Carbon neutral heating: is it possible? Not only is it possible, but as the years advance, it will become a matter of survival. As we’ve already mentioned, Britain’s oil and gas reserves are depleting fast and the bills are rising even faster. Every time I hear about someone converting from solid fuel to gas, I shake my head in amazement. Gas may be less polluting than coal, but wood is carbon neutral and readily available. Far better to spend the money installing a high efficiency stove or boiler.
Heating primarily refers to heating rooms, but we will also discuss how to heat your hot water supply in this section.
There are five methods of carbon neutral heating:
- solar hot water
- geothermal heat pump
- passive solar
These are in a rough order of feasibility, so we’ll start at the bottom and discount those least likely to be implemented.
There is absolutely no reason why a home can’t be heated by electricity throughout, and if that electric is drawn from a 100 per cent renewable electric company, or powered by renewable devices such as wind turbines, then the heating system would effectively be carbon neutral.
However, this isn’t too practical due to the cost. Having several kilowatt heaters around the home would soon stack up the electric bill! The place for electric heaters will probably be similar to their current role – as a backup to existing heating systems.
Having said this, there is always the option of storage heaters. These are electric heaters which store heat when electricity is available at a cheap rate, usually overnight, then release it throughout the next day. The heat is stored in bricks inside the heater. Obviously, your property needs to be on an electricity tariff which has cheap rate electricity, such as Economy 7.
Using storage heaters
Opinion seems to be deeply divided on the efficiency of storage heaters and the cost of electricity in the UK seems to be escalating at a similar rate to the cost of gas. The main drawbacks of storage heaters are:
- You must have adequate insulation. A poorly-insulated property will not be easy to heat with any fuel, but with storage heaters it will soon have you reaching for the peak electric heaters.
- You need to know how much heat you’ll need tomorrow. You’ll be setting the controls the night before.
- You may end up with excess heat. If the weather turns out milder than expected, it’s possible you’ll have to open the windows to allow the excess heat to escape.
For some properties, especially isolated rural properties, storage heaters may be a good option. However, do ensure that plenty of capacity is installed.
Using an immersion heater
Without fossil fuels, using a simple immersion heater is probably how most hot water will be supplied. All of the carbon neutral central heating systems available require a separate system for heating hot water, with a few rare exceptions.
Nuclear power stations
As Britain’s gas bonanza comes to its end, many of the gas-fired power stations could be supplemented with new nuclear power stations. While it is true that they are carbon neutral, they are controversial and the problem still remains of how to dispose of spent fuel rods. I am making no judgement here about nuclear power, only to point out that any plans for changing your house in Britain should take into account that the electricity market could change radically in the near future, and this may include new nuclear power stations.
PASSIVE SOLAR ENERGY
Passive solar is arguably the cheapest method of heating a home. Once installed it requires no energy. Passive solar simply works by having a home that is specially designed to absorb the heat of the sun. The house faces south, and instead of the traditional design of walls, windows and roof, the entire front ‘wall’ of the house is glass panels which are angled to allow for maximum absorption of the sun. To shade the house in sunny weather, huge blinds are pulled down across the panels. An essential part of such a design is plenty of insulation. The windows are triple-glazed, all doors are draught proof, and the small area of roof, the back wall and floor are all made from insulation material. And it works.
A good example of this is the Hockerton Housing Project, north of Nottingham, where four houses have been custom built to exactly this design. They are built in to huge mounds of earth, so that the roof, back and side walls are earth – excellent for insulation. The remainder is large, glass panels and a large conservatory. Each house cost around £95,000 to build, including labour and a wind turbine. However, this was well over 10 years ago, and house prices have changed somewhat since then!
New builds only
The flip side of this, of course, is that it cannot be retro-fitted to an existing home. Some houses already make use of some passive solar, such as conservatories. However, unless you have the means to build a new home from scratch, using passive solar as your sole means of heating isn’t an option, and certainly not for a country. Are we about to bulldoze and rebuild Britain’s entire housing stock? This is the only reason that passive solar is so low on the list.
GEOTHERMAL HEAT PUMP
If you bore down into the earth, you find that it is warmer than the surface temperature. This is geothermal heat. It is a simple leap of logic then, that water pumped down into the earth will heat itself for free. Pumped back up again, it can then heat a home. The only energy loss here is the electric to power the pump.
Coils of pipes are buried in a trench in the back garden filled with a conducting fluid such as anti-freeze. A heat pump must also be installed, and since these can create some noise and vibration it is best if they are in a utility room or garage, away from the main living area. To take advantage of cheap electricity, these usually run more at night. Finally, an under floor heating system is needed, as most systems do not run hot enough for a radiator system.
