Want to refurbish your home in a sustainable way? With over 25 years’ experience, including as tutor on CAT’s Eco Refurbishment course, Nick Parsons has some great advice – here are his top tips.
1. Make it air-tight.
Stop unintentional ventilation (this involves designating an air-tightness layer – and sticking to it!) and design in sufficient intentional ventilation. For a whole-house retrofit this will almost certainly be whole-house mechanical ventilation with heat recovery (MVHR), but for incremental retrofits, or those with less stringent air-tightness targets, passive ventilation may suffice.
2. Insulate, insulate, insulate!
Don’t automatically believe that Building Regulations standards of insulation are enough. They aren’t bad, but in many cases we should be aiming for far better. If you have the space – and the money – Passive House levels of insulation (U values of 0.15W/m2K or less) and air-tightness (less than one air change per hour for the refurbishment EnerPHit standard) can dramatically reduce your heating requirements and massively improve comfort.
3. Insulate externally! (Unless you can’t…)
External insulation of solid walls, if detailed properly, puts the entire building fabric inside a warm ‘tea-cosy’. But it does make your house look different.
4. Risk-manage your insulation
If you have to insulate your solid walls – or sometimes even add insulation to your cavity walls – internally, excellent detailing is critical. Insulating walls internally makes the room warmer but makes the walls themselves colder and more at risk of interstitial condensation – condensation within the new thickness of the wall, behind the insulation. This can rot joist ends and other embedded timbers, and maybe grow mould. Cold walls may also suffer from deterioration of the masonry due to frost damage.
If you insulate internally, make the whole process a documented risk management exercise – identify the risks, identify control measures and document how you will implement them. In certain circumstances, consider embedding sensors and monitoring equipment in hidden timbers so that you can know if moisture levels become critical. The expense may be off-putting, but it will be a great deal less than the remedial works if you have inadvertently shortened the life of your house by doing what you thought was the ‘right thing’.
In general the use of ‘breathable’ (water-vapour-permeable) insulants such as wood-fibre or cork may reduce risks, but very careful detailing is still required.
Greater risks exist with non-breathable insulants, but if they are installed with extreme care, the risks may be capable of being ‘managed’ and minimised. If you are installing them yourself, take advice from someone with a lot of experience. If someone else is installing them for you, are they experienced with such boards? Do they fully understand interstitial condensation and vapour control layers (VCLs)? Have they read the manufacturer’s installation instructions?
5. …and consider its environmental impact
Materials such as plastic insulation – made from crude oil – are high in embodied energy (the energy, including transport, used to get the product from raw material to the merchant’s shelf), but look at the units used. If the measure is weight, a heavy bit of ‘green’ insulation may be higher in embodied energy than a much lighter piece of ‘non-green’ insulation.
You may in any case wish to avoid wherever possible materials made from petrochemicals.
But ‘environment’ may mean more than ‘the world in general’. What about your immediate living environment? You may feel better in a room lined with vapour-permeable, moisture-buffering wood-fibre than in a room lined with petrochemical-based insulation.
6. Minimise thermal bridging
You may believe – perhaps because your builder or consultant told you – that having low (good) U values guarantees good performance but thermal performance may be let down by weak-points in the insulation layer. Typically this would be where partition or party walls interrupt the insulation layer, where walls turn into windows or doors, or where internal insulation has to be thinner to accommodate fixtures or fittings. In practice, your U value may not be as low as you believed it to be.
The picture on the left shows: on the left, a wall prepared for insulation to ‘return’ on to internal wall to cloak the thermal bridge; in the middle, Pavadentro wood-fibre board prior to plastering; and on the right an existing brick wall with a lime ‘parge coat’ (air-tightness layer) to reduce air-leakage through voids in the brick wall.
