Ground Source Heat Pump

ground source heat pump Ground Source Heat Pumps – Their Cost, Their Installation and Their Efficiency

Heating accounts for a significant portion of a household’s energy demand and a ground source heat pump system can provide a cost-effective and sustainable way to warm a home. The pump uses a small amount of electricity to transfer naturally occurring heat from the adjacent ground into the house.  As the temperature just a couple of metres below the surface remains more or less constant at 11°C to 12°C, it is possible to design a very efficient heat transfer system.

How does it work?

A sealed loop of fluid-filled pipe is buried in the garden or driveway. The length required depends on the size of the home and the amount of heat required. An average system for a family dwelling will typically require pipework up to 100m long.  Vertically drilled boreholes and deeper pipes can be used in more confined spaces. Once installed, the ground is restored to its original condition and the system becomes invisible.

The ground source heat pump circulates water and antifreeze around this loop. The fluid absorbs heat from the ground before it passes through a heat exchanger.  Energy is then transferred to the heating and hot water circuits of the home. The cooled fluid flows back into the ground loop in a continuous process for as long as the heating is required. Some systems can also be designed to meet cooling needs in summer.

While there are some minor residual energy and carbon costs, hooking the pump up to a home renewable technology such as a solar panel can increase its sustainability credentials even further.

What properties are suitable?

Ground source heat pump systems are not suited to every type of property. In general, they work most efficiently in well insulated homes with a relatively even and low heat demand. They produce heat at a lower temperature than more conventional central heating so a larger area is required for heat distribution. Underfloor heating is the ideal partner, though large heat pump system radiators are available. The system also requires sufficient outside space for installation. While minimal on-going maintenance is required, there can be considerable disruption during installation, and the system tends to be more attractive for new-build or as part of a wider home improvement project.

A typical domestic ground source pump is the size of a large upright fridge freezer. To save indoor space they can be installed in an outbuilding or basement.  They just need to be as close as possible to the end of the ground loop pipe. With a typical noise level of a little over 40dB at one metre away, they are as quiet as a fridge.  That’s considerably quieter than a typical gas or oil central heating boiler.

What do they cost and how much will I save?

Costs and savings will be dependant on the size of the pump, the length and depth of loop installation, the energy efficiency of the property, the sort of heating system that is being replaced and whether any additional work is required on the wider home heating system.  A typical domestic installation costs £12,000 to £15,000, with annual running costs of £600 to £700. At current prices, the payback from a ground source heat pumps is unlikely to represent an attractive alternative to an established mains gas central heating system. However, installers claim energy savings of nearly £1,500 annually for a typical four-bedroom house when compared with standard electric heating, or around £600 when compared to oil-fired central heating. That represents a saving of nearly 5,000kg of CO2 emissions each year.  Government Renewable Heat Incentive grants are currently available for installation.

Their installation will also greatly improve your energy efficiency score on your EPC.

If you liked this article, have a look at some of our other recent posts.

Property Size and Type and its Effect on Energy Usage and Your EPC

European Directives on Building Energy Performance

Top Tips for Selling Your Home

Comparing the Energy Efficiency of Modern and Traditional Walls

Waste Water Heat Recovery Systems (WWHRS) and your EPC

Are Conservatories Energy Inefficient?

Renewable Energy Keeps Getting More Popular

If you’d like to book an EPC for your home, simply contact us by phone or email, or fill in our contact form.


Renewable Energy Keeps Getting More Popular

renewable energyÄ_ti-rÄ_nana-annual-christmas-concert-8-december-2012,64 Renewables enjoy a rising wave of support

The UK Government monitors public attitude towards renewable energy technologies and climate change through a regular survey. The tracker was launched in March 2012 by the Department of Energy and Climate Change (DECC), now part of the Department for Business, Energy and Industrial Strategy (BEIS).

Known as the ‘Energy and Climate Change Public Attitudes Tracker’ (PAT), the main survey is carried out annually in March, with three supplementary short surveys in June, September and December. The repeat questions track the public’s views on important energy issues.  Each survey is known as a ‘Wave’ and the results of the Wave 25 survey were published recently. Wave 25 comprised 2,102 face-to-face, at-home interviews with a representative sample of UK adults. The background and detailed data are available on the UK Government website (here).

