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00:04You know, there is a material which is super abundant and super accessible on this planet
00:12and which holds the potential to unlock how we build truly, sustainably, to net zero.
00:18And you're thinking, aren't you, it can't be dirt, but it is.
00:23Although the key to unlocking the potential of Earth, that takes a special kind of human being.
00:34Nine years ago, I met Andrew, who'd spent his life obsessing over just such weighty matters.
00:41Our new home is going to be essentially one massive thermal experiment.
00:46It's a self-heating house.
00:48An engineer, Andrew had the vision...
00:50We're actually doing it, my love.
00:51...but only rookie-level building skills.
00:54I've never poured concrete before.
00:56That's not going hard.
00:57Too wet? Are you joking? I'm sorry. I'm just a little bit stressed.
01:02His wife, Margrethe, and their two children could only pray that Andrew's madcap scheme wasn't a dud.
01:08How much are we going to be able to get done before the money runs out?
01:12The dream was a pioneering self-heating house.
01:16Just metres and kilometres of pipes.
01:19But at what cost to family harmony?
01:21I just want it to be over now, to be honest.
01:23I just want to get back to a normal life.
01:26It's been, what, six years since I last saw Andrew and Margrethe, and, of course, the question is,
01:32did that madcap scheme work, or did they just end up living in a damp hole in the ground?
01:38But first, here's their story.
02:06This charming 17th century cottage in Buckinghamshire's Greenbelt
02:11has, for generations, been in the family of Andrew, an energy consultant.
02:15He lives here with his wife, Margrethe, a former midwife, and their kids, Jasper and Imogen.
02:22Can someone buy some salad, please?
02:24Oh, thanks very much.
02:25While Margrethe homeschools the kids, Andrew runs a company that helps his clients make their homes and offices greener.
02:33So, can you see that?
02:35That is spewing out heat there, out of that vent, which is completely needless, basically.
02:41For Andrew, saving energy and recycling everything possible is more than just a job.
02:46It fuels his life.
02:49Andrew is an eco-warrior.
02:51It affects everything.
02:53I am less so.
02:55I try to consume as little as possible.
02:57This watering can, I've had all my life, and it's perfectly good.
03:02I'm surrounded by stuff that I just wish we'd been able to pass on.
03:08Oh, occasionally I pick things out of the bin, yes.
03:11And there's a part of me that just rails and just says, I just want to do it my way.
03:16I probably take the eco-living to some extreme, Margrethe follows, but maybe not to the level that I take
03:23it.
03:24And this energy conservationist's passion is now stoked and fuelled like never before.
03:29He's risking all he has to build a highly experimental home, the first of its kind in the UK.
03:36Our new home is going to be essentially one massive thermal experiment.
03:42I sincerely hope that theory does match up with practice, because kind of my reputation's on the line there.
03:49And so is his childhood home, because he's selling it to part fond of this venture, although he'll keep three
03:56acres of his land for the new house, meaning he can also conserve his beloved woods.
04:01My dad planted all these trees, and I was literally just a baby at the time, and I apparently helped.
04:09But look at them now, hey? They're magnificent, don't they?
04:11It is idyllic. And that has meant a difficult journey through planning for his radical house, the proviso being that
04:19it has to blend into this landscape.
04:28What a beautiful place. It's not going to clearly be a tiggy-wimple-beams cottage, is it?
04:34It's not going to be that.
04:35It's going to be the complete opposite of the cottage. It's the antithesis of the cottage. No wobbly beams, no
04:40wonky walls.
04:41Yeah. So what are you building here?
04:43Essentially it's an earth-sheltered house, but with a difference. It's a self-heating house.
04:49What we're doing is gathering the sunlight in, which is a big glazing, transferring that heat with an underfloor transfer
04:55mechanism into the earth banks.
04:59And these earth banks will store the heat from summertime to wintertime.
05:05Right, so you're sort of using the earth bank, really, as a battery.
05:09Yeah, yeah. I love that. You know, people talk about, you know, is there future lead acid? No, it's not.
05:14Is it lithium-ion? Is it rare metal earths, you know, batteries? No, it's just soil.
05:19It will take two years to heat up.
05:22Two years we'll have to wear fleeces inside.
05:24Yeah. Wow. So you won't know until two years after you've built it whether it's truly performing.
05:29Well, we're going to put a lot of instrumentation out there in the soil to measure the performance.
05:34Yeah, yeah, yeah.
05:38Andrew's outlandish idea, realised with the help of an architect, begins a stone's throw from their cottage.
05:43Here, they'll cut the turf and keep it to one side for a living roof and move some trees.
05:49Andrew will then dig a hole, 19 by 19 metres, keeping the soil, and then pour a reinforced concrete slab
05:56straight onto the earth.
05:58For speed and cost, he'll use prefabricated concrete panels for the walls, for a central atrium, and for the roof.
06:07All this concrete will be damp-proofed, but not insulated.
06:12Instead, tonnes of earths placed around and over the building will get insulated,
06:16with sheets of polystyrene extending five metres out over the surrounding land
06:21to form a blanketed bubble of heat-retaining soil around the house.
06:27Andrew will then replant his rescued grass and make the home watertight.
06:32For Margareta, the beauty of the building perhaps takes precedent over its function.
06:38She wants a sleek interior with some new furniture.
06:41A contemporary home, not a science lab, thanks.
06:44And she wants it light, too.
06:46So at the building's core will sit an atrium, illuminating the earth-sheltered rooms with 16 windows.
06:52There'll be two bedrooms for the kids behind their parents' room.
06:55And at the back, where it's darker, cosier rooms like the den, study and guest bedroom.
07:01Outside, red cedar cladding makes a nod to the woodland setting.
07:06So how does it work?
07:08Well, the earth functions as a storage battery.
07:11The house is the collector, sucking summer heat through its large windows into its walls and floors
07:18and through an underfloor system of pipes into the earth's battery.
