Getting to grips with thermal comfort

John Butler reports from the latest module of the MSc Sustainability and Adaptation courses at CAT. John is a student on the MSc Sustainability and Adaptation in the Built Environment course. He normally blogs on his site http://thewoodlouse.blogspot.com/ and you can follow him on Twitter @the_woodlouse.

The March module of CATs Sustainability and Adaptation MSc was part B of Energy Flows in Buildings. Part A (in February) introduced us to ideas of thermal comfort and its relation to heat transfers from the human body to its surroundings. This was tied to the implications of maintaining that thermal comfort, and the impact on energy use. We learnt about calculating U-Values (used as a standard measure of the thermal efficiency of a building element), and daylighting: making best use of natural daylight in a building and calculating the resulting energy savings.

educational building
The view from a bedroom in the WISE building, home of the MSc and Part II Architecture students

Part B expanded on this getting into more detail about limiting the flows of energy through a building, whilst addressing issues around ventilation and movement of moisture. A sustainable building should maintain a comfortable environment – comfortably warm in winter, comfortably cool in summer, ideal humidity levels, good air quality – with minimal energy input, and without moisture ingress causing degradation of the building fabric. Throughout the week different elements of possible means to achieve this were discussed.

A recurring theme throughout the week was retrofit – upgrading the thermal efficiency of existing buildings to reduce their energy use and related CO2 emissions. The most commonly stated best-estimate is that around 80% of existing houses will still be in use by 2050; the potential contribution to reduced energy use and emissions from such a large number of buildings is huge, but presents a challenge. There are advantages and disadvantages to various approaches, from aesthetic considerations (eg: changing the appearance of a building when externally insulating it), to practical (eg: loss of space when internally insulating), to technical (eg: the risk of condensation forming at the meeting of new insulation and existing structure if it is not carefully considered). Planning and conservation concerns can also influence or restrict choices for retrofit.

viewing insulation retrofit
MSc students examine mockups of internal and external insulation, for solid-wall retrofit

There are also issues and trade-offs surrounding choice of insulation materials – the most highly efficient materials may have a greater overall environmental impact than some less efficient materials. Some are more breathable (open to passage of moisture vapour) than others, which can have both positive and negative implications, depending on application.

Another recurring theme was the need to account for future changes to our climate in both retrofit and new build. In particular, too much emphasis on designing to conserve heat could lead to overheating further down the line when atmospheric temperatures increase. Careful attention to placement of glazing and shading to control solar gain can help address this, allowing direct sunlight in to provide warmth in winter when the sun’s path is lower, and sheltering the building from the most intense direct sunlight in summer when the sun is higher.

The role of thermal mass in regulating internal temperatures was discussed in a number of lectures. Depending on climate and design, thermal mass may hang on to winter day-time heat, releasing it within the building through the night – or assist cooling by absorbing excess heat in summer, if combined with effective ventilation to purge that heat at night. Used inappropriately thermal mass may add to overheating, so its use must be considered carefully.

thermal image
Thermal imaging shows hot heating pipes (bright) and cold area where air is coming in around cables (dark areas)

A practical in the second half of the week provided a demonstration of heat loss through unplanned ventilation (ie: draughts). This was linked to the need to provide controlled ventilation (whether through opening windows or via mechanical ventilation), and highlighted the difficulties of achieving airtightness (eliminating draughts) in some existing buildings. The practical involved carrying out an air-pressure test to establish the air-permeability of the timber-framed selfbuild house on the CAT site (ie: how much air moved through the fabric of the building at a certain pressure). In groups we surveyed the building with thermal imaging cameras, before and during the test. The resulting images clearly showed how the cold incoming air cooled surrounding surfaces, demonstrating the impact of air infiltration on energy use. A scheme to retrofit the selfbuild house at CAT would have to include a means to reduce this.

air pressure test
The door-fan, used to de-pressurise a building to identify air-ingress