The latest survey results suggest a rising tide of public anxiety over climate change issues, with 74% of respondents saying that they were ‘very concerned’ or ‘fairly concerned’. The rise from 71% in May 2017 is a continuation of a growing trend. Perhaps due to on-going coverage in the media, a greater proportion of the public now accepts that climate change is the result of human activity rather than natural process. Just less than 50% said that they believed climate change problems were caused mainly by human activity, compared to only 10% who believed they were down solely to natural processes.

The latest Wave 25 results show overwhelming backing for renewable energy technologies, especially solar power and offshore wind farms. A comparison with the results from previous years reveals that public support for the use of renewable technologies to supply electricity, fuel, and heat has been climbing steadily.  It has now reached 85%, the highest recorded level since the tracker was set up. Only 3% were opposed.

In terms of the individual clean energy technologies, solar was given the greatest vote of confidence at 87%, with offshore wind reaching a record high of 83%. Close behind came wave and tidal power at 81%, onshore wind turbines at 76% and biomass power stations at 69%. The survey results also seem to indicate a reducing NIMBY effect, with people getting used to seeing and accepting large scale renewable projects in their own areas. 66% now say that they would be happy to have a development locally, compared to 58% in the same month of 2017.

By comparison, support for nuclear energy was largely unchanged over the year at 38%, with 22% opposed. The public’s attitude to shale gas extraction also remained essentially stable at just 18% in favour and 32% opposed.

The Wave 25 survey also included questions about perceptions of home energy efficiency.  Interviewees were asked what two things they thought use the most energy in the home. The answers included central heating (71%), large appliances (45%), and hot water (37%). When asked about home energy efficiency measures, 78% had installed double glazing, 65% loft insulation and 44% cavity wall insulation. Awareness of under floor insulation and solid wall insulation was much lower than for the other energy efficiency measures.

A question was also asked about home Energy Performance Certificates (EPCs).  63% were aware of EPCs, an increase over recent years, but only 9% claimed to know the rating of their own home.

It seems renewable energy is here to stay and will continue to play a greater role in all of our lives.

If you’d like to book an EPC, please feel free to contact us.

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Property Size and Type and its Effect on Energy Usage and Your EPC

Are Conservatories Energy Inefficient?

European Directives on Building Energy Performance

Comparing the Energy Efficiency of Modern and Traditional Walls

Property Size and Type and its Effect on Energy Usage and Your EPC


xenical purchase Energy usage by property size and type

It’s a simple fact that large old detached houses have a lower EPC score than modern flats.

Logic suggests that, on average, larger properties will generally use more energy for heating than comparable smaller ones. However, there are many variables involved in such a calculation, not least of which will be the type of property. Flats tend to have fewer external walls and roofs than terraced houses, which in turn have fewer than semi-detached or detached houses. The larger the external surfaces, the greater the expected loss of energy. Other variables such as the age of the property, building materials and the effectiveness of energy efficiency measures that have been installed also confuse the picture.

So although there are a lot of things you can do to influence the score of your EPC, some things you can’t.

A large sample of households would be needed to make an analysis of energy need by dwelling type statistically reliable. The Government’s Home Energy Efficiency Database (HEED) provides such a data set. While not freely available to individuals, the information is available to researchers and organisations planning and monitoring progress in home energy efficiency. It includes information collected between 1995 and 2012 on some 13 million dwellings in the UK, almost half of the country’s housing stock. The data includes property age, type, tenure and energy use, and details such as glazing type, wall type, heating systems and energy efficiency measures.  All of which are fundamental to EPC calculations too.

Researchers at the Energy Institute of University College London were given access to the database to undertake a wide range of analyses, including an evaluation of average energy usage by dwelling type and number of bedrooms.  Their research is reported in the journal Energy Policy (Energy efficiency in the British housing stock: Energy demand and the Homes Energy Efficiency Database. Hamilton I.G. et al, Energy Policy 60 (2013) pp 462-480).

