Archive for the ‘carbon conservation’ Category

Voltage reduction could save 15 million tonnes of greenhouse gas – part 2

Monday, July 13th, 2009

A few months ago I wrote a blog posting about how tighter regulation of electricity supply voltages could save Australia 15 million tonnes of greenhouse gas a year.

However a comment on that posting suggested that voltage reduction may not result in any useful savings.

Below I report on the results of an experiment we undertook to identify how much power can be saved, if any, by operating equipment at a lower voltage.

We measured a variety of single phase loads at different voltages. A variable transformer was used to vary the voltage. A German made Power Tech plus plug in power meter was used to measure voltage, current, power and power factor at the different loads. Loads experimented with included typical single phase lights, computer equipment and a fan.

experimental set up to measure power draw at different voltages of a range of single phase loads

experimental set up to measure power draw at different voltages of a range of single phase loads

The experimental set up is shown above. Below is a graph showing the results of the testing.

graph of power draw vs voltage for a variety of single phase loads

graph of power draw vs voltage for a variety of single phase loads

This graph clearly shows that for common lighting loads power consumption decreases with decreased voltage

  • Incandescent lamp (resistive load)
  • T8 fluorescent (inductive load)
  • T5 fluorescent (electronic ballast)

The reduction in power consumption with the T5 fluorescent (with an electronic ballast) was unexpected.

The fan, with a single phase (shaded pole?) motor, also used less power with lower voltage, interestingly the power factor improved as voltage was lowered, with the power factor the highest at 220 volts.

The PC computer and monitor both showed lowest power consumption at 230 and 240 volts, but power consumption generally did not decrease with voltage. Power factor improved a little at lower voltages.

This experiment shows that for a variety of loads power consumption is in fact less at lower voltage.

For heating or cooling loads equipment may need to run longer when at lowered voltage to reduce the same amount of heating or cooling, with no net energy savings.

Three phase synchronous motors are unlikely to use any more or less power (a theoretical assertion, we don’t have the equipment to test), having the motors run at 230 volts rather than 240 or 250 volts however is unlikely to cause motor damage due to excess current as the voltage difference is only small.

But with lighting and many single phase motors power consumption drops with lowered voltage.

My back of the envelope calculations still come up with a saving of around 15 million tonnes of greenhouse gas if voltages were closer to the 230 volt standard rather than being at 240 to 250 volts.

If high voltage drops in distribution were a problem additional network infrastructure could be used to deliver a more consistent voltage across the network. 2009 is the year of the “smart grid.” A smart grid could mean multitap transformers that can be changed on the fly to deliver a more consistent 230 volts across the whole electrical network.

Its nice to consulted on voluntary carbon abatement

Thursday, June 25th, 2009

Yesterday I attended the public consultation in Melbourne about accounting for and measuring voluntary greenhouse gas savings. The consultation was run by the Offsets Policy Team from the Department of Climate Change.  

It was good to be consulted and heard, and made me feel a little less disenfranchised by the CPRS.

Four or five years ago I attended a number of state government consultations on climate change. There was always strong disagreement and a lack of consensus. Yesterdays workshop was doubly satisfying for not only feeling that my opinions were being heard, but to also see that pretty well everyone else who attended was expressing the same view point. Many individuals and small businesses want to make a contribution to reducing greenhouse gas emissions. And we want our contribution to be a real, recognizable contribution that actually reduces carbon emissions and is additional to that which would be achieved by the CPRS.

It was reassuring to be able to ask questions like “what is the definition of a small business under the CPRS” and learn that this same question had been asked in similar workshops around the country.

Hopefully the workshops will help the government make changes such that voluntary carbon ababement by businesses and organisations not liable under the CPRS is recognised. In a way that the business doesn’t have to “pay twice” to get their carbon abatement recognised. And that withdraws the carbon voluntarily saved from the CPRS.

Have your say on whether voluntary energy savings are recognised under the CPRS

Thursday, June 11th, 2009

Starting today, public workshops are being held by the government to get public opionion and advice about how voluntary climate change action can be taken into account when setting emission caps for the Carbon Pollution Reduction Scheme (CPRS).

Workshops are being held on the following dates:
11 June 2009 9:00 am - 12:00 pm
Rydges Hotel Perth Corner Hay & King Street, Perth
12 June 2009 9:00 am - 12:00 pm
Mercure Grosvenor Hotel 125 North Terrace, Adelaide
30 June 2009 9:00 am - 12:00 pm
Chifley at Lennons 66 Queen Street Mall, Brisbane
16 June 2009 9:00 am - 12:00 pm
Wesley Conference Centre 220 Pitt Street, Sydney
24 June 2009 9:00 am - 12:00 pm
Rydges on Swanston 701 Swanston Street Carlton, Melbourne

To attend register your interest at:

Voluntary action isn’t recognised under the proposed CPRS unless you pay to have the carbon retired into the Carbon Trust. In other words you pay twice - you pay to actually cut your carbon emissions (eg upgrading your office lighting by installing reflectors. Then, if you want the carbon you’ve saved to be “retired” so it can’t be traded by one of the large companies participating in the CPRS you have to pay again to lock it up in the Carbon Trust.

