Carbon Conservation & Energy Efficiency


Bruce Rowse & Team

Archive for November, 2009

Why believe that climate change is caused by human activity?

Friday, November 27th, 2009

I generally like to focus the bulk of my articles in this blog on stories about that which is “climate positive” – by that I mean people, organisations, technologies that are cutting greenhouse gas emissions and providing an economic return.

However I am astounded at the number of people who are skeptical about climate change and their strident denial that humans have anything to do with it. There are now hundreds of millions or perhaps billions of people now around the world who reckon their opinion on climate change is right. But lets go to the real experts, scientists whose job it is to research and study the climate.

The most recent poll of these scientists that I am aware of was undertaken in 2009 by researchers from the University of Chicago. 10,257 earth scientists were polled, 3,146 replied to the poll. Of these 79 listed climate science as their specialisation and had published more than 50% of their recent peer reviewed papers on the subject of climate change.

So we have 79 climate experts answering this poll. Apparently only 77 responsed to the question that asked if human activity was significant in changing mean global temperatures. And 75 replied that yes, they believed human activity was responsible for the increase in global mean temperatures.

So, who do you believe? The vast majority of climate scientists, or the other experts such as:

  • Newspaper columnists passionately skeptical
  • Politicians apoplectically skeptical, based on the letters their constituents have written to them.
  • Your dyed in the wool neighbour?
  • The old salt telling a journalist that sea level rise is rubbish?

Still convinced your local politician or favourite columnist- you know, the one with the pHD in climateology (sic) is right?

Consider then major international scientific bodies. Below is a list of some of the organisations that support the assertion that “most of the warming observed over the last 50 years is attributable to human activities” or have made statements along these lines.

  • Intergovernmental Panel on Climate Change (IPCC)
  • US Global Change Research Program
  • Arctic Council
  • International Arctic Science Committee
  • European Academy of Sciences and Arts
  • InterAcadamy Society
  • International Council of Academics of Engineering and Technological Sciences
  • National Science Academies from around the world, including the US, China, India, Germany, the UK, Australia, etc.
  • Network of African Science Academies
  • Royal Society of New Zealand
  • Polish Academy of Sciences
  • National Research Council (US)

In fact as I write this there no scientific body of national or international repute known to reject the assertion that humans have caused climate change.

Learn more about this and where I got my information from at

I’m no climate expert. I’ve read a bit, but no, I haven’t put satellites up or deployed ocean bouys up to monitor sea level rise, I haven’t been to the Arctic, I haven’t seen the snow line change at Kilamanjaro. I don’t have the knowledge or instrumentation or tools to come to any conclusion about greenhouse gases and the greenhouse effect. And the chances are that neither do you, dear reader.

So I have to rely on the people who do. Those highly educated and trained people, steeped in the scientific method, who dedicate themselves to the study of climate. And my choice, the only reasonable choice in my opinion, is to believe what the majority of these scientists are saying. And not what a politician, columnist or crusty old salt twice my age may say.

Our culture is one which respects the lone maverick and generally respects age. But, given the stakes if the maverick and “seen it all” elderly are wrong, I’d prefer to believe the majority of those conservative people, climate scientists. I reckon thats a pretty good reason to believe that humans have caused climate change and that we should be doing something about it.

“Dry” evaporative cooler saves energy and eliminates the need for refrigerant based cooling

Monday, November 2nd, 2009

At the recent All Energy expo in Melbourne (early October) I came across the Coolerado cooler, distributed in Australia by Clear Solar. This is an ingenious, simple air cooler based on a combination of evaporative cooling and plate heat exchangers to deliver cooler air than is possible with conventional evaporative cooling but without the use of a refrigerant. It therefore has the energy efficiency of evaporative cooling, but with the performance of refrigerative cooling in dryer climates.

For a detailed explanation of how it works visit the Coolerado website. Below is a quick technical summary using the psychometric chart. You may prefer the Coolerado website if you don’t understand the properties of air at different moisture levels as displayed in the psychometric chart.

The unit splits air into two streams, either side of a plate heat exchanger. Moisture is added to one stream – the working stream. Its temperature drops using the evaporative process. This then sensibly cools the air on the other dry side of the plate, the process stream. Some of the process air is then split off and made into more working air. Moisture is added to this too. This then cools further, and through the plate heat exchanger it then further sensibly cools the process stream. By doing this multiple times the resultant process air exits at near the dew point temperature of the air. And around half of the total air going through the system ends up as useful process air. 