How much? According to the Energy Savings Trust, ‘A typical 8kW system costs £6,400-£9,600 plus the price of connection to the distribution system. This can vary with property and location’. It appears that this doesn’t include the under floor heating system. To offset the cost of installing geothermal heating systems, grants are available from the Low Carbon Buildings Programme of up to £1,200 or 30 per cent of the project, whichever is lower.
For every unit of electricity used to pump the heat, 3–4 units of heat are produced. Initially, this seems appears to make no saving as currently, electricity costs around three times more than gas. However, this ratio will increase over time as gas gradually depletes, and also cheap rate electric at night makes this much more affordable.
There are a number of requirements for the system:
- A garden in which to bury the pipes, although in some cases these can be bored vertically. Each system seems to use a different arrangement.
- A well-insulated home, typically a new build.
- Under-floor heating system.
Advantages and disadvantages
The advantages of geothermal heat are obvious: it is an automatic system, without the fuss of having to store and chop wood or rebuild your house, although there will be quite some upheaval, I imagine, during installation.
The main disadvantage is that you will still receive a monthly bill – for the electricity. The difference is that over the years, the equivalent gas bill will gradually increase over the equivalent electric for servicing the system.
The main problem with geothermal heating is that the number of houses suitable for such a system are relatively few. Not only does the house need to have a garden for burying the coils, it needs to have the under-floor heating system pre-installed, and the house itself needs to be a new-build with certain layers of insulating foam built into the walls inside and out. This is a tall order, and applies to a very small percentage of current housing stock. Fitting such a system to an older house would simply exchange a high gas bill for a high electricity bill.
Although at present there are very few of these systems installed in Britain each year, this could soon rise as fuel bills climb yet higher. In Sweden, the expense of fitting geothermal heating systems is even higher than Britain, but far more many systems are sold each year. Why? Because of the scarcity and expense of fossil fuels there. As this situation begins to appear in Britain, it is likely that those who are able will begin to take after the Swedes.
SOLAR HOT WATER
This has to be the most overlooked carbon neutral heating system available. These systems are as efficient as they’re probably ever going to be. They can be fitted to an existing system with little fuss in a short period of time. They are perfect for running alongside your existing hot water system, such as gas or the immersion heater. And as long as the sun is shining, you have a tank full of hot water for free. According to the LCBP, they ‘can provide almost all of your hot water during the summer months and about 50 per cent year round’.
These should be fitted to all ‘new build’ homes by law, in my opinion. Of course there is an initial setup cost, as with all systems. However, this should pay itself back within ten years, probably five, depending on your usage.
The system works regardless of the ambient temperature, so a sunny winter’s day will provide the same hot water as a sunny summer’s day. But even on a cloudy day, it’s not unusual to achieve temperatures of 20° in the water tank. This can then be topped up with the immersion heater for a bath.
Types of solar delivery system
There are two types of delivery system – direct and indirect.
The direct heating system works by having a solar panel, which heats up a small chamber of water on the roof. Once it is a number of degrees hotter than the hot water tank, a pump will switch on. This pumps the heated water down from the chamber to the tank, and in turn pumps cooler water back up to the chamber. Then the whole process begins again.
The indirect delivery system works by having an intermediary liquid, which is pumped up to the roof. This heating fluid is heated in a similar way, and then is pumped back down to a heat exchanger, which then heats the hot water tank.
The two delivery systems are similar, but the direct system tends to be cheaper, as there is no need for a heat exchanger. However there may be some heat loss in the colder months; if you are pumping water up to the roof, the pipes may freeze and burst on a cold night. To prevent this, hot water is pumped from the tank back up to the roof, essentially the reverse of the heating process. Heat loss does tend to be minimal. In indirect systems, the heating fluid which is exposed on the roof, freezes at temperatures far below zero, so there is no chance of burst pipes in this case.
Types of solar panel
There are two types of panel – flat plate and evacuated tube.
The flat plate system is less efficient, but cheaper to install. It essentially uses flat plates of darkened metal to absorb sunlight and transmit the heat. The evacuated tube system uses vacuum-sealed glass tubes, with a slender channel of heat-conducting fluid at the centre which carries the heat up to the pipe at the top. Evacuated tubes are the more efficient system, however they have a reputation for losing their seal after a time, as the tube heats and cools over the years.
These systems are a perfect accompaniment to the other central heating systems on the list, and immediately resolve the issue of having to run a wood-fired system on a hot summer’s day just to heat up the water.
