Archive for the ‘carbon conservation’ Category

What is a comfortable office temperature (2)

Wednesday, December 10th, 2008

A comfortable office temperature doesn’t depend just on the temperature, there are other factors that come into play. These include the relative humidity, the temperature of surrounding surfaces and the speed of any air movements.

Craig Ryan of Johnson Controls has prompted this second posting with some good observations about humidity and comfort on my first posting on a comfortable office temperature.

The more humid it is, the higher the temperature feels. This is shown in the thermal comfort chart below.

thermal comfort diagram - humidity vs temperature

thermal comfort diagram - humidity vs temperature

In climates which are always hot, or climates that are mostly cold, our bodies acclimatise somewhat to these conditions. The chart above is most appropriate for cooler rather than hot climates.

Moving air makes it feel colder. When its hot creating air movement (eg through fans) can mean that air conditioning systems can be set to provide higher temperatures than would otherwise be the case.

Radiant temperatures of nearby surfaces also make us feel warmer or colder. Because of this sitting next to a large window in winter may still feel cold even though the inside air temperature is 22 degrees Celcius.

By operating heating and cooling systems out to the limits of what is perceived to be a comfortable temperature significant energy and greenhouse gas savings can be achieved. Attention also needs to be paid to air movement and surface radiant temperatures.

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.

“The emperor is only wearing speedos!” – the folly of not urgently pursuing the obvious first step to slow global warming

Wednesday, November 26th, 2008

In the Hans Christian Anderson fairytale an emperor is proudly dressed in clothes that supposedly only the wise can see until a boy shouts out “the emperor has no clothes”.

When it comes to the climate change response the seemingly obvious first step, to a large extent, is being obscured. The first step being simply using less energy. The emperor isn’t totally naked – he might have underwear on – but to a large extent energy conservation – or using less energy - isn’t being pursued with the vigour it should be. And in a world in economic crisis – where saving energy saves money -  its crazy to be focussing the climate change debate on how much we need to spend rather than how much we can save.

There is common consensus that to slow climate change, to avoid run-away global warming, to provide a stable climate for future generations that we need to urgently reduce carbon emissions now. Some very experienced, respected and prominent climate change scientists, such as James Hansen, are saying that we actually need to go beyond reducing carbon emissions, we need to actually remove carbon from the air, as atmospheric greenhouse gas concentrations are already far too high.

The obvious starting point to solving the climate change challenge is using less energy, and thus producing less carbon.

  • Obvious because using less energy results in money being saved, not spent.
  • Obvious because the money saved can then be invested in cleaner power sources.
  • Obvious because in the current economic climate we all want to cut expenses.

Using less energy is clearly a win – win. It reduces carbon emissions. It saves money. To put it bluntly it’s a no-brainer.

Substituting fossil fuel power sources with clean energy sources comes next on the list. But this doesn’t give the financial return of energy conservation, as renewable power is still more expensive than black power.

Along with the switch from fossil fuel to renewable energy sources comes sequestration – removing carbon out of the atmosphere. This however costs money too.

So in order to minimise the cost of response to climate change the obvious strategy, to me anyway, is to reduce energy consumption, thus saving some money, then use the savings to purchase green power and fund carbon offsets. And becoming carbon positive, so that the net impact is extraction of carbon from the atmosphere. And to do this as fast as possible. Wouldn’t you agree?

Now the exciting thing is that if pursued vigorously, with focus, the savings from energy conservation – or energy efficiency, will more than cover the cost of green-power and the carbon offsets needed. So even becoming carbon positive can be a win-win.

An example is our office. We have a strong culture of energy conservation. Our energy consumption is around 1/3rd of the consumption of other offices the same size. This saving pays for 100% green power, carbon offsets, and some additional carbon sequestration over and beyond offsetting our organisation’s travel related emissions. We are saving money, and are climate positive. How good is that?!

Unfortunately however the climate change debate is largely centred around costs. The very real threat of dangerous climate change is compared with the cost of responding to it. A lose-lose scenario comes through strongly. Do nothing and planetary climate stability is at risk. Do something to avoid dangerous climate change and the economic system as we know it is at risk.

But this attitude is very dangerous because it causes paralysis. Why do anything if you will only lose no matter what you do?

However for many organisations, the savings from an aggressive carbon conservation approach will pay for the cost of becoming carbon neutral or even carbon positive. I am not saying that in all cases that carbon neutrality can be achieved at no cost, but based on my experience with thousands of buildings, if a choice is made to aggressively conserve carbon in many cases climate neutrality can be achieved and money left on the table.

In fact the carbon inefficiencies in most organisations are so gross – wasteful buildings, fat car fleets, very poor use of carbon saving communication technologies – that I believe the developed world could become carbon neutral at no net cost – if carbon conservation is passionately pursued. (And we build renewable generation fast enough and have the capacity to sequester any remaining emissions).

Finally, even if becoming carbon neutral or climate positive does come at a cost, is this cost going to destroy your organisation? For the vast majority of businesses the cost of energy is around 1 % of total operating revenue. Even if energy costs doubled in order to achieve carbon neutrality would that force the company into bankruptcy? I doubt it.

Significant carbon conservation requires cultural changes in attitudes to energy, no doubt about it. But with a positive approach to the challenge of climate change, and passionate carbon conservation, we might just create a world with a stable climate that is cleaner, greener and wealthier.