, a reduction of 14.0% compared with last year. This is consistent with savings over the previous three accounts of 15%, 15% and 14%.

Cutting back on power use has not been hard. It’s mainly about eliminating waste; for example by turning off standby lights, using long-life bulbs and, of course, having a solar hot water system. The fact that we don’t have energy hungry items such as dishwashers, air-conditioners, clothes dryer or a plasma TV, helps to keep our power usage low.

It will be interesting to see what additional efficiencies we can introduce for our second carbon-neutral year.

Micromanaging our electricity use

Hi, it’s Bruce here with news on our autumn electricity bill. This is the season when daylight saving stops, plunging us into darkness earlier at night. Also, the weather starts to cool, which means using the electric off-peak booster for our solar hot water system. We don’t rush to turn that on, waiting instead for cold shower complaints before flicking the switch, and if the weather warms up, we flick it off again. But eventually we leave the system on as cool becomes cold, as a result, our electricity consumption increases.

According to the bill, our electricity use for the 100-day autumn period was 1180 kWh (11.80/day), 14% less than the same period last year, and nearly 10% cheaper, which was pleasing. Given that the spring and summer quarters were both 15% down on the previous year, we are being remarkably consistent in terms of proportional reduction of our electricity use.

I was away for nearly 8 weeks during autumn, which would have lessened our electricity use, but as I was away for about 5 weeks the previous autumn, it probably didn’t contribute greatly to the reduction in use between the two periods.

As well as checking out our quarterly bills, I have been recording our electricity use on a weekly basis. This week, I decided to do daily measures at 8 am, to see if I could detect changes in use related to the previous day’s activities.

The results were intriguing. For example, we dined out on Friday night before going to see Becky perform in ‘Pig’, the school play — highly recommended! — so, no cooking dinner and little use of lights, and we used only 7 kWh for the day. Not so the next day, Saturday, with all of us home most of the day, and lots of cooking — including making several jars of green tomato relish from the tomatoes we salvaged after the first good frost —this pushed our energy use up to 18 kWh for the day, confirming our suspicions that we need to look at improving the efficiency of our stove, oven and microwave, all electric unfortunately.

Electricity bill

Hi, Bruce here — we have just received our electricity account for the summer months and the news is good. Our usage for the 3 months dropped from 846 to 636 kWh, a decline of 16.5% compared with the same period last year. Daily usage rate was 7.27 kWh, down from 8.71 kWh last year. This reduction is consistent with the spring account (see blog Electricity 24/01/07), where our usage dropped by about 15%.

The other good news is that the bill was 17% less than last year’s, in part due to lower usage, but also due (I think) to a new agreement we have with our supplier, Country Energy. In fact, the bill is the lowest we’ve had since the summer of 1998, so it will be interesting to see if this trend continues in future accounts.

I monitored usage on a daily basis a couple of weeks ago. It was fairly consistent Monday to Friday at around 6.5 to 7.0 kWh daily (I work from home), but jumped on weekends with more people, cooking, laundry and other things happening.

As we don’t have air-conditioning, clothes dryer or working dishwasher, our most energy hungry activity seems to be cooking, which we do a lot of, rather than buying processed foods or takeaways. Making vegetables soups and muffins, cooking quiches and turning home-bred chooks into casseroles uses more energy than if we bought these things, but at least we know where our food is coming from — the organic backyard!

Electricity bill

Hi, Bruce again – I don’t usually get excited when the electricity bill arrives but that’s just one of the side benefits of trying to be C neutral. The account covers most of the period since we began, so it’ll be interesting to see whether our efficiency measures – installing long life globes, turning off standby lights, having no more lights on than the number of people in the house, thinking about how to save energy when cooking (such as using the solar cooker!) and so on – have reduced our power usage compared with last year.

As I record our electricity use on a weekly basis, I have an idea of how much we are using, but the account will confirm this.

The news is good. Our usage has dropped from 1094 to 931 kWh for the quarter, a decrease of 163 kWh, or nearly 15%. On a daily basis, our usage for the 89 day period has declined from 12.29 to 10.46 kWh per day.

So, a 15% drop in consumption, means a 15% drop in the bill right?

Wrong!