The researchers analysed the data to provide an overview of the statistics for gas and electricity use in 2006 by different types and sizes of dwelling. The following tables summarise their findings, giving the median value in each case (i.e. the mid value when all data are set out in increasing order of size), as they showed this to be a more representative ‘average’ than the mean. The figures for gas and Economy 7 tariff electricity are likely to be most representative of energy demand for heating.

Median energy use for different types of property


Normal tariff  Electricity (kWh/yr) median

Economy 7  tariff  Electricity (kWh/yr) median

Gas (kWh/yr) median









Terraced house




Semi-detached house




Detached house




Median energy use for different numbers of bedrooms

Number of bedrooms

Normal tariff  Electricity (kWh/yr) median

Economy 7  tariff  Electricity (kWh/yr) median

Gas (kWh/yr) median





















As expected, the results confirm that detached houses and bungalows have the highest energy usage. The figures show a clear decrease in demand as the level of detachment declines, so that flats, with the highest number of party walls and ceilings, show least energy usage.  Something which EPC scores also make clear too.

The median gas demand increases on average by 22% for every additional bedroom over one in any property type. Overall electricity use also generally increases with additional bedrooms, though not as clearly and steeply as gas.

European Directives on Building Energy Performance

energy efficiency

The European perspective on building energy performance

Whilst looking at your EPC and considering the energy efficiency implications for your home, consider the wider perspective.

In April, the European Parliament gave its final consent to a revised Energy Performance of Buildings Directive. This is a key plank in the European Commission’s intention to lead the transition to clean renewable energy and to create ‘a resilient Energy Union and a forward-looking climate change policy’.  Whilst maintaining a fair deal for all energy consumers. It is the first of a series of measures to promote the EU’s ‘Clean Energy for All Europeans Package’, and a major contribution to its commitment to cut carbon dioxide emissions by at least 40% by 2030.

The Directive looks to up the rate of building renovations to make them more energy efficient and to foster more use of smart automation and control systems to improve energy performance in new buildings. It starts a clear path towards the creation of a low emission building stock across the EU by 2050 and underpins national roadmaps to decarbonise buildings.  This directly affects you if you require a commercial EPC.

The concept of a ‘smart readiness indicator’ is introduced. This measures the capacity of a building to use new technologies and electronic systems adapted to the needs of the occupier, optimise their operation and to successfully interact with the grid.

The EU is looking to realise the massive potential for energy efficiency improvements in the building sector, which is responsible for some 40% of final energy use.  It estimates that approximately 75% of buildings are energy inefficient and capable of improvement.  The rate of building renovation varies by Member State, but overall only 0.4% to 1.2% of the stock is renovated each year.

These data also highlight the potential economic opportunities of the programme. The construction sector generates some 9% of European GDP and directly supports 18 million jobs. Building renovation work and energy technology retrofits add almost twice as much value as the construction of new buildings, and these areas are particularly important for small and medium-sized businesses. The proposals will also help to create jobs in the smart technology sector, combat energy poverty and save consumers money through the renovation of older, less efficient buildings, and improve quality of life.

The EU recognises that significant up-front investment is required for the refurbishment of buildings and that public and private financing will need to be mobilised. The Directive is supported by financial enabling tools to help achieve the necessary investments. This include revised Eurostat guidance for energy performance contracts and a ‘Smart Finance for Smart Buildings Initiative’. The European Fund for Strategic Investments has also been expanded. This is focussed on sustainable investments that contribute to the EU’s energy and climate targets and help to deliver the transition to a resource-efficient, circular and low-carbon economy.  At least 40% of the Initiative’s infrastructure and innovation projects are intended to contribute to the European Commission’s commitments to climate action and energy transition in line with the Paris Agreement objectives.

Following the formal agreement of the introduction of the Directive by the Council of Ministers and its subsequent publication in the Official Journal of the Union, Member States will have to transpose the new elements of the Directive into national law within 20 months. This will therefore be one of the first tests of the UK’s reaction to an EU Directive once Brexit has been achieved.

How will the energy efficiency of the UK be affected?  Will it have an affect on your EPC requirements?

