Thursday, 27 January 2011

Ground Source Heat Pump @ One New Change

'One New Change', the shopping mall located adjacent to St Paul's Cathedral, opened its doors in October. Yesterday the Energy and Climate Change minister Greg Barker 'flipped the switch' to activate Europe's biggest ground source heat pump, expected to deliver between 15 and 20% of the sites energy demand. Designers had been set the task of delivering at least 10% of energy from 'renewable or low carbon' sources, so this, they claim, more than satisfies that figure. The system comprises over 60km of pipes over 150m deep into the ground.

All this sounds good right? Ground source heat pumps, Europe's biggest, must be clean as a whistle. Well hold on a second - ground source heat pumps are neither 'renewable' or 'low carbon'.

Ground source heat pumps work by pumping a refrigerant around pipework in the ground, collecting the heat from the ground (which, at just a few metres below ground level, is a constant temperature of around 12 degrees). This is then compressed, heating up the refrigerant, and passes the heat to water for useful space heating. The refrigerant is then expanded, and sent through the loop again.

'Pumping', 'compressing' and 'expanding' are not processes that occur without energy input. And in the case of GSHPs, this energy is sourced from that big dirty rock, coal. The coefficient of performance (COP) of a typical GSHP is around 3-4, meaning that for every 1 unit of electricity used, 3-4 units is obtained. Free energy no?!

No. If instead of installing this pink elephant, natural gas had been used to provide this 15-20% of demand, then there would have been very little difference in carbon emissions. This is because the process of burning coal is around 3-4 times 'dirtier' than burning gas. Heat pumps are best used in places off the grid, such as in rural areas. The only way this technology would reduce carbon emissions is if the electricity used for all this pumping, compressing and expanding was sourced from renewables - maybe used in conjunction with roof mounted PV panels (although we haven't studied the feasbility).

In our view, it is disappointing that this 'flagship scheme' should be allowed to shirk its environmental responsibilities in this manner. Once again, used in conjunction with a decarbonised grid, the system would be fantastic, multiplying renewable energy by 3 or 4 times - however, quietly using coal to power this beast and passing it off as low-carbon is an embarrassment to the sustainability credentials of our world city.

Anthony J.

Monday, 17 January 2011

Electric Vehicles - their time to shine?

In between all of the cuts the new government has been making (with the jury still out on Feed-In Tariffs), one promise which has survived is the £5,000 subsidy offered to buyers of electric vehicles, which was ratified in July last year and implemented in January this year. A list has been produced of all the eligible vehicles – noticeably absent is the Tesla Roadster, although even with a £5k discount this would be beyond the reaches of most!

So the government is directly pushing the purchase of electric vehicles. But how do they stand up to their gas-guzzling cousins? Here we assess their sustainability, from the triple-bottom line of Economy, Environment and Society.


A £5k government subsidy on each vehicle appears generous (although only 9 models are eligible, 6 are yet to be released, and of the three that are, 2 are currently only available for hire). So, the one remaining qualifying car that you can buy today - the Mitsubishi i-MiEV - is advertised as £24,000 after the subsidy. The Nissan Leaf, to be released in March, is the same post-subsidy price. 

Cost of driving the car will be cheaper. The cars will be exempt from tax. Professor David MacKay suggests that an electric car can do 62.5m (100km) on 21kWh electricity - at 10p/kWh, this works out at £2.10, or 3.4pence/mile. The AA suggest that for a petrol car in the equivalent price range, 15.77p/mile is more likely. If the car is used every weekday for 48 weeks for a roundtrip of 60miles to and from work, then the owner would save approximately £1,780/year on fuel costs.


The whole point of these electric vehicles are that they are more environmentally friendly than traditional vehicles. However, it should not be thought that they are zero-carbon, or zero-emission. They have no emissions at end-use, yet, in all likelihood, fuels have been burnt to produce the electricity from which it runs. The cars can only claim to be zero-emission (in operation) if the electricity has been produced from renewable sources (although this simplistic model ignores the impact of life-cycle emissions).

So, there are emissions associated with electric vehicles. But how much? Again, to MacKay - "21kWh per 100 km is equivalent to 105 g CO2 per km, assuming that electricity has a footprint of 500g CO2 per kWh."

Car pages suggest that the average emissions per kilometre figure for new cars is 164gCO2/km. Therefore, electric vehicles emit around 33% less carbon than standard vehicles. But there is more - as electric vehicles will be charged overnight, the efficiency of power plants will increase as demand is increased in period of lull. Further, as decarbonisation of the grid occurs, this figure will decrease, suggesting that electric car owners could travel with no footprint only if they procured their electricity from non-carbon sources. The number of energy companies offering this tariff is increasing all the time.

