Case studies

Ground source heat pump

Dr Lawn

When Dr Lawn decided to build a three-bedroom house he wanted to make its energy supply as sustainable as possible. He had been interested in the conservation of energy for many years and felt that wasting raw materials on heating was unnecessary when so many renewable energy sources were available. Having seen heat pumps working in America he was very impressed with what they could do, so when the opportunity arose to replace an old house with a new build he looked into the possibility of using a ground source heat pump.

Installing a heat pump

Dr Lawn’s installer and architect worked together closely to ensure that his new house was designed to maximise the efficiency of the heat pump. As heat pumps run at a lower temperature than normal central heating systems, he was advised that he would need under-floor heating combined with the right insulation in the walls, floors and loft.

To make even more savings, the windows were positioned to absorb passive heat from the sun into the house.  A solar water heating system, also funded by the Energy Saving Trust, was installed.

The location of Dr Lawn’s home was ideal for a ground source heat pump as he has plenty of ground space which allowed him to dig horizontal trenches for the ground loops. However, the installation process took longer than expected because large rocks were discovered when the trenches were being dug. This also increased the cost of the installation by several thousand pounds, making it more expensive than a normal system of this size.

The benefits

Dr Lawn is very proud that his house will use considerably less energy than it would have done without the heat pump and solar panels. Although the capital costs of installing a heat pump were quite high, he thinks the environmental benefits make it a worthwhile and sensible investment.

Key points

• Heat output: 10kW
• Type of ground loop: horizontal 'slinky'
• Electrical input to power heat pump system: 3kW
• Proportion of heating met by heat pump: 100 per cent
• Fuel being replaced: electricity
• Estimated fuel savings: approximately £500 a year
• Estimated carbon savings: approximately 3,000kg of carbon dioxide a year

Solar PV electricity panels

Yorkshire: John Digby-Anderson

John Digby-Anderson lives with his wife in a detached, three-bedroom house in Yorkshire. Inspired by an Energy Show at Olympia, he began researching the options for reducing their carbon footprint. When the bungalow needed re-roofing, it was the perfect opportunity to install Solar PV (photovoltaic) tiles to generate electricity.

Installing solar PV tiles

John applied for a grant for solar tiles as a green home improvement (from the Low Carbon Buildings Programme, which has now ended) - he applied online, was approved for it and got his grant offer letter in less than 30 minutes. He decided to have the PV tiles installed on the south facing roof to absorb the most sunlight. The tiles were bolted onto John's roof with the help of a contractor. Now the system is installed, it takes care of itself - nothing extra needs to be done and it is never turned off.

The benefits: 70% of annual electricity

Photovoltaic tiles use energy from the sun to generate electricity. John's system calculates how much electricity it generates on a second-by-second basis.

In the first year, over 70% of his annual electricity was home-generated. With rising electricity prices, John's is finding his system becoming more and more cost effective.

The verdict: "We have become more attuned to nature."

Since the installation, John and his wife have become more energy-aware. "We notice and care more how much the sun is out," says John. "We notice and care more how much electricity we are using. This valuing of natural processes is in the long run perhaps the most important result of installing solar systems."

South West: Michael Solomon

Michael is an estimator for a construction company, and lives in the South West with his wife and two kids. The family kitchen has sun tubes installed, funnelling light and heat in from outside. Already impressed by the potential of alternative energy, Michael and his wife decided to install solar panels to generate electricity.

Installing a solar electricity system

Michael's three-bedroom house has lots of roof space. He hired a sub-contractor to help install solar panels on his roof. With a growing array of designs and colours of solar panels, roof-mounted systems can be installed in most properties.

Michael applied for a renewable energy grant, which paid for part of the installation. He used an inheritance to cover the rest of the costs.

The benefits: electricity from daylight

Michael's solar panels use energy from the sun to light the family home and run appliances. The system generates power even when it's cloudy. Michael has noticed a sizeable drop in his electricity bills as a result.

The verdict: satisfaction from smaller bills

Michael and his wife enjoy watching their savings add up. They use a spreadsheet to document what they are using and generating, and to keep tabs on their gas and electricity bills. They are very pleased with their renewable technologies.

