Carbon Conservation & Energy Efficiency


Bruce Rowse & Team

Archive for December, 2008

Skylights slash our need for artificial lighting.

Monday, December 8th, 2008

Last weekend six solar tube skylights were installed in our office, which occupies the top floor of a two storey building. The skylights have eliminated the need for artificial lighting in thirteen of our work spaces.

It was amazing watching the reaction of staff as they came in this morning, many couldn’t contain their excitement. “Its so much brighter.” “The quality of light is fantastic.” “We don’t need the lights on at all.”

The cost installed was $5,550. Our landlord agreed to pay half of the costs. As we were pretty frugal with our lighting to start with, and it was already efficient, the lighting energy cost savings won’t be large, in the order of $500 a year. We may have to run the air conditioner more in summer because of the heat gain from the skylights, but this may also cut heating energy use in winter. Assuming it balances out the payback for us as tenants will probably be around 5 to 6 years in terms of energy savings. However daylight also makes the workplace more attractive, and may improve productivity. So there will be other benefits in addition to the cost savings. And of course the greenhouse gas savings will reduce the amount of green-power we need to purchase. If we were buying black power the skylights would be expected to save us around 2.5 tonnes of greenhouse gas a year.

How a school can save $300 and 1.2 tonnes of CO2 this summer holidays

Friday, December 5th, 2008

Schools waste a great deal of energy over the summer school holidays.

In 2005 CarbonetiX worked with the Victorian Department of Education and Training to produce a School Energy Shut Down Guide and then promoted its use to schools around Victoria, just before the summer holidays. When we followed up in February 2006, over forty schools sent their bills to us for analysis. How much had been saved? And the results were surprising, even to us.

Over the 6 week summer holiday period we calculated that improved switch off practices resulted in schools saving an average of $429 each!

Based on this experience I estimate that on average most Australian schools have the opportunity to save around $300 and 1.3 tonnes of greenhouse gas simply be getting better at turning things off before the summer holidays. This correlates to potential savings Australia wide of $2.8 million and 12,400 tonnes of greenhouse gas – equivalent to the annual emissions of 2,900 cars!

To make it easy for schools to realize these savings we have developed the online School Summer Energy Shut Down Blitz. It’s a simple, fast way to quickly come up with an action plan for your school, and shows you what you need to shut down before the holidays start. And it costs nothing to use.

You can access the blitz at

High mains voltage is causing 15 millions of tonnes of un-necessary greenhouse gas pollution

Tuesday, December 2nd, 2008

In Australia electricity codes stipulate that the supply voltage of mains electricity should be 230 volts (phase to neutral).

For example in Victoria the Essential Services Commission has mandated in the Electricity Supply Code that the voltage of supply should be 230 volts plus 10%, minus 6%. Distribution businesses supplying electricity err on the high side.

Hazelwood power station produces 15 million tonnes of greenhouse pollution annually.

Lowering mains voltages could save the same amount of greenhouse gas as that produced by Hazelwood power station annually

Voltage measurements and voltage logging undertake across multiple sites by CarbonetiX show however that phase to neutral voltages are typically in the range of 240 to 250 volts. In fact we regularly see cases where the maximum voltage exceeds the maximum permissible 253 volts.


With the exception of three phase synchronous motors (eg motor typically used to power equipment such as pumps, fans, chillers, industrial machinery etc), the lower the voltage the lower the power consumption. If you remember your high school physics, you’ll know that for a resistive load Power = Volts x Current, and based on Ohms law Volts = Current x Resistance. Put the two togehter and for a resistive load (eg a halogen light bulb) power consumption is proportional to the square of voltage. So a 10% drop in voltage leads to a 19% energy saving! For single phase inductive loads such as fluorescent lighting there is also a power saving when the voltage drops.

The supply of voltage at well over the 230 volt standard means that electricity consumption, and thus greenhouse gas emissions in most buildings across Australia is higher than it would be were the voltage to be kept closer to the 230 volt standard.

I estimate that across the country a 5% electricity and greenhouse gas saving could be achieved if voltages were generally kept in the 225 to 235 volt range rather than the 240 to 250 volt range we typically see. This would translate into a greenhouse gas saving in the order of 15 million tonnes. To put this in context, that’s equivalent to the annual greenhouse gas emissions of Australia’s most climate unfriendly power station – Hazelwood – pictured above.

Distribution businesses may be supplying voltage on the high side to enable them to cope with periods of high demand, when the voltage drops in the distribution network are higher (eg on a hot summer afternoon). However these periods of high demand typically only account for around 50 to 100 of the 8760 hours in a year.

Some organisations are now installing their own voltage reduction devices to compensate for the overly high mains voltage supplied and to thus achieve cost and greenhouse gas savings.

Whilst perhaps politically challenging, there would be much greater benefit to the environment and to consumers if standards were established that kept supply voltages lower and closer to the 230 volt standard.

For example the standard could be ammended to stipulate:

  • For 90% of the year the voltage shall be kept at 230 volts plus 4% minus 6%.
  • For 10% of the year the voltage shall be allowed to vary between 230 volts plus 10% minus 6%.

Regulation such as this would allow distribution businesses sufficient buffer to take precautionary measures when they think demand may spike (eg based on the weather forecast) whilst still saving significant amounts of greenhouse gas.

I would encourage any organisation keen to see Australia reduce its greenhouse gas emissions take up this important issue of voltage standards with the relevant government organisations. And lets hope that as emissions trading comes in this is recognised as an opportunity for electricity generators and distribution businesses to collaborate together for significant greenhouse gas savings.

Computers Off Australia

Monday, December 1st, 2008

Computers Off Australia is a not-for-profit organisation and Green IT labelling initiative designed to educate and recognise organisations that are doing their part to reduce their carbon footprint through the implementation of power management and virtualisation technology.

We all agree that computers are a great invention, and can be used to unlock all sorts of social, economic and environmental benefits – including reducing the carbon impact of our modern lifestyle.

But when they’re left idling for hours on end, they’re contributing to the greenhouse gas problem. For most of us, its an easy way to reduce the carbon impact of our computers by a third, a half or even more.

Go to to find out more