Tag: autonomous house

HPH220 : How to finish a self build when money is tight – with Mike Coe
Mike Coe provides a progress update on his second self build project, with finances being stretched as construction is set to begin.

Interview with Mike Coe

When Mike and Lizzie built The Autonomous House in Cropthorne, they weren’t prepared for quite how popular and influential it would become. Although Mike wanted it to be ground-breaking with as few demands on the environment as possible, he was surprised at how it captured so many people’s interest then, and does even now. With The Autonomous House now sold, Mike and Lizzie have moved to Scotland and are ready to embark on their next self build project, albeit this time taking a little more of a back seat role.

There is less enthusiasm the second time around!

Mike was very hands-on with the construction of The Autonomous House, expecting to be staying there for the long-term, but by the end of the three years it took he suffered from self-builder fatigue and had just about had enough!

So when they moved to Scotland they initially looked for a ready-built house that they could move into. Failing to find anything suitable they have instead purchased a plot of land and are preparing to employ contractors to take on most of the work for their new self build.

This build is following a more conventional path

Mike doesn’t recall signing contracts for the construction of The Autonomous House. Much of the team he used then was based around local networks on ad-hoc and informal bases.

This time he is using a much bigger architectural practice, Rural Design, who have been instrumental in challenging the traditional white-rendered walls and slate roof vernacular of local dwellings in the Isle of Skye area. The processes have been more formal, with tender documents assembled and sent out to local practices. The original contract period of 12 months has been extended to 15, to enable Mike to take on some of the work, though he hopes not as much as on the previous house!

The location has provided unique challenges to this project

Their planning decision was delayed by 4 months because the department had only one officer while another took maternity leave! This had knock-on effects to the programme as building in the Hebrides in the winter can be very difficult and best avoided.

The house is being built to the Passivhaus standard, so there has been additional design work involved which the local architects didn’t have any particular experience of.

As well as the absence of a large pool of local tradespeople used to building this way, just the availability and transporting of specialised products is a challenge, with extra expense incurred and some suppliers not even delivering there.

A delay could make the project unaffordable

Mike and Lizzie built The Autonomous House in a way which reflected their desire to live there for many years, so moving on and selling up only 4 years later has meant that they have lost a considerable amount of money from the sale.

They decided to proceed with their new project around a year ago when the pricing came back from the quantity surveyor and appeared to be just about affordable. However, when it went out to tender a year later they were shocked at how expensive the sums were being returned, with only one local contractor being any kind of an option to pursue. Mike concludes this has probably been down to a general increase in the price of materials and labour, heavy demand for contractors on the Isle of Skye, the Pound losing value against the Euro and general uncertainty about what will happen after leaving the EU. And with the interest on his savings not keeping up with inflation, the build is suddenly looking a lot less affordable.

With these factors likely to worsen, and not wanting to be in a position where it becomes too expensive in the future to proceed, Mike and Lizzie have decided to push ahead with the build now.

Without making a conscious choice to value engineer on the project, Mike thinks it has been built into the whole project anyway. It is however still the house they want to build and are still going to try and build.

The method of construction is based on The Autonomous House

Despite being a large plot, Mike and Lizzie haven’t felt pressured to build a bigger house than they need. In fact they intend all of the spaces in the house to be well utilised, with some areas having dual purpose.

Drawing on their experience of The Autonomous House, this time they have again opted for a high thermal mass house. The structure warms up during the summer and returns that heat to the interior during the winter. It also helps keep temperatures stable in the summer.

Items have been removed from the contract in order to proceed

After discovering their chosen contractor hadn’t included certain items like floor tiles and kitchen units, they decided to proceed on the basis that as a minimum (and he hopes a maximum), Mike would take on the electrical wiring and installation of the MVHR unit.

They have also removed a number of items from the contract, not wishing to commit to an amount they couldn’t be sure they could afford. Changes that have been made include the removal of the decorating from the contract, simplifying the plumbing, doing the pipe insulation themselves, and not proceeding with building the garage.

“Removing all these items got us down to a price where I could say I’ve got that much money. Let’s sign it and proceed from there, and then as we get nearer the end, we’ll see how things go.”

