Thursday, 25 May 2017

Do modern homes overheat more than older ones?

Modern homes have a reputation for overheating more than old ones partly because they tend to be more airtight and partly because they are often more lightweight constructions that heat up quickly. However, overheating is not an inevitable consequence. For example features such as green roofs and external window shades can make a huge difference – but apparently ‘people are resistant to changes to the aesthetic of the homes and other buildings they occupy’ and these features ‘may be resisted by house buyers’ – so builders won’t build them [1]. Is it all our own fault then?

Saturday, 13 May 2017

Should chicken be taxed higher than beef?

Meat production on farms is responsible for a sizable proportion of our greenhouse gas emissions - both directly from the animals and from producing the feed. Eating less meat is good for us in other ways too, and most of us eat much more than we need. But how to change our habits? One way is to tax meat consumption. How much should such taxes be? A comment piece by Simon Fairlie in the Guardian [1] references two conflicting sources. One, from Oxford University suggests 40% on beef and 8.5% on chicken [2]. The other, from Sweden's University of Agriculture, suggests 40% on chicken and only 28% on beef [3]. This was a surprise - I have always understood beef was much worse than chicken because cattle (and sheep) belch methane. Putting a cash value on environmental impacts is never easy but how can there by such widely differing estimates for similar products?

Monday, 1 May 2017

How much can we reduce heating demand, realistically?

Around 40% of our energy use is for heating in buildings, both space and water heating, and a large proportion of this is fuelled by gas with associated carbon emissions. We can reduce this either by switching fuel or by reducing demand or both. According to Zero Carbon Britain (ZCB) it is feasible to reduce the demand for domestic heating by 60%. However the Committee on Climate Change disagrees - they have assumed 17% in their scenarios. Which is right? Also, how much progress have we made so far?

Tuesday, 18 April 2017

5 year carbon savings advice review: changes

Five years ago I devised some 'carbon saving' cards to engage people at event stalls, with ideas like 'Switch your TV off when you are not watching', 'Run the dishwasher only when it full', 'Draught strip a leaky front door', 'Eat a vegan meal once a week', 'Keep your phone for 3 years before replacing it'. As I am doing a similar stall this Saturday (at the Earth Optimism Solutions Fair) I decided to review the cards - and found big changes to carbon savings from some of the activities. Should the advice we give change too?

The cards that have changed are mainly to do with electrical or electronic appliances and the emissions have changed for several reasons.

Friday, 7 April 2017

Think energy savings - think water savings too.

I have long been concerned about energy and climate change but recently I have been thinking about water too. There are a lot of similarities - in supply limitations, environmental impacts, and the fact that they are essentials for life but (for us in the developed world) extraordinarily cheap. The principles for water saving are the same as for energy too. If you have concerns about energy and climate change you should be thinking about water too.

Wednesday, 5 April 2017

Extra costs for Endurance wind turbine owners

This wind turbine was installed in May last year on a small sheep farm in Wales. It is an Endurance X35Q - quite small (180 kW) and very quiet. Six months later the manufacturer went out of business due to the cuts in the Feed in Tariff for small renewables [1]. There are about 900 Endurance wind turbines in the UK, mostly on farms. With luck they will continue to operate for many years as local service companies are collaborating on maintaining stocks of spare parts. However, it is still bad news for many turbine owners as warranties from Endurance are now invalid and they will have to take out new insurance or take the risk on themselves [2][3].

This Endurance wind turbine was installed in May last year. The manufacturer is now bankrupt.
This photo was taken by my nephew Mark Burchell

Tuesday, 21 March 2017

How well are my new inverters doing?

We installed our PV panels in 2011 and last year we upgraded the inverter system, installing SolarEdge equipment. We were promised better yields, but are we getting them? In this post I show how I have estimated the improvement, correlating yield with the old system with weather data from the MET office and using this to predict what we would have got recently if we had not upgraded. The prediction function I derived was 98% accurate, which I was very pleased with. Using this I have estimated the improvement to be 4.6% but we don't have a whole year with the new inverters and I think this is probably an underestimate.