07:24In winter, it acts backwards.
07:27The heat needed will move from the earth, through the concrete and back into the house.
07:34It has to work, because there'll be no radiators here,
07:37and because Andrew's family happiness and his livelihood depend on it.
07:42There are reputational issues here.
07:44You've got to provide something for your family,
07:45but also demonstrate to your customers in your business that you can do this, it's going to work.
07:50My neck is on the line, so, yes.
07:52And how much is it all going to cost?
07:54We're allowing for £300,000.
07:56So that's quite an aggressively small amount of money.
08:00Yes.
08:02Andrew's the optimist, aren't you?
08:04Yeah.
08:05Andrew the optimist has £200,000 in savings, and he'll borrow £100,000,
08:11repaying the debt after selling the cottage and splitting the equity with his sister.
08:17But Andrew the optimist needs to build his new home first,
08:20despite his inexperience, he's put himself in charge.
08:23So are you project managing it?
08:26Yes, that's right.
08:27How long, then, to build this house, do you reckon?
08:29We'll be in by next Christmas.
08:31OK, so that's 18 months from now.
08:32Yeah.
08:33I mean, you think sooner, but I think by next Christmas would be good.
08:35Yeah, yeah.
08:36OK, that sounds good to me.
08:37It should be a fairly simple build.
08:39I might be eating my words.
08:40So, tell me, when do you start on site?
08:42About six weeks from now.
08:50The first task for the ground worker is preserving several shrubs and trees on the site.
08:57Things like this lilac that we're moving, that's at least 40 years old.
09:01I mean, I don't know if they'll take, but at least we're giving them a chance.
09:05We're never to show what the outcome's going to be.
09:07We're going to try, aren't we? Try with the turf, we'll try with the trees, try with the house, see
09:11if it works.
09:12Push the boundaries.
09:14All very well and hopeful, but experiments can be dangerous, even lethal.
09:20Right now, Andrew's structural engineer, his brother-in-law, has some concerns that Andrew's roof,
09:26due to be built from concrete panels, could cave in.
09:30The structure that we're designing has got to hold up in excess of 500 tons of earth over a living
09:36area.
09:37I don't think it's a good idea to go with the precast concrete panels.
09:41The connections between the panels is often a point of weakness, which could result in literally a collapse.
09:47So, is Andrew going to listen to his structural engineer?
09:52Well, yes he is.
09:54Because the engineer determines whether or not a structure can be insurable, whether or not it's going to be safe.
10:00It's engineers that keep the world standing up.
10:03Yeah, he's going to listen to him.
10:04Oh, and not least, because in this case, the structural engineer is his brother-in-law.
10:10Which means that this project stops right now, dead in its tracks.
10:27Andrew and Margretta's plans to build their radical self-heating house have been dashed for nine months now.
10:33Now, Andrew's lost his bounce.
10:35He and his engineer have had to figure out a safer way to build.
10:39Because of the structural engineer's concerns, we've had to completely change the build system that we were going for,
10:46which blows out of the water what we were doing before.
10:49It is frustrating.
10:51You're poised to start and then, you know, you have to stop.
10:54But I would much rather stop, reconsider, get all plans sorted out before pressing the go button.
11:01His new plan is to pour the concrete on site and to make a rock-solid, seamless shell that has
11:07no weak joints.
11:09But it's going to cost £40,000 more.
11:12How much are we going to be able to get done before the money runs out?
11:15The budget as it stands at the moment will get us two-thirds finished house.
11:21We either bring in more income or we compromise on finishes.
11:26The finished beauty of their house is clearly important to Margretta.
11:30She's accelerated her plans to return to work.
11:33I've been retraining in a field of nursing that I can do slightly more independently.
11:38So I'm hopeful to be able to help support the family financially.
11:43There is quite a lot of pressure for me to get back and earning an income now.
11:46So, without enough money but a bag full of hope, Andrew and Margretta fully commit.
11:52And a year in, work begins in earnest to dig out the footprint of the house.
11:59We're actually doing it, my love.
12:01I'm a little nervous because there's obviously no going back now.
12:04We've wrecked a perfectly nice garden.
12:07And, you know, all you can do is take one step at a time.
12:10And this is a very big step.
12:13Andrew's house will be submerged, so 700 tonnes of soil need to be removed.
12:19And he needs to keep it all to one side because this earth is an essential part of his central
12:24heating.
12:24Most of this is going back around the house once we've done the concreting.
12:29So we'll be ending up creating sort of mini mountain range around two sides of the plot.
12:35Andrew is moving heaven and earth to create these giant heat-storing banks,
12:40key to this first-of-a-kind experiment.
12:43But putting untested theory into practice comes with real risk.
12:48In terms of will this work, I've run the maths many times.
12:53What we're doing is insulating the five metres beyond the edge of the building
12:57to trap that heat in and create this warm bubble.
13:01You obviously won't know till we do it,
13:03but I'm kind of putting my money where my mouth is in that regard.
13:10He certainly is into the first expensive part of the project,
13:15pouring the huge uninsulated slab.
13:18I'm very excited by this step.
13:20This has been the bit that makes it all seem real.
13:23Unsurprisingly, Andrew is using eco-concrete.
13:27But although it contains a by-product of iron manufacturing,
13:30blast furnace slag, it's not cheaper.
13:33In fact, their shell will cost a whopping £150,000,
13:37half their entire budget.
13:39And our novice project manager, Andrew, is in charge.
13:43There's a lot of nerves because I've never poured concrete before.
13:48Fingers crossed.
13:50Andrew's responsible for the traffic flow of the 12 mixer trucks.
13:54Next one.
13:55Yeah, OK, OK.
13:57He's anxious to keep the pour continuous so it dries evenly without cracks.
14:02He wants an unquestionably strong slab.
14:06He's also nervous about his budget.
14:09Better get to it.
14:10Yeah, we'll try and do it as good as possible because we get charged waiting time.
