Tag: thermal mass

HPH314 : Getting a self build over the finish line, despite setbacks – with Mike Coe

Mike Coe gives a final update on his now complete Portree Passivhaus, that has seen budgets stretched, contractors disappear for a year, and a Covid lockdown!

Interview with Mike Coe

Mike Coe is a returning guest to the podcast. We have been fortunate enough to speak with him about his previous self build, Cropthorne Autonomous House, and have been following his progress since moving to the Isle of Skye to build Portree Passivhaus with his partner Lizzie. Having been in the house for a year now, we pick up where we left off three years ago, in episode 259 when the house was almost watertight, and find out whether Mike has managed to be as hands-off with this project as he had intended!

Mike had always intended to do the MVHR installation and electrics himself

He had started on the MVHR installation as soon as there was enough building there for him to work on. The main ducts that bring the fresh air in and take the exhaust air out, went in almost at the foundation stage, as they were assembled as the wall was being built that the ducts pass through. This way it meant they could be built into the wall, rather than having to cut out a large hole afterwards. He also started channeling out for power points before the concrete blocks were even up to first floor level.

The specification of the MVHR was important for Mike as he wanted to build this house with no heating system whatsoever. They selected a system made by Nilan, which also contains a micro heat pump. It’s only around 60 or 70 watts, but it effectively aids the heat extraction process and makes it more efficient. It means that in the winter the heat pump comes on when the temperatures dictate it, making the incoming air temperature slightly warmer, and in the summer it provides a very small amount of cooling.

Their only other source of heating is from a single bar electric fire which they’ve used infrequently, just for the odd hour here and there.

It maintains a comfortable temperature

The internal temperature on the night they moved in was just 11 degrees (with a raging storm and a power cut for good measure!) But once Mike got the MVHR up and running a couple of days later, and they had a week or two of sunshine, and with the effect of the two of them living there, it took just a couple of weeks for the temperature to rise to 21 degrees. Since then, they have been pleasantly surprised at how well it keeps a steady and comfortable temperature, even more so than the Cropthorne house, despite its larger form and having been less fastidious in the attention to Passivhaus detail. Mike suspects this is because of using the concrete blocks which, as well as providing the structure of the building, also act as a thermal store. He is conscious that the use of the concrete blocks and steel means it has higher CO2 emissions from the manufacture than that of a lightweight timber structure, but this was primarily dictated by the planning department.

Mike’s previous Passivhaus experience paid off

With a contractor and architect that didn’t have experience of building a Passivhaus, Mike found one of his roles on site being that of quality control. When it came to airtightness tape, he was able to show them how the standard builder’s merchant tapes would just tear like paper, yet the Passivhaus airtightness tape was incredibly strong and flexible.

They didn’t mind and were happy for Mike to take on other pieces of work, such as some of the carpentry, especially as he and Lizzie were on site doing the MVHR and electrics anyway, and it meant the workload for their men was reduced.

It took twice as long to build as planned

The original plan was for a 15 month contract build period, but at the 10 month stage the contractor got called away to work on a 25 bedroom hotel extension, leaving just Mike, Lizzie and a freelance bricklayer to carry on with the work. This meant an incredibly frustrating almost year-long wait while the hotel project was finished, which unfortunately then coincided with the first Covid lockdown.

“So there we were, with another three months added on to the almost year long delay due to the hotel build. The hotel extension was sitting there virtually complete, but they couldn’t open it because of everything was shut down because of Covid, whereas our house was nowhere near complete and nobody could work on it except me.”

Mike managed to use that time as productively as possible to keep the project moving forward. Without being able to access new building materials as the merchants were closed, he dismantled some of the temporary stairwells that the contractor had put in so he could use the timber for building the stud partition walls. He used all the plasterboard that was laying around that he could, rescued timber that had been thrown out and used that for the stud walls, and also managed to build a new desk. Psychologically he found all this beneficial as it felt like progress was still being made.

