Good and bad tipping points

It has been a difficult year. Just when we thought we were past the worst with Covid, we get the war in Ukraine with devastating impacts on the supply of fuel, grain and other food goods. 

Climate change does not let up. Last year looks to be the warmest on record for the UK and in July the record for highest temperature in the UK was topped by an alarming 1.6°C [1]. We also had drought with river flows at record lows [2]. Worldwide, 2022 saw catastrophic floods in Pakistan [3], record forest fires across Europe [4], and extraordinarily sudden cold across large parts of North America (a drop of 23°C in one hour in Cheyenne, Wyoming) [5].

It reminds us of the danger of climate tipping points. Tipping points are moments when some part of the climate system changes in such a massive way that there’s no going back. Apparently there are several that may have already happened: melting ice sheets, the death of coral reefs, melting permafrost releasing methane and the loss of sea ice in the Barents Sea [6].

These tipping points are dangerous. However, tipping points can trigger changes for the good too. The war in Ukraine has shown how easy it is to weaponise supply of fossil fuels [7], triggering a rapid increase in investment in renewable energy worldwide. For the same reason we have seen much more action on energy efficiency, here and across Europe [8]. People are turning down thermostats and putting on more clothes to reduce bills [9]. (See also TC members tips). Solar PV installers are struggling to keep up with a spike in orders [10], and demand for heat pumps, which use electricity to heat buildings instead of gas, has also surged [11].

When we are close to a tipping point, little nudges can produce large changes in the way we think, feel and do things.

How is a reindeer's nose like a condensing boiler?

I am sure it has not escaped your notice that the weather recently has been unusually cold for the time of year. How have you been keeping warm? In our house we have turned down the heating a bit, because with the energy shortage due to the war in Ukraine it is very important to reduce our energy consumption as much as possible, to keep the prices down. (Even with the price guarantee, we will pay for it eventually, probably through our taxes.) As always it is worth taking a look at the natural world for tips. Since it is Christmas, reindeer are a good start. How do reindeer keep warm?

Working with contractors - pooled experiences

Are you considering getting builders in for any retrofit work? Or installing low carbon heating? How do you find a contractor to do the work (or part of the work if you want to do it DIY?) Do you need a project manager? This question comes up time and time again and there are no definitive answers. However, the energy group had a discussion about this at their last meeting and we now have an advice page which is a synthesis of our experience. 

Your energy saving tips

The energy saving survey is concluded now - thanks to all of you who filled it in and especially to those of you who gave us your tips. 

But first a reminder/plea from me - please do not just breathe a sigh of relief at the energy price cap and carry on as normal - the cap is supported by a subsidy and it still costs us money, albeit via taxes or reduced services. Fundamentally, the problem is an energy shortage and inevitably some people will have to use less; for fairness, this should not be the poorest and most vulnerable who have already cut their energy use to the bare minimum.

Now for your tips there are too many to list all of them but I have done my best.

Most renewable electricity tariffs are pointless

Do you get your electricity with a “100% renewable” electricity contract? Most of these contracts do nothing to promote renewable electricity and some of them make use of power with higher emissions than average on the grid. A few retailers genuinely supply renewable power. You may need to pay a bit more, (or maybe these days, a bit less, since they do not use gas)!

The energy group learned about this at our last meeting. One of our members, Adam, has just completed an MSc on the subject and explained all. Thanks Adam! This post was written by another member, Chris - thank you too!

What is renewable electricity?

Electricity is generated and pushed into the National Grid by “generator” companies. Some of them use gas, coal and nuclear power to generate electricity, which we call “non-renewable” because it is extracted from the Earth and can be used up. Gas and coal also contain carbon which they release (as carbon dioxide) when burned, which contributes to climate change (global heating).

Some generators use solar, wind, hydro, biomass (wood chip) or tidal power, which we call “renewable” because the Sun is constantly powering them, so they won’t run out. Building them emits carbon dioxide too, but they don’t usually emit any while operating (or, in the case of biomass, re-emit carbon dioxide that they recently removed from the air). We consider that they contribute much less to climate change.