The end of the week saw us discussing Passivhaus and visiting the Hyddgen Passivhaus office/community building in Machynlleth, with the building’s designer John Williamson. Some myths about Passivhaus were busted (for instance: you can open windows), and the physics-based fabric-first approach was explained. The standard is based around high comfort levels combined with incredibly low energy input. While on site we investigated the MVHR unit (Mechanical Ventilation with Heat Recovery), which removes stale air from the building, and uses it to heat fresh incoming air. These are a common feature of passivhaus, as they allow the removal of moist air and other airborne contaminants and it’s replacement with fresh air, whilst minimising heat loss. This system has been the subject of some heated debates with fellow students at CAT, due to questions about the amount of energy needed to run the system and how user-friendly it is or isn’t. We were shown that when installed correctly, the system recovers more energy than is needed to run it.

passivhaus
Hyddgen Passivhaus in Machynlleth

As ever, throughout this course connections were constantly drawn between all the different areas covered (the inescapable interconnectedness of all things!). Nothing stands in isolation; each decision in one area can have repercussions in another. The different elements of building physics and materials must be balanced with each other and with the effect of any action on the wider environment.

temperature recording
Measuring the air temperature in MVHR heating ducts at Hyddgen, prior to calculating the overall efficiency and heatloss/recovery of the the system

The immersive learning environment during module weeks at CAT is highly effective, and very intense. It’s a wonderfully stimulating and supportive place to be, but at the end of the week that intensity needs a release in order for us all to return to our normal lives without winding up our friends and family when we get there. That takes the form of the vitally essential Friday night social, which this month was themed around a Cyfarfod Bach, a laid back Welsh social. We had beautiful music and singing, comedy, artwork, silliness, a rousing rendition of the Welsh National Anthem (not too shabby, considering only a handful of people were Welsh speakers or had any idea how the tune went in advance) and finally a leg-shattering amount of dancing, ensuring we could all go home in physical pain but happily and calmly buzzing.

See more blogs about the MSc Sustainability and Adaptation course. 

Photo: A biofueled bus from Brighton!

Engineers Without Borders UK (EWB-UK) are no strangers to CAT, with five groups visiting us this year to learn about sustainable technologies. This week a group traveled from Brighton on a Big Lemon coach that runs on biodiesel from recycled cooking oil!

EWB-UK is a national student-led charity aimed at removing barriers to development through engineering and have a summer placement programme, which is now taking applications.

ZCBlog: Discussing a zero carbon future

The new ZCB report will layout a scenario for an emissions free 2030 but one of the wider project aims is to raise awareness for a more carbon responsible society. Because of this, the new report will include a series of discussion papers about how ZCB relates to wider topics.

The third ZCB report will focus on a number of specific areas for a 2030 scenario. However, the team would like to discuss how ZCB could relate to other subjects. The ZCB project is looking for contributors who want to use the ZCB scenario to highlight how reducing carbon emissions will affect the UK. These discussion papers should tackle themes and issues that are outside of ZCB’s core research.

Sure, the ZCB team have researched how to eliminate carbon emissions in energy production and land-use but how will the scenario affect less quantifiable subjects. For instance, how would the ZCB scenario affect wellbeing? Could it create or diminish green spaces for recreation?

Each “ZCB and…” discussion paper should be no more than 1,000 words but preferably be between 600 and 800. If you wish to be involved then let us know! You can get in touch here.

Not sure what subject to tackle? ZCBlog will be featuring news articles next week that reflect what is happening in relation to decarbonising the UK.

ZCBlog: Nuria Mera Chouza’s Internship

¡Hola! My name is Nuria. I am the one wearing red in the team photo and I’m a volunteer for the Zero Carbon Britain team until the end of December. Now it’s my turn to tell you something about what I do for ZCB!

I studied Chemical Engineering for five years at Cádiz University, Spain. I have been trying to focus my career on the energy sector, mainly renewable energy, so I applied for the European Leonardo da Vinci grant, to do an internship abroad. The scheme offers grants for Europeans to come and work in Britain. Knowing what I studied and my interest in sustainable energy, they told me about CAT. When they told me the tasks I would have here, I searched “Centre for Alternative Technology” on the internet and I said “I want to go there!”

Before arriving, I thought I would enjoy my work but living here would be hard. I am far away from home, and I am not as fluent in English as I would like! But things are never that hard when you are surrounded by nice people. Everyone at CAT has made me feel at home since my very first day here. They work hard on things that they really believe in. It proves that with just a little perseverance and an open mind, a brighter way of life and another future is possible. Having a walk through CAT you soon realise how many things we are missing and forgetting by living the way we do.

