A major goal for the ecovillage is energy independence. In other words, the ecovillage should produce enough energy for its own needs.
Solar and Wind Energy
At present it is expected that about 50% of this energy production will come from solar power, and about 50% from wind power.
Both solar and wind offer certain advantages and disadvantages. Neither solar nor wind will produce electricity all the time, simply because the sun is not always shining and the wind is not always blowing. However, solar and wind make an excellent combination, since it is often windier when the sun is not shining, such as at nighttime or during storms. Using both technologies together means a more consistent supply of electricity during a 24-hour period.
Solar energy is more reliable than wind, since on most days (especially in Queensland) the sun will shine for about 12 hours. However, although wind is less reliable, it offers the advantage of being much cheaper.
The solar panels will be positioned on the roofs of the homes, the community centre, and other buildings. The wind turbines will be located in the most windy (probably the highest) places on the site.
The community will be connected to the main electricity grid via an inverter, so that we will not need an energy storage solution (i.e. batteries) on site. This is good for the environment because batteries are hard to recycle, besides being costly.
A grid-connected system will mean that when the ecovillage is not producing enough electricity for its needs (e.g. when it is neither sunny nor windy), then electricity can be drawn from the main grid in the usual way. It also means that when the ecovillage is producing an excess of energy, this excess will be returned to the grid.
The ecovillage will only be billed by Origin (or whatever energy company) for the balance. If the energy system is well designed, then more often than not we will actually return more electricity to the grid than we use, in which case the ecovillage will receive payment from Origin for this surplus energy.
By designing the community for low energy usage, we greatly reduce the cost of construction, since solar panels and wind turbines are reasonably expensive at present.
One way that energy requirements can be significantly reduced is through passive heating and cooling solutions.
Designing for passive heating means positioning rooms such as the lounge room or home office on the north side of the house, since these often have people in them during the day, and it is the north side of the house which receives the most sunlight. This reduces the cost of heating in winter. Similarly, rooms such as a bedrooms, bathrooms and laundry can be located on the south side of the house, since these rooms are generally not occupied very much during the day, so it does not matter if they are cooler.
Designing for passive cooling means setting up breezeways so that air can flow through or under the house, in order to keep the house cool in summer. This is why many Australian homes are on posts, so that air can blow under the house. More modern designs use louvres and large openings to allow breezes to flow right through the home.
Silvergreen's homes will also include energy-saving light bulbs, flat-panel TV screens and computer monitors, heat pump hot water systems, energy-efficient refrigerators, and other energy-saving appliances and devices wherever possible. We may also include devices that ensure that TVs and DVD players do not sit on standby but switch to fully off, and occupancy sensors that automatically turn lights off when there is no-one in a room.
While an average suburban home requires about 5kW, with good design it should be possible to reduce this to around 3.5kW. This will greatly reduce the cost of our energy production system and be a good example of sustainable design.