Thursday, December 10, 2020

AS the days get colder, most of us are spending more money to stay warm in winter; most of our personal solutions focus on how to earn more to pay the bills, and most national energy solutions focus on how to get more energy for the country. There is, however, another solution: to use the sun – even the weak winter sun – to our advantage, to generate our own energy and severely reduce our bills.

When people think of solar panels, they usually think of photo-voltaics, or PV panels, which turn sunlight directly into electricity. These do have a higher initial cost and must be wired to your electric system, and take a few years to pay for themselves – but once they are installed you have the satisfaction of seeing your electric meter run backwards. They also continue to provide electricity through power cuts, and offer an immunity from price hikes. To heat your home in winter, however, there is a cheaper option – hot water solar panels.

Solar water panels are a simple technology that can function even in the absence of fossil fuels or electricity, can be made cheaply out of basic materials, and can cut your energy costs severely. So-called batch heaters can be as simple as tanks of water, painted black to absorb heat, in a box on the south side of your home to catch the angle of the sun. The boxes should be glass on the sunny side and insulated on the others, and you simply add cold water to it in the morning and remove the hot water in the evening.

Most of the solar panels you see are more convenient than that, however. Most would appear as black panels on the roof of a house, to catch the rays of the sun. Those panels are filled with water, and a well-insulated tank of water sits near them on or under the roof. The sun heats the water, which passes to your normal water heater, so your heater doesn’t have to work very hard. This is particularly important since water is one of the best thermal masses, meaning that heating it takes a lot of time and energy. On sunny days, you might never need your water heater at all.

Another basic technology that more people need to learn about is the thermosiphon air panel or TAP, a wide flat box with a glass panel on the sunny side, and a sheet of metal under the glass. It is insulated on the sides and back, and has a pipe at the top and bottom. Air flows in at the bottom, goes over the metal, and out the top into the space that needs heating – say, your living room.

If you want to get more ambitious, you could buy a polytunnel frame and attach it to the south side of your house, so that the walls of the house abut to the inside of the poytunnel rather than the cold outdoors. Sunlight coming in warms the inside of the greenhouse and cuts your heating bills on that side, and gives you a pleasant place to sit outside when it’s cold and raining. Of course you can plant a garden inside the polytunnel, and grow your food right outside your kitchen window. You can also paint the side of your house black inside the polytunnel, and place heat-absorbing bricks on the floor to absorb heat and transfer it to the rest of the house.

Insulating your home also goes a long way; according to one organisation, 65 per cent of homes have substandard insulation. That wasted energy – whether at the electrical power plant or in the home – has a real human cost; according to one study, retrofits across the USA would mean 6,500 fewer asthma attacks, and save hundreds of lives and $1.3 billion in health costs. That doesn’t even count the billions we would save in heating costs, the fossil fuels saved for future generations, and the greenhouse gases left un-gassed. For people who can’t afford new insulation, old clothes stuffed in the attic could also help. Or people can simply close off outer rooms and seal them off, keeping heat in areas where people spend most of their time. Finally, there are heavily insulated and heated clothing, which can keep you personally warm – which is, after all, the point.

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