But what I am doing here?

In the Zero Carbon Britain 2030 scenario, wind power is a very important energy source. But renewable energies are not perfect yet and the people who are against them say they are unreliable, they say it’s “because you can not have them when you need them”. Yes, wind is a variable source of power. It doesn’t blow every time we need it and sometimes it blows when we don’t need it. In fact, some wind farms need to stop even when the wind conditions are perfect because the energy demand is low. That means that the chance to produce energy is lost because we don’t need the power at that very minute.

“Wind power can’t be as good as fossil fuels,” say the pessimists. “Because it can’t be stored for later use.”

So I have accepted the challenge! For the new ZCB report we are studying how to store the energy produced from off-shore and on-shore wind turbines. It’s my role to research the feasibility of producing hydrogen as an energy carrier, from electricity by electrolysis, and then recover the energy stored in it. Electrolysis is an electro-chemical process which uses electricity to split water molecules (H2O), which produces hydrogen gas (H2) and oxygen gas (O2). This hydrogen gas can be used in hydrogen engines or fuel cells to recover energy, or it can be combined with CO2 to produce synthetic fuel in a chemical process called Fischer-Tropsch, where hydrogen and carbon are combined to build hydrocarbon chains or in other words, carbon-based fuels. So by using hydrogen in this way, we can make an intermittent energy source like wind power far more reliable.

Because I have been researching this, the rest of the team have been able to look at the bigger picture while I focused my energy on what I enjoy! The team have given me the support I needed to research my ideas and I’m proud of my contribution to the project. I am scheduled to leave CAT in December but I really want to stay and continue working in such a great environment! Everyone here keeps on telling me how important it is to have volunteers and different nationalities working here.

ZCB is a scenario for Britain but why not let people from other countries play their part!

 

CAT’s Energy Day to celebrate positive change towards a brighter energy future

 

This August 8th CAT will host Energy Day as part of its six-week Festival of the Future. Energy Day aims to celebrate positive change towards a brighter future with a family-oriented day of interactive energy workshops, panel discussions with leading environmental thinkers, presentations from CAT experts, talks, and energy-themed kids activities and games.

August 8th will see CAT transformed for this one-day event exploring energy and its role in shaping our lives into the future. Visitors will get to grips with renewable technologies in ‘behind-the-scenes’ tours of CAT’s on-site renewables. Householders can discover more about how they can make small, achievable changes in their homes and communities to support the transition to a more sustainable and energy efficient society. Friends of the Earth and Practical Action will contextualise the energy debate in talks on the UK’s energy policy and renewable energy and development, and the Guardian’s John Vidal will lead an insightful panel discussion on our energy futures.

CAT’s own Zero Carbon Britain research team and experts will be on hand to discuss sustainable solutions to our current energy scenario, whilst renewable energy companies and representatives from community energy projects will be here to share their industry experience.

The day will also be packed full of entertainment for children and young people. Energy-themed workshops and activities will take place throughout the day, and specially designed wide-games for kids and adults will be taking place across the CAT site. There will also be film screenings, music from a bike-powered sound system and pizza fresh from a wood-fired earth pizza oven.

CAT’s External Relations director, Paul Allen, said “re-thinking energy offers us a wide range of new opportunities, not least in terms of employment. Careers in both energy saving and generation from renewable energy sources offer exciting opportunities and can encourage young people to explore science, technology, engineering and maths whilst also working to protect the planet.”

While currently only a small amount of our energy originates from renewable sources, public support for renewable energy is growing. CAT’s Energy Day celebrates the small changes we can all make towards building a brighter and sustainable future together.

Visit Festival of the Future: Six weeks of fun and inspiration at CAT

 

Today we unveil our summer plans: CAT will be hosting a six week ‘Festival of the Future’ for tens of thousands of visitors. Daily activities for all the family and a programme of special one-day events mean a day trip to the Centre for Alternative Technology this August could inspire a revolution in the way you live.

