Tony's Heat Storage System

[Ferdinand]

I was reading what I think is Tony's blog, and the heating system he installed a few years ago is interesting.

 

The premise is a full basement with little insulation on the floor (I assume building regs minimum plus the 25mm on top of the slab), and shallow boreholes used to put excess heat into the ground under the house via waterpipe loops during the summer.

 

Rather than the pfaff about mega-insulated tanks of water or blocks of concrete, there is a simple reliance on heating up the ground under the slab.

 

Does anyone have any views on this, and @tonyshouse - does it work? ? Has it overheated, and if it did how would you manage that?

 

The idea of just using less insulation seems quite good under "reduce" as the first circuit of the green spiral. As an alternative use of heat that would be vented to atmosphere it seems a decent idea.

 

Articles:

http://tonyshouse.readinguk.org/heating-the-ground/

http://tonyshouse.readinguk.org/interseasonal-thermal-store/

 

Ferdinand

 

[joe90]

This was discussed a lot on the old green building forum a few years ago. Even wings of insulation in the ground outside to shield the heated ground!.

[tonyshouse]

It works a bit, not as much as I dreamed that it would, I have one thermal store and one house 

 

basement floor cold through the winter til some point in Feb when the basement starts warming up again 

 

it does not overheat 

 

the house remains cool in summer only struggling if we get an heatwave that lasts more than three weeks - rare those are 

 

In Alberta they have one store for 52 homes and that supplies 80% + of their heat and hot water, it is +30 in the summer, -30 in winter 

 

dlsc.ca   

[Mr Punter]

So not the best idea and neither the worst.  How so many things are.  Many of the other elements are 5*, some 4* and the basement heat concept 3*.

 

Meanwhile there are millions of flats and houses in this country that are 1* pissing heat away and no practical solution.

[tonyshouse]

Making use of excess solar heat and storing it is a workable idea that will l hope be built upon in the future. 

[Gone West]

From what I read years ago it works, but only well, on a large scale.

[SteamyTea]

If, with the UK's climate, we could make use of stored solar energy for use later, we would be doing it.  As would the rest of the world.

The numbers just do not stack up unless you have a huge area of land to collect the energy.

And then not loose any while it is stored.

This is why growing trees and then burning the timber seems so attractive.

 

Edited January 15, 2021 by SteamyTea

[TerryE]

Yup, it's that R² vs R³ thing, and the time integrates up.  It works well for stores the size of a car park or warehouse but not on a domestic scale. I've seen some builds which put a concrete keel with say 30cm structural EPS around it down the centre of the slab / foundation with a few pipe loops in it to act as an independent thermal store / buffer for the daily cycle but seasonal is a completely different scale.

[pdf27]

On 14/01/2021 at 18:12, Ferdinand said:

Rather than the pfaff about mega-insulated tanks of water or blocks of concrete, there is a simple reliance on heating up the ground under the slab.

 

Does anyone have any views on this, and @tonyshouse - does it work? ? Has it overheated, and if it did how would you manage that?

 

The idea of just using less insulation seems quite good under "reduce" as the first circuit of the green spiral. As an alternative use of heat that would be vented to atmosphere it seems a decent idea.

There are two issues here

1. One thing that a lot of people with cellulose-insulated houses rave about is the "long" time constant of the house - 24 hours between the weather changing and them noticing on the inside. For this to provide meaningful heating at the end of winter, you need to extend the time constant out to ~150 days: in practice this means living in a cave deep underground.
2. If you're just averaging out temperatures over the course of a year, you end up living in the average air temperature for the country - about 14°C where I am. Most people would find that unacceptably chilly, so you need to run with a lot of solar gain - enough to capture your entire heating requirements for the year, which risks overheating or demands a very big solar thermal system.

The fundamental problem I have with it given the technology we currently have is that PV is so cheap. Right now we have virtual storage (any PV generated displaces gas from the grid, allowing it to be drawn back at 100% efficiency in winter), and in future we'll have something like Hydrogen at 50% round trip efficiency. Combined with a heat pump, you can capture more useful heat from a given roof area with PV, with far less complexity and it can do your hot water into the bargain. There is also the issue that it's very easy to turn electricity into heat but hard to go backwards - and the ability to store heat for 24-48 hours gives you 80% of the energy savings of being able to do it for 6 months.

[Ferdinand]

On 14/01/2021 at 18:29, joe90 said:

This was discussed a lot on the old green building forum a few years ago. Even wings of insulation in the ground outside to shield the heated ground!.

 

I treat those also as an alternative to EWI, which has more problems identified than 10 years ago.

 

(The answer to the edges of panels showing up is obviously to paint the house tartan).

 

I have always  asked people quoting for EWI if any EWI job they did went down to the foundation, and only ever found one case. And EWI man rolled his eyes about an overly well-off green enthusiast.

[tonyshouse]

In Alberta in Canada there is a small estate of homes that solar thermal store energy from summer to winter and it provides all hot water and heating 

 

and it is -30C in the winter there too, should be very easy for us 

 

dlsc.ca 

[joe90]

@tonyshouse very interesting reading, especially warm air heating, and wet solar panels, but they are connected to a natural gas boiler to top up requirements so not all heating and DHW supplied (but a great contribution to it).

[SteamyTea]

46 minutes ago, joe90 said:

@tonyshouse very interesting reading, especially warm air heating, and wet solar panels, but they are connected to a natural gas boiler to top up requirements so not all heating and DHW supplied (but a great contribution to it).

It is interesting when you analysis the data on page 5 of the 2017 report.

 

 

It would be great if you could just drill a hole, pop a pipe into it, put any excess solar energy into some hot water, pass through the pipes, wait till winter, then pump it out again.

Edited February 4, 2021 by SteamyTea

[pdf27]

53 minutes ago, joe90 said:

@tonyshouse very interesting reading, especially warm air heating, and wet solar panels, but they are connected to a natural gas boiler to top up requirements so not all heating and DHW supplied (but a great contribution to it).

The other key point is hot water - that's provided by flat plate solar and natural gas, but appears to be excluded from the figures. For a well-insulated house that has the potential to be a very significant omission.

[joe90]

3 minutes ago, pdf27 said:

The other key point is hot water

That’s what I said.....

 

1 hour ago, joe90 said:

but they are connected to a natural gas boiler to top up requirements so not all heating and DHW supplied (but a great contribution to it).

?‍♂️
 

then again this thread is about @tonyshouse heat storage which does not include DHW.

Edited February 4, 2021 by joe90

[pdf27]

Point is that it's excluded from their report, which is a bit shady - it's likely to be half of their total energy consumption.

[SteamyTea]

Also look at the BTES efficiency.

Not any better than growing a tree.