Energy Optimisation Explained

To make this easy to understand, we will use a domestic setting to explain energy optimisation. 

Suppose you are confronted with a salesman who proposes the installation of a new solar water heater at your house.

Such a salesman may show you the following;

1. Your average monthly electricity bill is R 1 500.
2. 35% of this cost i.e. R 525 is as a result of your geyser.
3. A solar geyser will save you 60% of your geyser's cost (remember the sun does not always shine).  This means you can save R 315 per month by installing the solar geyser.
4. The geyser will cost you R 8 500 installed (after rebates and incentives).
5. This will give you a payback period of just over 2 years (2 years and 3 months).
6. The salesman is convincing, he shows you the SABS approval, Eskom approval and convinces you that the German manufacturing is the best available.  

You decide to go ahead with the installation of the solar geyser.

You will;

1. Save money (after the cost of the solar heater is recovered).
2. Reduce your environmental footprint.
3. Reduce your electricity consumption by 21%.
4. Set a good example for your neighbours to follow
5. Etc, etc.

But, have you optimised your energy use....?? Let's take a look....

You should have:

1. Considered why you want to save? - is it to save some money, to reduce your environmental footprint, because your existing geyser is at the end of its life, because you need more hot water, etc, etc.
2. Evaluated where you could save - is the geyser the only (or even the best) option?
3. Considered what it would take to make the changes.  Do you need to change plumbing, do you need to arrange for workmen at your home during the week?  Can you do it yourself?  Who should you get to do the work?
4. How will you know if the measures you are about to take will really save you money?  How will you monitor and measure it?
5. Can you claim incentives or tax credits if you install the new equipment?  What other alternatives and financing models are available?
6. How will you know by how much your environmental impact is reduced as a result?
7. Etc, etc.

Given this more comprehensive view of the options available to you, you may have decided to;

1. Reduce the thermostat set-point by 5 degrees centigrade.  This could save you an amount of
   (let's say) R 30 per month.  Cost = zero.
2. Insulate the pipes leading into and out of the geyser (the cold water and hot water pipes).  This could save you in the region of R 20 per month (figures are used merely to illustrate the concept). Cost = R 100.
3. Insulate the geyser by installing a geyser blanket.  This could save you in the region of a further R 20 per month. Cost = R 300.
4. Finally, you could install low-flow shower heads and flow restrictors on the hot water taps.  This can reduce your hot water consumption by as much as 30%, saving you an amount of
   R 160 per month. Cost = R 800.
5. Your total saving is now R 230 per month - this is 15% of your original consumption.  The cost was R 1 200, giving you a payback of 5 months.
6. You also still have R 8 500 - R 1 200 = R 7 300 left to spend on further energy improvements.
7. Suppose you can save an additional 15% of your energy consumption by spending the remaining R 7 300 (or less) wisely, this will bring your total saving to 30%. 

Comparing the two options reveals a total saving of 30% in the second case vs. 21% in the first case for the same (or less) capital outlay.  This example is not complete since we now have to consider additional aspects such as maintenance implications, aesthetics, ease of use, safety, etc, etc.

The approach described above is a (very simplified) example of energy optimisation engineering in action.  

• A holistic view is taken. 
• All options are considered.
• All alternatives (technology as well as operational) are evaluated and
• The most suitable solution mix is chosen. 

The results of this process are significantly better than the standard approach.

Please note: - this example illustrates the principle, it is not an opinion as to the viability of a solar geyser (the same reasoning applies to any technology).