What’s it like working in CAT’s Information Department?

by Tobi Kellner Information Department

“Can heat from rotting horse manure help reduce my gas bills?”
“How many solar panels do I need to power an electric car?”
“Is my land suitable for a wind turbine?”

These are the kinds of questions you encounter when you work in CAT’s information department. As part of CAT’s greater mission to “inform, inspire and enable”, our department aims to supply anyone who wants to live more sustainably with the advice and information they need to actually turn their aspirations into actions. In a typical week we receive more than 100 emails and phone calls with questions and provide detailed face-to-face advice to a similar number of people at the Information Desk, which is staffed 7 days a week as part of the CAT visitors centre. In addition, we constantly expand and update our part of the CAT website to ensure that each of the around 1,000 pages viewed every day is informative and accurate. All the information we provide is impartial and completely free of charge.
info_team Offering this service keeps our team of four information officers pretty busy – but of course that doesn’t stop CAT’s membership officer Catriona from charming us into writing articles for our members’ e-bulletin and the Clean Slate magazine…

Perhaps the most exciting thing about providing a service of this kind at CAT is that we’re right at the source. When we write about the durability of PV panels, we can draw on our engineers’ experience with one of the UK’s oldest large PV roofs. When we do a step-by-step guide to building with hemp and lime, we have a chat with Phil who oversaw the WISE project and also used the material to renovate his own home. Chances are, if you ask us a question we can’t answer directly then we bring it up with our engineers and university lectures over lunch, while munching on Roger’s delicious home-grown organic salad. Keep that in mind when you ask the next tricky question about compost toilets.

To ask your tricky sustainability question, contact us at here

“But how efficient is it” Musings on a tricky word

by Tobi Kellner Information Departmenttobi

One word that comes up again and again in the questions we receive at the CAT Information Service is “efficiency”.

It comes up all across the board: whether it’s gas, oil or biomass boilers, heat pumps, solar panels or wind turbines, often one of the first questions we hear is “Is it efficient?” The tricky thing about the word efficiency is that it doesn’t always mean what you think it does.

When talking about energy, efficiency can be defined as desired energy output per energy input. Say you’re talking about the energy efficiency of a coal power station. In this case, your energy input is the heat energy content of coal, i.e. the amount of heat energy you would produce if the coal is burnt under perfect conditions – around 10kWh per kg. And your desired output is the electricity produced – around 3kWh per kg of coal you put in. So you have 30% efficiency. Easy enough. And of course a more efficient coal power station would mean you need to produce less coal for the same amount of electricity, so it’s important to aim for the highest efficiency.

Now let’s look at a photovoltaic (solar electric) panel. Here the energy input is the amount of solar energy that falls on the panel surface, and the desired output is electricity. The efficiencies of good PV panels on the market are around 20%. Does that mean that a coal power station is more efficient than a solar panel? Well, yes, but you’re comparing fossil fuel energy input with energy input in the form of free, clean and renewable energy, so the comparison is pretty meaningless. Even between different forms of renewable energy, comparisons are of little value. Modern wind turbines are around 35% efficient in the sense that they can convert 35% of the kinetic energy of the moving air that’s flowing over their blades into electricity. Does that mean a 35% efficient wind turbine is better than a 20% efficient solar PV panel? Well no, because you’re comparing different technologies and forms of energy input. Similarly, it would be meaningless to compare the 20% efficiency of a PV panel to the 50% average efficiency that a solar water heating panel can achieve, because the desired energy output is in different forms – electricity and hot water – which are of different value.

Even when comparing efficiencies for different generators of the same technology, with the same forms of input and desired output, efficiency can be a deceiving concept. Monocrystalline PV panels are somewhat more efficient than those made from polycrystalline silicon, and that means under identical conditions you need a slightly bigger polycrystalline panel to produce the same amount of power. Does that make the less efficient panels an inferior choice? Not necessarily, as very often it is the size of your wallet and not the size of your roof that constrains your solar ambitions. In that case what you care for is where you get most useful electricity output per pound invested, not per area. In fact, a lot of research effort is put into developing amorphous “thin film” photovoltaic panels which use only a very thin layer of silicon. Under identical conditions they produce less power than traditional mono- or polycrystalline panels. In other words, they’re less efficient. And yet these low-efficiency panels could mean a great leap forward for PV technology because hopefully they will eventually be a lot cheaper to produce, making it possible to have PV as a standard building element.
In the end, we’re not after the technology that gives us most useful energy output per energy input. We’re after solutions that allow us to make most of the resources we have available.

Meet the media department


CAT aims to inform, inspire and enable positive solutions for sustainable living, the media department communicates CAT’s message to the  wider world via the mainstream and social media. Visibility and relevance is crucial engaging with people in the sustainability debate and attracting new people to the organisation. CAT’s media strategy focuses on building support and positive representation across all media platforms and to a wide range of audiences.

