subject: Analysing The Cost Of Your Existing Energy Utilization [print this page] We are going to be looking at calculating the cost of your existing energy consumption as an initial step to design your renewable home energy system as well as reducing your current energy needs. To do this you will have to carry out an inventory of your electrical appliances and home illumination. This is an perfect job for a spreadsheet.
This is an ideal task for a spreadsheet.
If we wish to use renewable energy for our home then it would be a good idea to know what our current energy usage is. Essentially you have to carry out an appraisal of your current energy usage so that you can establish a starting point from which you can calculate the load requirements of your micro-power generators i.e. your solar panels and wind turbines.
Consider each appliance in your home and its energy use. Some appliances such as kettles and toasters by their very nature use a considerable amount of energy when used but are only used for a comparatively short time each day.
Once you know what your current energy usage is you can take steps to start reducing the amount of energy you use.
Estimating and / or timing the duration that each appliance and light is in use and the energy expended by each appliance and light is a real revelation. It allows you to make informed choices when buying new appliances or installing new lights.
For instance, I know that it's a lot less hassle to dry our clothing in a tumble dryer than on a washing line. However to dry a single load can take up to between 70 minutes to 140 minutes. Assuming that, as a family of four, you have on average of 7 loads in a week, therefore with a 3.3 kWh/cycle (my current tumble dryer energy consumption), assuming a 12-hour constant tumbling time per week, you will be using an approximate 2059.2 kWh a year. This costs currently around 186.77 per year.
I can probably save up to half the cost by putting the washing on the washing line and spend the money on myself instead.
One of the changes that is relatively easy to make concerns the illumination of your home.
When considering the illumination of your home you should consider the following:
- The general lighting of a room;
- Localised or task lighting i.e. concentrated light for activities such as reading, sowing and cooking; and
- Accent or mood lighting to create atmosphere or to focus attention on certain objects or areas.
For instance in parts of my home I initially reduced eight 50-watt lights to 25 watt and then reduced them even further to 2-watt LED lights. The LED lights outlast the 50 and 25-watt by a considerable margin.
A simple calculation shows the savings made by carrying out each of these changes:
Running the 50 watt lights for 3 hours a night I would be using 1200 watt hours per night i.e. 438 kWh per year.
By using 25-Watt bulbs this was automatically halved.
However, with the 2 Watt LED light bulbs my energy use for this room has dropped to 17.52 kWh a year; a cost saving of 38.14 at current electricity prices i.e. 0.0907/kWh. It may not sound like much but you should consider that this was only for one room.
As appliances need replacing they are replaced with appliances with better energy rating. I look at the energy rating of the appliances as well as the price when comparing new appliances. For instance I had to replace our condenser tumble dryer and I opted for a vented tumble dryer as there was a 0.5 kWh difference per cycle.
Each individual saving adds up in the end and over time can make quite a difference to your pocket.
Each small saving made this way reduces the load requirement of your renewable energy, which in turn means less solar panels, and energy storage requirements.