Of course, energy is still needed to manufacture the car. Boundaries permitting, the only carbon neutral way to travel is by walking (although emissions are released through the manufacture of your shoes - yes I know its becoming a nightmare!)


So the electric cars are expensive, yet cheaper to run and produce less carbon emissions. But would society benefit from their take up? Well, some have voiced concern over the noise of the car - i.e. there isn't any. This could have an impact of children (and adults like myself) who consider all streets to be safe and don't look when they cross the road. I would like to see a study on this if anyone has one! Further, the best electric vehicles can only travel 100km after an 8 hour charge - pretty inflexible, and only really good for short journeys day to day.

But - obviously an increased take-up of electric cars could have benefits elsewhere. It could help people change their other carbon-intensive habits, and persuade them to cut their footprint. Electric cars could lead to greener lifestyles.


The jury is out on electric cars. They are no doubt the future of motoring, although it will be a while before we see standard vehicles made obselete. Like I mentioned in my last post, decarbonising the grid is essential, and will only aid in the environmental benefits of electric vehicles. For now, even with the reduced price, electric vehicles are prohibitively expensive, and for a current 33% improvement on carbon emissions, difficult to justify. But, like all advances in technology, prices will come down and performance will increase. Watch this space (but not whilst waiting - subsidies in Spain last year led to only 200 electric cars being sold out of a predicted 20,000!)

Anthony J.

Wednesday, 12 January 2011

Potential for super-efficient wind turbines in the UK

Much is being made of the new Skystream 600 wind turbine recently unveiled at the Consumer Electronics Show (CES) in Las Vegas. Manufacturers claim it produces 74% more energy than its predecessor the Skystream 3.7, and could provide around 7400kWh of electricity at 12mph wind speed, around 60% of the average demand of an American home. The turbine is horizontal axis and floor mounted.

This turbine performs 3 times better than the most productive in the Warwick wind trials, however will still be subject to similar limitations. Results of these trials conclude that domestic wind turbines 'would make a tangible contribution to energy and carbon saving only on the most exposed sites'.

At present, 90% of the UK's population reside in urban areas. This a larger proportion than in the US (82%), Spain (77%), Portugal (61%), China (45%) and Sweden (85%). In fact, after Belgium, we are the most urbanised state in the EU.

The cut in speed of most wind turbines is between 7-10mph. Wind speed in urban areas rarely reaches more than 10mph, much less 12mph. Actually, less than 1% of the UK's land has an average windspeed of more than 10mph.

Domestic wind turbines may have a role to play in reducing carbon emissions for some countries, especially large rural populations in developed countries, such as in the American midwest - in the UK however, the electricity generated by even the most efficient and productive wind turbine will be negligible for the majority of the population, and will rarely produce the level of savings needed to satisfy planning conditions for new residential developments. Offshore wind has a much larger potential for carbon reductions - in fact, many argue that concentrating on decarbonising the grid is of much more use than sticking energy producing gadgets on houses.

Monday, 10 January 2011

Tree-inspired Eco apartments in Mexico

This beautiful apartment block, designed by Taller 13 and built in Mexico City, is both environmentally and aesthetically pleasing. The design was created to mimic the the trees of the neighbourhood, inspired by both their form and their resistance to seismic activity.

The apartment building includes seven units with split levels and views of both the street and the quiet interior courtyard. Each apartment is properly isolated from the others with strawbales to improve insulation as well as sound barriers – you won’t hear crying babies here! Hot water is heated by a solar water system, rainwater is collected from the roof and waste is managed through a recycling program. On top of all that, non-toxic paint and certified wood were used, and there are terraces all throughout the building that allow residents to grow their own food.

Structurally, the building is designed to withstand seismic activity and its skeletal structure optimizes the use of materials (besides just looking plain cool). The form of the concrete beams and framing was inspired by the beautiful, shady trees of the neighborhood. On the roof, a large bamboo structure has been built in order to create a large living shade installation once the plants start growing over it.

Anthony J.

Adapted from INHABITAT

Sunday, 9 January 2011

Hello World

Hi everyone, and welcome to our blog. We intend to post opinion pieces about all aspects of sustainable design, including energy efficient design of buildings and environmentally-concious design of interiors.

Anthony is a sustainable design consultant at Phlorum Ltd, an environmental consultancy in Falmer. He specialises in helping architects design to achieve targets in Code for Sustainable Homes, passivhaus and BREEAM, as well as energy assessment and renewable energy feasibility studies.

Katherine is a student of interior design - her interests lie in the restoration of antique and vintage furniture to satisfy more modern needs, giving old products a new purpose.

Thanks for reading, we hope our blog is interesting and insightful, provokes discussion and gives a passionate yet informed view on sustainability in the built environment.

Anthony J.