Are Conservatories Energy Inefficient?


Do conservatories conserve energy?

How does a conservatory affect your EPC?

While undoubtedly being great for providing additional light-filled living space, the question of whether conservatories are good for energy conservation is less straightforward.   Just how much is your conservatory costing you and could it have a detrimental effect on your EPC?

A conservatory is a popular and relatively cheap way of extending a home. If it has a floor area of less than 30sqm, a door that thermally separates it from the house and it is not connected to the house heating system, a conservatory is also generally exempt from Building Regulations Part L controls, and possibly also planning permission, depending on its position and the history of extensions to the property.

However, all too often the conservatory becomes a very costly addition when on-going heating bills are considered.  The cheapest, aluminium-framed conservatories of the 1970s and 1980s and those with polycarbonate rather than glass roof panels are particularly poor in terms of energy efficiency, and there is very little retrofitting that can be done to make significant improvements.

In the right place, conservatories are great for harvesting heat from the sun, but this can mean they become too hot in the summer while being very inefficient in the short and often cloudy days of winter. A south-east facing conservatory is generally considered best, as it will collect heat from the morning sun and be less prone to overheating during the warmest part of the day.

The positive side of the winter story is that a closed and unheated conservatory may provide a slight buffer to the rest of the house against cold weather, reducing the temperature difference between the main room and the outside by a few degrees. For this to be effective, the conservatory must be thermally separated from the main part of the house with solid, draught-proof doors, or glass doors with thick curtains. Thermal mass in the conservatory will store winter heat for longer, so exposed brick walls that catch the sun and a stone floor will absorb then slowly release the energy.

The downside is that many families need the conservatory as a living space year-round, and soon discover just how inefficient they are at conserving heat.  It is simply not feasible to insulate such an extensively glazed space sufficiently, so the only energy and cost efficient way to run a conservatory is not to heat it.

While a conservatory can never be brought up to the thermal standard of even an un-insulated cavity walled room, for a family that has no option other then to use and heat the conservatory there are measures that can help a little. Modern double-glazing with ‘Four Seasons Glass’, blinds and shutters can all help to reduce the amount of wasted energy.

A more radical solution is to replace the glazed roof with solid, insulated panels. The situation in relation to planning permission and Building Regulations should be checked. Installers claim that modern panels can be up to eight times more efficient than a polycarbonate roof, and some fit ‘multifoil’ insulation which is very efficient at heat deflection in the summer while helping to protect against damp and condensation in the winter. This is said to reduce the hottest summer temperatures in the conservatory by 70% and make it 90% warmer in the winter. While such figures sound impressive, the conservatory will nevertheless still suffer a very significant loss of energy through the winter if heated.

Remember, conservatories that are not thermally separated can have a detrimental impact on your EPC score.

Building Regulations


Home energy efficiency and the Buildings Regulations

Britain has a long history of controls on building construction. As far back as the early 1200s, there were problems of uncontrolled building in London, especially around party walls, gutters, the siting of ablutions and fire risk. Local ordinances were developed to tackle the problems at a community level.

The Great Fire of London, exacerbated by the congested layout of buildings and combustible building materials, led to the introduction of the London Building Act 1667, covering the main City. This provided for the employment of enforcement surveyors. A comprehensive Act was introduced in 1774 to cover the whole of London’s built-up area, and local building control regulations had been introduced in many British cities by the end of the 18th century.

The widespread cholera epidemic of the 1830s shone a light on the public health implications of uncontrolled building, and for the first time is was recognised as a national problem requiring national legislation. Developers and local authorities resisted this and local control was maintained through the Local Government Act 1858. This empowered local authorities to make byelaws to control the construction of buildings.

The Public Health Act 1875 consolidated a raft of Victorian public heath legislation, and subsequent Acts of 1890, 1907 and 1936 gave local authorities even greater control over building, still with a focus on public health implications.

By 1936, 60 local authorities were still to develop building byelaws, raising the need for a national system again. The Second World War interrupted progress, and afterwards any form of intervention was seen as restricting the urgent need for reconstruction. The replacement of local byelaws by national legislation did not happen until the introduction of The Public Health Act 1961 and the Health and Safety etc Act 1974.

