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Minimising demand for energy through good design, conservation and efficiency is the most cost effective means of reducing operational and environmental costs for all home owners and tenants.
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Monitor your energy bills and check for unexpected increases and how they can be reduced through more efficient energy use.
Hot water heating along with space heating and cooling are the main energy consuming appliances in the home. In 1999 they accounted for nearly 70 percent of household energy use.
Energy rating programs (such as FirstRate and NatHERS) used for house energy ratings only assess the building fabric. They do not consider appliances. The programs simply rate based on the predicted expected heating and cooling energy requirements to make the building comfortable for the average person.
Basically, the better the rating the less mechanical or non-natural assistance the building should require for heating and cooling. This should give a good guide as to the extent and capacity of heating and cooling systems required.
Energy ratings reports from the above mentioned programs provide a breakdown of summer and winter performance. Use the report to understand the home's strengths and weaknesses. For example in heating climates such as Melbourne , a five star home with a good summer component to the rating may not require any air conditioning.
A considered and appropriately assessed selection of heating, cooling and hot water heating systems is important to compliment a good house energy rating and realise further savings. Conversely, ill considered and inappropriate selections of these major appliances can negate many of the benefits from a good building energy rating and compromise thermal comfort.
Renewable Energy and Green Power
Renewable energy sources produce no greenhouse gases in operation and reduce or eliminate the need for additional fossil fuel fired power stations.
Renewable energy sources include wind, solar.
The use of solar energy for generating electricity is increasingly common in remote areas away from the electricity grid. These systems are called RAPS or remote area power systems.
The solar panels used for generating electricity are called photovoltaic panels. These are completely different to the panels used in solar hot water systems. Photovoltaic panels generate DC current which is required to be connected to an inverter to change the electricity to 240V AC for use in the home.
To use solar energy to power your home you need to decide on one of two main systems:
- Grid interactive
- RAPS
The grid interactive system is cheaper, requires less space and also requires the home to be connected to the electricity grid. The system can't store any energy. In daylight hours the system generates some or all of your homes electricity demand. Any shortfall is supplied from the grid and any surplus goes in to the grid for others to use. When your system is supplying to the grid your meter will run backwards. An agreement is required with your electricity retailer for grid interactive systems. This gives the option of choosing a system size and capacity to suit your budgetary and other constraints. Unless you system is quite large and your home's electricity demand very low you will still have a percentage of your electricity effectively supplied from the grid. Systems range from $15,000 to $45,000 depending on the size.
The RAPS alternative has no interaction or connection with the mains grid. Because a homes energy demand at any time does not usually match the power the system is generating a storage bank is required. A battery system is necessary to absorb excess energy when generation exceeds demand and the batteries supply power when there is no generation (at night) and whenever demand exceeds generation. The need for batteries adds significant cost and dedicated storage space is required within the home. Systems generally start from around $30,000.
If you have an established or can secure a simple cost effective connection to the electricity grid the easiest and cheapest way by far to utilise renewable energy is by taking Green Energy from the electricity retailer. At between 3 and 5 cents per kWh extra over your standard supply rates your annual cost could be as low as $60 for low consumption and small homes and high as $400 for large and/or high consumption homes.
Consumption reduction strategies are normally implemented in homes before sizing and installing solar power systems to avoid excessive system size and cost.
Tips for reducing heating costs:
- Close windows and external doors. Keep doors to laundry, toilet, ensuite and room doors not being occupied to reduce heating area.
- Close blinds and curtains.
- Insulate your home if it isn't already.
- Keep you heating area to a minimum, i.e. close off sections of the home not being used.
- Purchase/install a correctly sized heater. To determine size floor area, ceiling height, energy rating of building, window treatments should all be considered.
- Determine and consider ways of improving the building's energy efficiency before selecting a heating system. For example, some of these hints listed here when combined will make a significant difference in most homes. This should result in a heating system capacity requirement which will cost less to buy and run.
- Beware when buying a heater from a retail department store. The sales people generally know little about energy efficiency and system sizing and will tend to sell you a larger system than you really need or one inappropriate for your situation.
- Turn off the pilot light on ducted gas heaters over summer; it could save $25 a year.
- Set your thermostat at a reasonable temperature such as 18 - 21 degrees. Each extra degree will add approx 15% to the running cost.
- Avoid vented down lights in ceilings, as they allow warm air to escape in to the ceiling and fire requirements necessitate the ceiling insulation immediately around them be removed.
- Identify drafts around windows, doors, floor boards, skirting boards, chimneys, old vents etc and seal with sealing or weather strips.
- Set ceiling fans on the winter setting (reverse direction) and use on low to distribute heat evenly around the room.
- Don't leave your heating on during all day especially when you need to go out for a while.
- Use timers and programmable thermostats to heat only when really needed.
- Wear appropriate clothing for the season.
- Open curtains right up during the day when windows are receiving direct sunlight to absorb the solar energy and light.
Poor house design, inadequate insulation and lack of suitable window shading results in many households investing in a cooling system to stay comfortable. The result for many people, especially in large homes with ducted air conditioners is additional energy costs of in excess of $500/year.