In total, the project took around 30 months to complete.

Money became very tight

With the planning department selecting the most expensive option, they always knew that the budget was going to be tight. In addition to the overruns caused by the lockdown, a number of other bills came in that caused them to go over by £34,000. This included £8,000 to install a water pipe from the mains halfway up the hill, rather than being able to connect from the supply of the neighbouring bungalow that they owned and were living in, and £750 for a tree survey to make sure that the pipe wasn’t going to damage any tree roots!

As they were running out of money and with cash being tied up in the neighbouring bungalow until it was sold, they had to take on more of the work than they had ever intended to do. Mike had been unimpressed with the plumber who had done the first fix, so ended up rectifying some of his work and also did the second fix plumbing. This meant he plumbed the washing machine, kitchen sink, dishwasher, and the fit-out of all the bathrooms.

With great reluctance, as it is a job he and Lizzie particularly dislike, they also ended up doing most of the decorating themselves.

One year on, there are problems to rectify

Having been in the house for a year, they are currently in the snagging period where the contractor will rectify some of the problems that crop up. Their contract allowed them to withhold a small percentage of the total payment, which will be paid once these have all been sorted. However, there are other problems which Mike intends to take on himself.

The door in the lower ground floor porch was never properly adjusted and would stick and not shut fully. When he got round to looking at why this was, Mike discovered that it was actually causing a serious damp problem. The damp had resulted in the hinges corroding, with the adjustment screws for the doors then being impossible to turn.

Something else that Mike will need to tackle, is an issue with the windows leaking. As they weren’t a standard specification that the contractor was familiar with, they installed them but weren’t confident to set them up, instead leaving this to Mike to organise. However, with all the other jobs and distractions going on, this got pushed lower down the list. With the driving rains they receive, several of the windows subsequently leak. Thankfully there are no serious structural leaks though, and when all the adjustments to doors and windows have been carried out then hopefully that should be an end to those problems.

During a period of extremely high winds recently, part of the zinc capping that goes around the roof parapet was torn off. Fortunately it doesn’t threaten the structure of the house in any way and it’s still watertight, but it’s something else to add to the list of jobs.

He has some carbon-saving projects lined up

Now that they have freed up their cash by selling the neighbouring bungalow, and once Mike gets over a certain amount of self-builder fatigue, he is keen to make headway on some other projects.

The first is installing a PV array that will make the house run more efficiently, as it will contribute to hot water and charging their new electric vehicle.

He is also in the early planning stages of putting a micro hydro generator (a little water turbine) into a stream that runs down through their site. If it works it will likely only generate around 100-150 watts per day, but that will be for 24 hours a day and virtually through the whole of the year.

He is adamant this will be his last self build!

Now he and Lizzie are able to reflect on their journey, they are able to say that although lots of things went wrong, they managed to get them corrected. Although they did have the benefit of experience from their previous self build, there were still new problems that this project threw up that had to be dealt with. Overall, Mike says they are pretty happy with the end result, just not necessarily with how they got there.

Find out more

Visit the website of Portee Passivhaus

Follow Portree Passivhaus on Twitter

Follow Mike Coe on Twitter

Catch up on previous episodes with Mike Coe

HPH259 : Constructing the masonry superstructure of Portree Passivhaus

HPH220 : How to finish a self build when money is tight

HPH152 : Should you consider the resale potential of your self build

HPH054 : Building an autonomous house

Transcript

Download a transcript of the interview with Mike Coe

How relevant is mass?

Es Tressider is a guest on the Building Sustainability Podcast, talking about whether adding mass to a building will make it more energy efficient.

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April 13, 2022

HPH191 : Key decisions that impact on the sustainability of a house build – with Lloyd Alter from TreeHugger

Lloyd Alter from TreeHugger shares his advice on what we should be prioritising as 21^st century self-builders.

