The federal government’s $8,000 rebate to householders installing a PV system runs out on 30 June. Time is running out if you want to take advantage of the rebate, which you are eligible for you if you own a home and your household income is less than $100,000 a year.

If you do an internet search or scan the papers you can find at least two companies offering a 1kW grid connect solar system for free, excluding the metering. You have to assign the installer the RECS (Renewable Energy Certificates) to get the system at this price, and may have to pay extra for variations to a standard install such as fitting it to a tiled roof. Considering the historical price of PV systems, the free offer is very good indeed. If you don’t already have a PV system - consider getting one now - but you should be quick, some of the free offers are expiring at the end of May or early in June.

The PV system on your roof will cut your power bills by about $200 a year for a 1 kW system, and should add value to your house. Lets say all up your costs including the meter install are say $1,000. That’s a 20% return on investment, which is pretty good.

By assigning the RECS to the system installer, and if the government’s proposed Carbon Pollution Reduction Scheme (CPRS) legislation goes through, don’t kid yourself that you are saving the planet by putting on the PV system. The clean energy provided by your PV system is assigned to the system installer when you give the installer the right to the RECS, and the carbon savings arising from the system essentially won’t count under the proposed CPRS.

So look at it as a chance to cut your bills, improve your property value, and make it look as though you are doing something to save the planet, although unfortunately under the proposed CPRS you won’t be. Its not clear to me if you’ll be able to voluntarily “lock up” the carbon savings by making a payment to the proposed Carbon Trust - and thus actually do something to slow climate change - if you’ve assigned the RECS to the installer.

If you go ahead, be aware that the metering install can be fraught with pitfalls. Make sure you follow the advice of your electricity distribution business - see www.bcse.org.au/default.asp?id=305 for a link to the guides offered by different distribution businesses.

And, even though you are putting in a solar system, also make sure that you are buying 100% governmetn accredited green power from your retailer. Keep you your greenpower purchases until the CPRS comes in, after which point it may not make a difference.

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
www.r-p-r.co.uk/wind_chill_table.htm

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.

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.

Direct quote from the government’s 2009 budget web site:

“Households and small businesses will be able to calculate the potential dollar savings from their energy efficiency actions and make tax deductible donations to the Energy Efficiency Savings Pledge Fund. The Australian Carbon Trust will use these donations to purchase and retire Australian emissions units or purchase carbon offsets.”

What this means:

• If you voluntarily cut your household energy consumption to save greenhouse gas - sorry the greenhouse savings don’t count! If you want to reduce greenhouse gas emissions, you have to actually now go and pay to “retire” the carbon you’ve saved - and pay the government to do so. See my earlier blog posting rantings about the disincentives in the CPRS (Carbon Pollution Reduction Scheme) for more detail. Basically if you don’t pay to retire the greenhouse gas you’ve saved, the entity generating the energy (say an electricity generator) can claim it. And trade it. And you have contributed no additional greenhouse savings beyond that which the emissions trading scheme would achieve anyway.
• If you are a small business…. hang on… what is a “small business”? As only Australia’s top emitters get to participate in the CPRS doesn’t the definition of a “small business” in this context mean anyone who can’t participate in the CPRS? To participate in the CPRS you either have to directly generate over 25,000 tonnes of carbon a year, or consume more than 100 Terajoules of energy. In other words you are a small business if your annual energy consumption is less than 100 TeraJoules of energy or you directly produce less than 25,000 tonnes of carbon. What is a tera joule? You are probably familiar with kilojoules (1,000 joules), a tera joule is actually 1,000,0000,000,000 Joules. 100 TJ equates to an annual energy expense of about $2 million (as does the production of 25,000 tonnes). So, if you spend less than around $2 million a year on energy you are a “small business”!

So let me rewrite what budget actually means in plain English. “If you spend less than around $2,000,000 a year on energy, and you cut your energy use, in order to be able to also say that you’ve cut Australia’s greenhouse gas emissions you need to pay the government for it to recognise that what you’ve saved is an actual saving.”