The bill dropped, I kid you not, by a miniscule $1.99, less than 1%!

Why?

Because over the intervening 12 months, the cost of power rose by nearly 8%, so the price hikes offset our efficiency gains. However, the main game is reducing power, and greenhouse emissions, so we were still happy with it.

The next quarter – the summer months of January to March – is our lowest use period due to daylight saving, not needing heating and not using air-conditioning. Canberra had its 3^rd hottest day (40.5ºC) a couple of weeks ago but our well insulated house was quite comfortable.

We are continuing to explore options for cutting back on power use. Even the fish weren’t spared, with a 50% reduction in their fluoro lighting - Wanda wasn’t happy.

More electricity

Hi, it’s Bruce again with more electricity use statistics.

Before installing the solar hot water system in April 2004 (assisted by a Federal Government rebate of about $1000), our daily electricity usage was 25.5 kWh per day. Over the following 12 months, it dropped to 12.5 kWh per day. This decline was due entirely to the solar unit, as we did not change any other aspects of our electricity use.

Since starting our attempt to become carbon neutral we have installed low-energy, long-life globes in most rooms (except where the light fittings are not suitable for those types of globe), and will continue to install them where possible.

We now turn off the TV, computers, CD player, etc at the power point, so standby lights are not on when the units are not in use. With room lights, we decided the number on should not exceed the number of people in the house, and we turn the light (and TV, etc) off when leaving a room. So, in theory, when we sit down for dinner at night, the only lights on are in the dining room. This sometimes results in a quick dash to the end of the house to turn off a forgotten light! ‘Switching on to switching off’, is not as easy as it sounds!

December is a low electricity usage month for us. Daylight saving reduces the lighting needed; it’s warm enough not to need heating, and not so hot that we need to have the fans on. We don’t have air conditioning.

I’ve been monitoring electricity usage over the past 6 weeks and we are now averaging 8 kWh per day. The fridge, fish tank, clock radios and a couple of microwave lights that we can’t switch off represent a base usage of about 2 kWh per day, which means we are using about 6 kWh discretionary power daily.

So, we have come down from 25.5 kWh in April 2004 to 8 kWh now, and while we will continue to look at ways to reduce this further, it’s probably time to move on to look at other emission areas such as our vehicle usage.

Electricity

We are an all electric, 3.2-person household. We do not have an air conditioner, clothes dryer or dish washer (apart from me!), and during winter the house is heated with wood from our own plantation. As we live in a rural area we have two electric water pumps.

In April 2004, we installed a solar hot water service. It’s been fantastic. Our electricity use dropped by 51%, and our hot water bill plummeted from $311 to $63 per annum, despite an 8% price rise. We figure the unit will pay for itself in about 9 years – less if the cost of electricity rises again.

According to our accounts, over the past 12 months we used 4847 kWh of electricity, or just over 13 kWh per day.  We use more in winter due to the shorter days, the need to boost our solar hot water system and the occasional use of a fan heater.

There’s a swag of emission calculators online but it’s important to use Australian ones as overseas calculators (eg from the US or UK) may use data from energy sources other than coal, hence give different results.

According to three Australian calculators, our use of 4847 kWh of electricity generated 4.1 tonnes of CO2, (www.greenfleet.com), 4.8 tonnes (www.carbonneutral.com.au) and 5.1 tonnes (www.elementree.com), giving an average of 4.7 tonnes.

The NSW Dept of Energy, Utilities and Sustainability advises that for every kWh of electricity used, 1.012kg of CO2 emissions are produced. On that basis, the 4847 kWh we used produced 4.9 tonnes, roughly the average of the three calculators.

However all this is academic ― in our case at least ― because if you subscribe to 100% green power – as we do – then your greenhouse emissions from electricity are zero (as two of the above web sites point out)! This is not strictly true, because there must be some energy expended in producing and distributing green energy, but zero is the figure they give. As our green power premium costs less than 20 cents per day, it’s an inexpensive way to reduce our personal greenhouse emissions.

Also, by using green power we are helping to create a demand for the product. As more households sign up for this option, the power supplier will be required to invest in more enviro-friendly sources of power, thus reducing the burning of greenhouse-gas producing coal in power stations.