With no contingency fund, if they hit groundworks issues when they get started shortly then their project will inevitably be prolonged. If necessary they could move into the new house in a barely habitable condition and convert the 1960s bungalow in which they’re currently living on the site into a holiday rental, which could prove lucrative. Taking out a small business loan to do this with reasonable interest rates and flexible repayment terms would mean they wouldn’t be taking money from the budget of the new house.

Find out more

Mike is putting video reports about his project on his website. There is also a webcam providing image updates every 30 seconds so once construction starts it can be followed in almost real time on a daily basis.

Visit the website of Portree Passivhaus

Follow the progress of Portree Passivhaus on Twitter

Follow Mike on Twitter

Listen to our previous podcasts with Mike, about The Cropthorne Autonomous House and whether you should consider the resale potential of your self build.

Transcript

Download a transcript of the interview with Mike Coe.

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July 1, 2018
From Passivhaus . . . to conventional house?

What makes someone swap the comfort of a Passivhaus self-build for a conventional 1960s bungalow? Former ITV news cameraman Mike Coe explains his unexpected transition.

When Mike Coe built his ultra-low-energy eco-build – the Cropthorne Autonomous House in Worcestershire – after he retired in 2006, he was determined to make a difference.

Water neutral and off-grid apart from electricity, the house trod as lightly on the earth’s surface as possible. It encapsulated Mike’s optimism that UK housebuilding was on the cusp of change.

But five years on, after much soul-searching, Mike and his partner Lizzie made the difficult decision to move on.

A shift in values, combined with an appetite for new adventure, has taken the couple from the comfort of a Passivhaus with no heating system, which never fell below 16°C even on the chilliest of winter nights – to a three-bed 1960s bungalow in Portree on the Isle of Skye. So what changed?

The comfortable Passivhaus they left behind

Reality check

“When we built The Autonomous House, I naively thought I was on the vanguard of some kind of movement in ultra-low energy homes,” says Mike. “But while I was attempting to build as ecologically as I possibly could, the government was in the process of trashing UK planning laws and allowing developers to build rubbish wherever they wanted. I became disillusioned quite quickly.

“I still feel The Autonomous House itself has value and was a great project – but I lost my sense of optimism that it was the dawn of a new era.”

Their current home – a traditionally built 1960s bungalow – is merely a temporary stop-over as they embark on another self-build challenge. And while Mike’s focus has changed since building his radical, largely off-grid Passivhaus, he hasn’t lost faith in low-energy building methods.

“I still try to live in an environmentally sympathetic way – and my next house will be a Passivhaus,” says Mike. “But I no longer think anything I’m doing will have any great impact on the world.

“Since retiring I returned to work as a cameraman, but only on carefully selected, mostly environmental projects. As a result I’ve met some of the world’s leading climate scientists and been able to talk to them informally. From what I’ve learned I’ve concluded that it could become uncomfortably hot in the south of England, even in my lifetime (I’m 60 now). This realisation was the trigger for a decision to move as far north as was practical without leaving the country – and we’ve ended up in Portree.”

Portree

Skye’s the limit

In planning their move north, Mike’s original intention wasn’t to build again. Despite being very practical and capable – having done all the electrics, plumbing and more at Cropthorne – he doesn’t particularly enjoy the building process. The couple’s first thought was to find an existing house that they could adapt.

“It quickly became obvious that we wouldn’t find anything that came close to what we had at Cropthorne in the areas we wanted to move to,” says Mike. “Once you’ve lived in a Passivhaus it’s very hard to settle for a conventional draughty house that’s expensive to heat and live in. So we decided to look for a temporary house, while we considered our options.”

It was during this search that they heard about a building plot with planning – that also had ready-made accommodation on site.

“While it wasn’t our intention to build again, the site we found, almost accidentally, had so much potential,” says Mike. “It had nine acres of croft land, two building plots with Permission in Principle (the Scottish equivalent of Outline Planning Permission) and a perfectly acceptable bungalow on site that we could move straight into. It was too good an opportunity to miss.

“It’s rare to find somewhere with ready-made accommodation on site when you build. We can build a south-facing, solar-heated home here with views over Portree harbour and distant views of the Cuillins. It’s perfect.”

View from the Croft

‘Conventional’ house v Passivhaus

So how does living back in a ‘normal’ home compare to the comfort of living in the Cropthorne Passivhaus?