Interview with Lloyd Alter

We catch up again with Lloyd Alter, whose work as an architect and a real estate developer led to his interest in modern building methods. He blogs for the website TreeHugger and also teaches sustainable design at Ryerson University in Toronto, Canada. Previously, Lloyd’s talked to us about worldwide trends in green designs.

Don’t measure value in pounds per square foot

Lloyd says that size will be the most important decision about a house build because so much relates to it. While building small may be preferable for sustainability, he acknowledges there are various problems to overcome.

Some contractors may refuse work on smaller houses, or argue that a bigger house is better value. Lloyd warns against buying more space than you need. A bigger house may cost less per square foot but that is a dangerous criterion for measuring value. He explains, “It will cost you more per unit of area to build smaller but the aggregate, it will still cost you less.” Operating and maintenance costs will also be less with a smaller dwelling.

House size may be dictated by the plot

Re-sale value can force a self-builder into a larger project. Often it’s the land that really has the value, so there’s a judgement to be made about the right sized house for the size of the plot. And Lloyd points out that putting in services costs the same regardless of house size, potentially making it harder to recoup costs on a smaller house.

By-laws can, in some instances, prevent small homes being built. For example, Lloyd explains that some North American municipalities fix minimum square footages to guarantee a minimum tax return.

Balance location with lifestyle

Lloyd recognises the dilemma for self-builders who want to minimise their carbon footprint but can’t afford the expensive land located close to facilities.

Low energy buildings can reduce environmental impact, and changing habits can also mitigate high-energy consumption. Someone Lloyd knows – who lives 9km away from town – cycles, uses a hybrid car when he has to drive, minimises shopping trips and avoids ordering things delivered by truck. Lloyd himself tries to balance his many air miles by cycling and keeping his house at “incredibly low temperatures”.

An independent expert will help you design for sustainability

In a poorly planned house, you pay more for a poor living experience. Lloyd mentions one self-builder who incorrectly fitted insulation and this decision threatened to destroy his house.

For Lloyd, an architect should “help you get to the essentials and put the essentials together in the most efficient, satisfying and beautiful way.” He sees this as directly linked to building sustainably: “The key to sustainability is living with less and the key to living with less is to have it designed properly.”

To choose an architect or builder, Lloyd suggests going to see their work and spending enough time with them to know that you like them, they understand you and that you can understand what they’re saying; clients shouldn’t have to deal with what he calls “Architectese”!

Simplicity should be designed into the house in the first place

So-called “smart homes” are fashionable but Lloyd is wary of unnecessary complexity that adds cost and needs maintenance. “My attitude is I like a dumb home!”, he says, citing the Passivhaus as a good example of this. Using less power means no need for a smart thermostat or a complicated solar panel system connected to the grid. “The house takes care of itself,” he says.

Another reason to keep house design simple is to accommodate changing technology. Low voltage LED bulbs have practically eliminated the problem of lighting load and our technology increasingly runs on low voltage DC wiring. Lloyd envisages future houses solely using DC, so any high voltage electric systems fitted now should be kept accessible.

As different building elements last different lengths of time, Lloyd’s advice is to prepare and keep things simple. “Put as little of it as you need in. Because at some point, you’re going to have to redo it anyway.” Homeowners should be able to access, change or fix any systems in the house:

Element of your property	How long it may last
Land	Forever
Frame of your house	500 years
Cladding	200 years
Windows	100 years
Plumbing	50 years
Electrical	20 years
Mechanical systems	10 years

Fabric first is fairer as well as simpler

Lloyd believes it is unreasonable to simply aim for “net zero carbon”, stating, “We have to use less, period. Even if we’re trying to offset it with energy from sun or wind.” Thus, investment in domestic energy production is another trend that Lloyd mistrusts. Compared to the huge amount of energy used for transport, he describes solar panels on roofs as inconsequential. “We should be going after the big things. And that’s efficiency, not solar panels on the roofs,” he says.

