
Our very own star. The Sun
It’s a minefield… planet shuddering from crisis to crisis, politicians fumbling for solutions or denying there’s a problem. Ever increasing bills. What are we supposed to do?
The solutions aren’t hugely difficult. If we all reduced our carbon emissions by 50%, the problem would be dealt with, but how? And what exactly should we be doing?
We’ve brought together the collected scientific and practical knowledge of our team, together with the timely wisdom of our subscriber base, and come up with a few practical rules and indicators
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1. Localise your Energy Production
For most homes, offices, factories, schools and other buildings, this is going to mean Photo-voltaic panels, usually on the roof, but they can go anywhere, even built into a fence or squeezed on a balcony if space it tight. Once expensive, prices have tumbled, and efficiency – once in the 10% region – can now exceed twice that. It might not sound much, but there is a lot of solar energy available, and some very big roofs to put the panels on. A fortunate few have access to wind, hydro or other energy sources, but everyone can have solar PV panels. You really have nothing to lose but your chains.
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2.Energy Storage: Battery and hot-water
In domestic terms, this is a much newer technology than solar PV, but it’s the essential partner that allows the panels to show their true worth. The sun is intermittent and unpredictable, but with a decent amount of storage you can use energy while it’s available or store it to use later on. Storage devices harvest solar energy that would otherwise to be exported to the electricity grid. The cheapest option is a device to transfer electrical energy into your domestic hot-water tank feeding the power into an immersion heater. The more complex, expensive and useful technology is a battery system, usually of the type fitted to eCars. Domestic battery systems are now widely available, and prices are falling. They liberate the user from expensive tariffs and free, but intermittent, solar energy. You can harvest solar energy in the afternoon, and charge your car later, or cook a meal, power the lights and heating all evening, and so on. The next day, you can repeat the operation. In winter, there’s little sun available (maybe only 10% as much), but with a variable tariff you can choose when to buy the cheapest energy from the grid and use it when the price is high. With a variable rate and solar panels on the roof, a battery will eliminate energy bills for about half the year and greatly reduce them at other times.
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3.Heating your Home: Heat-Pumps
If you haven’t made the transition yet, the chances are your home is heated with gas central-heating, or even worse oil, coal or wood (yes really).
Make sure your home has a condensing boiler while you make your plans, but you will need to move on, preferably using a heat-pump. Contrary to popular belief, these clever little machines don’t need to be crazily expensive to fit, and they can be very, very cheap to run. Without getting too technical, heat-pumps do exactly what it says on the tin – they move heat from one place to another. They do this without using any energy… except for the energy needed to drive the mechanism and it’s attached electronic whatnots.
Where canĀ you find enough heat? If you are heating a large National Trust property a school or your own 8-bed mansion, you really need to draw your heat from underground, or more rarely, the sea or a convenient river or lake and this is where it can get expensive. These are Ground-Souce Heat-Pumps, and the rest of us don’t need to worry about them.
Most heat-pump systems are described as Air-Source Heat-Pumps, in other words, they draw heat from the atmosphere and bring it into your house, which is straightforward and much cheaper than digging big holes in the garden, but there’s less heat available in the air (in winter at least), so they may struggle in really cold climates.
Air-Source systems are often fitted by plumbers for who it’s a useful sideline, but this inevitably means they will push a system that puts heat into water, often reusing parts of your existing central heating. This air-water-air heating is a problem. Heat-pumps can generate as much heat as you need, but they perform best when producing ‘low-grade’ heat, ie more of a luekwarm sort of heat than a roasting, burn your bum sort of heat when you lean on a radiator. So feeding this low-grade heat into the old radiators can be very disappointing, because they will only ever be lukewarm. Special heat-pumps can produce much hotter water, but they are less efficient, so they will use more electricity, making the whole exercise pointless.
Much better if you are starting with a new build, or have a huge reservoir of cash to play with is an air-floor-air or ground-floor-air, or even lake-floor-air system, which chucks out all the plumbing and puts the heating coils straight under the floor. This suits the heat-pump really well, gives a lovely gentle heat, without the need for radiators, but fitting it from scratch is expensive.
Cheapest of all by far is air-air. This brings the heat indoors to a little heat-exchanger unit, usually mounted high up on one wall in each room. The disadvantage is an internal fan. They are whisper-quiet on a low setting, but fairly noisy on a high one, so you are going to notice it in very cold weather. On the plus side, they are cheap to buy, fast to fit (typically less than a full day), and there’s no tedious paperwork because the government doesn’t get involved. This is because air-air is deemed not to deserve a financial grantfor the rather strange reasoning that most can also be used toreduce humidity, or cool the air during the summer. This means they are treated as air-conditioning (which they are effectively).
Small systems use a single external heat-pump to provide enough heat for one heat-exchanger in one room. Larger networks may use a more powerful heat-pump to supply heat-exchangers in several rooms. A full house supply will typically supply warm air through ducts to all the rooms. This eliminates the separate heat-exchangers and can be almost silent in operation, but it’s getting quite expensive
SUMMING UP: If you have piles of cash, ground-source allied to underfloor heating is effective, reliable and efficient. If you don’t have piles of cash, go for air-air. You can get it up and running very quickly for a few thousand pounds, perhaps initially heating two or three downstairs rooms this way. You may decide to fit a bigger, more sophisticated system later on, in which case the air-air components can be removed and sold just as quickly as they went in.
We used a double room system, serving the sitting room and front room/office in our chalet bungalow. Because we have a semi-open layout, the sitting room unit also provides warm air to the kitchen through the door and serving hatch. Heat from both units percolates upstairs
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4. Heating Your Home – Conservatory or Solar Wall
This is so easy, so cheap and so bleedin’ obvious, it’s frustrating that so few people do it. Not all homes are orientated south of course, and you really do need a south-facing wall. Build a conservatory! Spend a bit more on really good glazing, preferably triple-glazing, and fit insulation panels in the roof glass, and easily adjusted solar blinds to the vertical south-facing glass. And if at all possible, specify a large mass as part of the construction to store heat. This could be a concrete floor with underlying insulation, or something solid in the room.
A conservatory is very useful but flawed: it’s an extra room with a view, but a bit cold in winter (don’t try heating it), and a bit hot in the summer, although you can usually open it up to the outside. The magic ingredient for much of the cold season is a thermostatically-controlled fan, set high up in the conservatory, linked to the house via a pipe through the cavity wall. (A useful tip – we used a 6-inch fan, but it needed the power of an 8-inch fan. Whatever the size, you must choose one with automatic vanes to keep the fan closed when it’s turned off)
When the conservatory temperature falls below 22C, the fan is off, and the pipe kept closed by the automatic vanes. When the temperature rises above 22C, the fan starts, the vanes open and the conservatory produces heat. In the summer, the whole system will need to be turned off, but in autumn and spring it comes into its own, often producing enough heat during the day to keep the heat-pump off in the evening. During the winter, output is much lower, and the fan runs for a shorter time, even when it’s sunny, but this is free energy! The fan consumes very little power and it’s usually only consuming when the PV panels are producing electricity.
You can perform a similar trick by opening and closing the house/consvatory doors manually, but this won’t work when you’re out, or busy, and you have to remember to close the doors on an autumn evening, when the cooling conservatory will rapidly draw heat back out of the house.
If you can’t afford a conservatory, don’t have space, or just don’t want a sun-room, a solar wall will store energy almost as well. There are different types, but in principle you mount a glazed box on the outside wall and use a fan or convection to draw heat into the house. It’s not a common arrangement, because quite a large area of glazing is needed to have a worthwile effect, and this can work out expensive, without the bonus of a conservatory to offset the cost
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