Pros & Cons of 7 Renewable Home Energy Systems

We explore 7 popular renewable energy systems for your home.

One of the most effective ways to reduce your house’s carbon footprint is to install a renewable energy system which generates energy from sources that do not run out, such as the sun or wind.

Installing a renewable energy system in your home not only means you'll contribute fewer greenhouse gases or pollutants into the environment but will also help save you money on household energy bills.

Your overview of 7 of the most popular renewable home energy systems and the pros and cons of each.

1. Source Heat Pumps

Of the 41,000 heat pumps installed in 2019, one of the most popular is the air-to-water system.

These heat pumps work to push air from the outside, warm it up and then feed it into the home. The process is incredibly efficient, as it requires very little electricity to run and works very well in cooler climates like Ireland.

In recent years, air-to-water heat pumps have been installed for new builds as well as social housing heating retrofit programmes.

Homeowners have also installed heat pumps when renovating or extending their homes or embarking on an energy efficiency retrofit upgrade.

Pros:

• Heat Pumps can save you up to 75% on heating costs, will use less energy than gas or oil systems and will considerably reduce a home's environmental impact.
• Grants are also available from the Sustainable Energy Authority of Ireland (SEAI) which will cover about a third of the cost.

Cons:

• Heat Pumps will not work efficiently or be a viable option unless your home is at least a BER B2 energy rating and well insulated to prevent heat loss. 
• For many homes built before 2011, upfront costs could include cavity wall and attic insulation, new doors and windows and removal or sealing up of fireplaces.

Read more: Meet the Expert: Heat Pumps – How They Work, Savings & Costs

2. Underfloor Heating

Underfloor heating is considered a renewable heating source because generating heat from the floor up offers even heating throughout the home and can be run at lower energy rates.

Electric systems generate heat via electric wiring, while a water-based system runs hot water through pipes to create heat which can be connected to a heat pump, condensing boiler or solar heating system.

Pros:

• Underfloor heating reduces cold spots in the home and also frees the floor and wall space of radiators.
• There is a range of floor covering to choose from which underfloor heating works well including wood and laminate.
• There is also the benefit of cleaner air quality due to the reduction of dust and air allergens.

Cons:

• Underfloor heating is best planned for a new build or renovation project as retrofitting is not an option unless you want to remove the entire floor structure to install.
• If ceiling height is an issue in your home, then a floor heating system can reduce room height by a few centimetres depending on the system.

3. Heat Recovery Ventilation Systems

A heat recovery ventilation system works well in homes that have been insulated and airtight to a BER rating of A3 or higher.

The system recovers heat from the air in the home including bathrooms and kitchens and then transfers this heat into fresh, filtered and clean heated air.

As warm air is recovered in the home and reused, it maximises energy spent at a minimum cost.

During the warmer months, the unit can reverse controls to ensure that the house maintains a comfortable temperature, even during summer, while still remaining air-fresh.

Pros:

• Installing a heat recovery ventilation system will allow for a constant supply of fresh clean air, as well as reduce the heating demands of a house.
• It can be installed alongside any type of heating system, saving 15%-20% on heating bills.

Cons:

• For maximum efficiency, a house will need to be well sealed and insulated first - which could add additional expense to the cost of installation.
• A unit is typically ducted from the attic, so sufficient space will be required.
• Installation is best suited for renovation projects or new builds.
• While the unit can be controlled to reduce heat in the home, it will not cool the air in the summer months.

4. Solar Hot water

Even though we complain about a lack of sun in Ireland, solar energy can be derived from both direct and indirect sunlight, so even on a cloudy day, radiation can still be converted to useful heat using a solar water heater system.

Solar water heaters heat a reserve of water, which can then be used in taps and showers for the home. A solar water system is much cheaper than using gas or electricity to heat your water and is eco-friendlier.

A system will require a dual coil cylinder (or similar) for efficient storage of collected heated water. The roofing aspect and potential occupancy will determine the size and viability of a system for your home and the type of system recommended.

Pros:

• During daylight hours, solar thermal used for producing energy to heat water is twice as efficient as other forms of solar energy systems.
• The system is easy to install and other than antifreeze being replaced annually, will require very little maintenance.
• Hot water heating cost savings could be as much as €850 per year but will depend on the type of system installed.
• A well-maintained system should provide renewable solar hot water for more than 20 years.

Cons:

• Installing a solar water heater will only heat water and cannot convert energy for electricity.
• Heat can only be generated during daylight hours and the installation of a system will require a system specific hot water storage cylinder.
• A solar water heating system will only provide between 50%-65% of a home’s hot water requirements, which means another system for heat water will also be required like a gas boiler, electricity or heat pump.

5. Solar Electric

Like solar heating, solar electricity is installed on a roof to convert sunlight into electricity. Solar electric also known as photovoltaic (PV) solar systems will generate power for the home, but the amount of power will depend on the aspect of the roof and the number of panels installed.

It is recommended to install solar electricity with a battery to ensure that the energy generated is not lost but can either be stored for use during peak times or sent back to the grid* when available. 

*As the time of writing, the Irish government is looking at ways for homeowners to be able to sell excess electricity from their home systems back to the grid.

Pros:  

• Solar electricity will reduce the amount of electricity a home uses from the grid, and in Ireland, homeowners can receive a grant to install up to €2,800 from SEAI.

Cons: 

• Like solar heating, the level of energy generated will depend on the system installed and the aspect of the roof panel to capture radiation.  
• The solar PV system will not heat your house or water and while the cost of PV solar systems is falling, there is still a considerable investment to be made and payback on investment could take many years before a return is realised.

6. Condensing Boiler

A condensing boiler burns gas to produce a combination of carbon dioxide and water vapour but unlike a traditional heating system, it is more efficient due to a larger heat exchanger which enables the unit to recycle heat, rather than lose heat through the flue.

Pros: 

• If a home has an older boiler installed, a condensing boiler replacement is a less disruptive replacement than other renewable home energy systems and will increase energy efficiency by as much as 30% and save up to 20% on energy bills.

Cons: 

• Condensing boilers are a more complex system and therefore are more expensive to purchase, install and maintain than non-condensing models.

7. Central Heating Controls

Central heating controls allow a homeowner to control a home’s heating or hot water and improve energy efficiency and reduce running costs. A thermostat is set to determine when the internal temperature is reached and send a signal to the heating system to heat up or cool down.

Pros:

• Central heating controls and room thermostats can be installed without replacing a boiler, enabling a homeowner to regulate the use of energy in areas of the home depending on heating needs.  
• The process of installation is much simpler than any other renewable home energy upgrade and can save a homeowner up to 20% in home energy costs.

Cons:

• There are many different types of central heating control options and deciding what you want, or need can take a bit of research.
• The more complex the set-up, the more difficult troubleshooting can be for the homeowner and the need to call upon a central heating engineer when issues occur.

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