“The most notable thing is how rapidly the temperature inside conventional buildings follows the temperature outside,” says Mike. “The heating goes off and half an hour later you notice that it’s really cooling down. Two hours later, it’s freezing.

“In our Passivhaus, which was high-mass with thermal storage in the structure of the building, the process was slowed down. In autumn, when you started getting chilly nights, you simply weren’t aware of it.

“Living here has made me realise how lucky we’ve been to live in a Passivhaus. The bungalow’s clunky old oil boiler drinks kerosene that I have to pay for. It’s not cheap – whereas at Cropthorne we had no heating bills, and it was more comfortable. That’s a stark contrast.”

The warm and cosy upstairs at the Cropthorne Autonomous House

Laying plans for a new adventure

What of Mike’s plans for the new build? Have his shifting views led to a fundamentally different approach this time?

“It will still be a very low energy design for both comfort and running costs, because it’s a good way to live,” says Mike. “It just won’t have unrealistic goals.

“With the Cropthorne project we were quite hard line. The house used entirely harvested rainwater, we had composting toilets, and everything was designed to minimise impact. We’ll still follow that path to some extent. For example, we’ll aim for zero heat, even though the climate here is different. There’s also a stream running down the site that should be capable of powering a small hydro generator to provide some of our electricity. Eventually we may even add a wind turbine.

“But this house will have more mainstream appeal. The autonomous systems at Cropthorne were brilliant but they added to the costs, and you don’t get those back when you sell. We had practical reasons for doing what we did there. On Skye, water is in abundant supply, so we’ll probably connect to the mains.

“So, overall, the new house will still be very comfortable, environmentally benign and energy-efficient, but will be more mainstream and more saleable – just in case I have another brilliant idea in five years’ time and we end up moving again!”

Artist’s impression of Portree Passivhaus

July 10, 2017
HPH152 : Should you consider the resale potential of your self build? – with Mike Coe
Mike Coe explains what he’s learned while trying to sell his energy-efficient home and how it has made him re-evaluate for his second self build project.

Interview with Mike Coe

Back in 2011 Mike and his partner Lizzie moved into “The Autonomous House” – a self build project described as one of the UK’s most sustainable homes, which we featured in Episode 54. At the time they built it they were expecting to be living there for the forseeable future, but have recently made the decision to relocate to Scotland. Now that they’re looking to sell their house they’re discovering that finding a buyer for such a unique property is not without its challenges.

Visit Cropthorne Autonomous House as part of the Passivhaus Open Days.

The lure of one more project is compelling!

Mike has devoted a lot of time researching climate change, and his own feeling is that in the next few years the temperatures in the south of England will get far hotter. Approaching his 60th birthday he is also starting to get a sense of excitement at the prospect of taking on one more big project, so although it is with a great sense of reluctance to be leaving The Autonomous House, a move to the Isle of Skye and a new self build project is on the cards.

Using a conventional estate agent has not found a purchaser for this unconventional house

Despite having a couple of interested parties, using a traditional estate agent has not secured a buyer for The Autonomous House. Mike believes that it won’t be for another 15-20 years that people will really understand the value of a house like it, with many people being put off by a lack of understanding about some of the features, eg composting toilet, rainwater harvesting system etc.

“So I think the attitude is changing but I think it’s going to be some time before we have the level of awareness that perhaps they do in Germany where there are a lot more low energy houses, a lot more Passivhauses, people understand them, they’re not afraid of them. ”

With the conventional estate agent route not yielding any results, Mike and Lizzie paid to advertise on the Green Moves website, which by its nature attracts people who are genuinely motivated to buy a sustainable home. Through this they are optimistic that they have found a potential purchaser and are now in a chain waiting for them to sell their property.

Despite the systems Mike has built into the house, he explains that it’s actually a very simple house to live in. It might be different to living in a conventional house, but is no more difficult. It doesn’t for example have central heating systems and boilers to worry about maintaining, or complicated electrical systems to understand. He thinks that anyone with a basic degree of DIY knowledge and experience would be able to maintain it without difficulty.

Selling the house will come at a financial loss

When Mike and Lizzie built The Autonomous House, their plan was for it to be their home for the forseeable future. They didn’t build it thinking about potential resale value. Perhaps if they had, Mike says they might have been able to fit a bigger house on the site or done other things a little differently, to create a larger resale value.

