Earth-sheltered building, Sheffield

[Flyfisher]

one of those pulley-operated drying racks

Aah - a good old Lazy Susan (as my gran used to call it).

I've always known them as a Lazy Sheila - we have two and they work a treat. Having never heard of a Lazy Susan I checked it out and found it's a turntable used for serving food on a large table, which I had seen before but not by the name of Lazy Susan.

Still, if it span fast enough it might dry clothes as well :wink:

 

[Jane Smith]

Another problem with drying all our washing in the kitchen was that all our clothes ended up smelling of frying onions, which is not nice. We do have a pulley dryer but it got in our way in our previous kitchen (prior to renovations) and so we didn't put it up in this one. I wouldn't be able to heave it up now, as it would be too heavy for my wrecked and poorly little darling hands (I have RSI and fibromyalgia as well as Reynaud's, which makes a lot of stuff difficult). And whether they're called lazy susans or lazy shielas, our big problem here is a lazy jane!

Coal as a fuel was no better than wood, in that it didn't warm the house (very draughty and uninsulated it was then, and the system was gravity-fed rather than pumped, and so hopeless), and it still went out overnight. A shame, as we could often get it cheap or free (lots of ex-mine-workers in my family, including my husband and his father). And the ash and clinker it produced was truly horrible. Bleck.

NT, our stables are roofed in fetching pink concrete tiles. Not slate. Would have been stone originally and it's likely that the Peak Park could make us return it to stone in return for giving us planning permission for all that we want to do. It does need re-roofing, and we're planning on doing that first, but it's going to need a lot of insulation too which would be difficult if it were glassed. Also, as it runs north-south, and only gets the sun obliquely, would it really be worth it? Wouldn't the little heat-gain a glass roof would give us be overwhelmed by all the heat puthering out of it when we had cold winter weather (like today--I'm still snowed in)?

 

[NT]

Jane, just before I answer that I'll mention another option for the tumble. A small radiator or fanned exchanger fitted to the TD and supplied by the house's radiator circuit via washing machine type connectors. Now all through winter the TD runs on oil (IIRC) not electrickery.

Your situation is non-standard in that I'll bet youre paying a very high rate for electricity, so shifting loads off leccy is an especially desirable move. Do you know what you end up paying per unit with your setup?


NT

 

[NT]

And whether they're called lazy susans or lazy shielas, our big problem here is a lazy jane!

Ha! I think in that situation people are anything but lazy, daily life is pushing it much of the time.

NT, our stables are roofed in fetching pink concrete tiles. Not slate. Would have been stone originally and it's likely that the Peak Park could make us return it to stone in return for giving us planning permission for all that we want to do. It does need re-roofing, and we're planning on doing that first,

well, that much is pretty convenient. You can use the solar roof concept as a real selling point for the planners. Call it new invisible solar energy technology that could enable houses in city centres to be built with huge solar roofs yet maintain their traditional appearance 100%. And youre willing to trial it and let other people see it at your own expense. Thers a lot of interest in this kind of thing just now.

Glass tiles look very like slate from the ground. You can test this by cutting a few pieces, arranging them on a real slate roof and viewing from the ground.

but it's going to need a lot of insulation too which would be difficult if it were glassed.

Glass makes no difference to roof insulation. Glass slates take up no more or less space than slate ones. Since its for winter use and at a poor angle you'd need to use a secondary film layer to give double glazing, and the insulation plus the heat capture of the roof would reverse the heat movement direction.

Also, as it runs north-south, and only gets the sun obliquely, would it really be worth it?

Usually no, but youre paying a steep price for your electric power. In that situation, when you need to power a 2nd building, cutting down electricity use makes way mroe financial sense than adding more generting capacity. You're one of the few people where all sorts of things that usually would barely pay their way would be financially advantageous for you. This is why I asked if you'd worked out your per unit electricity cost.

There are better ways to arrange things if they can be accomodated, such as for 2 examples... Wood fencing can be modified and pressed into service as a solar collector, and if you want a large collector that will be seen nearby but not from a distance, a sunken collector is also possible.

Wouldn't the little heat-gain a glass roof would give us be overwhelmed by all the heat puthering out of it when we had cold winter weather (like today--I'm still snowed in)?

Heat loss is determined by insulation, heat gain is determined by collector design, or how much youre prepared to spend on or work on the collector. Your high electricity price makes systems that would struggle to pay with other buildings much more of a realistic option on yours.

With solar you can achieve almost whatever end result you want, including solar houses that are self heating all winter, but what you want and what the constraints are determine which designs can be used and what you can achieve with them. Warm air collectors work in a much wider range of conditions and much more efficiently than flat plate hot water panels, which are what people are most familiar with.

If you really want solar expertise, news:alt.solar.thermal is the place to be, theres far more expertise there than I could give you. I can really just talk about the principles, options, and various associated issues. Electronics is my home ground.

