Self-confessed 'eco-warrior' who was criticised for his 'utterly bonkers' and 'environmentally unfriendly' £300,000 plans to build UK's first self-heating home insists it was all worth it on Grand Designs

A self-confessed 'eco-warrior' who was criticised for his 'utterly bonkers' decision to create the UK's first self-heating home has insisted it was all worth it to create his 'dream' family home. 

In 2017, Dr Andrew Smith, and his wife Margretta, from Bletchey, Buckinghamshire, set out to construct the nation's first ever self-heating house in just 18 months with an ambitious budget of £300,000 on Channel 4's Grand Designs. 

Built with a concrete base, walls and roof, the home would rely on the warmth of the summer sun stored in insulated earth banks over and around the house. If successful, the heat could then be radiated back into the rooms of the home throughout the year.

But online critics were hugely sceptical of his project, with viewers questioning the vast amount of 'plastic and polystyrene' used. Others, meanwhile, branded him an 'ego warrior' who built an 'environmentally unfriendly' property. 

'The only eco thing about this house is the heating system, so much concrete, polystyrene and plastic!' criticised one X user, while another added: 'Mixed feelings about all the concrete used in the construction... not very eco-friendly? Could an alternative not have been used'. 

Following a tumultuous construction period that saw their project halted by the likes of 'sloppy concrete', in 2020 the pair finally moved into the unique new home with their children, Jasper and Imogen.

Now, six years since the move, host Kevin McCloud returned to Andrew and Margretta's quirky leafy haven for the show's series finale to discover if their controversial plans had come to fruition. 

Despite the public backlash and Margretta's own reservations about the project, Andrew insisted that the 'blood, sweat and tears', of which he confessed there had been many, were all worth it in the long-run. 

Arriving at the sunken-in minimalist home, Kevin was instantly impressed with the overall look and feel of the property but remained curious what the reality would be once they stepped indoors.

Andrew had initially estimated that the home would take two years to begin heating up, though the brisk temperatures of last winter and unprecedented summer heatwave left Kevin sceptical of its success.

However, greeting Kevin outside, Margretta, a former midwife, confessed: 'We're enjoying the home. It’s looking after us, it's serving us as a home and it’s lovely.’

Reflecting on how the experimental build had navigated Britain's warmest summer on record, Andrew revealed: 'It's been remarkably cool. We’ve had people come in thinking we’ve got air con. 

'The norms we grew up with climatically are changing without a doubt and certainly in the UK we’ve got to deal with overheating.’

Inside, Andrew and Margretta gave Kevin an in-depth tour of the property, which boasts four bedrooms, a spacious kitchen-living space with a log burner, alongside an outdoor central courtyard to provide an abundance of natural light. 

'From the top of the courtyard we have got light coming into all of the rooms,' Andrew explained. 'You do not feel like you are deep underground. When we first moved in, it felt like that light you get on holiday.'

Kevin also noted that the bedrooms arranged along the back wall of the home have remained dry and mould free, despite being enclosed by the earth's bank surrounding the property.

In Imogen's room, patterns of light bounced along the wall and carpet. The teenager's space had been tastefully designed with plenty of space, and even an en-suite to enjoy.

Meanwhile, in Andrew and Margretta's bedroom, a large walk-in-wardrobe provides plenty of space for Andrew's old fleeces, while the en-suite adds an additional surprising touch of luxury to the eco-friendly home. 

And as with several aspects of the home, Andrew explained that the hot water system is far from conventional. 

He said: 'I tried to make the hot water usage in the bathrooms as efficient as possible. We’re covering the heat out of the outgoing shower water.’

Showcasing a prototype to explain how the innovative system works, he added: 'Your waste water goes through there and it washes over the copper coil and at the same time, your fresh water for your shower is going through the copper coil. 

'It’s basically doing shower heat recovery so you end up with lets say cold at 10 degrees, that will come out at about 25.

‘It typically can save between a third and a half of your hot water and it just makes a limited tank last half as long.’

Yet this is not the only aspect of the home that is relying upon environmental methods of energy conservation - with VB panels installed for electricity, while solar dupes help to heat the water in the summer.

The earthbank heat store, fully plumbed by Andrew himself, sees the heat harvested from the summertime sent in 'dump circuits around the back of the house that goes into the earthbank'.

He added: 'We're taking heat from a slab being heated by the sun to then use in February. What we’ve got stored in there already is this year’s heatwave, so that’s already there.’

Prior to their move, Andrew and Margretta were living in a stunning countryside cottage that he had inherited from his parents when they decided they wanted to build themselves a new home.

While Margretta, who was a full-time mother home schooling their children, wanted a  contemporary and beautiful house, Andrew’s focus was primarily on his gigantic thermal experiment. 

Margretta previously confessed: 'Andrew is an eco-warrior, I am less so. I'm surrounded by stuff that I wish we'd be able to pass on.'

Andrew admitted: 'Occasionally I pull stuff out the bin. I probably take eco-living to the extreme.' 

His passion was stoked and fuelled by his ambition to build the UK's first self-heating home, as he revealed: 'Our new home is going to be essentially one big thermal experiment. 

'I sincerely hope our theory does match up with the practice because my reputation is on the line there.' 

Fortunately for Andrew and Margretta, their children spoke highly of life in their rather unique home during the show's new episode - with Imogen praising its 'unique' setup. 

'I think it did take up a big chunk of our childhood but i quite enjoyed the process. We used to have sleepovers in the house while it was being built.’

Jasper added: ‘I really like it compared to the cottage. The cottage had charm, but this house I really do like it. I’m really proud of both of them. It’s a lovely house.’

Elsewhere, Andrew explained that the pair had tried to used the 'cleanest' concrete possible for the build, which amounted to 60 per cent less carbon than expected in normal concrete. 

He estimated that it would take the pair between 8 to 10 years to reach a state of carbon neutrality. 

And while the pair had initially hoped to spend £300,000 on the project, they managed to finish the project at a cost of £330,000 all in - a figure which Kevin was remarkably surprised by. 

He noted that their previous cottage used eight times the kilowatt hours compared to what they use now, despite being a smaller building. However, there have understandably been some setbacks throughout the process. 

'What's not costed is our labour. We've put blood, sweat and tears into this,' Andrew confessed.

Margretta added that she had been surprised by how challenging she had found the 'physical labour' of crafting the home, though she praised her husband's 'positive attitude' throughout the process. 

When considering what the future holds, Margretta shared she was happy for Andrew to keep 'experimenting' creatively to make it as energy-efficient as possible, so long as the home retained its sense of comfort and functionality. 

Andrew added: ‘The house works. On a basic level, this house is a shelter and it's seen us through the winter and the summer. 

'We’ve got things like the fire and we can make hot water without any electricity. We can cook without it. If it came to it, we could be completely off grid.’