Housing prices in Worcestershire have remained fairly stagnant since 2007/2008 so they have also been hit by property not being a reliable investment over that time. Mike explains that the only way to not lose money on the property now would be to remain there for several more years and wait for property prices to catch up. Being reluctant to do that, they have decided to accept that they will lose money on the house. He is conscious that, while they intend their new project in Scotland to be their home for the forseeable future with low energy and off-grid features, he will be bearing in mind potential resale values and maybe being a little more conventional, just in case!

“So in some senses it’s going to be a little more conventional and I’m not going to do things like have a whole house basement in order to store rainwater, because it’s a very expensive thing to build. So I’m keeping a little bit more of an eye on those kind of costs and I’m compromising a little I suppose but not very much. I’m compromising a little with an eye on possible future sale.”

The new challenge!

While Mike and Lizzie were looking for potential houses to buy for when they first make the move to Scotland, they were introduced to a plot which they quickly realised was going to be better than anything else they were going to find. With a great deal of financial manoeuvring they were able to buy it and are now looking forward to the new challenge that awaits!

The plot is on the edge of Portree, a principle town on the Isle of Skye, which although not large, does have a good number of facilities for its size. The land is a sloping site which will give them views across Portree Bay, will be close to south facing giving them the option of another solar heated design, and has very little likelihood of further development happening nearby. There is also a stream running down the site which may give Mike the opportunity to run a micro-hydro system which, while probably not justifiable in economic terms, is something he says he has always wanted to do.

The site from above – on the left behind the trees is the roof of a 3 bedroom bungalow that was included in the package

The site from below, looking up the hill

View from the croft, looking back towards the site and over Portree Bay

Find out more

Read the blog about creating The Autonomous House

Follow Mike Coe on Twitter

Transcript

Download a transcript of the interview with Mike Coe

Passivhaus Goes Personal

This is a video we have produced for the Passivhaus Trust which was recently launched at the Passivhaus Conference as part of a campaign aimed at self builders. If you’re a self builder and haven’t made up your mind yet whether Passivhaus is for you, this will provide you with all the clear information to help you with your decision.

The Hub update

Our second video from Buckinghamshire Passivhaus is now available for Hub members. This one is all about how it’s going to be built, with details of the PH15 system along with some of the designs, plus how it’s being positioned on the site.

We also have our second progress call where Hub members can get together to discuss challenges or other aspects of their projects. The recording of the call is available for members to catch up with at any time.

Our latest module in The Hub is all about reclaiming VAT to make sure you don’t miss out on that 20% benefit.

In 4 weeks we will be increasing the price of Hub membership, but if you join now you will pay at a lock-in price for as long as you continue to renew. Check out www.houseplanninghelp.com/join to find out more!

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November 2, 2016
HPH106 : An Energy Positive House That Addresses Cost, Performance and Buildability – with Professor Phil Jones
Professor Phil Jones works at the Welsh School of Architecture at Cardiff University where, over the last 12 months, they have designed, built and are monitoring the UK’s first energy-positive house.

Interview with Professor Phil Jones

Phil Jones’ background is in building physics, but over the last 15-20 years he has been working as an environmental designer on a number of projects, on both a small and urban scale.

As part of the University’s Low Carbon Research Institute, they have been developing a number of technologies in partnership with industry, and have designed and built a home with the aim of it producing more energy over the year than it uses.

©Cardiff University

It has Taken Just 18 Months to Design and Build

From previous projects that they’ve worked on, they knew the technologies that they wanted to optimise into the process.

The Wales European Funding Office provided some of the funds which needed to be spent fairly quickly, so that provided an incentive to get it done!

They managed the project themselves but employed a construction manager to oversee the site. That way they were able to keep control of the project and ensure they remained within budget.

Integration of Technologies and Architecture

A systems approach has been used to integrate the technologies together, and to integrate those technologies into the architecture. The energy demand of the house is close to Passivhaus levels, and both thermal and electricity energy storage has been incorporated. It utilises SIPs panel construction and has a render applied to the outside, except for where the thermal air collector is.

Solar electricity – used for the lighting and small items, runs the heat pump for the heating system, charges the batteries and heats the water. Any excess is exported back to the grid. The PV panels form the south facing roof of the building.