7. Minimise thermal by-pass
Thermal by-pass, or ‘wind-wash’, occurs when cold air is allowed to get to the ‘warm side’ of the insulation. This can best be explained in two scenarios:
The first is a loft-conversion. The eaves areas are cold voids. The stud walls to the room (which are built off the floorboards) have been insulated to a good standard but there is only 100mm of insulation between the 150mm floor joists.
The ventilation air which enters at the eaves vents (a good ‘howling gale’ to keep all the timbers healthy) can blow directly under the floor of the heated bedroom, providing instant cooling!
Small pieces of plywood or similar board, sealed at all perimeters, placed between the joists at the edge of the floor on both sides of the bedroom will cure the problem. ‘Plugs’ of quilt insulation placed in the gaps will not do such a good job (as quilt insulation is generally air-permeable), but will be better than nothing. Once these gaps have been sealed, the insulation should in any case be increased to approximately 300mm.
The second scenario involves insulation to the sloping ceilings above an attic bedroom, carried out, as the law requires, by roofing contractors when re-roofing the house.
The house was sold and the new owner decided to remove all the attic ceilings. All but about six of the sheets of insulation fell out from between the rafters. What this tells us is that, while the insulation was in place, the cold air in the ventilation gap between the insulation and the slates was able to migrate to the warm side of the insulation, rendering the insulation almost useless.
8. Plan to do it all!
Many insulation plans are carried out incrementally, perhaps as other work is required, or when a room needs comprehensive re-decoration or (externally) when the cost of re-pointing an elevation can be avoided and put towards the cost of externally insulating that elevation.
When planning your works, ideally plan to do the whole house, even if you know it is going to take you 10 years to achieve it. I’m 29 years in and starting to re-do the internal insulation using better materials and methods than were available in 1987! Plan how your individual works are going to ‘knit together’ so as to limit thermal bridges, where condensation and mould may otherwise occur.
Above all, you don’t want your works – undertaken with the best of intentions – ultimately to shorten the life of your house.
About the author
Nick Parsons has worked in energy-efficient and sustainable building and renewable energy for over 25 years. He provides consultancy and project management services to individuals, small businesses and community organisations and is a regular tutor at CAT and elsewhere. See www.sustainablebuilding.org.uk for details.
The next eco-refurbishment course with Nick takes place from 4th to 7th November. For more information and to book, please visit http://courses.cat.org.uk/ or call us on 01654 704966.
A figure emerges from the undergrowth, with mud-covered face and a wild look in the eyes. Is it a fox? A badger? A wildcat? No… it’s a participant on CAT’s nature connection course! Kara Moses reports…
Traditionally, people have had an intimate, even sacred, relationship with nature, recognising and honouring our dependency on the natural world for our very survival – indeed understanding that we are the natural world, not separate from it. As Thich Nhat Hanh says, “The Earth is not the environment. The Earth is us. Everything depends on whether we have this insight or not.”
In more recent times in our history, we have come to see ourselves as somehow separate from nature. We have created socio-economic systems that don’t honour our place within the web of life; nature is treated as a resource to be used for human profit and pleasure, as a waste dump to discard the spoils of consumerism, or as an adventure playground.
This separation works to devastating effect, causing not only ecological – even civilisation – collapse, but exploitation of people, growing inequality and greater suffering in our world. There is a clear need for a deep shift in perspective individually and collectively, towards a life-affirming worldview and social structures that honour our Earthly home.
Why connect with nature?
The emerging field of ecopsychology is discovering that it is not only our relationships with our family and society that fundamentally affect our well-being and inform patterns of behaviour, but also our relationship with nature. To begin to heal the broken relationship with the natural world and each other we must reclaim meaningful connection that brings us into a deep, embodied sense of participating in a cosmos full of wisdom, value and meaning.
Rekindling this sacred connection to the earth and all its inhabitants has the potential to heal the sickness of our times, transforming social relationships. A growing body of research shows that increased time in nature brings greater happiness, better mental and physical health and emotional resilience. Connecting to nature supports us to connect more deeply with our selves and others.