He remarks that policies of domestic generation of electricity disproportionately favour people who have south-facing roofs. Someone without a roof or who can’t afford solar panels will pay more for their electricity, meaning the poor end up paying for the grid. A fairer system in Lloyd’s view would be for everyone to live in houses that are built to a higher standard and use less energy.

Preferred methods of building continue to change

Lloyd teaches a sustainable design course and the content can change every year. Ten years ago, he taught about spray foam that seals and insulates efficiently, but we know now this foam contains unhealthy flame-retardants and some don’t even work below three degrees Celsius. The current insulation trend is for low carbon cellulose, although Lloyd prefers rockwool.

On the subject of new building techniques, Lloyd says, “I’ve become very conservative as I’ve gotten older.” He sees people who want the “latest new thing” demolishing existing houses on highly sought-after plots. This discourages building really good quality houses because “they don’t seem to be building them forever anymore”.

Construction methods can be more suited to specific locations

Building with “brick and block” gives thermal mass, holding heat in the day and releasing it at night. Lloyd says that this principle works well in the high Arizona desert, with hot days and cold nights. In less extreme climates such as the UK it is less effective, and making bricks, concrete and mortar releases a lot of carbon dioxide before construction even begins.

Homes should be comfortable, safe, secure and resilient

A self-build should bring comfort and happiness. Just because it’s environmentally friendly doesn’t mean you have to suffer!

Considering our changing world, Lloyd advises self-builders to prepare for power outages, provide some storage for water and food, and build high enough and not in the middle of a flood plain. He adds that if you have to cycle to get milk, then make sure you can actually do it! “That’s what a home is supposed to be,” he says. “A place of security and comfort. That’s what we should all be striving for.”

Find out more

Visit the website of TreeHugger

Follow Lloyd Alter on Twitter

Transcript

Download a transcript of the interview with Lloyd Alter

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September 25, 2017

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
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
HPH012 : Should You Invest in Renewable Energy? – with Dr Derek Taylor from Altechnica
Dr Derek Taylor from Altechnica weighs up the pros and cons of various renewable energy sources and shares his thoughts on whether you should be generating at home. He also talks about his role in creating one of the UK’s most energy-efficient homes.

Interview with Dr Derek Taylor

Dr Taylor trained at the Architectural Association but got interested in renewable energy and low energy building design in 1972. From then he started to pursue more of a renewables orientated career and did a masters in designing wind turbines and renewables, and came to the Open University. He is particularly interested in bringing together renewable energy and architecture to try and make it much more effective.

There are still Fossil Fuels Available But CO₂ Emissions are the Problem

A lot of people believe we have reached peak oil and that we are now at the point of depletion. There’s still a lot of coal in the ground and a fair amount of gas available but their CO₂ emissions are a big concern for climate change. It’s clear we need to make a step change. The scientists say we need to cut CO₂emissions by 80% in the next few decades.

UK’s Best Renewable Energy Source is Wind

In terms of renewable energy Dr Taylor believes wind energy and offshore wind energy offers the most promise to the UK. He explains that 40% of the potential wind energy resource in Europe is actually in the UK. That figure is looking at land based resources, with even more potential offshore.

Phenomenal Increase in Wind Power

Dr Taylor has recently been updating the wind energy section of the Open University renewable energy course. He noted that in the year 2000 there was about 30,000 MW of wind energy globally whereas in 2010, there was 38,000 MW installed in just one year. Now globally there is over 200 GW. Dr Taylor is impressed with the progress. The UK currently has the largest offshore wind farm in the world, which is off the coast of Thanet (installed by Swedish company Vattenfall), and they’re currently building a third offshore wind farm in the Thames Estuary, called the London Array, which will produce a fair proportion of London’s electricity needs.

Floating Wind Energy Technology Has a Huge Potential

Tapping into floating wind energy technology, the wind energy resources in UK waters would be equivalent to the Gulf Oil reserves but every year.

