In this edition:

GreenTalk – ‘radical’, ‘inspiring’ and short!

When is PV on churches a good deal?

8 habits of highly effective carbon reduction in schools.

Farm renewables: Beware white elephants and expensive mistakes.

Policy: Greener leaner development in urban areas.

Comment: Are government proposals to raise the motorway speed limit a ploy to addressing flagging sales of petrol and diesel?

And is the Code for Sustainable Homes a creaking door?

Plus staff and other news.

As September segued into June and another UK temperature record fell the Transport Secretary Philip Hammond announced plans to consult on raising the motorway speed limit from 70 to 80mph.

The announcement coincides with government figures showing a slump in sales of petrol and diesel which according to the AA has deprived the Treasury of almost £1bn in fuel duty over the first six months of the year (1).

Increasing the limit by 10mph means that given an empty stretch of motorway, you could shave very nearly eleven minutes off a 100 mile journey (2). The Government thinks this will bring ‘huge economic benefits’ and ‘hundreds of millions’ of pounds to the economy. But don’t start planning how you’ll use all that free time just yet.

Contrary to what might be expected a higher speed limit is more likely to increase congestion and journey times than reduce them.

As speed increases so too do the typical (safe) stopping distances between vehicles (3). This reduces the number of cars you can slot into any stretch of road. Move up from 70mph to 80mph and it drops from 16 cars per mile (4) (of motorway lane) to 13 (and just 6.5 when wet and stopping distances double). That may not sound much but that’s 300 fewer cars per 100 miles of motorway lane on a dry day which adds about another mile (5) of tailback leading to more not less congestion.

Then there is safety. We can expect a big dust-up between the petrol heads and road safety campaigners on this one. But whatever the arguments about improvements in vehicle design, there’s some basic physics which may be a bit dry, but can’t be ignored.

The energy of a moving vehicle increases in proportion to the square of its speed. This means that a one tonne car travelling at 80mph has 35% more kinetic energy than one travelling at 70mph (6). So what? In energy terms that’s equivalent to dumping 350kg (7) of cement in back of the car and driving at 70.

That’s a lot of extra energy to get rid of in the event of a crash.

Given that people’s reaction times don’t speed-up as you go faster, it will be interesting to hear the views of the NHS and emergency services on a higher speed limit as they will be ones picking up the pieces, and the cost of any reduction in safety. The Department for Transport certainly used to think that speed was a significant risk factor in road safety. Why else install speed cameras and run TV adverts reminding us that ‘Speed Kills’?

So what’s behind this proposal? The real reason may be to do with fuel consumption, and another dry but revealing characteristic of moving vehicles.

The power required by a car on a motorway is roughly proportional to the cube of its speed. What this means in practice is that at 70mph a typical car requires about 80kW of power to push it along. At 80mph this increases one and half times to 120kW (8) of power. (That’s the same power requirement as 120 one bar electric fires turned on at the same time, or 1200 incandescent 100W light bulbs). More power means more energy consumption per hour (see footnote (9) for just how much) and more fuel consumption.

So raise the speed limit for the fleet of cars and motorcycles in England and Wales and at a stroke you dramatically increase the amount of fuel consumed. Of course officials in the Department for Transport (at least in Scotland), know this. There you’ll find signs on the motorway encouraging drivers to slow down to 60mph to save fuel which indeed it does by more than halving the power required to drive at 80mph (10).

So it’s difficult to escape the conclusion that this is simply a ploy to put more money in the Treasury’s coffers by getting us to buy more fuel.

Aside from the fact that it is likely to achieve very little of positive benefit, it drives a Chelsea Tractor through the Government’s claim to want to be the greenest ever and to be serious about responding to climate change. Will the emission increases from higher fuel consumption be met by reductions elsewhere in the economy? If so from where? And does this indicate a shift in policy so that action on climate change is no-longer a priority and government departments such as the DfT may now treat this as optional?