If you want to look at some interesting ideas, most of which will probably not be good for your situation, there are a couple of good pages listing lots of clever solar techs on this site:
http://www.builditsolar.com/


NT

 

[Jane Smith]

Jane, just before I answer that I'll mention another option for the tumble. A small radiator or fanned exchanger fitted to the TD and supplied by the house's radiator circuit via washing machine type connectors. Now all through winter the TD runs on oil (IIRC) not electrickery.

That seems like a very bad idea to me! At present our tumble dryer runs only on wind-generated electricity. We only use it when our dump-loads are on, so when we have electricity available which is surplus to our needs. Why change this over to run on oil? Especially when we've hardly run our oil central heating this year, as the wind power is also heating our house? We had the oil heating on yesterday, for a couple of hours, as the wind dropped: but today we're back to wind-power only. The last time we ran our oil heating was on Christmas morning, I think.

Your situation is non-standard in that I'll bet youre paying a very high rate for electricity, so shifting loads off leccy is an especially desirable move. Do you know what you end up paying per unit with your setup?

We've never calculated it. But it's almost certainly a negative figure, as we get paid for every unit we generate with the wind turbine, and the amount we should get this year should far outweigh the cost of running the generator. Have you perhaps forgotten that we have no mains connections here? And so no utility bills apart from our phone bill? (which makes it fun when we're asked to provide a utility bill as identification as the phone bill is in my name and so my husband can't prove he is who he thinks he is.)

 

[Jane Smith]

You can use the solar roof concept as a real selling point for the planners.

You've not met the Peak Park planners, have you?

Call it new invisible solar energy technology that could enable houses in city centres to be built with huge solar roofs yet maintain their traditional appearance 100%. And youre willing to trial it and let other people see it at your own expense. Thers a lot of interest in this kind of thing just now.

I'm only willing to trial things that we know will give us some real payback, and to be honest one of the reasons we live a mile off the road is because we prefer not to have people all over the place. I realise that this could be interesting, but I'm not convinced that a solar roof is appropriate in our location, and on the building we're considering renovating.

Glass makes no difference to roof insulation. Glass slates take up no more or less space than slate ones. Since its for winter use and at a poor angle you'd need to use a secondary film layer to give double glazing, and the insulation plus the heat capture of the roof would reverse the heat movement direction.

So how does this work? We put in a top layer of glass slates; then another layer to provide double glazing; then our usual roof insulation. So what advantage does this give us? If it allows heat into the building how does it get past the insulation?

Usually no, but youre paying a steep price for your electric power. In that situation, when you need to power a 2nd building, cutting down electricity use makes way mroe financial sense than adding more generting capacity. You're one of the few people where all sorts of things that usually would barely pay their way would be financially advantageous for you. This is why I asked if you'd worked out your per unit electricity cost.

Ah. I understand that now--your questions regardign the cost of our electricity. But yes, we are very aware of every bit of electricity we use, and we do go to all sorts of lengths to reduce and limit our use. To the extent of using carpet sweepers rather than vaccuum cleaners most of the time! And we only bought a microwave at Christmas, but to be honest I've only used it twice.

There are better ways to arrange things if they can be accomodated, such as for 2 examples... Wood fencing can be modified and pressed into service as a solar collector, and if you want a large collector that will be seen nearby but not from a distance, a sunken collector is also possible.

We're back to the Peak Park planners again. We'd not be allowed to run vast solar collectors all over the place; and we only have drystone walls, anyway. No wooden fences. The problem with ground-mounted collectors here are that there are lots of sheep around, and that it's difficult to mount them securely enough to ensure they don't fly away when we get strong winds. We'd have to use a huge amount of concrete for a very tiny solar gain.

With solar you can achieve almost whatever end result you want, including solar houses that are self heating all winter, but what you want and what the constraints are determine which designs can be used and what you can achieve with them. Warm air collectors work in a much wider range of conditions and much more efficiently than flat plate hot water panels, which are what people are most familiar with.

We have investigated passive solar collectors to provide warm air for heating the house. This principle can work brilliantly on new-build, especially when combined with earth-sheltered design, but it is difficult to retrofit to a period house unless you're very lucky. We considered building a huge conservatory onto the house's south-facing wall (9m long, 6m out from the house, and two stories tall) in order to provide a heat-sink for the house; and eventually calculated that this structure, if built with metre-high collectors all around the base, and a good black floor to soak up more heat, would provide enough winter warmth to heat our sitting room for just twelve minutes a day. Our stables don't have a big expanse of south-facing wall. And so despite all your ideas, it's simply not practical to do this, as technology stands.

 

[NT]

That seems like a very bad idea to me! At present our tumble dryer runs only on wind-generated electricity. We only use it when our dump-loads are on, so when we have electricity available which is surplus to our needs. Why change this over to run on oil?

Right, I thought you ran it for all wash loads on demand, which one could not normally do as a dump load all year long.

But primarily I was really thinking in terms of a new building, if you built one you'd want more electricity to power it, and shifting electric loads to nonelectric power is much cheaper than adding additional generating or storage capacity.

Do you know what you end up paying per unit with your setup?