14:14Awesome.
14:15This is a wagon at 8 of 12, and each one costs just over £700.
14:21Not only the foundations, but the concrete walls start to take shape.
14:25So far, Andrew has excelled as project manager.
14:28I am very proud of Andrew.
14:30I was just really concerned that he was working outside of his skill set,
14:32and hats off to him.
14:33I'm humbled, really, by how he's done everything so well.
14:37But none of this matters if the science doesn't work
14:40and the concrete doesn't heat the earth around it.
14:42So Andrew's rigging it with temperature probes.
14:45So this pipe is where I'm going to insert a thermocouple probe
14:50just so as we can measure the deeper temperature under the house.
14:53I'll also be having similar probes behind the walls here
14:56and let us know how great heat batteries will work.
14:59So if I can get data that shows that this is a successful way
15:02of building energy efficiently, it's got to be a good thing.
15:12By late summer, two months later, they've made real progress.
15:16The slab and walls have been unshuttered
15:18and timber boards now lie on top of the structure
15:21ready for the final concrete pour
15:23for the critical load-bearing roof.
15:26Hello.
15:28It's good to see you.
15:28Good to see this so well advanced.
15:30Oh, thank you, yes.
15:31We're really pleased.
15:32Oh, I'm delighted.
15:34Margrethe's delight is completely understandable
15:36because at last there's some beauty to behold.
15:39Ha, ha, ha.
15:41Oh, look at that.
15:43This is the winning feature for me.
15:46The whole project is just really functional.
15:48This for me is just the bit that's actually going to bring pleasure.
15:51It's going to be beautiful.
15:52It's going to be exquisite, isn't it?
15:53It's going to be very special.
15:55Big hole in the middle of the building.
15:56Yay.
15:58In terms of the heat loss of the building?
16:00Well, it's a compromise, isn't it?
16:02Oh, this is the win.
16:04Engineering.
16:04Yeah.
16:05Joy.
16:06Yeah.
16:07But here the engineering always comes first
16:10and pouring a concrete roof on this angled wooden formwork
16:13will be some feat.
16:14It has to defy gravity.
16:16We need to get the mix dry enough so it doesn't slump.
16:20Yeah.
16:20But wet enough so it will go through the pump.
16:22I thought using the earth's energy, the heat in the ground,
16:25would be the tricky thing with this project.
16:27But the perilous thing is that sloping concrete roof.
16:29That's going to be some day, isn't it?
16:35That big day comes two weeks later.
16:39It's the crack of dawn.
16:41Andrew has nine labourers on standby for this extraordinary undertaking.
16:45But I'm still not sure how they're going to do it.
16:48First of about seven, I think.
16:50Obviously, I've never done this before, poured concrete at an angle.
16:53If it's too runny, obviously, it'll just flow like a liquid.
16:56And that means it's all going to slump down.
16:58Andrew?
17:00Yeah?
17:00Too wet.
17:01Too wet?
17:02Yeah.
17:02Are you joking?
17:05The worst has already happened.
17:08That's not going hard.
17:10Hello?
17:11Look.
17:12Yeah, the worst lot of concrete is going to have to go back.
17:15To dispose of it, it costs three times as much as it costs to buy it.
17:19And it costs £730, that one.
17:21So if I sent that back, it would be over £2,000 for nothing.
17:25We can always give it a go, but I don't think it's going to hold.
17:29OK.
17:31The supplier is adamant that it's the consistency ordered,
17:34and Andrew's team don't want to take the hit.
17:37But they decide to give the sloppy concrete a go.
17:40It seems a crazy decision.
17:43So it should be thicker.
17:44It's blood over the edge.
17:46Nice and slowly.
17:48Keep it in a bit more.
17:49Use the popcorn up here.
17:51The foreman, Brian, throws all his men at the task in hand.
17:55That's kind of going up on a bit of him down now.
17:58Is it OK, Brian?
17:59Only just for here, but it needs to be joy.
18:04For 20 adrenaline-filled minutes,
18:06they fight to keep the concrete in the right place before it sets.
18:10They can't really afford to get any more problematic batches.
18:13It'll be impossible to control closer down by the edge.
18:16It does need to be drier, please.
18:18I'm sorry.
18:20I'm just a little bit stressed.
18:22The all-too-critical next batch arrives.
18:26Looks good, hey?
18:26It could be.
18:30It is drier, but five more truckloads are needed
18:33for this whopper of a roof, and each one is critical.
18:37It's like Goldilocks' porridge.
18:38You want to get it just right.
18:40It takes seven hours of struggle, pushing concrete uphill.
18:44Nearly there.
18:45This is the last lot.
18:47Fill in that last little bit.
18:50Until it's finished.
18:52Isn't that amazing?
18:54We'll have to sign our names in it.
18:56Don't you dare.
18:58It's a relief for everyone,
19:01including Andrew and Margretta's kids,
19:03for an unexpected reason.
19:04I used to think there would be, like, earth as a roof,
19:08if you know what I mean.
19:09No concrete, and then moles fall in.
19:11And I have an umbrella over our beds.
19:14And then I realised that it's probably not going to happen.
19:17Yeah.
19:18Luckily.
19:20Six weeks later, the roof has dried through.
19:24So inside, the grid of supporting props has been struck.
19:28It's quite some revelation.
19:29It's so great to see all the props down.
19:32Initially, the building seems a little bit fragile.
19:36But the space inside is just glorious.
19:39And I can start to picture how the rooms are going to work.
19:43While Margretta dreams of interiors,
19:46Andrew focuses his optimism on the next construction phase,
19:49his central heating system, made by burying his house.
19:56So, what I'm doing here is just...
19:59We're putting the first bit of earth on.
20:01We've got 50 tonnes of earth going on this compartment of the roof.
20:05And it's a great feeling,
20:06because this is the mass that will be storing the heat.
