Friday, 6 March 2009

Plan for our land - Heating and Cooling

Next in the series... click on links for sections already posted

1. Plan for the main house

2. Cooling and Heating

3.Adega / New build bit

4.A note on building materials

5.The transit camp

6. The watermills

7. Land and permaculture

8. Biogas


There are lots of things to cool - our home, our food. Ourselves !

Here I am dealing with the question of keeping food cool.

Every kitchen has a fridge these days, well, except my dad’s. His is outdoors, but that’s another story. With the kitchen being the warmest room of the house, the fridge has to work itself hard most of the time to get cool and to stay there (bit like all those groovy people…). So we thought about making a cool room: an area surrounded by stone or marble, no light, but a good fridge like door.

Keep sunlight out and it should stay nice and chilled.

In fact if we leave a bottle of water on stone shelves in the house, when it’s hot out, the water stays cold. So it works. We are lucky to have a bit of space on the North-facing side of the kitchen we can use for this. OK the olden days word for this is a larder, it’s just that I don’t see them getting designed in anywhere these days. This will need lights, plenty of stone shelves and a good seal around the door. If it works, we can store all our fruit and veg there without stressing about the rot factor.


Heat is a fairly critical factor in temperate Europe or anywhere else that gets cold in winter. We need it in two forms: as hot water, and, to keep warm (techies call this ‘space heating’). It obviously makes sense to make use of the freely available heat coming off the sun, every day: this should be enough for most normal homes’ hot water supply throughout most of the year but will not cover space heating in the winter (unless you install dozens of solar hot water panels at mega cost).

Solar hot water panels are not cheap either. Together with the hot water cylinder, the whole set up including installation can cost 3 to 5,000 euros. This is a lot of cash, considering that the cost of hot water alone using conventional gas or heating oil is around 200 euros a year (with relatively good efficiency of above 85% let’s say). So that’s a payback of around 20 years!

However all things are not static – especially oil prices, so that figure could change. Furthermore, if you take out the cost of the hot water cylinder, which you will probably need anyway for your heating system, the investment itself goes down quite a lot. Also, in summer, when you shower a lot, it seems crazy to not capture all that heat. Why burn sunlight from 100 million years ago to heat your water when you can use today's? In other words, the feel-good factor.

If I've got my sums wrong by the way - please let me know!

Our plan is to get a good sized hot water cylinder (at least 250 litres) which has the facility to receive multiple hot water feeds. One from the solar hot water panels, another from the cooker in the kitchen which we will fire up with wood, one from a log boiler in the cave downstairs. The only issue with wood is the time/work factor for gathering, chopping, drying and loading it all in to the house. And for smallish ranges or stoves, the logs can't be too big. And small twigs burn too quick. So if I break another bone (which has been a regular occurance this past couple of years) it could be a bother.

Talking of kitchen stoves / water heaters, I got a great reply from Giles, recommending the Wamsler range - made in Germany since around Bismarck's time (late 1800s) and they seem to have about as robust a reputation as he. Cheap, they are not. Their brochure says they can kick up to 18kw of heat into the hot water system. That's the capacity of modern gas boilers for a small apartment in Scotland somewhere. That would be a lot of small bits of wood. To avoid splitting logs I suppose you could use coppiced branches, or cuttings from trees. Every woodfuel expert will tell you that the most important thing is to allow your wood to dry properly.

There is the option of a heat pump - using electricity to generate heat from an underground source, or a type of solar panels. One unit of electricity can produce between 3 and 4 units of heat, so fairly efficient. But given that most grid electricity is still produced with fossil fuels (even in renewables-tiger Portugal) it is far from a "renewable" source some people claim it to be. For those people with their own source of renewable energy - a little hydro power supply for example - it would be seriously attractive. A free source of heat, and with few moving parts the systems can go for many years with few problems. Also free from the toil of moving wood endlessly.

As for space heating, we’ll probably go for underfloor heating pipes in most walls, some floors, and have thermostats around the place so we can turn on/off whole areas depending on how it feels.

As solar panels can get super hot on a sunny day, and cooking carries on further heating the tank, it could easily reach the point of being filled to capacity with hot water. These systems have a kind of escape valve for this, a “dump load” where the excess heat is released as steam. Our heat dump will take the form of a large, octagonal sitting area, filled with water, and surrounded by a wooden deck: the outdoor tub. Our thinking goes that why not use it as the heat dump (send a heating pipe through the tub, under the benches or something). Using fossil fuels to heat an outdoor tub or pool should be discouraged everywhere, but excess super-heat from the sun: this sounds better.


King Green said...

This is one great and environmental article here. Going green is really important to our mother nature. Thanks for sharing your thoughts here.

ZenHomeEnergy said...

Solar panels are a very effective means of consuming light energy and producing electric energy.


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Going without heat during the winter for many people is simply not an option. It is smart to have your heating system checked periodically each year before and after winter has come to make sure you are well prepared and functioning properly for the next time the weather turns cold.

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