We've never calculated it. But it's almost certainly a negative figure, as we get paid for every unit we generate with the wind turbine, and the amount we should get this year should far outweigh the cost of running the generator. Have you perhaps forgotten that we have no mains connections here?

No. I don't see how anyone could generate electricity for a negative cost. AIUI you paid over 10k for a system with limited lifetime, and amortising that cost will give you quite a steep energy price, somewhere vaguely in the 500-2k per year region for a limited supply.

I'm only willing to trial things that we know will give us some real payback,

of course, I was speaking of marketing spin for planners there.

So how does this work? We put in a top layer of glass slates; then another layer to provide double glazing; then our usual roof insulation. So what advantage does this give us? If it allows heat into the building how does it get past the insulation?

The top layer is glass slates.
The layer below is a transparent plastic film
The layer below that is dark grey collector surface
Below that is an air circulation gap
Below that is roof insulation.

Air is circulated across the dark collector by fan when collector temp is above indoor temp and more heat is wanted. The fan only comes on when there is gain to be had. One could regard this as a way to run electric heating at 1000% efficiency.

The secondary (lesser) heat path is that through the insulation. When the roof sees sunshine, this smaller heat flow is inward rather than outward.

The problem with ground-mounted collectors here are that there are lots of sheep around, and that it's difficult to mount them securely enough to ensure they don't fly away when we get strong winds. We'd have to use a huge amount of concrete for a very tiny solar gain.

I gave you the builditsolar and alt.solar.thermal links so you could see some of the wide range of solar technologies around. As you'd see not all suffer the concerns you mention there. There are more methods besides those as well.

And so despite all your ideas, it's simply not practical to do this, as technology stands.

It sounds as if you think because one design doesnt work all the others cant either.


NT

 

[Jane Smith]

Ah, I see the thing about the glass roof now. But I'm still not sure it would work for a retrofit--probably for a new-build.

Sorry if I'm seeming negative about all your ideas, NT. It's just that we have researched all this in quite a lot of depth over the years and despite all the advantages of passive solar heating it is almost impossible to retrofit that sort of design into our house, for all sorts of reasons. The planners here are very rigid, our house is large and faces the wrong direction, the weather is not appropriate: I know it sounds like I'm making excuses, but that's not the case. It's not appropriate for here, although I wish it were. I read an interesting article about a man in Montana who has built a solar collector which delivers about 165,000 BTH per 24 hours in the depth of winter: fabulous that it works in such cold, snowy conditions but our current oil boiler is I think a 140,000 BTH one, so the Montana collector would only replace our boiiler for an hour and a bit each day. Not much, for the outlay concerned. I do have a plan, though, to install a hot tub which runs entirely on renewables, including solar thermals. Now THAT would be worth doing.

As for the negative cost of our energy, I was confused--I thought you meant our monthly bills now. We don't pay any, and we get paid to generate our electricity. So in a way we do make a "profit" out of it. Especially when you factor in the £2,000 a year we were paying for our electricity before the turbine went up (a combination of diesel, servicing and repairs).

Our wind turbine should last a lot longer than 10 years--there are some of this type a lot older than that. 10 years is the minimum, though. Which averages out to a cost of £1,200 per year, on installation costs of the turbine alone (£1,800 if you factor in the new inverter and batteries we also had to get as the old ones were dead). When you compare that to our previous expenses then you can see we're all ready doing quite well. Add to that the money we get via ROCs, which should be £800-£1,000 each year, and the unexpected savings we're getting on our heating bill (at least £1,000 a year, probably more) because of the dump loads, and you can see why we're so happy with it.

 

[Flyfisher]

As for the negative cost of our energy, I was confused--I thought you meant our monthly bills now. We don't pay any, and we get paid to generate our electricity. So in a way we do make a "profit" out of it.

I'm still confused about how you are making a 'profit' out of generating your own electricity. How can you be paid for it if you have no grid connection through which to sell any surplus?

I can understand that you're saving money compared with your previous costs, but that's not the same as being paid and making a profit.

 

[Jane Smith]

Flyfisher, we meter all the electricity the wind turbine generates. In April every year we send off that meter reading to Clean Energy, which duly sends us back a cheque for about 4.5p per kW generated. Clean Energy then sells our electricity on to the power companies to contribute to the amount of "green" electricity that they produce.

However, as you've spotted, we have no grid connection so our electricity never reaches the grid. Instead we use it all. Despite that, we get paid for it, and so do lots of other people wiht solar or wind generation, and power companies still add that power to their green energy tallies.

It's the cheat's way round the 10% that power companies will be obligated to generate by renewables by 2010. Even people who micro-generate with a grid-connect get a similar deal. In effect, their generated power is double-counted.

 

[Flyfisher]

Ah, now I understand your 'profit' comment!

How bizarre that you can sell something without actually delivering it, and even more bizarre that you're effectively selling something you're actually consuming for yourself.

When I first read that you were not on the grid I thought 'that's a shame, no way to sell your suplus power' - little did I know that you're actually much better off not being on the grid!