Solar water heating

Aberdeen City, Scotland: the Kapurs

Mr and Mrs Kapur live in a three-bedroom semi-detached house in the centre of Aberdeen. When they first moved into their property they felt that the incumbent heating system was “archaic” and that the 30-year-old boiler needed replacing. Furthermore, the roof needed re-slating which prompted them to investigate installing a solar hot water system. Another deciding fact was that Mr Kapur’s father had installed a solar thermal system, and was pleased with the way it had performed.

In general they have been pleasantly satisfied: they have been able to turn off their boiler from mid-April to mid-October. Mrs Kapur says that they had an initial figure of a 10 to 15-year payback in mind, but with the grant this could be more like seven to ten years – they believe they are likely to be around half way through payback now. However, they clearly stated this is not why they installed their system and they don’t want money to override their environmental reasons for doing so, and as such they have not really looked at what reduction they have seen on their energy bills.

The total cost of the system was £3,000 with the help of a grant, which contributed to approximately 30% of the upfront capital cost.

Sussex: the Murrells

Mr and Mrs Murrell are both retired and have downsized to a three-bedroom bungalow, which has been retrofitted with both a solar thermal and solar photovoltaic (electricity generating) system. The Murrells currently benefit from feed-in tariff payments derived from their solar photovoltaic (PV) installation.

One of their main reasons for downsizing and installing renewable energy technology was to minimise their financial outgoings; and in order to maximise their savings they have also added additional loft and cavity wall insulation. The key factors driving them to invest in a solar thermal system (as well as solar PV) were a lack of return from their ISA and increasing energy prices. They were also looking towards retirement when their monthly outgoings would need to be reduced.

The cost of the solar thermal installation was approximately £4,000, of which they received grant assistance of £400 through the Low Carbon Building Programme. The rest of the money was raised through personal savings.

The Murrells feel that expectations to reduce their energy bills have largely been met, particularly in the summer months where they believe their solar thermal system can provide up to 100% of their hot water needs. The installation and operation of both the solar thermal system and solar PV system has been very pleasurable with Mr and Mrs Murrell seeing immediate benefits in terms of financial savings. They say that they would definitely recommend both solar technologies to others and would also consider an additional renewable energy system – such as a heat pump.

The LCBP grant the Murrells received is no longer available.

West Glamorgan, Wales: the Griffiths

Mr and Mrs Griffiths live in a four-bedroom detached house. They built their own home and already have under-floor heating in place, heated by oil.

They visited the Home Building Show at Birmingham NEC and were spurred to investigate installing a solar thermal system. The system cost was £3.500, minus a £400 grant (from the Low Carbon Building Programme grant, no longer running) and an additional £800 grant from Powys Council. The balance was made up from personal savings.

The Griffiths say that their key driver was to reduce energy bills and to that end, they confirm that they have already noticed ‘significant’ reductions in the use of oil. Current predictions would suggest that they would achieve payback in around six years.

There are more people in their house during the school holiday periods, but the solar system has coped with the additional extraction.

Wood-fuelled heating

Wales: Alice Cowell

A freelance environmental consultant in Wales, Alice was already conscious of energy issues. When she and her husband bought a new house with no mains gas, they decided a wood stove would be the best option.

A wood stove can be installed in a single day. Alice's stove was installed in mid-December, just in time to keep her family snug for the winter.

The benefits: a carbon-neutral way of heating

A wood stove provides heat for Alice's home. All they need to keep it running is a regular supply of wood as fuel. Burning wood only releases as much carbon dioxide as the tree absorbed while growing - and because trees can be replanted, the wood stove is carbon neutral.

Alice's home is now warmer and more comfortable, as well as environmentally friendly. The stove is also an attractive feature that adds value to the property.

The verdict: a green option - but with a learning curve

It took Alice and her family around a month to learn how to manage their stove. Their main challenge was finding a wood supplier who could tell them about the best way to run their stove. They now use small pieces of dry wood, which keep the stove running efficiently.

Alice would like to see a registration system for wood suppliers, to help other stove-owners find the right wood and the right advice.