The costs involved can vary from as little as £2,000 to as much as £5,000, so shop around and see what you can find. When looking at buying a system, don’t just look at cost, but also at efficiency and any potential issues such as the water pump breaking down, or water leakage. If possible, try to get to see a working system when the sun is shining, so you can see what temperatures you will get.
The Low Carbon Buildings Programme funds solar hot water systems for £400 up to a maximum of 30 per cent of the project.
When wood is burned it creates heat and smoke – carbon. That smoke is then absorbed back into a tree, and so the cycle carbon neutral is complete. Tried and tested for thousands of years, it is simple and practical. And as technology marches on we have ever more efficient wood burners – so efficient in fact, that they are suitable for burning in a smoke control zone. This efficiency is obtained by moving the flow of smoke so that it is burned over and over, until all useful energy has been taken from it, leaving only a tiny whisp of smoke. Many are billed as being 70 per cent efficient, as opposed to an open fire which is around 30 per cent efficient.
Smoke control areas
There are several models of wood burner that are exempt from the smoke control regulations, due to their high efficiency and low emissions. The full list for the UK is here: http://www.uksmokecontrolareas.co.uk/appliances. php?country=e
Types of wood burners
Wood-fuelled burners come in all shapes and sizes, but break down into boilers and stoves. Most of the appliances which are approved for funding by the LCBP or by the smoke control authorities only use wood pellets as their fuel, which have to be ordered. The reason for the move towards pellet burners is that they are easier to automate. A hopper (feed mechanism) on the top of a boiler or stove can be filled and the appliance itself will take in pellets as required. It doesn’t need to be constantly tended like a log stove, for example.
Grants and funding
The LCBP provides grants for approved appliances on the following basis:
- 1.Room heater/stoves automated wood pellet feed: overall maximum of £600 or 20 per cent of the relevant eligible costs, whichever is the lower;
- 2.Wood-fuelled boiler systems: overall maximum of £1,500 or 30 per cent of the relevant eligible costs, whichever is the lower.
The full list of approved appliances for LCBP funding are available here: http://www.clear-skies.org/households/RecognisedProducts.aspx
Boiler or stove?
Boilers can be transplanted into existing central heating systems, simply substituting a wood boiler for existing gas or oil boilers. Access and fuelling have to be considered here, depending on the make and model of boiler to be fitted. They are not designed to be a centrepiece for your hearth, but a functional piece of kit to be hidden away at the back of your house, like a gas boiler.
Stoves on the other hand directly heat a single room, and can be pleasant to view. However, when it comes to pellet stoves, this means that each room will require its own stove with ventilation and fuelling issues.
The happy medium you may wish to consider is an efficient wood stove (as opposed to a pellet stove), with a back boiler. These can burn dry wood and heat the hot water tank, and central heating system. There are also several which are approved for use in a smoke control zone (for example the British-made Yorkshire Stove from Dunsley). The only drawback here is that the LCBP has not approved a single wood stove for funding, so you will have to find the full amount yourself.
Points to consider
The discrepancies between the LCBP and the smoke control regulations can be quite frustrating. Most of the appliances approved for funding for wood or pellet burning are not approved for a smoke control zone. Given that the objective here is to move towards becoming carbon neutral and to avoid pollution, this seems puzzling to say the least. So take plenty of time when considering how to convert your system over to carbon neutral, thinking about:
- Type of appliance: boiler or stove.
- Type of fuel: logs, wood, pellets or other, such as switchgrass. This will be determined by the appliance, but you ought to have some idea of the fuel you’ll be sourcing, and its cost.
- Funding required: together with the two items above, this will restrict your choice of system. If you are willing to forgo funding, then this will widen your choice. But if you will need the funding to complete the job, then look carefully at which systems you can choose.
- Smoke control zone: as mentioned above, surprisingly few appliances are on both the LCBP and smoke control approved lists, so check this list also if you are siting an appliance in a smoke control zone.
- Your house: do you have a chimney? Many houses nowadays are built for gas, without a chimney. You will have to speak to your installer about this.
- Wood source: do investigate where the wood is sourced from. If your supplier is deforesting areas of natural beauty, then you may as well stick to gas! Ideally waste or recycled wood should be burned where possible, or at least wood from sustainable, local sources.
Advantages and disadvantages
There are several drawbacks to having a wood-fuelled heating system.
- Cost of fitting: The cost of having a gas central heating system refitted for wood is around £5,000 at time of writing. If you are wary of switching your whole system over, it is possible to have a dual-fuel home – wood and gas. Of course, such a system would cost more. Ask your local heating engineer for quotes. Bear in mind that even your installer must be on the approved list for funding, not just the appliance. So if funding is an issue, ensure you go with an approved installer.