Renewable Energy Solutions Fit into Different Scales

Generally there are three types of solution: building scale, an intermediate scale – which Dr Taylor calls neighbourhood or community scale – and large scale.

Solar Makes The Most Sense For Buildings

In terms of buildings, solar energy often makes the most sense for electricity generation, hot water and also for reducing space heating loads. In the summertime it can be used for cooling.

Heat Pumps

The temperature of the ground below a certain depth is constant throughout the year, so this provides another ambient source of energy.

Wind Energy Isn’t Normally a Good Solution for Urban Areas

The usability of renewables depends on the location as to whether they will perform effectively. Wind energy can make sense but in most cases it doesn’t in urban areas. Wind energy technology usually starts to make sense at community scale upwards, for example, a medium scale turbine might be appropriate for a village or a town. Costs can then be spread amongst householders.

Former Watermill Sites Could Have Potential for Hydro Power

The best sites for hydro tend to be in mountainous areas, but Dr Taylor suggests that former watermill sites could be good places to generate. It’s important to note that when watermills were in use there was less water extraction so there was more water running through the system. Dr Taylor did a renewable energy study for Merton Council which found that a short stretch (19km) of the River Wandle once had about 90 watermills in operation.

Biofuels Make Most Sense When it’s a Waste Product

Growing energy fuels is very difficult to justify when you haven’t got much land. A forested area can obviously provide wood as a fuel. Dr Taylor believes the situation with biofuels probably makes sense if you can use it as waste, such as food waste and oil waste. You can then process that with biology to produce gases and fuels. In Denmark there are community digesters where manure, food waste and sewage combine to produce methane – the process mimics a cow’s stomach and produces gas that can run small power stations.

Tidal Barrages Expensive to Build and Maintain

The main problem with tidal energy is that it’s been exploited using tidal barrages, like a big dam across an estuary. These are very expensive to build and can impact on the rich eco systems. In France, there is an example of a successful barrage called La Rance.

Tidal Stream Technology Shows Promise

Essentially they are underwater wind turbines which capture the currents as they flow around the coasts. One of the big advantages is that because water is 800 times denser than air for a given size of rotor diameter you get a lot more power out compared to wind turbines because air is very low density. This means much smaller devices can give more power output. The downside is that these devices are situated in difficult locations and have to be able to cope with the water reliably. They’re still in the early stages of development.

Devices Built to Harness Wave Energy Have to Survive The Stormiest Seas

Dr Taylor reckons that wave energy is an even more difficult one to achieve. The energy resources from the waves are substantial but you have to build devices which can survive 24/7 in the most stormy seas.

Failures Important to Progressing the Technologies

Very few of the wave energy projects actually go through the iterative stages that are needed to develop a technology. Lots of funding goes into building one device and that fails and there’s no money to carry on. Those failures are vital to progressing the technology.

We Can Use Fossil Fuel Reserves Much More Effectively

While fossil fuels might still be available, Dr Taylor believes that the price will be the main constraint to using them. He stresses how in other countries they’re actually much further on with many aspects of design, performance of houses and also the use of wind energy.

Combined Heat and Power Makes Use of Waste Heat

One approach for district heating is to use the waste heat from power stations to heat houses. Dr Taylor calculated that if you add up all the energy being lost from the cooling towers around Britain, it amounts to more energy than is used to heat all the houses in Britain. Currently this energy is just allowed to go into the atmosphere or into the sea at coastal locations. In Denmark 65% of houses are heated this way or from large scale boilers. To achieve this heat mains are laid under roads or gardens and each house is then connected up. Part of the difficulty is that electricity networks are privatised and they would rather do what they’ve always done.

Heat Stores Play an Important Part

Dr Taylor explains that Battersea Power Station was a combined heat and power station when it was operating. There was a pipe under the Thames which provided heat for 4000 houses in Pimlico. They’ve subsequently re-installed a small combined heat and power station at Pimlico which delivers the same thing. Part of that scale of development enables very large heat stores to be built in, so that heat can be stored when you’re generating electricity for use later. Heat from other sources such as solar or wind energy can also be used to charge up the heat stores.