20:10And it's earth, it's free.
20:12A bit more on the top corner.
20:15Free it may be, but he needs a mountain of the stuff.
20:18So will his new roof take the weight?
20:20If this roof was loaded with way too much earth,
20:24it would essentially buckle and could collapse.
20:29So he's slowly working with just one labourer, his mate, Mark.
20:36Mark?
20:38Mark?
20:39I can feel quite vibrations in my feet,
20:41slacken it off a little bit.
20:43I'm just going to go inside,
20:45so there's no ominous cracks or anything.
20:48The tiniest crack in his ceiling
20:50could become a gaping chasm in the project
20:53if it means replacing the roof.
20:57If I saw a crack right now, I'd probably cry.
21:00In fact, there's no probably.
21:02Andrew's right to be alarmed.
21:04He can't afford any mistakes.
21:06And yet, this is one big experiment
21:09with hundreds of tonnes still to pile on.
21:24Andrew, the eco-warrior...
21:26You want to come up?
21:27...has been building his experimental self-heating home
21:30for 18 months.
21:32His family want to have moved in by now.
21:34What do you reckon?
21:35Good!
21:36For the last week, he's been slowly burying his structure.
21:40Thankfully, there's still not a crack in sight.
21:44But Margrethe has buckled under their financial pressures.
21:48Being a former midwife,
21:49she's set up a business specialising in medical skin treatments
21:52like anti-wrinkle fillers.
21:55This works really well with 15-round homeschooling.
21:57It's flexible and it gives me the opportunity to do both things.
22:00With the build, we've got a finite pot of money.
22:04Andrew and I have very different ideas
22:06about what a beautiful home will look like.
22:08In order to get the finishes that I want,
22:11I really need to be able to afford them.
22:14Her drive is understandable,
22:16given Andrew's very different priorities.
22:18The most important thing in the interior to me
22:20is, believe it or not, the heat transfer system
22:23so that we get that working correctly
22:26because then the building can function like a machine.
22:29To you, me and Margrethe, this is a house.
22:32To Andrew, it's a heat transfer machine.
22:34And unlike any other earth-sheltered buildings,
22:36he's putting insulation over the top of his earth mountain.
22:41Completely weird way of making a building.
22:44And it's a really complicated sandwich.
22:46What we've got under here is earth.
22:50Then we've got polythene.
22:51And then finally, the critical part of it,
22:54which is the polystyrene.
22:56The earth around the building still holds some summer heat.
23:00All right, there we go.
23:01So he's anxious to cover it quickly as it's turning chilly.
23:04I've been on this pretty much seven days a week, actually.
23:07The rush at the moment,
23:08just getting this, you know, polythene and polystyrene
23:11on before winter properly bites
23:13means we can lock in some of that heat.
23:16It's going to take two years for the house
23:19to accumulate enough heat to work fully.
23:21So, as soon as possible,
23:23the high-spec windows with special heat-retaining coatings go in.
23:27Quarter of a tunnel hanging around.
23:30Fitting them is a delicate operation.
23:33We don't want to be here without dustpan and brushes.
23:35I'm going to hold it upright like that.
23:37Now I want you to move it.
23:39Unfortunately, there's a great big pillar in the way,
23:41which makes the job more head-scratchingly tricky.
23:45It's a very important pillar
23:46because it's holding up 100 tonnes of earth,
23:48but when you're playing with glass and steel and concrete,
23:52you've really got to edge it in.
23:53Oh, that's very close.
23:55All right.
23:56Give it in.
23:57Am I good?
23:58That's it.
24:00And breathe.
24:03Very happy.
24:05With the windows in and sealed,
24:07the house is at last watertight,
24:09and the self-heating can immediately begin.
24:14In spring, just as the ground is thawing,
24:17it's time to transplant turf to the roof of the building,
24:20and the house starts to disappear, kind of.
24:26The only telltale sign, of course,
24:29is the ubiquitous, the ever-present sign
24:32that there is somewhere buried under this,
24:34a house, and that is yards and yards of blue plastic.
24:38The pressing question is, however,
24:40since it's spring, is the place starting to heat up?
24:43You've got a pulley on.
24:45It does feel a bit cooler in here,
24:47but when it's been cold,
24:48it's been much warmer in here than the outside.
24:50Slowly going up in temperature.
24:52It should be 15, 16 degrees by the end of the summer,
24:55which will feel, you know, noticeably warm.
24:59Andrew is clearly convinced his machine is already working.
25:02I'll believe it when it's the dead of winter.
25:05But his face is born from scientific principles.
25:09So this is a thermal camera,
25:11so it measures infrared radiation.
25:13If you were to just quickly put your hand on the wall,
25:15and now just take it away.
25:18So that heat has left your hand,
25:20gone to the wall,
25:22because heat will always go from hot to cold.
25:23This whole wall and the 500 tonnes of earth behind it
25:28is steadily growing in temperature.
25:32Nuts, but clever.
25:34Exactly, exactly.
25:38Summer 2019 is hot and dry,
25:41ideal for Andrew's heat machine,
25:43which can soak up its second cycle of sun.
25:45This is a great, great trend.
25:47And remarkably, Andrew is laying yet more insulation,
25:51not on his house,
25:52but extending five metres beyond it.
25:56Inside, Margrethe is working alone,
25:59prepping, sealing and undercoating.
26:02For the last three months,
26:03Andrew's mostly been working on the outside of the house.
26:06I thought we'd be inside by now.
26:09It just feels very frustrating sometimes.
26:12Look at that curve, eh?
26:14Yeah, no, progress has been all right.
26:16I'm happy with where we are,
26:18and I can see us completing the insulation
26:20before autumn really starts getting cold.
26:24It's really hard because it feels to me
26:27a lot like it's Andrew's baby.
26:28I don't really feel in control of it.
26:31It's not up to me.
26:32I'm standing with my paintbrush,
26:33painting walls and not much I can do.
