Grand Designs (again)

So, according to Kevin's voiceover, the house the guy was building was being built of materials which stored heat from the summer to release in the winter!

How does that work then? Surely for there to be enough heat put into the walls for there to be any left at the end of the winter the house would be unbearably warm in the summer!

Oh and 40 grand for a wind turbine that doesn't work! What a great investment that was.

tim

Reply to
tim....
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Then he's just wrong. Those dense bricks will hold heat overnight, but not for much longer.

I like trombe walls and we're thinking of building one here (if we demolish the kitchen and conservatory). However the simple form in that house requires line-of-sight (i.e. no intervening furniture) onto the blocks and you end up with the "prison cell" look. If you allow circulation fans during the day, you can achieve a better looking system by placing the blocks in lattice stacks lower down, or even in a basement.

Read a Dutch trade magazine like "Tomatoes and Tomato News" (there are such things). It's a very big topic in the Netherlands at present, and beginning to be one in Lancashire. Commercial glasshouses have been using water-sourced heat pumps for winter heating for some years, but now they're also starting to run them in reverse over the Summer. It's not only coooling, it provides a source of heat over the Winter season.

Less than 40 grand, I thought? I thought 40 was for the one he had wanted (maybe a QR5?, as 40k is the usual quote for them) and so presumably the clumsy lumper they bought instead had been cheaper. It just shows that not all turbines are equal, not even vertical axis machines, and two-bladers are far more visually intrusive. What a great Nelson's Column of a tower that thing needed too!

Reply to
Andy Dingley

But the same principle is used for storage heaters and...er, they don't work either...

(or at least mine didn't)

Reply to
Halmyre

Indeed. But buying number one of anything has its risks. I did wonder about the super efficient gearbox. That would have applications for anything - so smelt of hype.

Reply to
Dave Plowman (News)

Oh I know how they work overnight, and if they don't work for you then it is your insulation that's at fault :-(

tim

Reply to
tim....

The probable answer is that it wont work. There is no way you could store enough heat energy in this way for an entire winter.

Reply to
T

Although as I calculated here, a meter deep insulated pool of boiling water under the house, could.

As with most grand designs,. long on imagination, short on basic engineering mathematics.

Reply to
The Natural Philosopher

[...]

Even better if you can use molten salt:

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've not seen the program yet, but "being built of materials which stored heat" enough for seasonal storage, not just day/night storage, sounds pretty implausible. Phase change materials let you pump heat in without raising the temperature, but even now Google tells me there are ones designed for use in building materials, I can't see it working for a _seasonal_ store.
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you can fill a basement with an insulated pool of boiling water, then phase change materials might be a more efficient way of doing the same thing.
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building out of materials which will act as a store isn't the same as designing a building around a huge store.)

Reply to
Alan Braggins

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the insulation requirements for hot water are a lot less demanding than molten salt :-)

As are the heat exchangers.

It was a thought experiment, but it essentially showed that a tank of almost boiling water could hold a shitload of heat.

hat counts is, once its big enough, the rate of heat loss. Again boiling water is not so hot that its gonna radiate much, and insulation would keep it cosy.

No..which was my point

The house here is pretty massive, but even so its time constant is 3 days, not three months...

Reply to
The Natural Philosopher

That depends on the salt.

Reply to
Andy Dingley

That depends. The microencapsulated salt hydrate:

(But yes, molten sodium chloride isn't likely to be a domestic application.)

I'm sure it isn't. Potentially a lot easier to use than a tank of boiling water though, and so cheaper overall.

Reply to
Alan Braggins

Ah. I assmued you meant salt, not salt ;-)

Reply to
The Natural Philosopher

One point that never seems to considered by builders on Grand Designs is that if you build a house that looks like an aircraft departure lounge or a nuclear bunker, will it be saleable if they ever want to move?

Reply to
T

If it really meets it's (net) zero electricity usage then I'm sure it will.

But it probably wont

tim

Reply to
tim....

Molten sodium is the stuff to use. Then you can add water and use the hydrogen in an emergency. ;-)

I remember the trials of aluminium and sodium hydroxide as emergency batteries for exchanges if anyone has scrap aluminium around.

Reply to
dennis

You let the salt go cold to ambient temperature afterwards. The energy is stored in it purely as the phase change, not as sensible heat.

Reply to
Andy Dingley

Most vertical axis turbines (actually most domestic scale turbines, either way) have a 100% efficient gearbox by simple virtue of not needing one - just drive the generator directly. TNP seems to think that a gearbox and model aircraft motor is the way to go, so what more evidence do you need?

The turbine on Grand Designs looked like a Skyrota, the bunch out Londonderry way.

Reply to
Andy Dingley

Most gearboxes are pretty efficient..90-95% is typical of a decent setup.

Depends on torque loading though - a drive train tends to look like a the frictional device, so the more power you put through it, the more efficient it gets.

Reply to
The Natural Philosopher

I spent the whole weekend a couple ago in the middle of a wind farm in the NE of Scotland. Was surprised just how slow they turned. Have those no gearbox too?

Reply to
Dave Plowman (News)

They have gearboxes. They also have 3MW generators and masts you can climb up the inside of for maintenance.

Reply to
Andy Dingley

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