Nuclear Energy is Expensive and Funding Must Be Offset to Look After The Waste

In France about 80% of their electricity comes from nuclear, but this doesn’t mean its future is clear. Not only is it expensive but disposing of nuclear waste is still a big problem. How much money will be needed in the future to look after nuclear waste from the past? There are also discussions about what’s going to be the most useful type of fuel after uranium.

Low Energy Buildings Fall into Two Strands

Historically there are two strands of developing low energy buildings. One is known as the super insulated approach that tends to be a lightweight construction with lots of insulation. The other approach is known as passive solar, which is reliant on lots of solar orientation, lots of glazing and high thermal mass. The solar gains are trapped in the thermal mass so that it acts like a storage heater.

Super Passive Solar

In the UK passive solar hasn’t worked well in the spring or autumn times when there tends to be quite high cloud cover. There is also not much benefit in the winter time whereas super insulation then works well. So a super passive solar approach combines the two so you have a high level of thermal mass but it’s inside a super insulated envelope. Dr Taylor worked on a house in Herefordshire which might be one of the UK’s most energy efficient homes.

Super Passive Solar Goes a Step Further Than Passivhaus

Dr Taylor really likes the Passivhaus standard although he finds it unfortunate that they chose the name Passivhaus as it’s easily confused with passive solar. It is really an ultra super insulation approach. The Passivhaus design system doesn’t really take into account the thermal gains from thermal mass, so you can’t get that extra point further of actually optimising the design to get to zero space heating, although a lot of Passivhaus buildings are getting pretty close to that.

With New Builds, Push the Envelope as far as You Can

For new buildings Dr Taylor thinks you have to push the building’s envelope as far as you can because it’s much more difficult to upgrade. If you can design as much insulation as possible and get to Passivhaus standards then it will be well worth doing and shouldn’t cost you a great deal more on top of the building.

If You Have The Money, a Passivhaus Retrofit Can be a Good Investment

Upgrading an existing building to Passivhaus is not a cheap option. However it’s probably better using that money to go into the building’s fabric rather than getting an expensive new kitchen!

Internal Insulation Must be Done Correctly or You Risk Damaging the Building

External insulation is a much easier solution but risks affecting the aesthetics. The problem with internally insulating walls is that there will be a reduction of floor area. Also, with solid walls, for instance, prior to that wall being internally insulated, it’s been kept warm by the space heating of the house but once the insulation is between it and the heating then it’s obviously a cold object and it’s a cold surface. So, unless the internal insulation is done correctly, if any vapour gets into that structure it will hit the cold wall and condense. This can cause rotting problems.

Combined Heat and Power Could Buy us Some Time to Retrofit

Dr Taylor refers back to how we might reduce the CO₂ emissions from buildings. Investing in combined heat and power, and district heating would enable the existing buildings to start to use heating which is actually low carbon. It would also buy some time to upgrade the performance of the existing housing stock.

We Only Have One Chance to Make our Homes Energy Efficient

In order to reach 80% reductions in CO₂ Dr Taylor believes that we must go beyond a little cavity wall insulation. He thinks we only get one shot at this and it should be done properly. The challenge will be funding it. If there were a scheme where everyone was connected to a heat network then there’s a potential revenue stream for the sale of that heat to people which could be used to fund insulation of buildings down the road.

Incremental Improvements Should Have a Long Term Plan

Try and have a plan or a strategy so you’re not going to foreclose on the options. Do the thinking upfront so that improvements compliment each other. If you have a loft that can be insulated then certainly the more upgrades you can do to that the better.

Dr Derek Taylor’s company
- Altechnica
Transcript

Download a transcript of the interview with Dr Derek Taylor.

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January 2, 2013