Plumbing with renewables

The CIPHE is encouraging homeowners and developers to consider sustainable alternatives to traditional heating and hot water systems where possible.

If you need to replace your current heating and hot water system, are undertaking a new-build, or want to add green technology to your existing set-up, there are a number of ways to make your home more sustainable.

The technology you use will depend on your situation and requirements, but one thing is for sure, everything you can do to lower your carbon footprint is a step in the right direction.

Solar energy

In the UK domestic setting, there are two main types of solar panel systems in use, namely photovoltaic solar power (PV) or solar water heating.

Photovoltaic Solar Panels (PV)

This type of solar panel converts free and sustainable sunlight into electricity by using photovoltaic cells.

How PV solar panels work

PV cells are made from layers of semi-conducting material, usually silicon. When sunlight shines on the cell it creates an electric field across the layers. The panels send this direct current (DC) to an inverter, which turns it into alternating current (AC) – this electricity can be used in any application in your home. The stronger the sunshine, the more electricity is produced. Groups of cells are grouped together in panels or modules that can be mounted on your roof.

Pros and cons of photovoltaic solar panels

• Solar power can cut your electricity bills and your carbon footprint by up to 1.6 tonnes of carbon per year.
• The panels will still work even on cloudy days, though to a lesser capacity.
• Greater savings will be made during the daytime and during the summer, rather than the winter, due to daylight quality and quantity.
• You can be paid for any surplus electricity generated if you sell it back to the grid.
• Or you can keep the surplus energy and use it to power an emersion heater in a hot water tank etc.
• You can also combine PV with other renewable technologies such as heat pumps and solar water heating panels.
• You’ll need a decent amount of space on your roof to install this system, which should ideally face south, in an unshaded location and a pitch angle of 30-40 degrees.
• As a general rule, 10m² - 20m² for PV panels will generate between 20-40% of a typical household’s electricity needs.
• The greatest benefits come to those who use electricity during the day.

Initial installation costs are high, but as long as you stay in your home long enough, you can recoup the installation price through the savings the system makes.

Solar water heating

This system again uses free heat from the sun, but this time to warm domestic hot water.

How solar water heating works

Solar water heating systems use solar panels, called collectors, fitted to your roof. There are two main types of panels in use in the UK market:

1. Evacuated tubes - a bank of glass tubes mounted on the roof tiles.
2. Flat plate collectors - which can be fixed on the roof tiles or integrated into the roof.

In both cases heat from the sun is used to heat up water, which is stored in a hot water cylinder. A boiler or immersion heater can be used as a back-up to heat the water further to reach the temperature you want.

Pros and cons of solar water heating

• Solar water heating will provide hot water throughout the year, but just as in PV systems, the panels will generate less heat during the winter.
• You’ll still need use of a boiler or immersion heater as a back up – especially in winter. Check to see if your boiler is compatible with solar water heating before you have anything installed.
• Solar water heating will cut your bills and cut your carbon footprint.
• Solar water heating can be used with other renewable technologies such as PV and heat pumps.
• Solar water heating panels offer more flexibility in siting and size than PV panels.
• To get the best out of the system you’ll need approximately 5m² of roof space that faces East to West through South, and receives direct sunlight for the main part of the day.
• It’s likely you’ll also need a larger hot water cylinder or a dedicated solar cylinder with a solar heating coil.
• You won’t be able to sell back any additional heat generated to the grid – all hot water is for your use only.
• Initial installation costs are high, but as long as you stay in your home long enough, you can recoup the installation price through the savings the system makes.

Both types of solar powered systems can offer genuine ‘green’ solutions for helping you cut your energy bills and your carbon footprint.

However, you will need to talk to your heating engineer to see what system is right for you. As always, use an experienced professional via our Find a plumber or heating engineer online tool. 

Heat pumps

In the UK domestic heating sector there are two main types of heat pump technology, air source heat pumps (ASHPs) or ground source heat pumps (GSHPs). Both absorb heat from another element (the air or ground) to heat your home and hot water.

Air source heat pumps (ASHPs)

ASHPs can be used for heating, cooling and hot water. In UK residential use, air-to-water ASHPs are the most popular as they are compatible with wet central heating systems.

Heat pump technology has been used for many decades in air conditioning systems to provide cooling, or heating and cooling, in mainly commercial and industrial applications. It’s a tried and tested technology, which is set to take a greater hold in the domestic market thanks to the Government’s drive to low carbon technology.

How air source heat pumps work

Heat from the air is drawn into the heat pump and absorbed at a low temperature into a fluid. This fluid passes through a compressor that increases the temperature. It then transfers the higher temperature heat into the heating and hot water circuits of the property.

In basic terms, ASHPs extract renewable heat from the air, and transfer it to your heating and hot water system. While it does use electricity to do this, the heat output is higher than the electricity input, making it a sustainable system.

The Energy Savings Trust has a very good video on this process on its website energysavingtrust.org.uk

Pros and cons of air source heat pumps

• ASHPs need electricity to run, but are highly efficient.
• ASHPs can extract heat all year round and still work when air temperatures are as low as -15°C.
• ASHPs works particularly well with under floor heating and properties with larger radiators.
• ASHPs need to be installed outside, with enough space around it for good airflow. You will need room to either install it in your garden or attach it to the side of your building.
• The more heat and hot water you need, the bigger the ASHP will be.
• ASHPs will use more electricity in winter as they have to work harder to extract the heat from colder air, so you will still have higher winter heating bills.
• To get the best out of the system, your home will need to be well insulated.
• If you are replacing an electric heating system with a ASHP you will see a big reduction in running costs. However, if you are replacing a gas central heating system, then your running costs are likely to be similar.
• Depending on your Local Authority and if you are in a conservation zone, you may need planning permission to install a heat pump.
• ASHPs will cut your carbon footprint.
• ASHPs can be used with other renewable technologies such as PV and solar water heating.
• Depending on your type of heat pump, you can be paid for any surplus electricity generated if you sell it back to the grid.