Or, lets do a hypothetical here. Lets assume that you are a “small business” - ie your energy expense is less than $2 million a year. (What a tiny, wee business you’ve got if you’re not spending $2 million a year on energy!) You invest $10,000 in upgrading your lighting (using Mirrorlux Reflectors say). This saves you  $5000 a year on your electricity bills and about 25 tonnes of carbon annually. But if you want to say that your investment has reduced Australia’s emissions you actually have to pay. Lets say the carbon price settles at $50 a tonne. You’ll have to spend $1,250 a year to be able to genuinely say that your investment in your lighting upgrade is saving greenhouse gas. Because if you don’t, under the CPRS, the electricity generator supplying you the power that energises your lights has the right to the carbon you’ve saved.

Another hypothetical. This time you invest in a new gas heating system in your school. You spend $300,000 to put in gas space heaters and eliminate the old central heating system. It saves you approximately $20,000 a year in gas costs, and about 160 tonnes of greenhouse gas emissions a year. At $50 a tonne you have to pay the government $8,000 to “retire” the carbon you’ve saved. 40% of the financial savings you’ve realised goes to the government if you want to be able to say that your investment is actually reducing greenhouse gas emissions.

Are, you, like me, someone who believes that personal or “small business” action can do something to avert dangerous climate change? Do you, like me, spend less than TWO MILLION DOLLARS a year on energy? Well the government is clearly telling you and me that if we want to make a difference we have to pay twice. Pay for the investment to cut your emissions. And then pay the government to retire those emissions.

Isn’t there something really really wrong if we have to spend twice to cut our greenhouse gas emissions?

(Part One)

One of the most energy intensive (and therefore costly) processes in any house is the heating of water. Heating water accounts to about 37% - 40% of the annual energy consumption in an average Australian household and about 20% of its greenhouse emissions. Therefore it is important to consider all the alternatives, such as using the heat of the sun in solar hot water systems.

The diagram below summarises the GHG emissions of each type of hot water system.

GHG emissions from hot water systems

Throughout the day, a sensor monitors the difference in water temperature between the water in the storage tank and the water in the collector (typically mounted on the roof). At a preset temperature difference, the sensor triggers a pump to circulate the water through the collectors where it absorbs solar heat.

Below is a summary of the two types of commonly used domestic solar hot water systems. Both the flat panel and evacuated systems have several versions, where gas or electricity is used to boost the water temperature if it is not sufficiently hot coming out of the water tank. In most cases the sun is simply used to ‘preheat’ the water to higher temperatures (40-70 C) before it goes into a storage tank. A pump may be used to circulate the water from the tank to the collectors until it is used. In addition the flat panel systems may use a heat-exchange mechanism typically where the water may freeze.

Flat panel or evacuated tubes?

In recent years evacuated tubes have become more popular and affordable and together with the flat panels have become widely used in Australia, especially since generous government rebates have been introduced. However, it is still disputed which system is better than the other. Obviously the manufacturers of each type of system claim that theirs is better than the other (sometimes claiming 90% to 160% more efficiency than the other system). The following reasons have been cited: because it captures sunlight better, is better in certain climates, is more cost effective, has better output for dollar spent, has faster payback, is less prone to failure or damage, is cheaper to repair, requires less roof installation area, etc.

It is difficult to find impartial opinions on the subject. It seems that each system should be examined in its own context. The climatic conditions and application will determine the better collector. One of them may be the preferred choice over the other due to a number of variables, such as the environment, availability of sunlight, elevation, orientation, average outdoor temperature, greenhouse gas savings, ease of installation including existing plumbing, payback period, running cost, availability of natural gas to use for boosting water temperature, how well the hot water tanks are insulated and many other factors. So which one is better and how do they compare?

To be continued……..soon……….