The first set of national building standards to prescribe specifications for local regulations was introduced in the Building Regulations 1965. A nationwide Building Act was finally introduced in 1984, 144 years after it had first been proposed. Section 1 of the Act gave powers to the Secretary of State to make Building Regulations ‘for the purposes of ‘…furthering the conservation of fuel and power’.

The inclusion of energy efficiency considerations in Building Regulations can be traced back to 1962, when provisions were added to control condensation, with indirect implications for energy use. In 1972 this was extended to include home energy conservation measures. Subsequent iterations in 1976, 1985, 1990, 1995, 2002, 2006 and 2013 tightened up standards for home energy efficiency.

The main thrust of energy efficiency measures were set out in Part L of the 1984 Act, which gave guidance on building fabric. It was updated in 1995 with a wider focus on energy efficiency. Part L went through fundamental changes in 2006, introducing the Standard Assessment Procedure (SAP) for the assessment of the energy and environmental performance of dwellings, including, for the first time, consideration of carbon emissions.

Part L of the current Building Regulations 2010, Conservation of fuel and power, is now supported by four guidance documents and two compliance guides.

Most of the recent changes to the Building Regulations focus on the U-value of homes. This is a measure of the effectiveness of insulation. Over time, the requirements for walls have been tightened significantly:

  • 1965; 1.70
  • 1976; 1.00 (1.70 for semi-exposed walls)
  • 1985; 0.60 (1.00 for semi-exposed walls) – cavity wall insulation being installed as standard
  • 1990; 0.45 (0.60 for semi-exposed walls) – thicker wall cavities adopted
  • 2002; 0.35
  • Current; 0.30

There have also been radical improvements in roof space insulation as a result of the following U-value requirements:

  • 1965; 1.40 (achievable with less than 3cm of insulation)
  • 1973; 0.60 (approximately 7cm of insulation)
  • 1985; 0.35
  • 1990; 0.25
  • 2002; 0.20
  • Current; 0.17 (approximately 25cm of insulation)

Building regulations make up an important part of your EPC calculations.  Book an EPC today to find out how energy efficient your home is.

Energy Performance Contracts


Where now for domestic energy efficiency policy?

While the UK Government concentrates policy effort on developing new, more flexible energy sources, there is an increasing realisation that there is another side to the equation. Perhaps the single most significant measure we could adopt to secure our energy future and to reduce carbon emissions is to make more efficient use of energy by reducing demand and wasting less.

The UK unnecessarily throws away almost a third of the energy it uses. This represents a major cost to consumers and the environment. Implementing further energy efficiency measures would reduce carbon emissions, create jobs and ultimately save more money than it costs. However, at the household level, policy and schemes that have been tried so far have made little impression on the opportunity.

The Government’s Green Deal scheme was scrapped in 2015 after a disappointing take up. While more than 300,000 assessments were undertaken, less than 2,000 resulted in active projects, a conversion rate of less than 1%. The Green Deal was a ‘pay-as-you-save’ scheme with loans made available to pay for energy efficiency measures. These were to be repaid over a period of up to 25 years through electricity bills from the financial savings that resulted. However, the 7% to 10% APR interest rate charged to home owners proved unattractive, unsurprisingly perhaps given that it was several percentage points higher than ordinary bank loans available at the time. 

So where will Government policy guide us next? High cost loans have not worked. While many householders have implemented low cost energy efficiency measures, it seems that incentives may be necessary to persuade them to go further. The goal must be to encourage them down the route of implementing more effective measures such as insulation, renewables and energy efficient heating, but policy tools are needed to deal with the high capital costs and often long return periods.

Maybe there is a clue towards the future direction of policy travel in a glimmer of hope in the public sector, where there is an increasing interest in Energy Performance Contracts (another ‘EPC’).  These formal partnerships between a public body and its energy services company (ESCO) were introduced by The Energy Efficiency (Encouragement, Assessment and Information) Regulations 2014. The contract covers the design and provision of specific energy-saving measures and on-going monitoring. It guarantees that the measures will generate sufficient savings to pay for the project, ensuring a secured financial saving over the period of the agreement. Any savings beyond the end of the contract go to the customer.