26:40It takes another two months
26:43while the exterior gets clad
26:44before work picks up inside.
26:46It's October,
26:48and the partitioning is going in.
26:51Andrew's labourers, Kevin and Andy,
26:53are both aware that,
26:54as in any science lab,
26:56there are rules.
26:59Please close doors to keep heat in.
27:02I told them about opening the doors,
27:03but as you can see,
27:05it's hot in here
27:05because it makes me sweat.
27:08We usually open the doors
27:09when there's nobody about,
27:10but here, come down and close them.
27:12I presume because he takes
27:13a log in down of temperatures.
27:16Andrew enthusiastically
27:17takes daily temperature readings
27:18from the probes he's inserted
27:20deep into the earth bubble
27:21around the house.
27:23He was just going to have
27:24six monitoring points,
27:25but as time's gone on,
27:26I've just wanted to measure
27:27in more and more places.
27:28I've got about 20 now.
27:29It's all good data.
27:31It just shows how well
27:32the building is performing
27:33because I want to be able
27:34to confidently say
27:36that we have stored that heat.
27:38And I'd like to get that earth
27:39up to about 17 centigrade
27:41on average.
27:43Of course,
27:44only by living in the finished house
27:45will he prove his theory,
27:47if it ever gets completed.
27:512020 begins.
27:53Andrew is nearly two years
27:55into what should have been
27:56in an 18-month schedule,
27:58but it doesn't look like
27:59they're moving in soon.
28:00The earth battery was only
28:02part of the experiment.
28:03Inside, there's a mile
28:04of underfloor pipes to go in
28:06that'll transfer heat
28:07around the building.
28:09The pipes, they can gather heat
28:11from the sunny side
28:12of the building
28:12and dump it where the earth is.
28:15Neither of us have done this before.
28:17It's the blind leading the blind,
28:18so we'll see how we go.
28:19Progress is quite slow.
28:22This kind of work
28:23that's happening
28:24in the house right now
28:24is the same that happened
28:25outside the house.
28:26Lots of pipes going in places.
28:28Just pipes,
28:29just metres and kilometres
28:30of pipes.
28:32And then, of course,
28:32it all gets buried.
28:33And Andrew's very excited.
28:35He's marked out.
28:35He's got little drawings
28:36of where little pipes go.
28:38Oh, dear.
28:39How can these two visions
28:40be reconciled?
28:42That of the aesthetic homemaker
28:44versus the data-obsessed scientist?
28:47What are your plans?
28:48I mean, do you simply
28:49take the furniture out of here
28:50and move it into
28:51a freshly-paged space?
28:53No, no.
28:54Andrew's in a slight disagreement
28:56with me about that.
28:57Well, he would be
28:57because he's an environmentalist,
28:59so he'll be interested
28:59in recycling what you have.
29:01You're looking at that
29:02tattoo you read so far.
29:03I am.
29:04None of this would work well
29:05in the new house.
29:06The new house is a blank slate.
29:07It needs to be treated like that.
29:09That's what I'm hoping.
29:13But as the coronavirus
29:15lockdowns arrive,
29:16Margrethe's work dries up.
29:18Cash flow takes a large hit.
29:20And more of the effort
29:21on-site falls to her.
29:23It's all taking its toll.
29:26The last eight or nine months
29:28have just been grueling.
29:30They've just been really hard.
29:32I just feel like
29:33my whole life
29:33has been consumed
29:34by this build.
29:36The only way back
29:38to normality
29:39is to somehow summon the energy
29:40to get over the finish line.
29:45And after three and a half years
29:47of spending money
29:48on what at times
29:49had come to feel like
29:50an uninhabitable science experiment,
29:52I paid them my last visit
29:54on an icy winter morning.
29:56Perfect testing conditions
29:58for this radical self-heating house.
30:01This project was never
30:02about aesthetics, was it?
30:04There was always an experiment.
30:08But I am pleasantly surprised.
30:13The house had truly escaped
30:15from the science lab
30:16and become a thing of beauty.
30:19Sleeker
30:19than I ever could have imagined.
30:22With all that sun-trapping blazing
30:25acting as a mirror
30:26to the luscious landscape.
30:27Although from some angles
30:29it looked like
30:29it had magically cross-fertilized
30:31with the shaggy
30:32Celtic burial mound.
30:35Heya!
30:36Hello!
30:37How are you?
30:38Oh, thank you.
30:39This is remarkable.
30:40Beauty had triumphed outside,
30:43but what about indoors?
30:45I had no idea
30:46it would be so finished,
30:47so beautiful.
30:48This submerged house
30:50was light and airy.
30:52And there were even hints
30:53that its self-heating powers
30:55were beginning to awaken.
30:57And I have to say
30:58it is warm.
30:59As I put my hand
30:59nearer the ceiling,
31:00do you know
31:01I can actually feel it?
31:03Thermal imaging
31:04comparing the old house
31:06with the new
31:07showed how effectively
31:08its highly insulated shell
31:10was retaining heat.
31:12But the complex pipework
31:14essential to make
31:15the whole system function
31:16was yet to be plumbed in.
31:18Andrew was predicting
31:19a minimum of two years
31:21for the earth bank
31:22to slowly drink in
31:23enough heat
31:24so they didn't have to wear
31:25two pullovers indoors.
31:27This was going to be
31:28a long waiting game.
31:30It's been a real journey.
31:32Just want to live
31:33in this beautiful home
31:34and just be a family in it.
31:37Andrew's brave experiment
31:38in intentionally building
31:40a house with no conventional
31:41central heating system
31:42of any sort
31:43promised great things.
31:45But the family
31:46had only just moved in
31:47and the house was yet
31:48to be tested
31:49in the burning heat
31:50of summer.
31:52It was too soon
31:54to declare victory.
31:57Andrew knew
31:58that he needed time
32:00to discover whether or not
32:02the system he designed
32:03would really work.