This is a tremendous disincentive for voluntary action. So have your say at these workshops.

Energy saving opportunities in dynamic office spaces

Monday, May 18th, 2009

During energy audits, our team often finds situations where walls or partitions have been moved or an extension has been added to a building and the electrical and mechanical services have not been considered. This leads to reduced occupancy comfort and energy wastage. The major energy saving opportunities lie in the duct design and the lighting layout. The following case study examines the opportunities brought about by re-examining duct design.

(part 1) HVAC opportunities

The following diagrams show a case study of an existing duct layout where an extension has been added on the west facing windows of the office. Measuring the flow rates of the packaged units servicing the area alerted us to the fact that air velocities were excessive and fresh air rates were greater than 10 litres per second per person.

Figure 1 – Mechanical service duct layout with measured diffuser air velocities

What is the affect of high air velocities and what energy saving options does this present?

High air velocities cause wind chill. Wind chill is a convection process which increases the transfer of heat from surfaces such as skin and clothes.

Figure 2 – Wind chill cartoon from

In figure 1, occupants were complaining of feeling cold even though the temperature in the area was measured at a comfortable 23 degrees Celsius.

Rule of thumb

At 25 degrees C, an air speed of 1m/sec will be felt by the body as 2 degrees cooler.

If air velocities are too high there may exist an opportunity to slow the air handling fan down. This can be done via the installation of a Variable speed drive (VSD) or in belt driven fans, by changing the pulley size. Both of these methods result in fan energy savings.

Note: care must be taken not to reduce the air speed excessively in refrigerant systems as this could lead to malfunction or excessive wear and tear on the unit.

It is also important to consider what happens to the fresh air volume when slowing down air handling systems. If the fresh air intake is set to 10% which provided the occupants with precisely 10 litres per second per occupant and then adjustments are made to reduce the air flow rate by 25%, this would result in new fresh air volumes of 7.5 litres which may be too low. In a fixed fresh air system this may mean opening the fresh air damper (if it is adjustable) and in a modulating system, this will require adjustments at the controller or in the Building Management System (BMS).

An alternative to increasing the fresh air rate may exist in installing CO2 monitoring. The opportunities of which will be the subject of a later blog.

In our case study we have identified that there is an abundance of air volume and higher than required fresh air volumes. The small west positioned packaged unit was installed initially to service a different heat load presented by the west facing glass. Since then the building has been extended and the glass is now internal. This has the effect of reducing the heat load on this part of the office.

By simply reviewing duct design, a complete packaged unit has been removed from service!

By measuring the air volumes at each diffuser we can determine the quantity of excess air and how we can balance the system to improve occupancy comfort. Auditing the diffusers also highlighted some areas that did not require air conditioning such a store room, and a copy room that has been retrofitted with its own split system and extraction system (see diagram above). The following diagram shows the new layout of the HVAC ducts. Note that AC unit 3, and 4, have been extended to allow the removal of AC unit 5. By simply reviewing duct design, a complete packaged unit has been removed from service.

Figure 3 – Mechanical services duct layout after changes

It should be noted that this analysis has been made significantly easier because of the access to up to date mechanical services drawings and accurate floor plans. As any alterations are made to buildings it is important to update the floor layouts, mechanical, and electrical services drawings. If your facility does not have up to date drawings, it may be worth while seeking the services of a drafting company to develop a Computer Aid Design (CAD) set. This will allow the facilities department to track any changes as they occur and allow more efficient analysis of problems for contractors which ultimately will result in faster and more comprehensive analysis of problems.

Climate Positive Diet - Belgium’s Ghent leads the way

Friday, May 15th, 2009

If you know much about climate change you’ll know that cows and sheep produce a lot of greenhouse gas. In fact a cow can produce around 200 litres of methane a day, and methane has global warming potential 23 times greater than carbon dioxide. To put that into context thats 1.2 tonnes of greenhouse gas a year per cow, a bit over one quarter of the greenhouse gas produced by a car over a year. I once did an audit of a large business that grazed cattle basically to keep grass under control (it was by no means their core business), and the cattle accounted for 10% of their carbon emissions. Needless to say I recommended they switch to grazing kangaroos, which don’t produce methane.

As reported by MX The town of Ghent in Belgium has now declared Thursday a vegetarian day to help reduce carbon emissions. All government departments and schools are banning the consumption of meat on Thursdays.

Now this may seem radical to some, but I believe this is a fantastic “climate positive” initiative. In fact its something we may start in our office - a vegetarian Thursday. Its easy to do, it will save you money, and its good for the environment, and if you eat a lot of meat its good for your health too. A triple win!

And if you do enjoy meat the other days of the week consider kangaroo. Its lean. Its inexpensive. You can buy it in the supermarket, and it tastes delicious. YOu can buy it as a roast, plain, marinated and you can even get kangaroo sausages. My favourite is roast skippy.