While it is early days, one EPC between E.ON and Leeds City Council is tackling energy efficiency in nine public buildings, including schools, leisure centres and data centres. The seven-year contract is projected to achieve a 26% saving in energy costs through a range of measures, such as new lighting, boiler and voltage optimisation, and upgraded building management systems. E.ON is responsible for the up-front investment, and has guaranteed that the savings over the seven years will cover all equipment and installation costs. In addition to being able to fund the repayments from the savings made, Leeds City Council will see reductions in energy costs over the long-term, improved building performance and the project is helping it meet its own environmental aspirations and obligations as a public sector body.

Book an EPC to find out how you can make your home more energy efficient.

A Proactive Approach to a Passive House

EPC - Passive House

A proactive approach to a Passive House

‘Passive House’ is a standard for a cost-effective, low-energy construction concept that produces buildings with remarkable energy efficiency qualities without compromising on comfort.  

With all of the necessary information published freely on-line, it is claimed that any competent architect can design a Passive House. The standard is also relevant to non-residential buildings such as schools and offices. While it is most simply achieved with a new-build, it can also be successfully applied during a major building renovation.

Passive House buildings combine the use of energy efficient materials, a very high level of floor, window, roof and wall insulation and an airtight design. They are designed to be ‘thermal bridge free’, meaning the insulation has no cold corners or weak spots, reducing any problems with condensation. Ventilation is nevertheless essential, and an unobtrusive system supplies constant fresh air to maintain high levels of internal air quality without creating draughts. It incorporates a highly efficient heat recovery unit that captures heat for re-use in the building.

The designers ensure that the building makes such efficient use of the sun, internal heat sources such as domestic appliances and heat recovery that a conventional heating system is unnecessary, even on the coldest days of winter. This is what defines a Passive House. During the summer, passive techniques such as strategic shading help to keep the building comfortably cool.

Tests and calculations on existing Passive House dwellings are producing some impressive data. Measurements carried out on more than a hundred Passive House properties in central Europe as part of the European Union’s CEPHEUS project showed average energy savings of approximately 90% by comparison with traditional building stock, and 75% savings against new-build equivalents.

As a result, Passive Houses are environmentally friendly by definition. While some additional energy may be required initially for their materials and construction, this is insignificant by comparison with the energy savings they enable throughout the life of the building.

Similarly, the necessary financial investment in high quality materials and design required by the Passive House standard will be offset by the greatly reduced cost of installing and running heating and cooling systems. Calculations for German Passive Houses suggest that initial construction costs are now only approximately 5% higher than those of a comparable traditionally built house. Payback periods of course depend on the size and construction cost of the building, but under most circumstances the reduced running costs are likely to offset the construction costs in two to three decades, even allowing for loan repayments.

The Building Research Establishment (BRE) is one of the certifying bodies for Passive Houses, and there are fewer than a hundred of its Passivhaus buildings in the UK. The ‘Sleepy Dorset’ blog (here) tells the story of one family’s self-build Passive House since 2016 and its successful achievement of Passivhaus status. It relates how the house performed in Dorset’s coldest winter weather for many years in March 2018, and how the family awoke each morning to a comfortable 18ºC without any heating, despite outside temperatures of -6ºC and thick snow.

Draught Proofing – The Cheapest Way to Energy Efficiency

Draught proofing

Dealing with draughts

Draught proofing windows and doors is one of the least expensive ways of increasing the energy efficiency of a home. Some ventilation is required to reduce condensation and prevent mould, but the method should be controllable so that welcoming fresh air in the relative warmth of the day does not become an uncomfortable cold draught by the evening.

As simple as it is, draught proofing is a consideration for an assessor when providing a home with an EPC.

Do not alter external air bricks or wall vents without professional advice, as these may be essential for maintaining the fabric of the building. Flues that are in use for fireplaces or boilers must not be blocked.