©Cardiff University

The thermal system – air is brought into the building using a transpired solar collector (an air collector wall on the south elevation). The heating in the house is from the air being pre-heated by the sun, picking up heat from the MVHR and being topped up by a heat pump. The heat pump uses internal air, so is more efficient than using an air source version which works on external air temperatures.

©Cardiff University

The ‘buildability’ of the design is aided by the components being readily available locally, and local skills and contractors being used.

©Cardiff University

The House is Around 75% Autonomous

This is based on their predictions. There will be periods when the house will draw from the grid, but over the course of the year it is estimated it will put back in roughly 70% more to the grid than it will take from it.

Battery Technology is Developing at a Fast Pace

They opted for lithium batteries as, although they were more expensive, they were lighter and had more capacity for the size. They’re bolted to the wall and don’t need any maintenance from the occupants. Phil notes that since building the house prices have fallen by around a half. He says Tesla for example have produced a 7kWh lithium battery for the housing market for around £3500, with costs predicted to come down further.

©Cardiff University

Cost Increases Have Been Offset by Cost Reductions

Some things have inevitably cost a little more, such as the heating and battery systems, but there have also been savings. Using the ventilation system to heat the house means that there are no radiators or wet services around the building. No radiators also means that the room spaces can be more flexible.

©Cardiff University

With the PV panels being the actual roof, it has not been much more expensive than a normal roof, and the air collector forms part of the wall construction.

Costs are expected to be around the price of standard social housing, or the price of something that has been produced by a quality private developer.

Solcer House Has Been Well Received by Visitors

Feedback from the public that have been to visit the house or seen the details on the internet has all been very positive. The principles that have been used in the building can be adjusted to suit different aesthetics and different building types.

While volume house builders have been interested in seeing the house, Phil suspects it is not something they will be trying at the present time. They won’t do anything new until such times as they have to.

Builders of social housing have been more interested as they can appreciate the performance over time and the sense of having a building that people can afford to live in in the future.

Smaller scale developers are likely to see this as a market opportunity, to meet the demands of people who are confused as to why all houses can’t perform like this one.

Find Out More

Follow Professor Phil Jones on Twitter

Find out more about the Welsh School of Architecture

View the Solcer House brochure

This video explains more about the construction of Solcer House:

Transcript

Download a transcript of the interview with Professor Phil Jones.

Ecomotive Event

We featured Jackson Moulding of Ecomotive in Episode 77, where he spoke about the Ashley Vale group self build scheme which initially had to fend off a large developer in order to secure their plot of land.

Ecomotive are putting on a week-long series of talks and workshops in Bristol, aimed at inspiring people who want to go down this route and looking at some of the challenges they can expect to face. Ben Adam-Smith has been invited along on Saturday 5th December 2015 to share what he has learned so far.

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November 3, 2015
HPH054 : Building an Autonomous House – with Mike Coe
Mike Coe lives in an autonomous house with his partner Lizzie Stoodley. He shares the story behind this self-build project and why it’s ultimately left them with a deeper connection to their environment.

Take a Video Tour of the Autonomous House

Mike has produced a great video about his house that gets into all the details.

Interview with Mike Coe

After many happy years working as an ITV News cameraman Mike Coe had the opportunity to take voluntary redundancy. With an increasing concern about the environment he saw this as a way that he could make a difference, building an ultra-low energy house.

Architects Brenda and Robert Vale Inspired the Project

In the mid 1990s Mike was sent to Southwell, Nottinghamshire, to cover a story about an environmentally-friendly ‘autonomous’ house.

Unfortunately the feature never made the ITV News because a bigger story broke, but visiting the house made a lasting impression on Mike.

Brenda and Robert Vale’s book (affiliate link)

External Services are Inefficient

One of the reasons Mike brought the provision of water supply and the disposal of waste in-house was because a considerable amount energy is used in providing these services. For example, drinking water is first treated, then pumped to our houses and once it’s been used, the waste has to be taken away and the process starts again.

Mike says: “We’ve effectively eliminated the energy that is used in providing those services so that reduces the energy footprint of this house even further, but ironically those factors are not normally considered when looking at the overall energy demand of a dwelling.”

This Level of Autonomy Would Not Make Sense in a City

In a densely-packed town or city centre, becoming more autonomous would not work so well.

Mike gives an example of how space would be needed for the composting chamber as well as a garden to deal with the waste.