Climate change is as real as the economic crisis. It requires real solutions that add up, and which cannot be put on hold until the economy is fixed. It is possible to align the solutions to both the financial and climate crisis, thereby cutting emissions, improving our energy security, saving money and creating new jobs. Raising the speed limit does none of these. Insulating the nation’s homes so they are fit for purpose, rebuilding our energy infrastructure to name but two, could.

At a time when the pain of government cuts is being felt across the country it is galling to see time, effort and money being diverted into a flawed consultation.

© Climate Works Ltd, October 2011.

Footnotes and sources

(1) Source: http://www.channel4.com/news/cash-­‐strapped-­‐drivers-­‐cut-­‐petrol-­‐use-­‐by-­‐15-­‐per-­‐cent

(2) Time = distance/speed

So at 70mph time = 100/70 = 1.43 hours = 85.8mins

And at 80mph time = 100/80 = 1.25 hours = 75mins

Difference = 10.8mins

(3) Safe stopping distance at 60mph (dry) = 73m

And at 70mph (dry) = 96m

Source: Direct gov – The Highway Code. http://www.direct.gov.uk/en/TravelAndTransport/Highwaycode/DG_070304

Estimated stopping distance at 80mph = 400ft = 122m

Source: Various sources. Consensus seems to be that typical (dry) stopping distance at 80mph is 400ft.

According to the highway code stopping distances are double in wet conditions.

(4) Cars per mile.

Assume length of average car is 4m

At 70mph car plus typical stopping distance is 96m + 4m = 100m

Cars per mile = 1609/100 = 16

At 70mph (wet) car plus typical stopping distance is 192 + 4 = 196m

Cars per mile = 1609/196=8

At 80mph car plus typical stopping distance (dry) is 122m + 4m = 126m

Cars per mile = 1609/126=12.8=13

At 80mph (wet) car plus typical stopping distance is 244m + 4m = 248m

Cars per mile = 1609/248 = 6.5

1 mile = 1609m

Source: Average length of car – Highway Code.

(5) Additional tail back with 80mph speed limit.

Assume average car is 4m in length and average space between cars is 2m.

300 cars require 300 x 6m = 1800m = 1.1miles

(6) Kinetic energy of a moving vehicle = ½mv⌃2

So for a one tonne car moving at 70mph (31 m/s) the kinetic energy of the vehicle is:

1/2 x 1000 x 31 x 31 = 480,500 Joules = 0.13kWh

And at 80mph (36m/s) the kinetic energy is:

1/2 x 1000 x 36 x 36 = 648,000 Joules = 0.18kWh

((648,000-480,500)/480,500) x 100 = 34.86% ≈ 35%

(7) To increase the kinetic energy of a one tonne car travelling at 70mph (31m/s) add 350kg to the mass of the car.

New mass of the car  = (648000/(31 x 31)) x 2 = 1349kg ≈ 1350kg

(8) The power consumed by the engine is estimated to be roughly:

4 x ½ρAv⌃3 where A is the frontal area of the car, v is speed in meters per second and ρ is the density of air (kg per cubic meter).

Assume the frontal area of a typical car to be 1 sq meter and the density of air to be 1.3kg per cubic meter

So at 70mph (31m/s)the sum is:

2 x 1.3 x 1 x 31 x 31 x 31 = 77.5 kW ≈ 80kW

And at 80mph (36m/s) the sum is:

2 x 1.3 x 1 x 36 x 36 x 36 = 121kW ≈ 120kW

And at 60mph (27m/s) the sum is:

2 x 1.3 x 1 x 27 x 27 x 27 = 51kW ≈ 50 kW

Source (equation): Sustainable Energy Without the Hot Air, Cars II, page 256, MacKay, David, J.C.

These calculations ignore rolling resistance which increases the power requirement by about 15% when travelling at constant speed.

(9) How much energy is required to drive 100 miles at 60mph, 70mph and 80mph?

At 60mph it takes 1.67 hours to complete the journey.