Ground source heat pumps (GSHPs)

Ground source heat pumps can be used for heating, cooling and hot water. Like ASHPs they extract renewable heat from natural elements – in this case the earth.

How ground source heat pumps work

The system uses long lengths of looped pipe (known as ground loops) that are buried in the ground to extract heat from the earth. It does this by absorbing low temperature heat into a fluid inside the pipe and then running it through a compressor to raise it to a higher temperature. It then transfers the higher temperature heat into the heating and hot water circuits of the property. GSHP’s extract renewable heat from the ground and transfer it to your heating and hot water system. While it does use electricity to do this, the heat output is higher than the electricity input, making it a sustainable system.

The Energy Savings Trust has a very good video on this process at energysavingtrust.org.uk

Pros and cons of ground source heat pumps

• Just like ASHPs, GSHP’s need electricity to run, but are highly efficient.
• As land temperature stays reasonably consistent (between 10-13^oC all year round), GSHPs are effective throughout the year and are often more efficient than ASHPs.
• GSHPs work particularly well with under floor heating and warm air heating.
• GSHPs are low maintenance.
• You will need a garden or suitable amount of land to install this system.
• GSHPs are much more labour intensive and costly to install.
• The length of ground loops required depends on the size of your home and the amount of heat you need. Longer loops can draw more heat from the ground, but need more space to be buried in. If space is limited, a vertical borehole can be drilled instead.
• Vertical boreholes need to extract heat from much further down in the ground and typically measure 90m - 160m deep.
• To get the best out of the system, your home will need to be well insulated.
• If you are replacing an electric heating system with a GSHP you will see a big reduction in running costs. However, if you are replacing an efficient gas central heating system, then the reduction will be small.
• GSHPs will cut your carbon footprint.
• GSHPs can be used with other renewable technologies such as PV and solar water heating.
• You can be paid for any surplus electricity generated if you sell it back to the grid.

Biomass

Biomass can be used to heat your whole home, hot water or just a single room depending on the system you go for. While wood burning stoves are popular for heating single rooms - especially as feature fireplaces in living rooms - a biomass boiler can work along the same lines as a traditional boiler in heating your whole home and providing hot water too.

How biomass works

Biomass systems burn either wood pellets, chips or logs instead of using gas, oil or electric. This may not immediately look like a sustainable option as burning wood creates carbon dioxide (CO₂) and cutting down trees is bad for the environment. However, CO₂ is created at a much lower level than coal or oil and when the fuel is sourced locally its carbon footprint drops furthermore. The real sustainable element comes in when new plants are grown to replace those cut down for fuel, therefore creating a cycle where the fuel source is constantly replenished in a way that has less environmental impact.

Pros and cons of biomass

• The price of wood is low compared to alternative fuels.
• Biomass boilers can do the work of a standard boiler, so are compatible with wet central heating systems.
• If you choose to install a stove to heat a single room, e.g. living room, there is also the option to add a back boiler to provide hot water.
• A number of pellet and chip boilers use automatic fuel feeders, so there’s no need to manually refill them every time you need the system to work.
• If you’re considering a biomass boiler, you will need space for the boiler itself, which would be bigger than a gas or oil equivalent, as well as space to store the fuel.
• Many people buy fuel in bulk, so bills won’t be split into monthly costs like they are from the gas and utility companies.
• You will be reliant on fuel being delivered to you.
• You would also need a flue which meets the regulations for wood-burning appliances.
• Biomass appliances will require annual maintenance along with regular cleaning /ash removal. Some appliances have self-cleaning systems. Please refer to the manufacturers instructions.
• Flues and chimneys also require regular cleaning. Please refer to the manufacturers instructions.
• To get the best out of the system, your home will need to be well insulated.
• If you are replacing an electric heating system with a Biomass boiler you will see a big reduction in running costs. However, if you are replacing an efficient gas or LPG central heating system, then it may actually cost you more to run.
• Biomass will cut your carbon footprint.
• You won’t be able to sell back any additional heat or hot water generated to the grid – all heat and hot water is for your use only.

Ways to improve traditional heating and hot water systems

If the above systems are not currently suitable, then there are still steps you can take to make your current system as green as possible.

Use a green energy tariff

The majority of energy suppliers also offer green tariffs where electricity is generated from sustainable sources such as solar or wind farms. Ask your energy supplier for more details.

Ensure your system is regularly serviced

Appliances that are regularly serviced will be working at their peak efficiency and will be less prone to breakdowns. Make sure you have your gas appliances serviced annually.

System health check

It’s not just about ensuring your boiler is working properly, as while it may be the heart of the system, you could be losing efficiency in other areas. Ask your engineer for a full system health check to make sure everything is running as effectively as possible.

Insulate, insulate, insulate!

Make sure your loft and walls are adequately insulated to help stop heat escaping. Draught-proof any areas such as windows and doors too.

If you want more tips visit our how to save money on your fuel bills page.

Energy saving links

To gain professional advice on which sustainable system that is best for you, or on improving the efficiency of your current systems, talk to your local heating engineer. Find one online via our find a plumber or heating engineer tool.

Visit the Energy Saving Trust website for consumer information on energy savings at energysavingtrust.org.uk