Tips for keeping your home cool in summer:
- Ensure windows are well shaded from summer sun. External shading can come from awnings, eaves, shrubs/trees, screens, lattices, security shutters.
- Install a simple indoor and outdoor temperature to monitor when the outside temperature exceeds and falls below the inside temperature.
- Set thermostats on cooling systems to around 24 to 26 degrees for summer comfort. Thermostats settings below that will use much more energy, each extra degree lower will increase your power consumption by around 10% to 15%.
- On hot days, close all blinds, curtains, windows and doors to keep the heat out.
- Insulate the ceiling.
- Consider installing roof ventilators to expel hot air from the roof space. Ideally these should be sealable/closable for winter time.
- Use fans to generate cooling breezes.
- Close off warm areas of the house not being used and cool only the rooms required.
- Wear lightweight clothing so that allows air to move across your body to evaporate moisture
- Open windows when outside temperature below inside temperature.
- Put off heat generating jobs such as cooking and ironing until cooler times of the day.
- Regularly clean the air conditioner or cooler to keep coils and fans free of dust to maintain efficiency and air quality.
When purchasing small appliances make sure you choose the size for your needs and look at the energy efficiency rating. Generally, the more stars, the more energy efficient the model.
However, the energy efficiency rating takes the capacity of the appliance in to account. In other words, a 5 star appliance will still probably consume more power per year than a 3 star rated appliance that is only half the capacity.
Look at the energy consumed in kWh per year or MJ per year for gas appliances on the energy efficiency labels. It enables comparison of different size models and easy calculation of cost per year to run.
Annual and Lifetime Running Costs of Electrical Appliances
A reasonably good guide for determining the annual running cost of electrical appliances is to take the energy consumption in kWh per year on the energy efficiency label, divide it by 10, and then multiply it by 1.5. This is based on an electricity tariff of $0.15/kWh and closely approximates the tariff most Australian electricity suppliers are charging in 2005.
e.g. for an appliance with an energy consumption of 600kWh per year, the annual running cost would be:
600 ÷ 10 = 60 x 1.5 = $90
To get an idea of the running costs over the life of the appliance, multiply the annual running cost by 10 or 12, whichever is most appropriate for the expected life of the appliance.
e.g. for the above appliance the lifetime running cost would be between:
$90 x 10 = $900 and $90 x 12 = $1,080
Lifetime running costs as calculated above would be conservative if energy costs rise to any significant extent of the ten or twelve year period. For example, the annual running cost in year 10 for the above appliance would be $146 (1.62 times) for an annual energy cost increase of only 5% p.a. because of the compounding effect. The Lifetime running cost would be $1,189 over 10 years or $1,504 over 12 years.
An easy guide for approximating lifetime running costs with consideration for annual increases in energy prices comes with an assumed life of 11 years. You take the annual increase rate in %p.a. and multiply it by 10, add it to 100% and apply it to the 10 year lifetime running cost calculated previously (for no annual increases).
e.g. Over an 11 year life, with 5% annual increases in energy prices, the above appliance would have a lifetime running cost of:
(5% x 10) + 100% = 150% x $900 = $1,350
Similarly, for 3% annual increase the Lifetime running cost would be 130% x $900 or $1,170 and for a 10% annual price increase the LRC would be 200% x $900 or $1,800.
Depending on the type of appliance, its size and its efficiency, the lifetime running costs could amount to anywhere between 50% and 350% of its purchase cost. This highlights the need to choose an energy efficient model that is the most appropriate size for your needs.
Energy consumption in residential dwellings is the greatest source of greenhouse gas emissions from Australian households. The average household's energy use is responsible for approx 8 tonnes of greenhouse gas emissions per year (mainly carbon dioxide CO2).
Household greenhouse emissions can be reduced through better home design and more efficient use of energy through appropriate and efficient appliance selection and occupants who are aware of how best to utilise the features of their home and appliances.
The other main contributors to household greenhouse emissions home are transport and waste. This brings the average total greenhouse emissions per Australian household to around 15 tonnes.
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Greenhouse gases from home energy use (based on AGO 1999). |
Choosing the most appropriate fuel or energy source can reduce your greenhouse gas emissions and energy bills significantly. Natural gas produces only about one third the greenhouse emissions compared to conventional electricity.
The main energy consuming appliances in the home are also the ones where some choice of energy source exists, such as heating, cooling, hot water and cooking. With all but cooking (in the modern home) the use of renewable energy sources is available to some extent. The best times to select or change an energy source is when you are building, extending, doing major renovations or looking to replace appliances.
Natural gas and LPG gas generates much less greenhouse gas emissions than electricity supplied from Coal fired power stations.
Conventional electricity from the supply grid currently produces the largest amount of CO2 of any energy source per unit of energy used.
Most of Australia's electricity is generated from black coal, except in Tasmania where hydro electric power is used. In Victoria, where brown coal is used, the CO2 emissions per unit of energy are even greater. In Victoria, 1 tonne of greenhouse gas is produced for every 700kWh of electricity.