At 70mph 1.43 hours and at 80mph 1.25 hours

The energy needed to make the journey is given by the equation: Power x time

So at 60mph the energy = 50kW x 1.67 = 83.5kWh

And at 70mph = 80kW x 1.43 = 114kWh

And at 80mph = 120kW x 1.25 = 150kWh

In each case we ignore rolling resistance which adds about 15% to these figures.

So driving at 80 rather than 70mph adds roughly 36kWh to the energy required to push the air out of the way. But these figures ignore the efficiency of the engine.

If we assume this is 25% then the energy required to push the car along (again ignoring rolling resistance) is:

At 60mph: Energy required = 83.5kWh x (100/25) = 334kWh

At 70mph Energy required = 114kWh x (100/25) = 456kWh

At 80mph Energy required = 150kWh x (100/25) = 600kWh

A one bar (1kW) electric fire will consume 1kWh of energy if running for one hour. So the energy required to complete 100 miles at 80mph is equivalent to running a one bar fire for 600 hours or 600 one bar fires for one hour.

(10) – See footnotes 8 and 9 above.

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The council built a prototype pair of semi-detached dwellings and a terrace of six homes. Following monitoring a further 200 or so homes were built for the council. The prototype homes were monitored through 1980-82 by Salford University Industrial Centre Ltd, and 30 years on have been reassessed to see how the design performs today in terms of energy and maintenance costs and compares with current and proposed building standards.

The Salford houses were constructed within the Government’s cost ‘yardstick’ for social housing applicable at the time. And though a local Housing Association incorporated the design principles into a sheltered housing development and a private developer used it in a small development of houses and flats, the radical changes to housing policy in the 1980′s brought the council’s own programme of house building to a stop despite the obvious benefits of the approach.

From the outside the homes are entirely conventional in their appearance, so much so that for this latest research there were problems establishing which homes were built to the Salford Design.

The real innovations are beneath the brick clad exteriors. In designing the homes Dr John Randell and colleagues of Salford University went back to first principles and basic building physics to come up with a dwelling with very high thermal mass, inside a well insulated envelope which was designed to minimise cold bridges. This they combined with simple mechanically assisted ventilation.

The Salford house is ‘heavy and tight’ in construction, and similar in design approach to other very low energy homes such as those at Hockerton Housing Project and the Autonomous House in Nottingham, designed by architects Robert and Brenda Vale.

Though well insulated the Salford homes are by no-means ‘super-insulated’, with a nominal thickness of 200mm insulation all round (and just 173mm of insulation in the walls). The windows were proprietary, sliding, dual-glazed units made of treated timber. External doors were separated from main living areas by a lobby or hall and draught-stripped.

The key to the benefits of this approach is that unlike conventional brick and block construction which places the heavy materials outside the insulated envelope, in this case the thermal mass is on the inside, wrapped by insulation in the walls, floor and loft.

This provides a thermal buffer or reservoir, absorbing heat from occupants, appliances, and the sun and re-emitting this energy slowly over time. The result is a home which maintains an even day-night and day-to-day temperature and has a very low space heating requirement.

On construction the Salford homes were fitted with only one, and in some cases two, balanced flue gas convector heaters providing between 1.5 and 2.5kW of space heating. Indeed, under normal occupancy levels the homes would be habitable (if not comfortable by today’s standards) without any additional space heating at all. The high thermal mass also makes the homes very resilient to higher average and peak summer temperatures.

Other notable features include the use of orientation to minimize glazing on the North West aspect with increased glazing on the South East aspect and the use of mechanical extraction ventilation in the kitchen, bathroom and toilet.

The recent survey of the Salford houses shows that they continue to perform to specification and use about 75% less energy than the average requirement for space heating in the UK and over 40% less than homes built to the latest 2010 Building Regulations. Given that the performance of the dwellings is on a par with the energy efficiency required for the revised zero carbon standard (due to take effect in 2016), the research team believe that this design approach offers a cost effective and proven route to meeting this standard.

The report reiterates the findings of other research about the importance of occupant behaviour on energy consumption and running costs. In the houses revisited for this study household consumption varied by a factor of five, a spread largely attributed to differences in internal temperatures. What was also clear was that advice and training are essential in helping occupants to understand how to use and get the best from the thermal mass and small heating systems.

