If I was on the citizen's assembly for Cambridge transport ...

The Greater Cambridge Partnership did not get a clear message from the survey they ran earlier this year so now they are running a citizen's assembly. I thoroughly approve - if done well a citizen's assembly allows for a representative panel of ordinary people to hear evidence from a range of experts and consider a topic in depth. Transport is a complex problem because different people have different needs and it is hard to satisfy everyone. Using your own car is always going to be more convenient if you have one - as long as the traffic is actually flowing rather than in gridlock. I would want to see evidence for solutions that will bring benefits to most people at least some of the time.

I believe the invites have gone out and I have not got one so I won't be able to take part. However, if I were, this is what I would like to discuss while on the panel.

Surprising results of air tightness tests in new homes

No-one wants to live in a draughty home. They are uncomfortable to sit in and have high energy bills. Building regulations have stringent rules about ventilation levels and air tightness - but there is strong evidence to suggest that they are not working very well. New homes are often much more draughty than they should be, and adding an extension to an existing home can introduce draughts in the main part of the house, if not done properly. This post draws on evidence from a study by UCL researchers of 144,000 air tightness certificates lodged with the ATTMA database (Air Tightness Testing and Measurement Association) [1]. Also I have included anecdotal evidence reported to me by Paul Buckingham of Sustainable Lifestyles Ltd and others.

How is a house like 3/4 of a cow?

One way to decarbonise our home heating is to use anaerobic digestion (AD) to process biomass (such as grass) into biogas. So we can grow grass as cattle feed or to heat our homes. How do cows and houses compare in terms of grass demand? Here is a back of the envelope calculation - and the conclusion is: one house is about 0.75 cows. Based on this (rough) figure, if we repurposed all our land that currently supports sheep and cattle to grow grass for biogas, we could supply about 13 million households, a little less than half the current number in the UK (27 million) [1].

The grass these cows are eating could be used to heat our homes instead.

Low carbon heating in real houses

The quick way to get to low carbon heating is to replace our gas boilers with heat pumps. We don’t have to wait for low carbon gas or district heating infrastructure to be installed - we can do it tomorrow. However, it isn’t always that easy. The Energy Systems Catapult (ESC) have done a fantastic job of modelling how this could work in five real homes [1]. They envisage a staged conversion in each case, usually starting with fabric upgrades and moving on to a heat pump (or district heating) later on, over 10-15 years. Each house (two semi detached, two terraced and one detached) has its own story, but I am not going to worry about the paths, just about the end points. Interestingly, in two cases they envisage keeping a boiler in place as well as the heat pump, running the heating in a hybrid scenario.

Hiring an electric bike

Last week I had my first experience of an electric bike, which I hired for travelling to and from a business meeting. It was not an unqualified success. I wonder if anyone has any thoughts around this. The problem was not the electric bit, it was the hiring bit.

The situation was that I needed to go to a business meeting in Hardwick. This is a little outside my comfort range for a bike ride. I generally reckon up to 4 miles OK but this was 6 miles and up a hill. (Yes I know other people consider that normal but I am not very fit. I don’t like to arrive for a business meeting with people I do not know well dripping with sweat.)

I know there is a bus but I wanted to try an electric bike, and also to test - is it sensible to hire an electric bike for those occasions when I want to go a little further afield? (One risk is that I would like the electric bike so much I would want to buy my own and use it all the time. This would not be good for my fitness).

Electric Blue - a new kind of sustainable investment?

Community energy schemes used to be the no-brainer sustainable investment, for people with moderate levels of spare cash that could be tied up for a few years. I personally have investments in one community solar farm, two wind turbines and two renewable energy suppliers. But this year I have added a new string to my sustainable portfolio that does not generate any energy at all: Electric Blue is in the business of installing and managing EV charging facilities in our city streets. This particular bond issue is for a project in Cambridge.

A case for energy services - spreading the risk.

Recently I have completed some research into how cost-effectiveness of energy efficiency is measured and was struck by the huge differences we see, depending on context. For a householder or a small business, cost effectiveness is normally considered around financial costs and savings, with a time horizon of up to five years. In a context of evaluating national housing stock upgrades, the UKERC, for example [1], consider additional wider benefits including air quality, thermal comfort and carbon emissions, and a much longer timescale, at least 20 years. This is by no means exceptional - I found evaluations based on up to 60 years.

Risk gets too little attention.
However, it is not just the addition of non-monetary benefits and long timescales that worries me, the issue of risk gets too little attention, in my view. It is very hard to predict actual energy savings from retrofits due to a variety of factors, from inadequate understanding of the structure already present to variable installation quality. The recommendations we get on energy certificates have an allowance called the 'in-use' factor that partly covers these uncertainties - but these factors are based on averages. Also the in-use factor excludes comfort taking, which may or may not be due to actual changes in control settings by the occupants (see also my review of 'The Rebound effect in Home Heating' by Ray Galvin). This means that estimates of financial savings have a large element of uncertainty.

EnergieSprong's performance guarantee is a promising strategy.
While I would not wish to discourage anyone from installing energy efficiency improvements in their home, I would hesitate to recommend this purely on a cost saving basis, at least without an assessment of uncertainty or some kind of performance guarantee. This is why I find the EnergieSprong initiative interesting. The concept has apparently been working well in the Netherlands and is now coming to the UK, with an initial pilot in Nottingham [2].