Energy Saving Survey

Here are some interim results from our survey on energy saving at home. If you haven't filled it in yet it is not too late; we will update this page as we go. Many of us are already keen energy savers anyway to reduce carbon but it is more important than ever now even if you can afford not to. The price increases on both gas and electricity are due to a global shortage of gas that does not come from Russia. Prices will continue to climb until global demand reduces to match supply. In the EU there are proposals for ever higher targets for energy saving by 2030 (see EU Parliament groups unite behind 14.5% energy savings goal for 2030). Individual countries are considering a range of measures to save energy including reducing heating in public buildings, reducing street lighting and even cutting hours of business (see Tariff shields and turning off lights: how Europe is tackling the energy crisis). 

What is holding up our retrofit plans? – and advice

Every house is different, but it is still useful to share problems and tips around retrofit – often similar problems keep cropping up. I asked the energy group members what is holding up their plans and we discussed some ways forward. There are common themes. At bottom, we see inconsistency in planning rules and inconsistency in advice from installers. Plus a chronic lack of installers. All this means progress can be very slow but we do believe it is important to keep up the pressure, or nothing will change. If you have more stories and/or advice we would love to hear them.

Some of the problems are due to recent changes in regulations for retrofit. It will take a while for the industry to get used to the requirements of PAS 2035, a framework for approaching whole house retrofit with best practice. Also there are not enough trained retrofit coordinators yet. This can be very frustrating.

(Names have been changed in this article)

Planning permission for EWI – yes you need it but you don’t need to pay a consultant.
If you want to install external wall insulation, you will need planning permission if there is a significant change in external appearance. So if your house is already rendered, you can probably get away without. Or if you are now brick and you intend to use brick slips to cover the insulation and they are a reasonable match, also fine. However, for most of us we need planning permission. Richard told us that he spoke to two planning officers at the council and they both said he needed to submit technical drawings. This would mean (for Richard at least), hiring a consultant to prepare them, at considerable expense. He was quoted £1,200. However, when he complained to his councillor they checked with the department and apparently this is not necessary. You only need to supply:

• A site location plan with the outline in red (you can buy the maps for these online for less than £20 e.g from the planning portal or from UK Planning Maps
• Photo of the property, indicating where there would be render
• Details of the rendering system e.g. product sheet.

Others in the group have put in applications in this way with success. However, non-trivial cases can take a long time to process. This can be a show-stopper if you are relying on a grant scheme that has a limited timespan. So get your planning application in as soon as you can.

Unfortunately, the planning department is under-resourced, and inexperienced staff can give inconsistent responses. This is a problem across the whole country – as described by this article in the Architects Journal . Staff turnover is high (from hearsay, because good planners are quickly poached by consultancies).


Planning on solid wall insulation - you may need floor insulation too.
Sarah was told that, due to rule changes, if you put external wall insulation on a house with suspended floors you must also install floor insulation. This is not always true. Revised standards do require that retrofits should avoid thermal bridges, routes where heat can leak out bypassing the insulation. These heat leaks can lead to cold spots where you could get condensation. Previously, most EWI installations stopped above the damp proof course, which leaves a cold bridge as shown in the diagram. Internal wall insulation poses a similar problem.

Diagram of a cold bridge caused by EWI that stops above the damp proof course.

You might argue this cold bridge is no worse than before, but it is the relative difference in temperature between the warm and the cold areas that matters. The walls have got warmer but the floor has not.

How bad this is for your house depends, amongst other things, on how far the insulation extends below floor level. Best practice would be to extend the insulation below the DPC and into the wall footings. Some installers have always done this. You need a waterproof insulation below the DPC and the DPC itself will be extended through the insulation. Without it there will always be a cold bridge between the outside and the underfloor void. However, even with the added insulation there will still be some heat leakage because you will have air bricks ventilating the underfloor void and letting cold air in. Floor insulation fixes this but adds to cost and can be very disruptive.

It is all a bit of a grey area. Houses vary and no-one should give you firm advice without checking your particular case. The advice from the Transition Cambridge Energy Group was that it is worth asking different installers. You should also bear in mind that when installers are busy they may fob you off with ‘it’s too difficult’ because they do not want the job, not because you cannot do it.