Homes which perform on a par with the proposed zero carbon standard and which were constructed using conventional building methods and materials (albeit in a revised configuration), over 30 years ago gives the lie to arguments put forward by parts of the housing sector that it is simply not possible to reach this target within the next five years.

Certainly there are issues to do with the requirements and expectations of housing built for the private sector. The Salford houses where designed for the social rather than private sector and would be unlikely to meet the requirements of the private sector market then or now. But the design principles used in Salford could equally be applied to executive homes in Surrey.

There will also be arguments over the high embodied energy and carbon of ‘heavy and tight’ homes, which can score less well under the Code for Sustainable Homes than ‘light and tight’ homes. Despite a preference in many parts of the industry for lighter construction methods, the embodied energy of ‘heavy and tight’ dwellings tends to be a small part of the lifetime carbon costs, particularly if heated and cooled passively, and can be partially addressed in other ways.

Perhaps the biggest lesson from the Salford study is that achieving homes with very low energy and running costs needs to be approached from first principles. Thermal mass, insulation and simple ventilation systems will never be a sexy as renewable energy, phase change materials and the latest boiler energy management system. But as this research shows, thirty years after they were constructed they still work.

Further information:

Click here to view ‘The Salford low-energy house: learning from our past’.

CWL’s course Towards Zero Carbon Development, is a one and two day course covering the principles and practice of very low energy and low carbon design incorporating the design principles used in Salford. Click here for further information about the course, or contact Mark Letcher on 0117 902 0697.

Posted by Climate Works Ltd 6th July 2011.

©Richard Dunne June 2011

When the curtain did go up just after 6.30pm, over 170 people filled Arnolfini in Bristol to hear talks from eleven of the UK’s leading practitioners and thinkers on climate change, food and energy security and the natural world.

With the spotlight on responses and solutions rather than barriers and problems, speakers engaged the audience with series of lively, challenging and at times moving presentations. And with the longest talk lasting less than 12 minutes GreenTalk presented some big ideas in a short format.

The talks, variously described by members of the audience as ‘inspirational’, ‘revolutionary’, and ‘brilliant’ are now being edited and will be made available on-line via the GreenTalk website.

GreenTalk was organised and produced by Climate Works Ltd in collaboration with Bristol’s Green Capital Partnership, as part of Good Living Week. The project received financial support from The Design Programme, Environmental iNet and the Creative Industries iNet.

Image taken from Richard Dunne’s GreenTalk ‘Lessons from Antarctica’, ©Richard Dunne, Ashley Primary School, June 2011.

Posted: Mark Letcher, Climate Works Ltd.

Enquiries: Mark Letcher, Climate Works Ltd, mark.letcher@climate-works.co.uk

Thanks to the efforts of one of our interns Rob Dixon, knowing exactly what we are emitting will be a lot easier from here on. Electricity consumption from our use of computers, printers and appliances is now monitored using simple plug-in consumption monitors. And using Filemaker Pro Rob has created a database which we now us to track our energy consumption (including lighting), transport emissions and use of paper.

We are testing the beta version right now with a plan to make the database (which is cross platform) available as a free and open source application for use by other businesses, in due course.

And for those difficult to reach transport emissions there is a version which runs on an iPhone.

FFI please contact office@climate-works.co.uk.

Climate Works Ltd

12th May 2011

GreenTalk is bringing together  the leading thinkers and doers from Bristol, the South West and the UK on climate change, energy security and the natural world, to talk about the challenges, solutions and responses to these issues.

The programme includes:

Dan Weisselberg – Bristol Green Doors, ‘Can a neighbour really inspire me to green my home?’

Hannah Smith – Climate Outreach and Information Network, ‘Do ‘Climate Refugees’ exist? Dispelling some key myths around climate change and migration’.

Adrian Campbell – Low2No, ‘Sustainability: reality bites’.

Dr Tim Chatterton – UWE, Bristol, ‘Changing behaviour: changing society’.