Research also shows that feeling more connected to nature also leads to an acting as well. Through recognising that we are in fact part of it, people who feel more connected to nature are more likely to display ‘pro-environmental behaviour’. They begin to see that we are not defending nature – we are nature defending itself.
Here at CAT we’ve recently added nature connection to our short course programme. The first one ran in late summer, and went down a treat. Through play, mindfulness and practical nature connection exercises, we developed our powers of observation and saw all sorts of natural delights we would normally miss, with a renewed sense of awe and understanding.
Together we developed skills to interpret the natural world, such as tracking, understanding bird language and the body language of trees. We played games to help increase our sphere of awareness and reduce our sphere of disturbance to see and understand more of our wild cousins, and explored the theories of deep ecology and radical ecology. And we spent lots of time outdoors in the beautiful surroundings of CAT – we were a pretty feral bunch by the end!
More feral less fearful
I’m glad to say that the participants have been putting their experience and learning into practise in their daily lives, enjoying more time out in nature cultivating meaningful connections. One participant said a week after the course: “I’m listening to the birds with a new sense of understanding and joy.”
Some have made even bigger life changes: “I spoke about wanting to make a healthier more sustainable life and career change. It’s always a nerve wracking thing to leap from what you know into what you don’t, but the course inspired me to take this step and run nature connection walks myself. It’s great to connect with people over a subject that is intrinsically meaningful. More feral less fearful!”
After the success of this course, we’re offering more weekends in November 2016 and in April and July 2017 at affordable rates from £35/day. The last one sold out so book here soon if you too want to rewild your self and become more feral!
Kara Moses leads nature connection courses at CAT and independently. She also takes care of CAT’s natural water treatment systems and is a freelance journalist, Forest School leader and grassroots trainer.
Get out into the woods this October with some great weekend and day courses at CAT. Forage for mushrooms or herbal remedies, learn about woodland management, or get to grips with wood fires as we settle into autumn.
Enjoy some seasonal foraging on 1st-2nd October with a mushroom and fungi identification course, where you can discover what’s good to eat – and what’s not. Go on a woodland ramble with our fungi forager then come back and cook up what you’ve found. You’ll also learn how to grow your own mushrooms using different cultivation techniques, so you can enjoy home-grown fungi feasts all year round!
As the days start to get shorter, get prepared for those cold winter nights by learning how to make the most of your wood burner with our Wood Fire Guru course on 1st October. Learn about choosing, storing and even growing your own wood, plus stove maintenance and safety to help you stay cosy right through to spring.
On 22nd October, learn how to make your own balms and tinctures with an Introduction to Herbal Medicine, including plant identification and collecting, gathering and storing as well as preparation for therapeutic use.
CAT Short Courses Coordinator Steph Robinson said: “We’re so lucky to be surrounded by some of the most beautiful woodlands in Britain. We created these courses to help people learn new skills that will allow them to make the most of what’s on their doorstep.”
And don’t forget to join us for our Quarry Trail launch party on 24th October – see visit.cat.org.uk for details.
Do you know where your water comes from? You probably just turn on the tap and there it is. Flush the toilet and off it goes. Most of us have no idea where our water comes from, or where our sewage goes.
At CAT we do things differently. We’re completely off-grid when it comes to water – we have no mains water supply or sewage treatment. So we have to think very carefully about how we use this precious resource.
Here’s how our water works.
Reduce, reduce, reduce!
We start by minimising the volume of water that we use. Low flush toilets, waterless urinals and compost toilets help by reducing the amount that gets flushed away. Low flow taps and water efficient shower heads mean less goes down the drain. Which of these things could you do at home?
So what’s left? We need it for drinking water, for hydro electric turbines and to power our cliff railway. Let’s focus on how we get it clean enough to drink, and how we treat the wastewater so it can be safely returned to the river that flows past CAT.