Inconsistent advice from installers
Mike complained that he has got different answers from different installers when asking basic questions such as how to avoid thermal bridging when using a mixture of external and internal insulation. On this particular issue, some say not to worry and some say you should have an overlap of at least 30cm. Who is right? This is an area where the 30cm rule of thumb is probably good enough for most cases…

To check advice you need to buy the standards

… but if you actually want to check yourself, it will cost you £50 to download the standard for calculating thermal bridges and temperature factors from the Building Research Establishment. You can look at the building regulations part L for free but to read the calculation methodology you are required to use you have to pay. It costs another £50 for the U-value calculations (£60 for the calculator but that only runs on Windows, not MACs).

These costs are not huge but they are significant. Competent DIYers can save a lot of money if they do the installation bit themselves, and can often go ahead without grants which removes another barrier. However, they need guidance. These documents (and others) might help. (Should we get them for group members to borrow?)


For heat pump noise, permitted development rules are less strict than full planning.
Installing a heat pump is usually a permitted development but several people we know of have incorporated a heat pump into a larger retrofit which needed planning permission. Unfortunately the rules for noise in planning applications are much more strict than the rules than are used for the permitted development case. Basically, the permitted development rule is based on a typical background noise level but the planning department may require that you actually measure the background noise level at your location. In John’s case, this led to ludicrously severe noise restrictions on the heat pump – the area was so quiet that he would have needed to enclose the heat pump in a sound insulated metal box. The installer was dubious and asked the manufacturer of the heat pump; they refused to give a warranty for the setup.

Heat pumps allowed under permitted development can be challenged if there is a noise nuisance.
The obvious way around this is to keep the heat pump off the application and do it afterwards under permitted development rules. However, if there is a complaint about the noise you may be liable anyway. The planning conditions are based on noise nuisance rules and conforming to permitted development rules is not a defence. So the advice is to be careful about siting your heat pump and be friendly with your neighbours.


We hope these tips help you. If you have other stories or tips do let us know. 

Demand and supply of natural gas

This is a quick post based around three charts describing our natural gas supply and demand. As households we are responsible for gas use both directly in our homes and via the electricity supply. Given the constraints on non-Russian supply at the moment, and the increase in prices for both gas and electricity, restraint is called for all round.

This chart is from Energy Trends showing demand for gas by quarter.  Domestic demand is at the top. 'Other' is mostly other buildings. We are currently in Q2 and demand is decreasing but there is still lots of demand for electricity generation.

Chart from [1]

Easy ways to keep warm with less energy

With an expected 54% increase in energy bills from 1st April 2022, what can individuals do to minimise the impact of these cost pressures? Cutting our use of gas and electricity at home improves UK energy security and helps to keep prices low for everyone. 

Following an insightful talk from Karen Igho of PECT about fuel poverty and the services PECT provides, the Cambridge Transition energy group pooled experiences on energy saving at home. Here are some easy, low cost or no cost, wins we have found useful. 

• Lower the radiator temperature (if you have a condensing boiler)
• Get moving
• Wrap up warm and/or use heated clothing
• Only warm the room you use the most
• Share your home

Using a battery to save carbon emissions

This post was updated on 1st March with more recent data.

The Transition Cambridge Energy Group is a great place to kick around ideas and share experiences. One topic that keeps coming up again and again is batteries – are they worthwhile? One of our members, Ian, has taken the plunge and would like to share his reasoning and experience with you. 

Ian likes to be an early adopter of low carbon technology though like the rest of us he does not have infinite money to spend! He installed a heat pump and PV panels in 2011. He also has an electric car, and since mid January, he has a 15 kWh battery and is delighted with the carbon savings. At this time of year there is usually a considerable difference in the carbon intensity of electricity between night time, when demand is low, and day time when demand is high so by charging at night for use in the day he makes a considerable saving. 

How do you get carbon savings from using a battery? 

This chart from grid watch shows where we have been getting our electricity from over the last month. You can see how demand fluctuates sharply through each 24 cycle between daytime and night time. The overall emissions are mainly to do with how much orange there is – from gas power stations. Wind is blue. During the first few days in January the wind was very strong but since then we have used a lot of gas, especially during the day when demand is high. 

Chart from https://gridwatch.co.uk/ showing much less use of gas power stations overnight than in the day. Grey is nuclear, orange is CCGT, red is biomass blue is wind, solar is yellow. The others include coal, hydro electric power, and interchanges with other countries.