Festival of the Future takes place throughout the school summer holidays from 21st July until 31st August. Daily activities will incorporate creative renewable energy and sustainability themed activities for children, with talks and informative tours led by staff and researchers at CAT for adults. Every Wednesday will see special events for kids and adults such as storytelling and specialist tours of CAT’s renewable energy systems.

Two one-day special events will form the climaxes of the summer programme: Energy Day on the 8th August and an Arts and Sustainability Fair on the 29th August. Both days will be packed full of informative and inspiring activities and entertainment including stalls, music, workshops, storytelling, exhibitions, guest speakers and more, all themed around building a brighter, more sustainable future for the UK and beyond.

We will be posting a series of articles on the blog on the theme of Festival of the Future.

This packed summer programme aims to provide a fun and active day out for families and other visitors to CAT, but also to give people ideas about the positive contribution they can make to a sustainable future.

Visitors will be able to meet face to face with some of the experts from CAT who will be giving guided tours and hosting engaging discussions about eco-lifestyle changes and action that people can take in their own community to respond to bigger picture challenges.

Allan Shepherd, author of CAT’s latest book The Home Energy Handbook will be one of the CAT staff members talking to visitors. Allan said:

“There are loads of positive things that people can do to help build more sustainable communities that are fun to take part in. Festival of the Future is a great opportunity for people to come and learn a bit more about sustainable futures as well as picking up tips on everything from eco-friendly living to getting involved in your local community. It should be entertaining as well as inspiring.”

All the events going on as part of Festival of the Future are included in the normal CAT entrance fee. The Visitor Centre also has a restaurant serving delicious vegetarian food and a shop selling books and gifts. A full programme of Festival of the Future events, which run from 21st July to 31st August, can be found on the website: http://visit.cat.org.uk/festival-of-the-future. Festival of the Future is sponsored by Good Energy, the UK’s only 100% renewable electricity supplier.

 

 

A chance to find out more about our sustainable postgraduate courses…

 

On June 22nd, we’ll be running another of our popular open days offering prospective students the chance to find out more about our masters course in renewable energy and the built environment.

The course, which is taught with an unique combination of academic study and practical experimentation, explores the theory and practices of renewable energy technologies with special reference to the built environment. It’s aimed at those interested in becoming more knowledgeable about the benefits and drawbacks of the major renewable energy technologies, including biomass, solar photovoltaics, wind power, solar thermal and hydro electricity.

Leanda, a student who has worked in the construction industry in Bristol for the past seven years, has been writing about the modules and her experiences at the Graduate School of the Environment on her blog. She says “one of my favourite things about this course is the people on it. You get to know them so much better than you would on a standard university course. The course is pretty intense; you spend a lot of time time with each other. However, I’m lucky to be surrounded by such great people. No-one else at home would engage in conversations with me about the possibility of harnessing power in a giant hampster wheel. Big ideas have to start somewhere!”

The open day will give anyone interested in joining the course the opportunity to meet students and lecturers and explore the unique study environment that is CAT. Visitors will be given an introduction to the course, an update on the jobs market and the experiences of past students, a site tour of CAT with all its fascinating displays of renewable energy systems and the chance to sit in on lectures.

For more information, head to gse.cat.org.uk/opendays, where the schedule for the day will shortly be available. Email msc.rebe@cat.org.uk if you’d like to book a place.

Renewable energy in Wales: conference at CAT October 17th

Current protests over wind power are threatening the future of the renewable energy industry in Wales, slowing down the development of sustainable low carbon technologies and starving our communities of vital investment in regeneration, jobs and infrastructure. Furthermore, they are obstructing the development of green skills, training and research which could revitalise our manufacturing industry to the benefit of many small and large businesses. It is time for the renewable energy industry and its supporters  to work together to communicate a shared vision to build a sustainable, low carbon Wales and rebuild confidence and trust in the future of our Welsh green economy and the many benefits that renewable energy offers.


The Future of Renewable Energy in Wales / Centre for Alternative Technology / October 17th / book your place


The conference in October will provide a forum for discussion over a new vision to deliver a successful future for clean energy generation in Wales. Ultimately this may lead to the launch of a broad organisation to speak for all individuals and organisations that want to see Wales do more to generate electricity from renewable sources.

Turbine Nacelle