Friday, 12 January 2018

Would Green Mortgages make energy efficient homes more affordable?

Do you think lenders ought to take into account the energy efficiency of a house (and hence your energy bills) when deciding how much you can afford to borrow? In some parts of the country there appears to be a price premium for a good EPC rating - the overall average for England is an extra £16,000 for 2 levels of EPC grade (D to B or G to E) [1]. This is good news for owners and further encouragement to people thinking of upgrading their homes, but not necessarily good news for buyers. If lenders did take into account your energy bills, how much difference would that make?

Tuesday, 2 January 2018

A bottle deposit scheme is tinkering round the edges.

Much of the news reporting on the parliament report ‘Turning back the plastic tide’ has been about implementing a bottle deposit scheme for plastic bottles. However this is not the most important of the recommendations made.  The key ones, in my view, are those designed to build a market for recycled plastic and to shift the burden of handling packaging waste onto producers.

First a quick recap of the numbers. Annually in the UK
  • 13 billion plastic bottles used
  • 7.5 billion recycled
  • 3 billion incinerated
  • 2.5 billion go to landfill

Thursday, 28 December 2017

Does ordering stuff online increase carbon emissions?

How much of your shopping do you do online? Are you worried about the climate change impacts of online shopping? A recent study of parcel delivery in Central London [1] gives some insights into how this compares with shopping on the high street. London is a bit different from the rest of the country: I have extrapolated these results to Cambridge, with plausible assumptions.

Delivery in Central London is equivalent to driving about 1km in a car, for Cambridge it is nearer 3km. If the parcel is plastic wrapped the carbon emissions for packaging are small but for a medium sized box you need to add another 1.3 km. There are a number of ways in which these emissions could be reduced.

Tuesday, 12 December 2017

Being together without travelling

Christmas is a time for being together, with family or with friends. But it is not a good time to travel, with bad weather often disrupting trains and planes and the roads clogged with extra traffic even when there hasn’t been an accident bringing progress to a standstill. Fortunately, there are other ways to contact family without actually being there, and they have come a long way from my childhood when there was only a phone with a huge handset and only one of us could talk at a time. These days:

  • You can put the phone to speaker mode, so groups can take part at either end.
  • You can wear a head set, and talk while moving around (exercising, cooking…)
  • You can use a phone with a camera (or a web cam) and have video as well as audio.
  • You can use a tele-presence robot which gives you freedom to move and look around at the other end.


Monday, 4 December 2017

The future of Transport

Will we have self driving cars or not? 'Travel in Britain in 2035' describes three plausible(ish) scenarios and only in one of them do self driving cars play a major role. They do make a big difference though. I heard about this report at 'The Future of Transport' organised by Cambridge Network. There were 6 presentations in total of which three involved driverless vehicles: one on self driving cars, one on self driving delivery drones and one on self driving mass transit vehicles. (Actually this was mostly about tunnels; the self driving bit was only incidental; driverless transit vehicles are common enough to be uninteresting, for example the London DLR). The other three presentations were the one on the future scenarios report, one on local transport plans (from the council) and last, but perhaps most interesting, one on local transport from the consumer side: Andy Williams from Astra Zenica discussing how their staff will get to and from work.

Friday, 24 November 2017

Energy performance for windows

A proportion of heat loss from our homes escapes through our windows - this is often quoted as 25% but it could be even more if the rest of the house is well insulated. How do you know when you buy a window that it is energy efficient? There is a rating scheme in common use, defined by the BFRC (British Fenestration Rating Council) and it combines several performance factors. Somewhere like the Green Building Store, that really cares about efficiency,  specifies each factor separately. You may not want the same kind of window everywhere, depending on the direction the window is facing and how much it is shaded.

The BFRC certificates look similar to EU energy certificates for TVs, fridges and such like, even though they are nothing to do with the EU.  The rating scheme (which goes up to A++) is based on a combination of three performance factors:
  • Conductive heat loss i.e. window U-value
  • Thermal transmittance, a measure of how much of the sun's heat energy will pass through as solar gain (this is different from transmittance of visible light).
  • Air tightness.

Unfortunately they do not publish the details of how these measures are combined to give a rating. (All the EU standards are described in detail on the Eur Lex website.)

Saturday, 4 November 2017

How is a thermal store different from a hot water tank?

People often ask if they can use heat from their solar panels for heating as well as hot water. The short answer is no, because the solar panels heat your hot water tank which supplies hot water to your taps, not your radiators. The long answer is you could, if you installed a thermal store instead of a hot water tank, though this may or may not be a good idea. A thermal store is also a big tank of water it works in a different way so it can be used for space heating as well as hot water. Thermal stores can be useful in various situations:
  • You can combine heat from different sources, e.g. solar panels or a wood stove as well as your boiler
  • You can store heat to optimise use of your heating system - for example if it is inefficient to turn on and off according to demand (particularly useful for log burners but also for other biomass boilers or even heat pumps).
  • It can store heat when power is cheap for use when it is expensive. For example, using a thermal store you can avoid running your heat pump at peak times and get a cheaper tariff (at least you will when we all have smart meters and time of use tariffs are available).
The size you need depends on what you want to do with it.