Even a slight draught can make a room feel disproportionately chilly in cold weather.  A well-insulated room will feel warmer and more comfortable, often meaning that the thermostat can be turned down a little, doubling up on the energy and cost savings.  For an average house, a thorough draught-proofing job can reduce heating bills by £20 to £30 a year.

This is also one of the easiest home energy efficiency projects to do. A professional job is likely to cost less than £300 for an average house, or most of the measures can be carried out quite simply by householders with the most basic of DIY skills and tools for less than £100.

DIY stores and hardware shops carry a bewildering array of draught proofing materials and it is worth investing in good quality and tested products that carry the BSI kite mark.  The larger stores offer instruction leaflets that help you to choose and install the best products.

Before you start, undertake a detailed audit of places where draughts may be entering your home and make a list and measurements to take to the store.

Amongst the most common sources of draughts are letterboxes and keyholes in external doors. Loft hatches are another common culprit. All are easily dealt with using proprietary products. 

The next group of sources to consider are the unintentional gaps left during building and maintenance:

  • window frames
  • opening windows
  • door frames
  • doors
  • floorboards
  • pipes that lead from rooms to the outside
  • electrical sockets and fittings on walls and ceilings
  • joints where walls meet the ceiling.

Most of these can be dealt with using a suitable flexible silicone sealant. Add self-adhesive draught-proofing strips or brushes around opening windows and use the sealant in any gaps between the frame and the wall. Foam strips do not work well on sliding sash windows, so fit brush strips or consult a professional.

For external doors, buy a drop-down keyhole cover and a letterbox flap or brush. Gaps between the door and the frame can be sealed with foam or brush strips like those used for windows.  A large brush or hinged flap draught excluder will deal with the larger gap at the bottom of the door. Gaps around the frame can be filled with the sealant.

Keeping doors closed is good practice and an old-fashioned draught-excluder can be laid across the bottom of any door to stop the last remnants of draughts and to give a feeling of comfort.

The Biomass Boiler Alternative

Biomass Boiler

An Introduction to Biomass

Households that are not keen on modern renewable energy technologies might prefer a more traditional wood burner or biomass boiler. Man has been burning wood to provide heat since he first harnessed the power of fire in his cave, but a modern biomass boiler offers a more sophisticated solution to home heating.

Simple wood burning stoves provide heat and a focal point for the main room and can include a back boiler to run small-scale central heating and hot water systems. A biomass boiler works like a normal gas or oil boiler but they burn renewable biomass instead. New generation systems are easy to use and deliver greater than 75% energy efficiency using pellets or properly dried wood.

Systems are available for a range of fuels, including logs, wood chips, sawdust, grass-derived biomass pellets or even peat. The choice of fuel will be dictated by the availability and price of a reliable local supply and the type of storage available. The greatest savings are made when buying in bulk so to get the best deal a significant amount of storage space is required.

Pellets are much easier to transport and store than logs, and provide a more controllable heat. Pellet-fuelled biomass boilers are available with automatic fuel feeders and they can be programmed in much the same way as conventional gas boilers. Log-burning stoves and boilers involve considerably more work and are less controllable.

The installed cost of a wood burning stove will be around £2,500 to £7,500, depending on the model and the availability of a flue. The price of a full biomass boiler system is greater than that of a comparable gas boiler at between £10,000 and £20,000, depending on model, size and ease of installation.

After the initial outlay, the system should reduce energy bills over time, with some studies suggesting that a biomass boiler can save the average household up to £800 a year when compared with standard electric heating, or up to £210 a year compared with an old G-rated gas boiler. However, at typical 2018 prices, running a biomass boiler is likely to cost more than a modern condensing gas boiler.

To maintain efficiency, the flue will need to be cleaned annually at a cost of around £50. Another downside is the need to remove and dispose of ash. Some biomass boiler systems have automatic ash removal and compression systems that make the job easier.

Government support is available for the installation of a biomass boiler or biomass stoves with a back boiler through the Renewable Heat Incentive scheme. The income depends on the system and the amount of energy it produces but the payment for a biomass boiler in a four-bedroom, detached house may be nearly £2,000 per annum. To be eligible, the property must have a compliant EPC that is less than two years old.  There is a calculator and information on the BEIS website here.