- Supply of fuel: It must somehow be sourced. This isn’t usually too difficult – we get all our wood for free from a local workshop. It’s amazing how much wood folks actually throw out. If you can get the word out that you’re after wood, you will probably get it coming to your front door. (Of course, wood must also be stored somewhere dry such as a wood shed, and possibly chopped up if it isn’t available in smaller pieces.)
- The system is manual: You have to fuel the fire, and clean out the ash. This is the part that many people dread, having ash all over their living room. But it needn’t be the case – metal ash carriers of all sizes are available for around £40 from specialists ‘Tippy’, among others.
- Hot water in the summer: Some people burn their fire all year round; most efficient boilers can heat enough water for a bath in as little as twenty minutes. But it may be as well to use the immersion instead. Who wants a roaring fire in the height of summer? The perfect complement to the wood-fuelled system is the hot water solar panel, heating the water throughout the summer months.
But despite these drawbacks, a wood-fuelled heating system may still be the best option for many. Despite the need for sourcing fuel, it is often free or very cheap. This alone should offset the cost of the initial system within ten years at the most. With the efficiency of systems improving all the time, the amount of wood consumed is far less than an open fire. And it is also reliable. Even if the pump breaks down, you can still heat at least one room in the house. That has a lot to be said for it.
When it comes to selecting an appliance, you will need to buy one that is adequate for your heating needs. Heating systems are measured in BTUs (British Thermal Units), e.g. 40,000 BTUs. To calculate roughly the BTUs of the property you are heating, you will need about 5.95 BTUs per cubic foot (0.02 cubic metres) of room space (down to about 5.45 with double glazing and good insulation). But this is only a rough estimate, and a heating engineer will be able to give you a more accurate figure. You also need to remember to include an extra 10,000 BTUs for the hot water.
The issue here is insulation. Before spending thousands on a new heating system, you would be as well to consider spending just a few hundred insulating your home. Ironically, when it comes to insulation, the cheapest measures are often the most efficient. Double glazing, which costs several thousand pounds, only reaps a saving of around £20-30 per year, with a pay-back period of around 100 years! At the other end of the scale, a cylinder jacket will cost around £10 and pay itself back in less than twelve months. So don’t splash out on expensive systems straight away; get the basics right first.
INSULATING YOUR HOME
Our homes lose heat from all points of contact with the outside. This includes:
- walls 35%
- floors 15%
- roof 25%
- doors 15%
- windows 10%.
Every box needs to be ticked to save heat, energy and money. The good news is that this is probably the cheapest, most cost effective improvement you can make to your home. Government funding is available to everyone and low income groups may receive many of these benefits for free. (Please note that costs were correct at the time of writing.)
Loft insulation: this should be 25 cm thick. £100 (fitted) from the local city council, free for many. Saving of £50 per year.
Cavity wall insulation: £125 from the council, return of £80 per year.
Cylinder jacket: £10 from a DIY shop, saving of £15 per year.
Extra thick curtains: cost and return will vary here. You don’t need to replace existing curtains, simply purchase a liner that hangs alongside on the same set of curtain hooks. You might also consider putting up a curtain across front and back doors for extra insulation.
Draught excluders: these vary from the DIY variety for old socks, to fitted rubber seals around doors.
Radiator reflectors: £7.50 each, save £5–15 per year. Anywhere up to 40 per cent of the heat from a radiator on an outside wall can be lost immediately. Straightforward reflectors return that heat back to the room.
Other options are available, but they are costly and take many years to pay themselves back. They include:
High efficiency boilers: condensing boilers, combi-boilers, etc. They operate on the premise of efficiency. They also operate on gas. I’d be much happier spending this money on switching to a wood boiler or geothermal heating.
Insulating wallpaper: very expensive and time consuming for what it returns, but in a perfect world every house would be papered in it.
Double glazing: bottom of the list. Expensive and returns very little. Also expensive to maintain, as breakages and replacements require a replacement unit, rather than just glass. That unit is made with plastic, and plastic is made from oil. Over the coming years we may return to simple wood and glass.
If you are unsure about how to set about getting your home insulated, then pick up the phone and call one of the many agencies out there that have been set up to help. The Energy Savings Trust (www.est.org) would be a good place to start. In many areas there are schemes running to help people insulate their home, many for free or at a substantial discount. More than any other step, insulation will probably be the biggest contribution you make to reducing carbon emissions. So what are you waiting for?