Good enough to drink
The CAT reservoir, which is nestled in the hills behind the visitor centre, holds most of the water used on site. It was created to directly power the machinery for the old quarry on which CAT is built. The other sources of CAT’s water are rainfall into the lakes, ponds and rainwater butts across the site.
The water is siphoned from the middle of the reservoir, using atmospheric pressure to force it up through a pipe. This method doesn’t use a pump, which ensures that the system is low-energy.
Water is then piped down the hill to CAT. Water to be used for drinking passes through slow sand filters to remove pollutants. While this process effectively removes pathogens, the water is later treated by ultraviolet (UV) purifiers to finish the job.
Greywater and foul water from CAT flows into settlement tanks, where solids are separated from liquids. Solids are composted whilst liquids are passed into a series of reed beds which sit below the CAT site.
The reed beds clean the water through a combination of the micro-organisms in the reed beds, and the physical and chemical properties of the reeds.
After being passed through these beds, the now clean water is returned to the river below CAT, where it is joined by the water that has powered our hydro turbines, driven the cliff railway and heated a building through a water-source heat pump. All of it borrowed – and made to work very hard – on its way from the mountains to the sea.
Over the summer, we’ll be giving free guided tours of the CAT water systems so you can get a close-up look at some of these systems. Take a look at our events calendar for details of what’s on when.
If you’d like more in-depth info, the three courses mentioned above run back-to-back and can be booked as a package. Book two or more of these and we’ll give you 10% off. See courses.cat.org.uk for details, or call us 01654 704966.
There’s a quiet revolution happening in South Korea. People are moving ‘back to the village’ in huge numbers following the economic crisis and rejection of the consumerist and competitive urban lifestyle.
For many this is a difficult transition from a highly service-orientated city culture, but there is a group for whom it is particularly challenging and that is the unmarried women who are making the shift in large numbers. These women are not only bravely embracing a new way of life with limited skills but are also tackling long standing traditions and prejudice around gender roles.
This week we welcomed two such women: Jijeong and Bohyun from the Wanju Ladies Club, a cooperative established to up-skill and enable single women returning to the country. In just three years they’ve established the cooperative and created training courses and materials on heating, cooking, renewable energy, insulation, rainwater harvesting and up-cycling. Jijeong and Bohyun are two of the seven founding members who are all activists in social and environmental movements and experts in the field of alternative and appropriated technology.
By up-skilling women in this way the club hopes to enable women to be more autonomous in their homes but also to elevate their status within their communities, improve the lives of the village as a whole, and to establish these women as role models for future generations of girls to become learners and teachers, transforming culture over time to be more inclusive and welcoming.
Jijeong and Bohyun came all this way to learn about CAT’s evolution and how we’ve challenged gender stereotypes over the years, from hiring a female builder Cindy Harris to lead construction at CAT for 17 years, to continually questioning our thinking and actions to attract a more diverse audience to CAT as members, visitors and students. Our latest Zero Carbon Britain research ‘Making it Happen’ (coming soon!) also features special content on gender and race equality and the author Helen Atkins was interviewed by Jijeong and Bohyun during their stay.
We are the first to admit we don’t have all the answers but hope we can help them during their visit by sharing how we aim to inspire people from diverse backgrounds. So what’s next for the Wanju Ladies Club? Well they’ll be setting up an advice service for aspiring community energy projects as well as a construction cooperative for social housing initiatives, and that’s just for starters…. We wish them all the best for what sounds like an amazing and very worthwhile project.
The next Zero Carbon Britain short course will explore ways we can deliver a climate positive future, while maintaining a modern lifestyle. We also look at how ZCB can be used successfully to inspire positive action, stimulate debate and build consensus in our communities and places of work.
Scholarship entries will be judged by a panel of CAT staff and announced on 17th August on the CAT Facebook page.
By entering, you accept that CAT will post the winner’s first name and surname initial to our Facebook page.
The prize includes all course fees and full board accommodation at CAT.
