Renewable energy technology: Is there a catch?


Generating your own renewable energy is a prospect that many consider too complicated or costly to put into action. However, the tide is turning with renewables as the long term benefits are starting to more easily outweigh the initial upfront costs.


Modern new build homes, however energy efficient they may be, still require electricity and some form of heat. Whilst the decarbonisation of the electrical grid means that it is now the greenest energy network option available, it is still better to generate your own energy on site if you can.


As we are attempting to move away from gas boilers and the use of fossil fuels (whether this is successful in the next 10 years or not) an entirely electric home is an exciting and necessary option to consider. Added to the environmental and cost benefits, electric only homes have more opportunity to be fully reliant on renewable energy, vastly lowering the carbon footprint of the homes we live in.



First step: Reduce the amount of energy your home requires


Building an airtight home with excellent thermal performance means that it requires much less energy to run in the first place. This should always be the starting point when building a new home, and the first port of call for an existing home should be to upgrade the building’s fabric e.g. roof insulation, better glazing etc. so that you retain more heat than before.


If you are interested in creating an even more sustainable home, integrating renewable energy technologies can lower its environmental impact, and running costs, even further.


Next step: Consider renewable energy sources


Renewable energy comes from a sustainable source that doesn’t run out. The main renewable energy sources that can be used for individual homes are the sun, the wind and running water.


These translate into solar energy, wind energy and hydro energy, while the lesser known (and used) biomass energy can also be used to create heat for homes.



What are the main options for generating renewable electricity?


1. Photovoltaic panels


Better known as solar panels, these are the most established renewable energy technology in the homebuilding industry. They capture energy directly from the sun and turn it into electricity. The falling costs of this technology means they can now be installed from about £6,000 to £10,000.


Traditionally placed onto south facing, pitched roofs, emerging technologies have shown they can be integrated seamlessly into the design of a home, e.g. solar tiles from Tesla. Alternatively they can be carefully hidden from view on flat roof properties, or even placed within the surrounding landscape.


2. Hydroelectric systems


Small-scale hydroelectric systems can be used to power a home. Hydroelectric technology harnesses the power of water in motion. It is not a viable option for many people because it is dependent on the access to a source of running water, as well as how fast it flows and how much volume of water passes through.


A typical 5kW system to power one home will cost around £25,000. The good news is that once the system is installed it requires very little upkeep.


3. Micro-wind turbine systems


The UK is already the world leader in offshore wind energy generation, but individual domestic turbines are also readily available. Placing these systems in an exposed position, wind power can produce more than enough energy to power the lights and electrical appliances in a home.


Requiring a very specific site, and subject to planning permission, standalone turbines cost between £9,900 and £19,000 for a 2.5kW system, while a 6kW version is likely to be between £21,000 and £30,000. Some of the larger wind turbines feature artistic and architectural designs that offer an aesthetic as well as functional benefit.



What are the main options for generating renewable heat?


1. Air source heat pumps


Absorbing heat from the outside air to provide heat and hot water for a home, these pumps continue to extract heat from the air even when temperatures are as low as -15 degrees celsius.


Heat from the air is absorbed at a low temperature into a fluid, which passes through a compressor, increasing the temperature. This temperature is then transferred to the heating and hot water circuits of the house. Whilst it uses electricity to compress that energy, you get a good return.


An air source heat pump before installation at our Hertfordshire project.

2. Ground source heat pumps


Harnessing solar energy from below the earth’s surface, heat from the sun that has been store up in the ground is absorbed at low temperatures into a fluid inside a loop of pipe buried underground, either in trenches or a vertical borehole. As with air source, the fluid then passes through a compressor that raises it to a higher temperature, which is used to heat water for the house.


Despite the greater upfront cost, this type of pump is more efficient than an air source heat pump when it comes to heating your home, so is often a better option if you have the space outside.


3. Solar thermal systems


Using the heat from the sun to heat the hot water for a home, these systems are robust, simple and effective with a long life and relatively cheap installation costs. They qualify for the Renewable Heat Incentive (RHI) and there are two main types of system: flat plate and evacuated tube.


Both systems are placed on the roof of a home (preferably a south facing roof) and could be mistaken for solar panels. Photovoltaic thermal (PVT) systems combine the two solar systems to offer energy generation for hot water and electricity.


4. Biomass heating


Not always strictly considered a renewable energy source due to not having an infinite supply, biomass heating depends on the combustion of grown products, such as wood pellets, logs and chips. They do also contribute to carbon dioxide emissions.


However, wood can be considered a renewable resource provided it comes from sustainably managed forests. Biomass boilers are larger than a normal boiler and so a site would need the space to house them, along with storage for the fuel (chips etc.). Costs are around £5,000-£12,000 depending on whether you choose a log batch boiler or pellet boiler.

Solar panels are just visible on the right hand side of this latest Facit Home in Stroud.

Is there a catch?


One main drawback of electricity generation is that you have to use the energy as you are producing it or it will be fed into the national grid with precious little payback. Therefore when, and how much, you use it has always been a major factor to consider.


But the market has responded, as it always does, with home batteries. At this stage it is a relatively infant technology but it allows you to store the electricity you generate throughout the day and use it on demand. Tesla Powerwall is one of the available options for battery storage. Expect to see more players enter the market and for this solution to mature very quickly.


These technologies all have an upfront cost, which will take time to pay itself back to you via lower energy bills. When you create a home that is highly energy efficient and uses less energy than a conventional home, it’s worth considering that this payback will take even longer but the environmental benefit could be seen as justification in itself.


The tech is also continuing to improve and costs will continue to fall. There are still some government backed subsidies for those using them, such as Renewable Heat Incentive (RHI), and the huge environmental benefits could be seen to justify the cost.


If you were to use your own electricity generation (e.g. solar energy) to power a heat pump (e.g. ground source heat pump), the dream of a fully off grid home is well within reach.


Has Facit Homes installed any of this renewable energy technology?


Many of our customers have been interested in generating their own energy. We have installed many solar panels, as well as both ground and air source heat pumps which work well with our underfloor heating system. No wind turbines quite yet though…


We discuss all of these options with our customers at the outset of a project, to make sure that we are factoring the cost of any requirements to the overall project budget and any design implications that may need to be considered.

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