32:04He thought he needed,
32:05in fact, years
32:06to figure out
32:07whether or not
32:07it would store enough
32:08heat and course
32:10so that they wouldn't
32:12be freezing their nibs
32:13off in winter
32:14or, for that matter,
32:15baking in these hot summers
32:17we've been having.
32:19It'd be really curious
32:20to find out.
32:21I don't know
32:22whether it was
32:23a monumental folly,
32:24but I do think
32:25six years is long enough
32:26to wait to find out.
32:43Back in 2017,
32:45Andrew and Margrethe
32:47began their wild experiment
32:49to discover
32:50if it was possible
32:51to create a comfortable
32:52modern home
32:53that kept itself
32:54at the perfect temperature
32:55through the bitterest
32:57of winters.
32:58for free
32:58without the conventional
33:00heating systems
33:01the rest of us rely on.
33:05This project
33:06was always
33:07an important prototype.
33:09It was a game changer.
33:10It was an innovative experiment.
33:13But,
33:14as we all know,
33:15if you want an experiment
33:17to succeed,
33:18you're going to need
33:19lots and lots
33:21of data.
33:23When I last visited,
33:25the family had only
33:26just moved in
33:26and the house
33:27had barely begun
33:28its two-year cycle
33:29to slowly warm up
33:30and become
33:31the cosy family home
33:32Andrew had promised.
33:34Oh, look.
33:35There you go.
33:37A shaggy mound
33:38and just a little hint
33:39of house.
33:45But the dried-up rooftop foliage
33:48is testament
33:49to how we've just
33:50lived through
33:50the hottest summer
33:51on record.
33:52So how has the building
33:53been indoors?
33:56Six years on,
33:57it's time to find out
33:59if Andrew's experiment
34:00was a success.
34:02Hey!
34:02Hello!
34:03Hello!
34:04How are you?
34:05Yeah, yeah, good.
34:05How are you?
34:06Very good.
34:07Yeah, enjoying the home.
34:09Enjoying it?
34:09Very much so.
34:10That sounds promising.
34:13Yeah, definitely.
34:14It all looks kind of
34:15really embedded,
34:16which is so nice.
34:17That was always the idea,
34:19so it would just be
34:20sunk in.
34:21To not be able to see it.
34:22It's settled,
34:22as have we.
34:23I was thinking about you
34:24because this summer,
34:26right, it's been, what,
34:2740 degrees in places?
34:28So what was it like here?
34:29Because you designed this house
34:31for the winter months.
34:32You designed it to keep warm.
34:34Absolutely.
34:35And actually,
34:36during the heatwave,
34:37it's been remarkably cool.
34:38We've had people come in
34:40thinking we've got aircon.
34:41Amazing.
34:42The norms that we grew up
34:43with climatically,
34:44you know,
34:44are changing without a doubt.
34:46And certainly in the UK,
34:47we've got to deal
34:48with overheating.
34:49You're completely right.
34:50It absolutely is.
34:51He's looking after us.
34:51It's serving us as a home.
34:53It's lovely.
34:53It's really lovely to be here.
34:55Can we get in?
34:56Yeah, come on in.
34:57Yeah.
34:59This is the first time
35:00I've been through the front door,
35:01you know.
35:02This is no dank
35:04subterranean hobbit hole.
35:06It is crisp
35:07and generously proportioned.
35:09The rooms are bright
35:10and sunlit
35:10thanks to the building's
35:12central courtyard.
35:13And the bedrooms,
35:14arranged along the back wall,
35:16have remained dry
35:17and mould-free
35:18despite being directly enclosed
35:20by the earth's bank.
35:22These spaces may be buried,
35:24but the neat architectural trick
35:25of that courtyard
35:26dispels any darkness.
35:28From the top of the courtyard,
35:30we have got light
35:30coming down into all the rooms.
35:32That means every room
35:33gets independent.
35:35You do not feel like
35:37you're deep underground.
35:38Yeah.
35:39Do you know,
35:39I think this house
35:40is one of the lightest
35:42places I've been to.
35:43When we first moved in,
35:44it kind of felt like
35:46that light you get on holiday.
35:50So that actually,
35:51the courtyard is the big trick.
35:52Yeah, no, definitely.
35:55I'm sensing
35:56Margareta's finesse
35:58in this house,
35:59although one corner
36:00has escaped her touch.
36:02Andrew's study.
36:04That's the only bit
36:05of exposed concrete
36:06in the building
36:06I was allowed.
36:07Yeah, I started painting it
36:09and then I got stopped.
36:10I look up at him,
36:11I'm happy.
36:14So who gets
36:15the choice bedroom
36:16at the end here?
36:16Imogen's bedroom.
36:17I've noticed
36:18coming through here
36:19the patterns of light
36:20on the floor.
36:21On the wall
36:22from these
36:23clear story windows
36:24it's sort of genius really
36:26because you don't expect it.
36:28Oh,
36:29and an ensuite.
36:30That's lovely.
36:31Imogen gives that
36:32all to herself, right?
36:33She does.
36:33Teenagers use
36:34so much hot water.
36:36I suppose one thing I did
36:37was try to make
36:38the hot water usage
36:39in the bathroom
36:40as efficient as possible.
36:42What, does that mean
36:43like you're allowed
36:44to shower for 35 seconds
36:46and then later?
36:46I mean, I think
36:47in your ideal world
36:47probably.
36:48Yeah, but that's not
36:49unfortunately working
36:50but actually recovering
36:51the heat
36:52out of the
36:53outgoing shower water.
36:54I've got a little
36:55example here.
36:57I'm sure you do.
36:58I'm sure.
36:59How many prototypes
37:00have you done?
37:01I couldn't resist this.
37:02Whoa.
