Tuesday, 11 June 2019

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.

Thursday, 6 June 2019

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).

Friday, 24 May 2019

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.

Tuesday, 16 April 2019

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].

Sunday, 13 January 2019

One third of microplastic in the oceans comes from washing clothes - really?

I recently heard a claim that a third of microplastic in the ocean comes from laundry, as synthetic clothes shed fibres in the wash. (This was on a radio program called New Year Solutions: clothes, on radio 4.) This struck me as unlikely so I checked and I believe I found the source: a report from the IUCN in 2017[1]. They do indeed estimate that a third of primary microplastics come from laundry – averaged over the world. However this varies hugely in different regions. I found estimates specific to the UK in a report by Eunomia for Friends of the Earth [2]. They found that only 8% of UK primary microplastic is from laundry. The bulk is actually from tyre wear from cars and lorries.

Thursday, 3 January 2019

Some facts about food waste

Michael Gove has announced that we could divert 250 million meals per year to the most needy in society [1]. Is this a lot? There are 67 million people in the UK (approx). If we each eat 2 meals per day, that comes to 49 billion meals per year. The quoted 250 million meals is 0.5% of consumption. That seems a very low level of wastage to me, though we should still redistribute it if that is practical. We waste a lot more food at home. Here are some more facts about food waste.

Friday, 23 November 2018

Are hybrid heat pumps the solution for low carbon heating?

The Committee on Climate Change has just published their view on the role of hydrogen in a low carbon economy [1]. Their recommendation for people currently on gas is to insulate your home as much as possible and then install a hybrid heat pump/boiler system. You can get hybrid systems now, only burning methane gas rather than hydrogen. The idea with a hybrid is that the heat pump supplies all the heat most of the time, but with a boiler for backup when demand is very high or electricity supply is expensive. In theory, a hybrid system should supply around 90% of the heat from the heat pump - however, this is only the case when the system is configured correctly. In field trials the proportion of heat from the heat pump has ranged from 96% down to 30% [2]. No wonder the RHI subsidy requires that hybrid heat pumps have metering to actually measure how much renewable heat is supplied through the heat pump [3]. If hybrid heating systems are to play their part in a sustainable future we have to learn how to manage them properly.