Individual waste or rainwater treatment may not be such a good solution on a large scale development either, but it could make more sense on a localised scale (similar to how district heating works).

The House Does Not Have a Heating System

The Cropthorne Autonomous House has an extremely high mass, and all the construction was based around large amounts of concrete and high density concrete blocks.

The mass was surrounded by a very large amount of insulation and then the house was built airtight with a mechanical ventilation system. As the house is specifically oriented to the south it takes advantage of passive solar gains.

Although they did not set out to build a Passivhaus, all the thermal modelling was done using the Passive House Planning Package. So the performance of the house exceeds the Passivhaus standard at between 3 – 5 kWh per m2 per year.

Incidental Heat Gains Help in the Depths of Winter

The house warms up slowly throughout the summer and during the winter months, as temperatures outside drop, the mass begins to give the heat back.

Mike says: “It actually carries through December and into January before you begin to notice that the thermal mass of the building is dropping.”

The building is so efficient that incidental gains – the heat that comes from things like cooking, computers, televisions, etc. – contribute to keeping the house warm.

The Inverted Layout Takes Advantage of Rising Heat

Mike wanted his living areas upstairs and bedrooms downstairs because of the fact that heat rises.

In winter this means that the areas where they spend most time – the kitchen and living room – are the warmest parts of the building. It doesn’t matter so much if the bedrooms are cooler because they can throw on an extra duvet.

Also in the summer, if there is a very warm spell, they avoid the problem of not being able to sleep because of overheating bedrooms.

Rainwater is Harvested and Stored Under the House

With no connection to the water mains, rainwater is harvested from the roof and channelled into bulk orange juice transport containers (1500 litres each). These tanks would otherwise be destined for landfill and so are being recycled for this project. Mike bought them direct from the Britvic factory in Norwich.

10 of them store raw untreated rainwater, while the 11th is a slow sand filter which almost completely purifies the water. This leaves the 12th as a storage vessel.

The total capacity of 17 tons is enough for all their water needs for over 100 days.

Taking Responsibility of Resources Puts You in Touch with the Environment

One of the things that Mike really likes about the house is that it puts you back in touch with the seasons and the weather outside.

For example, if there’s going to be a prolonged dry spell then they would have to be more careful with their resources and not water the garden or wash the car. So they have to manage their water supply where as most of us just trust that water will be there when we turn on our taps.

Living in an Autonomous House is No Harder

Mike continues: “I wouldn’t say that living in this house is more difficult than living in a house with conventional servicing. I’d say it’s different.”

While they might have to look after their water supply and deal with their waste, there are other things they don’t have to worry about. For example, with no boiler that also means no servicing!

Composting Toilets Eliminate the Need for Water to Flush

The composting toilets work much in the same way as any compost heap. In this case human excrement falls into a special chamber together with handfuls of wood shavings, which keep the compost pile healthy. The urine is also separated.

This completely eliminates the need to use water for flushing the toilets. Most countries in the developed world use clean drinking water to flush the toilets which is immensely wasteful.

When human waste and clean drinking water is mixed it also produces a problem substance called sewage which then has to be transported away, separated out and made clean again. This all requires energy.

The resulting compost from this dry system is useful as a fertiliser and can be put straight onto the lawn or plants, etc.

Maintaining a Connection to the Grid has Benefits

The autonomous house is connected to the electricity grid (and there’s also a telephone line). The reason for this is that they still draw power from the grid in the evening.

They have a 2.3 kW photovoltaic array which is not that large by most standards but is based on supplying a house which is already very efficient. So the PV system covers virtually all of their energy needs throughout the year. Therefore their net electricity usage is close to zero.

Overcoming Building Control Objections was a Challenge

The only discharge from the house is grey water and that goes straight into a soak away in the garden.

Unfortunately the Building Control inspector wouldn’t accept this approach, despite the approval of the Environment Agency. This meant an uphill battle but it was eventually overcome.

Concentrate Less on Style and More on Resilience

Mike believes that anyone wanting to self build should consider what’s going to be important in the future. Will fuel prices continue to rise? He wonders whether we need to concentrate less on style and airy interiors, and build in a little bit of resilience.

Reducing your energy demands down to a tiny amount will certainly mean that rising fuel prices have less impact on you.

