Fossil fuels are not the only available means of providing energy for your home. There are many kinds of renewable energy, which provide a viable alternative energy source for household use. The benefits of renewable household energy include;
- Security of supply
- More environmentally friendly
- Reduction of external energy bill
Below, is a list of the key home renewable energy options some that provide heat and others that provide electricity. To find out full details on renewable energy for the home, visit the Sustainable Energy Ireland website.
Solar hot water systems
Solar collectors (panels), typically roof mounted, convert sunlight into heat. This heat is normally used to provide hot water, but can also be used to provide space heating in a combined system, although this is more unusual.
There are two standard types of collector: flat plate or evacuated tube. An appropriately sized solar water system can provide you with 50-65% of your hot water requirements. Solar hot water systems need to be supported by a conventional heat source to increase water to usable temperatures. Such systems include a boiler or an electric immersion heater. Solar thermal systems are easy to install and are reliable – a professional installer is required
Life Expectancy: c 30 years
Payback Period: 8-20 years
Photovoltaics (PV) for electricity
Photovoltaic solar cells directly convert sunlight into electricity. They can be installed on an existing roof, or on a nearby structure. Alternatively, they can be moulded into solar slates or solar tiles for integration into roofs or bonded onto glass or metal sheets for incorporation into architectural glazing and fascia systems. Different types of PV technology exist that use different materials and manufacturing techniques with conversion efficiency ranging from 8% to approximately 20%. PV solar cells are expensive but safe and reliable and require minimum maintenance.
Life Expectancy: 25-30 years
Payback Period: 20 years
Ground Source Heat Pumps
Ground Source Heat Pumps (GSHP) can be used for space heating and cooling, and for water heating. Ground heat pumps obtain energy from several meters below the surface of the earth. The energy is then transferred from a series of pipes in the ground to a heat pump and a distribution system such as radiators or an underfloor heating system. Geothermal heat pumps are one of the most energy and cost efficient methods of home heating and cooling, provided the building has adequate space for installation. Given the costs associated with installation in an urban environment due to space limitations, this method may be more suitable for newly constructed housing, where sufficient space can be incorporated at the planning stage.
Life Expectancy: c 20 years
Payback Period: 8-15 years
Air Source Heat Pumps
Air source heat pumps (ASHPs) use the same principles as GHPs but draw low grade heat from the surrounding air using a fan to pull the air over a heat exchanger. This energy is then upgraded and the heat released via another heat exchanger. Due to variation in the air temperature in Ireland these systems are less efficient than the ground source heat pumps but the systems can have a lower capital cost. It is also likely that this system would need to be used in conjunction with a conventional system.
Life Expectancy: Unknown
Payback Period: 8-15 years
Biomass - Wood Chip / Wood Pellet
Biomass in the domestic sector nearly always refer to wood fuelled systems, which can burn logs, wood chips or wood pellets from sustainable forests, can be considered a clean and highly efficient alternative to fossil fuel systems. The two main types of biomass heating devices are radian heat stoves or boilers.
They can be used to provide space heating or a combination of space heating and hot water. The occupants of a house which uses a biomass system can benefit from lower energy costs, secure supply and clean, environmentally friendly fuel, as wood chips and wood pellets are carbon neutral. Wood pellets and chips to fuel the stove are priced similar to oil or gas and can be bought in bulk. These are generally low risk and reliable technologies.
Life Expectancy: 25 years
Payback Period: 12 years for wood pellet boilers at current prices
Wind
The energy in wind is converted to electricity by a wind turbine. Most domestic scale technologies are like miniture versions of the wind farm machines. These small scale wind turbines can be installed near/on your house but need strong foundations. Domestic wind turbines should be located high up, on the side of a building, facing the prevailing wind and away from chimney or flues. The installation of a wind turbine on your home or on your land usually requires permission from the local authority, so it's important to always check with your local authority about planning issues before you have a system installed. It is also advisable to consult with a building engineer to make sure the property is suitable structurally.
Life Expectancy: up to 20 years with occasional maintenance and a mid life overhaul
Payback Period: c.15 years
Funding for Renewable Energy in the home
Home renewable energy systems are relatively new technologies. While they are more widespread overseas, they are not yet very common in Ireland. The government, through SEI have devised the ‘Greener Homes’ scheme to provide financial and advisory support for home owners who wish to purchase renewable energy heating systems for new or existing homes. The scheme provides funding for:
- Heat pumps – geothermal, water and air
- Solar Heating
- Wood chip / pellet stoves
- Wood chip / pellet boilers
Go to the Greener Homes website for more information