Find out all you need to know about building your dream home with a visit to Build It Live Bicester self-build show and see live demonstrations from CAT. 11-12th June.
The Centre for Alternative Technology, in association with Build It Live, are offering pairs of FREE tickets (worth £24) – just by following this link.
Build It Live self-build show will take place on 11 & 12 June in Bicester, on the borders of Oxfordshire, Buckinghamshire and Northamptonshire. The latest addition to the Build It show calendar, Build It Live Bicester is brand new and is being run in association with Graven Hill – the UK’s first large-scale self-build project. Graven Hill has outline planning for 1,900 new homes, along with a primary school, local pub and shops and lies just 5 minutes’ drive from the exhibition.
Many of us dream of creating our own little eco home, somewhere where we can live a greener life in a space that we’ve designed and built ourselves. But finding the perfect spot and gaining planning permission isn’t always easy. It’s with this in mind that the Graven Hill project has been developed in Bicester, Oxfordshire.
Spearheaded by Cherwell District Council, the project has outline planning permission for 1,900 new homes, and offers opportunities for a range of different sized projects, including detached, semi-detached and bungalow designs, using a mix of kit homes and self-build projects. There’s the potential for groups of people to work collaboratively, for example by creating a terrace of eco homes, and a primary school, local pub and shops are also planned.
All properties will be built to high environmental standards, complying with Passivhaus principals for energy efficiency, and there’s the flexibility for individual designs to incorporate higher environmental standards, so this could be a useful route in for anyone wanting to create an eco home of their own.
Join CAT at Build It Live
Whether you’re interested in a plot at Graven Hill, thinking of building a home elsewhere, or if you’d like to retrofit an existing property, come to Build It Live Bicester on 11 and 12 June to meet experts in a range of building materials and methods.
Taking place just a few miles away from the Graven Hill site, the show is an opportunity to discover thousands of cutting-edge and traditional products and meet over 150 of the UK’s most innovative suppliers. There are around 30 free seminars and workshops, developed to address specific problems and inspire confidence when taking on a building or renovation project.Here’s a flavour of what’s on offer:
At the Build It Manchester show earlier this year, CAT’s carpenter Carwyn Jones demonstrated eco-friendly building techniques and upcycling with pallets.
Eco friendly building techniques: Come along to see CAT doing talks and live demonstrations covering a range of topics including environmentally-friendly building techniques, renewable energy, eco-sanitation and woodland management. There will be a daily demo programme and experts on hand to answer your questions. Also see the free seminar on Building a Sustainable Home, at 3.30pm daily. Graven Hill zone: Find out about opportunities to build your own home on Graven Hill and join the live Q&A to discover how to reserve a plot. Speak to the Graven Hill team and listen to their keynote session in the main seminar theatre at 11.10am each day. See the various homes that can be built and learn about the Design Code. The Naked House: See a section of a new build as it comes together – a fascinating insight into how things are installed, from underfloor heating to roof trusses and floor joists.
Find a builder: Talk to the Federation of Master Builders who can guide you through the process of finding the right contractor for your project. Access their database of trusted builders in your area.
Self builders’ stories live: Gain inspiration and confidence from people who have realised their self build dreams. Hear their stories in the live theatre, on the show floor.
The brown-field site was previously used as an ordnance depot by the Ministry of Defence (MOD) and acted as the main supply base for the British Army’s operations during the Second World War. Materials from the demolished MOD buildings will be recycled for use in the construction works.
The project team have worked with ecologists to ensure their plans protect and encourage biodiversity, and more than half the site will be set aside as community woodland and open space. Allotments, cycle paths and sports pitches are also planned.
Later this year sees construction of the first ten ‘pioneer’ homes, one of which has been designed by Ed Green, joint programme leader on CAT’s Professional Diploma in Architecture, who is keen to develop self-build designs that can be delivered at a lower cost than more mainstream building projects.