Mike has Learnt How Acidic Water is

As with any self build project, Mike has learned a lot along the way. One shocking discovery was that the harvested rainwater started to dissolve their copper plumbing!

This is because rainwater is now extremely acidic due to the amount of carbon dioxide in the atmosphere so it is effectively raining carbonic acid! All water at the autonomous house has to be pH corrected.

Terracotta Tiles Offer a Great Alternative to Carpets!

Mike has terracotta tiles on the floor because if he put down carpets it would insulate the thermal mass and it wouldn’t work as effectively.

However, using terracotta tiles has led him to realise a few things. Firstly if they are looked after they will probably last for the lifetime of the building. Even if one cracks it could be cut out and easily replaced.

Secondly Mike has realised that a lot of the economy thrives on waste. In the case of carpets he suggests that they will probably be replaced every 15 – 20 years. In the UK alone that amounts to half a million tons of carpet going to landfill every year.

Mike says: “If you eliminate the waste, so if everybody tiled their floor with terracotta floor tiles and nobody bought any more carpets it would be a big problem for a lot of people who would lose their livelihoods. So I think there is an irreconcilable payoff between having a healthy, thriving, functioning economy and economising where it really matters in terms of environmental damage and consumption and so forth.”

Find Out More

Visit Mike’s website on the Cropthorne Autonomous House.

Follow Mike Coe on Twitter.

Transcript

Download a transcript of the interview with Mike Coe.

Under 10 Days Left on Our Kickstarter Project!

We’ve had some fantastic support as we’ve tried to crowd-fund a documentary on the future of housing but we still have some way to go. So please become a backer and help us reach our funding goal! Thank you in advance.

As an experienced cameraman today’s guest, Mike Coe, will also be involved in our documentary should it get the go-head.

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May 21, 2014
What is an Autonomous House?

Do you feel that you’re lacking a connection with your environment?

Would you like to live in a house where you are in control of the services?

This article is a case study of a couple who created an autonomous house. We find out why they did it and how different it is to live this way.

Autonomous Means Possessing a Large Degree of Self-Governance

Mike Coe and Lizzie Stoodley built themselves an autonomous house in Cropthorne, Worcestershire. Although being autonomous might imply no connection to the outside world, in their case this is not strictly true because they are linked to the grid (albeit to export more electricity than they use!).

If they were completely self-sufficient and off-grid in all respects they would have an autarkic house, but autonomous is a better description of their home. They have no gas supply, they derive their water from harvested rain and they deal with their own human waste.

Architects Brenda and Robert Vale Inspired Them

The initial seed of an idea came in the 1990s, before they had any plans to build a house. Mike was an ITV News cameraman and he was sent to Southwell, Nottinghamshire, on an assignment to do a story on a new kind of house.

Mike describes his visit: “Nobody had the faintest idea what it was. Only when I got there did I realise that it was fascinating. We did an interview with Robert Vale and he showed us around and I thought this is a really interesting project.”

The feature was never shown on ITV because another story broke, but Mike’s journey was not in vain. He had been inspired.

Many years later Mike and Lizzie were considering a long-term plan to leave London and live somewhere less hectic, when they returned to the idea of an autonomous house.

Increasingly concerned about what the human race was doing to the environment and with a strong desire to take action somehow, the ideas came together in their ultra low energy house. It would be based on the house at Southwell but would try to take everything to the next level, with improved materials and greater experience, etc. As this was a once-in-a-lifetime opportunity they wanted to do this properly and take the ideas as far as was sensible.

In 2006 Mike and Lizzie bought their plot of land

Passivhaus Offered the Best Approach

Mike was convinced that the basic configuration of Brenda and Robert Vale’s house was correct. It had a very high thermal mass – based on a concrete core – surrounded by a huge amount of insulation, built as airtight as possible with super high performance windows. Although Brenda and Robert Vale’s house had a small wood stove, Mike and Lizzie believed they could create a house that didn’t need a heating system and just relied on incidental heat (body warmth, cooking, heat from appliances and so on).

While the house was designed and constructed using Passivhaus principles it hasn’t been certified, although this could (easily) be done at a later date. In fact the primary energy requirement of their house is between 3 – 4 kWh per m²per year, which is four to five times better than the Passivhaus requirement.