From left to right

Nick (left)

Nick has come to join us for a couple of weeks in the media department, he is a fantastic photographer and has been working with lots of different departments to get some new shots of the work going on here at CAT.  “I arrived on Monday and I have taken over 500 photo’s so far, I have been made to feel that I am part of the CAT family.”

Alex ( middle)

Alex is part of the furniture in top office, the longest serving media department member- he had been here for over 6 years. He joined CAT as a volunteer after studying a philosophy degree at Durham Uni. “The best thing about working at CAT is the co-operative and the second best thing- hot chocolate from the restaurant.”

Kim (right)

Kim joined the CAT media department last year and has been loving the job ever since. ” CAT is a brilliant place to work, the people are lovely and the site is fantastic. ” She studied Media at John Moores University in Liverpool and has worked for a number of publications and organisations since then developing media communications and popular education projects.

Nature: winter visitors to CAT

by Rennie Telford

Now that all our summer migrants have long gone to avoid the British winter and spend the time in much warmer and sunnier climes (and very sensible of them to), it is time to keep an eye out for the yearly influx of winter visitors. These are the birds who consider our much maligned winter months to be a balmy haven compared with the conditions they would have to endure if they stayed put. It’s really worth taking a trip down to the coastal estuaries at this time of year, where particularly around the Dyfi estuary you will see Wigeon, Redshank, Greenshank, Shelduck, Geese and loads more in their hundreds but we also get our share of visitors around CAT. Two regular arrivals to watch out for are the Fieldfare and the Redwing both members of the rather unfortunately named Turdidae family (Turdus pilaris and Turdus iliacus respectively).

They are superficially similar to our more familiar resident Thrushes, the Mistle and Song, but with a bit of practice are easily identified, although it can be confusing at times as in the winter you will often see mixed flocks of Fieldfares, Redwings and Song Thrushes which have formed large feeding parties both for protection and to improve the chances of discovering food sources (berries, windfall fruit and the like). Anyway, what does it matter if you can’t distinguish one from the other at first?– just enjoy watching them –it’s never worried me too much if I’ve failed to positively identify a bird, although the more you observe them the easier it gets–well until your eyesight gets as bad as mine– I haven’t quite got to the ‘What’s that bird in that tree?–What tree?’ stage yet, but I do like to have my binoculars with me at all times now!

The engineers investigate Air Source Heat Pumps

The CAT engineers have just installed an Air Source Heat Pump. Dave Hood answers some questions about what it is and what we’re hoping to find out.


What does an Air Source Heat Pump actually do?
It is a device for converting low grade heat in the air into usable heat for heating buildings and service hot water. It uses the same vapour-compression cycle that is used in fridges and air conditioning units, but in this application to bring heat into, rather reject heat from, somewhere, in this case a building. It has been kindly donated by Sanyo and Oceanair for use on the CAT visitors circuit and for our MSc and Installers courses.

Why is it interesting?
Heat pumps have been around for a long while, but the technology has been evolving to make them more energy efficient. This system uses an inverter driven compressor as part of its operation, and these are more responsive and more energy efficient than previous versions. This means that the system uses less electricity to generate the usable heat for the building. The system also utilises Carbon Dioxide (CO2) as the refrigerant. All vapour compression systems need a refrigerant, but most are potentially very harmful to the environment if they leak or are disposed of incorrectly. Those refrigerants that damage the ozone layer have mostly been banned, but the ones still used are potent greenhouse gasses, which are up to 1500 times worse than CO2. By using CO2 the potential damage is much less. Also, CO2 has the potential to operate at higher temperatures, which may fit better with the way we use heat in our homes. There are currently very few heat pumps of this type installed in the UK, and we are excited to have the opportunity to investigate it at CAT.

What are we hoping to find out from this experiment?
CAT have installed the ASHP unit to heat one of our buildings and we will be monitoring the system to see how well it performs under a range of climatic and occupational conditions.

How will this experiment benefit the public?
The system is on the CAT visitors circuit so that people can see and understand it’s operation. We will be using it for training both our Heat Pump Installers programme and on the MSc Renewable Energy in the Built Environment course. The students from this programme will be monitoring the long term data to assess its performance, and they will be in communication with both Sanyo and Oceanair to feed back our results to aid ongoing understanding and development of this technology.

The Secret History of the National Grid. CAT features on BBC 4 documentary

CAT pioneers Bob and Liz Todd took part in the BBC 4 Documentary ‘The Secret History of the National Grid’. The programme looked at the history of the grid and how it has shaped the politics of the UK. CAT was featured because of the pioneering role we play in demonstrating alternatives to conventional fossil fuel and nuclear electricity generation. You can watch the programme on iPlayer (below) and it will be on again on BBC2 on the 17th of November at 11.20pm