Alice Ferguson and Amy Rose – Playing Out ‘Reclaiming Streets for play’.

Plus:

Arthur Potts Dawson – The Peoples’ Supermarket

John Gapper - Brighton and Hove, District Council

The event will be filmed and talks will be available on-line (following the event).

Tickets: £7, and £5 (concessions) available from here

Venue: Arnolfini, 16 Narrow Quay, Bristol, BS1 4QA. Click here for a map

Date & Time: 14th June, 6.30pm-8.45pm – please be seated by 6.20pm.

Click here for further information.

But when the Tobacco Factory Arts Trust, wanted to generate a proportion of the electricity used in the theatre housed on the second floor one existing feature came to the for.

Like many buildings of its era the Tobacco factory was built with a series of parallel ‘saw-tooth’ roofs with windows running along the north facing slopes. These ‘north lights’ were designed to give an even, year round light in the laboratories below. They also provided ideal south facing slopes on which to install PV panels.

The Tobacco Factory PV system

Climate Works Ltd was approached to investigate how these might be best used, and how much electricity a PV system could generate as well as the financial and carbon savings it might achieve. Using a system model developed in-house we were able to assess the potential yield, cost, and electricity and carbon savings from a PV system. And to assist with an application for funding under the last round of the Low Carbon Buildings Programme.

The result? – a 22.5kW PV system which was officially switched on at the start of this month. How much will it produce? The estimate is around 19,000kWh per annum, (around 1/3 of the electricity consumption of the theatre) but so far it is running ahead of the estimates most likely due to the bright spring (combined with cool air temperatures).

For the theatre the roof is one part of their broader carbon saving programme, as well as great PR. But it is also insurance against the rising cost of energy now and in the future.

For advice and information about the use of renewables and energy efficiency measures in your building please contact Mark Letcher or Liz Vosper on 0117 902 0697.

Climate Works Ltd 15th April 2011.

We are looking for a bright, enthusiastic graduate for a 3 month internship. You will help us develop new work areas and deliver a high profile project with a global reach.

For a job description please e-mail liz.vosper@climate-works.co.uk with the subject line Internship. Deadline for applications (by CV) 5.00pm 18th February 2011.

Despite high expectations amongst developed countries that carbon markets will cut emissions, interviewed in today’s Independent, Hansen is scathing. Though government representatives all say they will bring down emissions using carbon markets, ‘you can prove that this is horseshit because they’re building more coal plants’.

Cap and Trade schemes operate by imposing an overall cap on emissions, which is reduced incrementally. Members which could be countries, organizations or individuals, trade emissions within the cap and can purchase emission allowances from other members who don’t require or use their full emissions quota.

It’s a system designed to stimulate investment in carbon reduction by increasing the price of carbon emissions year on year, as the cap tightens. But to work it requires the cap to be set tight enough so the price of carbon stimulates investment in clean alternatives, and for governments to hold their nerve and maintain the cap. It also requires a transparent means of trading emission credits and a way of monitoring and regulating the system to make sure members don’t cheat. Despite the faith of western governments there is increasing concern that supposed reductions in emissions using Cap and Trade are illusory.

What Hansen proposes is a framework built around the introduction of a carbon tax in both the US and China. Under his proposal all of the revenue from a carbon tax is returned in equal amounts to citizens so that those with lower carbon footprints are likely to be better off.

But why should China that has refused a cap outright impose a carbon tax? Hansen argues that China is well aware of its vulnerability to the direct impacts of climate change and needs to deal with existing problems to do with air and water pollution. Having invested in carbon-free energy and become the leading producer of solar, wind and nuclear they need to put a price on carbon so that clean energy can take over from fossil fuels.

With Cap and Trade legislation effectively dead in the water in the US with a new Republican Dominated House of Representatives there is no doubt about the need for fresh thinking on this issue. Hansen is using his expertise and reputation to persuade governments that it should become a reality.

Tags: Cap and Trade, carbon taxes, carbon policy, Goddard Institute