An Inverted Layout Takes Advantage of the Fact That Heat Rises

In terms of design the house is upside-down. So the living area is upstairs, taking advantage of the fact that heat rises. In a house with no heating it makes sense to live where it’s warmer during the winter. Also, during very hot summer weather, the bedrooms, being downstairs, stay cool and are therefore more comfortable.

If Mike ever builds another house he would definitely do it the same way again.

You Must be Adaptable to Live Like This

Living in an autonomous house requires more thought than a conventional dwelling. However, it’s good thought! The user needs to understand how the building works in order to get the most out of it. For example, controlling the temperature is about considering what to do with the heat. During the summer, Mike and Lizzie warm up the core of the house to a comfortable temperature. They make sure that they close windows and doors when they need to store up heat for the winter. Also, in autumn and winter the mechanical ventilation system is in heat reclaim mode whereas during the summer they don’t reclaim any heat.

Mike says: “You’re much more in touch with the seasons and the outdoor environment and you modify your behaviour accordingly. You have to be prepared in the depths of winter to wear a jumper.”

Responsibility for Resources is Back with You

In today’s world, so long as we have money we know (or perceive) we can have the resources. This not only shifts the responsibility onto somebody else – our service providers – but it distances us from what we’re actually doing to the environment. To live in an autonomous house it is necessary to be more in touch with the environment which Mike sees as a very good thing.

Mike and Lizzie have 17 tonnes of water storage in their basement, but they still need to modify their behaviour if they are anticipating a prolonged period of dry weather. This might mean not cleaning the car or taking showers less often.

“We derive all of our water supply from water that falls on the roof. We store it, we purify it, we drink it, we wash in it and we wash our clothes in it. And it ends up back in a soakaway in the garden.”

The same amount of water enters the site as would have done had the house never been built. All they do is borrow it.

Mains Electricity Makes Sense at the Moment

Mike explains that it’s not environmentally and economically sensible to go off-grid if you have access to a mains electricity supply. This is because storing electricity is not straightforward. For example they could use banks of lithium or nickel metal hydride accumulators but they contain a lot of chemicals. Plus, with this set-up there might still be trouble supplying the house at periods of peak demand.

So, at the current time there is little financial or environmental advantage. Instead they effectively use the grid as a battery!

Most of the electricity generated by their 2.3kW ground-mounted photovoltaic array gets exported because the energy demands of the house are so low. At night time they consume power from the grid, but it’s a small amount. The total electricity bill for the house is in the region of £350 per year and as the payment they receive from the photovoltaic array is about £900, they make about £500 income.

Mains Water and Sewage Systems are Not Efficient

There’s a lot of energy involved in providing houses with clean water and removing the sewage.

While doing his research Mike discovered that 30 – 40% of the water consumed in a normal house is used for flushing the toilets. In most cases it is also clean drinking water, which is of course very wasteful.

Human waste is actually quite a useful substance because it has similar properties to a fertiliser. Mike sums it up well: “What we normally do is we mix useful human waste with useful clean drinking water and we produce a problem substance called sewage, which we then have to pump several miles using energy and process it in a local sewage treatment plant.”

The composting toilet being installed

Composting Toilets Made Sense

With heating and lighting, adjusting lifestyle can often result in huge energy savings. However, when it’s comes to human waste you can’t really reduce the number of times you need to go to the loo! That’s why Mike and Lizzie were keen to bring all those services in house and provide them without using any external energy.

Mike explains how it works: “Every two months, with two of us living here, we have to maintain the chamber which means we have to drain out all the liquid compost and we have to take out the solid compost [that’s mixed with wood shavings], but by the time you come to do that it genuinely isn’t unpleasant.”

This compost then goes on the garden and this also means that they don’t need to buy any fertilisers.

In the Event of Fuel Shortages, They Would be Well Placed

Building an ultra low energy house is in a sense adding an element of autonomy, because you’re reducing your reliance on external fuel supplies. Reflecting on how their life would alter in times of scarcity or blackouts, Mike says they would stay warm because there’s no heating system to go off! There would be no issues with their water either. Electricity would be fine during the day but they might be inconvenienced with a prolonged power cut.

Running an Autonomous House is Rewarding

Mike and Lizzie have never looked back since embracing this way of living. Mike concludes: “The main thing is you have to think and you have to want to be responsible for your actions. That isn’t a hardship – it’s quite rewarding. I think it’s a good way to live.”

October 18, 2013