37:02So what this is
37:03is your waste water
37:04goes through there
37:06and it washes
37:06over this copper coil
37:08and at the same time
37:09your fresh water
37:10for your shower
37:10is going through
37:11the copper coil
37:13and it's basically
37:14doing shower heat recovery
37:15so you end up
37:16with, let's say,
37:18cold at 10 degrees
37:19normally going in there.
37:20Yeah.
37:21That'll come out
37:21about 25.
37:22It means you need
37:23less hot water
37:24because some of your
37:25cold water's coming
37:26in at 25 degrees.
37:28That's really neat.
37:29It typically can save
37:31between a third
37:32and a half
37:32of your total hot water
37:34and the other thing
37:35is it just makes
37:37a limited tank
37:38last, you know,
37:39twice as long.
37:40So everybody gets
37:41to have a hot shower
37:42not just imagery.
37:43Yeah, no, absolutely.
37:43Andrew, you're
37:44holding that
37:45like your own baby.
37:48I care about it.
37:50The house is brimming
37:52with Andrew's attempts
37:53to squeeze every drop
37:55of energy efficiency
37:56from the place
37:57from PV panels
37:58for electricity
37:59to solar tubes
38:01to heat the water
38:02in summer.
38:03But the heart
38:04of this heat-conserving home
38:05was always
38:06the Earth Bank
38:07Heat Store
38:08now fully plumbed
38:10in by Andrew.
38:12So this is
38:12mission control.
38:13Yeah, OK.
38:14Yeah.
38:15I'm so pleased
38:15they didn't use
38:16this system
38:17when launching Apollo
38:18or the Space Shuttle.
38:20If I employed
38:21a plumber
38:21who wrote
38:22circuit numbers
38:23and instructions
38:24on bits
38:24of old cardboard
38:25box
38:26rammed behind pipes
38:27I'd be phoning
38:28another plumber.
38:29Well, I suppose
38:30we didn't have to pay
38:31for that plumber
38:31though, did we?
38:32At the end of the day
38:33it was a freebie plumber.
38:34Shut up, OK.
38:34What am I looking at here?
38:35So what you've got here
38:36is the system
38:37that harvests
38:38the heat
38:38from the warm
38:39corner of the house
38:40in the summertime
38:41and send it round
38:43the, what we call
38:44the dump circuits
38:44round the back
38:45of the house
38:45so it goes
38:46into the Earth Bank
38:48and that's been
38:48really successful.
38:50For me
38:50that's the core
38:51quality about the system
38:53is you taking heat
38:54from, not a heat pump
38:57but from a slab
38:58being heated
38:59by the sun
39:00to then use
39:01in February.
39:02Well, indeed.
39:03Indeed.
39:03And what we've got
39:05stored in there
39:06already is
39:07this year's heat wave.
39:08Yeah.
39:09So that's already banked.
39:10Next time I come
39:11can this have a bit
39:12more of a plumber's
39:13touch to it?
39:14I sincerely doubt it.
39:16You're not letting
39:16anybody put their
39:17hands on it.
39:20But be under
39:21no illusion
39:21that Andrew
39:22and Margrethe's house
39:23is all about
39:24the ingenious
39:25pipes and plumbing.
39:26There is luxury
39:27in abundance too.
39:29The main bedroom
39:30still offers
39:31indulgence.
39:32It has a walk-in
39:33wardrobe
39:33over all of
39:34Andrew's old
39:34fleeces
39:35and a generous
39:36en suite.
39:37And you also get
39:38the terrace window
39:40onto the woodland.
39:41You just walk out
39:42into the woods.
39:43That's too good.
39:44West-facing?
39:45It is.
39:46Yeah.
39:46So,
39:47by rights,
39:48this room,
39:49by the time you get
39:50into it,
39:50over summer's evening,
39:51should be baking.
39:53Yeah,
39:54except there's
39:54lots of thermal mass.
39:56Simply the thermal mass
39:58of all this concrete.
39:59So in those really hot days
40:01in the late 30s,
40:02you were still comfortable
40:03in here.
40:03It's been really nice
40:04actually over the summer,
40:05really surprisingly,
40:07because as you say,
40:08there's a lot of sunlight
40:09coming through.
40:09Somebody who's not a fan
40:11of concrete would say
40:12this is an enormously
40:13carbon-intensive
40:15approach to building,
40:16right?
40:16Well,
40:17I mean,
40:17we went to as clean
40:18a concrete as we could,
40:19which was 60% less carbon
40:23than normal concrete.
40:24How many years
40:25before you achieved
40:26carbon neutrality
40:27between all the carbon
40:28you've saved
40:28and all the carbon
40:29you've spent
40:29on all that concrete?
40:30It's about eight
40:31to ten years,
40:32something like that.
40:33It's quite compelling,
40:34isn't it?
40:35Yeah.
40:35Yeah,
40:35you're very happy with it.
40:36I am,
40:37yeah,
40:37I love it.
40:37I can tell.
40:38That's great.
40:38He's very happy
40:39with all these graphs
40:40and data,
40:42and for us,
40:42it's just a lovely,
40:43comfortable place to live.
40:44Yeah.
40:46The vast living room
40:47and kitchen
40:48provides for modern
40:49open-plan life,
40:51the sun-inviting,
40:52glazing on all sides
40:53suggests more Hollywood Hills
40:55than Home Counties.
40:57But there is
40:58a cosy log burner,
41:00which, by the way,
41:01can heat the water too
41:02to suggest a nod
41:03to the old cottage.
41:05So is anyone
41:06in the family
41:07pining for the old place?
41:09I really like
41:10a competitive cottage.
41:11I mean,
41:12the cottage has a charm,
41:13but this house,
41:14I really do like it.
41:15I just like how,
41:15like, unique it is.
41:16I think it did, like,
41:17take up a big chunk
41:19of our childhood,
41:20but I quite enjoyed
41:21the process.
41:22I think it was fun.
41:23We used to have, like,
41:24sleepovers in the house
41:25whilst it was being built.
