Would it surprise you to know that the price you pay for fossil fuels could be as little as 20% of their real cost? That's because they're often subsidised by the government. Cynics would say that this is to keep prices low and ensure that business keeps booming for the people who control the resources and, in many ways, history shows they're right.
One of the most compelling arguments for widespread adoption of renewable energy systems is the frightening idea that the world is going to run out of fossil fuels. While this is not an immediate concern, there is a strong movement to switch entirely to renewable sources by the middle of the century.
A solar thermal space heating installation with storage is one of the most complicated systems to size. There are so many variables: storage size, collector array size, expansion tank size, piping size, heat exchanger size and heat load requirements. There are two ways of working out how big everything needs to be: the complex mathematical way or by rules of thumb.
Space heating with solar thermal installations revolves around Btus. If you've sized the heat generation part of your system already, you'll be familiar with this. The next step is to work out how big the collector array needs to be.
If you have a heat-load analysis performed on your property, the results are likely to come back in a very odd measurement: Btu per heating degree day per square foot. How can you use this to work out your solar thermal space heating requirements?
As you might expect, a drainback installation for space heating is much like a similar solar thermal system for hot water. However, the space heating setup has three main options.
With any solar-powered heating system, whether it's for the domestic hot water supply or space heating, a diversion load can be essential to safety and the system's lifespan.
The Earth has an abundant wood supply. Rotting trees emit similar greenhouse gases and heat energy to those burned in your stove. It is important to manage the cutting of dying or damaged trees as these are potential fuel for any home. Your heating system will function according to the wood's type and quality. Freshly-cut or wet wood contains about 50% moisture: ignition is difficult and less heat is produced, with high pollution. Well-dried, old wood ignites quickly to give double the heat with less effort.
It's hard to know how much wood you need until you try out your heating system. A well-insulated house may use 2-3 full cords of hardwood and a little softwood every year. In comparison, a smaller contemporary stone home with no insulation could use 6 full cords. An inefficient outdoor boiler may use 3-4 times more wood than a high-efficiency indoor stove. The general rule of thumb is to purchase more than your heating needs. If your wood is covered, it can last at least 3 years without rotting. You won't be wasting your money.