Psychometric chart showing how the Coolerado cools air

Psychometric chart showing how the Coolerado cools air. Click on chart to enlarge it.

The chart above shows the principal of operation marked on it assuming the process stream is split up 3 times and perfect evaporative cooling (ie to the wet bulb temperature). In the Coolarado 13 stages are used to get air down to near dry bulb temperature.

As you can see in the my chart below – for 35 degree air at 20% humidity (at sea level) with a conventional evaporative cooler we can get the temperature down to near the wet bulb temperature of 19 degrees, but at 100% relative humidity. With the Coolerado we can get the temperature close to the dew point of 9 degrees, or if we are only cooling to 19 degrees do so with a relative humidity of around 55%, which is perfectly comfortable.

A variable speed fan in the unit controls the air flow and thus the exit temperature and relative humidity of the air it supplies.

For hot dry climates the Coolarado can completely substitute conventional refrigerative air conditioning. And in more humid climates it extends the usefulness of evaporative cooling.

The Coolarado website also has a chart based on historical weather data for hundreds of sites world wide, showing its applicability, including several Australian cities. Or, if you know your local weather and can use a psychometric chart, its possible to figure out its suitability. In Australia for example the Coolarado is well suited for use in Adelaide.

I’m not sure of the maintenance regime for the heat transfer plates and cooling pads – presumably similar to those of a conventional evaporative cooler, and obviously the system whilst saving energy does use water.

In addition to the energy savings another advantage of the Coolarado is it doesn’t have any refrigerants in it, so you don’t need to worry about the global warming potential of any leaked refrigerant. And the only moving part is its fan, which is a high efficiency direct drive unit, reducing mechanical maintenance requirements. 

Innovations such as this are going to help enable a low carbon economy, and as prices drop will start drive it.

LED lighting update

Monday, November 2nd, 2009

In October 2008 we started an independent evaluation of LED lights as a substitute for fluorescent lighting. The evaluation was undertaken in partnership with the Sustainability Fund, managed by Sustainability Victoria, and with the support of Frankston City Council. We chose to focus on fluorescent lighting because this is by far the most common form of lighting used in commercial buildings.

The trial has involved firstly a desk-top evaluation of LED products, then selection of lamps from those six manufacturers who appeared to have the best products. These were then tested by CarbonetiX for light output and power consumption. The best performing lamp was then sent to a NATA certified laboratory for photometric testing.

The useful light provided by the best lamp in a standard office fluorescent fitting was similar to that of a used halo-phosphor fluoro tube – a surprising result as earlier testing we had undertaken indicated the LEDs were just not bright enough to be used as a fluorescent substitute.”

We then replaced 176 fluorescent tubes with the lamp that had performed best in our testing  in the Mahogany Neighbourhood Community Centre in the City of Frankston.  Users of the facility were surveyed before and after the upgrade and noted either no change or an improvement in the lighting. An illumination assessment showed that illumination levels after the upgrade were around the same as before. Yet power consumption has dropped from over 40 watts per lamp down to 18 watts.

In October we undertook another check up of the lamps, eight months after they were installed. Illumination levels were similar to when they were installed, and none of the LED lights had failed.  Eight months of operation is not nearly long enough to establish whether or not the lamps will operate for 50,000 hours or not as claimed by the manufacturer. But it is a good start.

LEDs as a fluorescent substitute are still expensive, with roughly a ten year return on investment in an office environment. But this trial indicates that if the technology continues to evolve and prices drop that LEDs could help halve the use the energy used by lighting in commercial buildings.

In June the US Department of Energy launched the $10 million “L Prize” for the development of a 21st century lamp that produces more than 150 lumens per watt (current lighting technology is around 100 lumens per watt).  It also challenged the industry to develop a 10 watt LED replacement for the 60 watt incandescent light bulb. Philips have already submitted an entry in the 10 watt incandescent replacement.

With stimulation like this LED technology can only improve.

Not withstanding this good news, a strong word of caution for the here and now is necessary. After our testing we had a lot of LEDs from a number of manufacturers lying around our office. So of course we took out our fluoro tubes and put them in. All of these LED tubes, from five different manufacturers, have now failed. My advice would be for anyone contemplating the use of LEDs – firstly make sure you are happy with the level of illumination provided, then secondly ask the supplier to provide a minimum 3 year or 15,000 hour guarantee, with lumen depreciation (loss of light output) to be no more than 10% over the 15,000 hours.