41:26But, yeah,
41:27I'm proud,
41:28really proud of both of them.
41:29It's a lovely house.
41:31And there is
41:32every reason for pride.
41:34Andrew and Margretta
41:35took a huge leap of faith,
41:37sinking everything
41:37they possessed
41:38into an experimental
41:39building concept
41:40which had never
41:41been attempted before.
41:43The stakes were high,
41:45but, boy,
41:45did they pull it off.
41:47I know it's been
41:48a long time,
41:49but do you remember
41:50how much money
41:50you were intending to spend?
41:51300.
41:52And I think
41:52when you were here last,
41:53we clocked up 310,
41:56but then we did
41:56some more work
41:57and we got it up
41:57to 330 all in.
41:59That seems like
42:00amazingly good value,
42:01by the way.
42:01No, absolutely.
42:02I mean,
42:03what's not costed
42:04is our labour.
42:04I mean,
42:05we put blood,
42:06sweat and tears
42:06into this.
42:07Yeah,
42:07of course you did.
42:08Blood, sweat
42:09and genius.
42:10There you go.
42:12And tears.
42:13Yeah.
42:14And tears.
42:16What were your
42:16low moments,
42:17by the way?
42:17I think I just
42:18hadn't realised
42:19how hard I'd be
42:20working on the build.
42:21I don't know,
42:22I just sort of
42:22thought I'd be going,
42:23that's nice, dear,
42:24and popping down now
42:25and again to look
42:25at how the site
42:26was developing.
42:27I didn't expect
42:28to be as involved
42:28with the physical
42:30labour of it.
42:31I mean,
42:31we both worked
42:32really hard
42:32and I think you
42:33had a really
42:33positive attitude
42:34and that definitely
42:35helped.
42:35Okay,
42:36so just speak clear,
42:36we just had a year
42:37where it got to,
42:38what, minus 5,
42:38minus 10 in places
42:40and our summer
42:41temperatures were up
42:42to 38 or 40 degrees.
42:44You know,
42:44the seasons go
42:45through like that,
42:46our temperature
42:47goes through like that
42:48and, you know,
42:50we're probably,
42:51from maximum to minimum,
42:52only 4 to 5 degrees.
42:55Different.
42:55Yeah.
42:56Talking of the old house,
42:57do you know how
42:58energy efficient this building
42:59is relative to
43:00where you were living?
43:00In terms of, like,
43:01the kilowatt hours,
43:02it's basically
43:03eight times
43:03what we use here.
43:05Wow.
43:05Quite a staggering
43:06multiplier, isn't it?
43:08Eight times.
43:09It's a smaller building
43:11and not only that,
43:12it was also cold.
43:14Yes, draughty.
43:15Do you feel like
43:16you're building the future?
43:18I, put it this way,
43:20the house works
43:22and it's,
43:23at a basic level,
43:24the house is a shelter
43:25and this place
43:26has seen us
43:27through the winter
43:27and the summer.
43:28We've got things
43:29like the fire
43:30and we can make hot water
43:31without any electricity
43:33and we can cook
43:34without that
43:34if it all came to it.
43:35So you could be
43:35completely off-grid.
43:36If it came to it,
43:37come the apocalypse,
43:38as it were.
43:38Yeah, yeah.
43:39Your concrete bunker
43:40looks after you.
43:41Oh, wow.
43:42Do you dream
43:43of an entire village
43:44of houses like this,
43:47hobbit homes
43:47built into the ground?
43:49I think in principle,
43:50though,
43:50you can adopt
43:51the principles
43:52and shape them
43:52to whatever your terrain
43:53looks like
43:54or the group of people
43:54that you've got
43:55are working together.
43:55I think that's
43:56really adaptable.
43:57You keep the basic
43:58principles in mind
43:59but you can adapt them
43:59to the environment
44:00that you find yourself in.
44:02Does this ever stop?
44:04Is it somewhere
44:05that you continue
44:06to experiment with
44:07to still innovate with?
44:10Doubtless.
44:11Does that trouble you
44:12to hear all that,
44:13Margaret?
44:14Do you?
44:15As long as it
44:16keeps functioning well
44:18and it looks
44:20and feels comfortable
44:21and then I'm happy
44:22and then you can just,
44:23you like to experiment anyway
44:24and as long as you're happy
44:25doing that,
44:26pottering around.
44:27Definitely.
44:28It's your measurements.
44:29Yeah.
44:31Pottering around.
44:32Yeah.
44:32That's another great definition
44:33of British engineering.
44:35There you go.
44:38Andrew's experimental pottering
44:41and Margaretta's stylish eye
44:43have collaborated here
44:45to create not just
44:46a delightful family home
44:48but one which takes full account
44:50of its impact on the planet.
44:56Most of us instinctively
44:58would insulate our homes
44:59under the floors,
45:00in the walls,
45:02in the attic.
45:03Except Andrew
45:04has taken that idea
45:06and he's flipped it.
45:07He's put the insulation
45:08outside, here,
45:09up there, at the back.
45:11He's put it everywhere
45:11where you don't expect
45:12to find it
45:13in pursuit of a radical idea.
45:15He's taken convention
45:16and turned it on its head.
45:20What he and Margaretta
45:22have done here
45:23has also put their money
45:26where their mouth is.
45:27They've invested
45:28in an idea
45:30and that is something
45:31we do really well
45:32in this country.
45:33We export
45:35our engineering talents,
45:36our design skills,
45:37our expertise,
45:38our experimentation
45:39around the globe
45:41and we need reminding
45:42more often
45:43that we're really good at that.
45:45So thank you,
45:47Andrew and Margaretta.
45:49And more of that thinking, please.
46:01Mud, mud,
46:03glorious blood,
46:05nothing quite like it
46:07for cooling the blood.
46:09So follow me, follow
46:12down to the hollow
46:15and there, let us
46:17swallow
46:18in glorious blood.
46:25謝謝 to you,聞