Monitoring on-site renewable requirements

The Merton rule is old hat and even ‘Merton plus’ is becoming yesterday’s solution.  Planning requirements that are intended to reduce the carbon emissions of a development need to begin with the energy hierarchy, prioritising decentralised energy before insisting on 10-25% reductions from on-site renewable energy installations.  If the policy does not allow for flexibility with the on-site renewable contribution it could reduce the overall CO2 savings.  Nevertheless, authorities still have Merton-type policies – and considering the time it takes to change planning policies, they may be with us for some time.

LB Westminster planners hosted an event on monitoring renewable energy planning policies in late July.  Two ex-Merton officers, Adrian Hewitt and Ed Cotterill, presented an automated energy monitoring system that they have developed.  Here’s how it works:  There’s a data logging box installed on-site that measures the productivity of renewable energy installations.  This information is automatically sent off to a network.  A planning officer or developer can log-in to the network and see how the renewable energy installation is doing.  Planners or monitoring officers could keep track of compliance with the carbon reduction policies for all developments that had on-site technologies.  As you might expect, this recently developed technology has exposed some underperforming energy installations. 

It’s obvious if you think about it.  Calculations are done using estimates and a technology is approved by the planning service (this is not a clean-cut process).  A building is then fitted with PV panels or a wind turbine and the job is done.  But what if the PV panel wasn’t properly connected or the wind hardly blows in that area?

That’s exactly what LB Merton found when they used this new monitoring technology.  One development had PV panels that were not installed correctly (a simple issue of wiring) and they had produced zero electricity over two years.  There were several examples of wind turbines that hadn’t produced enough electricity to offset the carbon emitted to create them.  The technology shows the authority that their requirements aren’t being met and therefore the developer, owner or occupier (I’m not sure which) should be required to make adjustments.  How authorities would force them to comply could be tricky and I don’t know how it would work in practice.  On top of that, the technology isn’t free to use.  Hewitt quoted £1000 to fit the data logger in a development and £10,000 per year for a council to use the service.  There is potential to fund this annual subscription through S106 agreements.  But would this add an additional ‘sustainability’ cost on developments and potentially make them unviable?  How else can we accurately monitor on-site renewables?

I suggested that perhaps these initial findings show that the Merton rule isn’t the ideal planning policy to reduce emissions.  If we require energy efficiency and connection to district heating (or contributions to set one up) then we’ll probably end up with a higher carbon reduction overall and less tricky on-site jobs to monitor.  There was mixed support for this idea in the room, perhaps because most planners were from London and therefore they’re already using the energy hierarchy in the London Plan.  I know that this isn’t the case across the country.

The major advantage of this technology is that it starts to develop an evidence base of what works in the area.  Once you have data to show that wind turbines don’t work in Merton, for example, you can strongly discourage their use.  It would also help monitor carbon reductions in the borough or on council buildings, which would be useful for national indicator 185 and 186, as well as the Annual Monitoring Report.  And if councils shared the data we would get a picture of the most successful technologies across varying geographical settings.


If this doesn’t kick off with great popularity and we don’t get the data, the Energy Saving Trust have commissioned field studies for different technologies and published reports.  The reports allow anyone to see the factors that make certain renewable technologies less productive in practice than the lab estimates originally tell you.  Here’s an example: EST report of a field trial done for domestic wind turbines

A report was done by London South Bank University on Monitoring the London Plan Energy Policies (Dec 2009) that provides evidence showing why increased priority for decentralised systems provided better carbon reductions than on-site policies alone.  Unfortunately, not every authority can get a university to monitor its policies.


One thought on “Monitoring on-site renewable requirements

  1. Having worked for developers and councils (including with Ed at Merton) I can tell you that the Merton Rule and other prescriptive on site renewables targets are one of the biggest things I see making carbon reductions come at a higher price than they need to be.

    Take the example of a 10% on-site renewable energy target. You can choose to reduce the amount of renewables required to meet that target by increasing the energy efficiency of the development. But for each 10% you reduce the development’s emissions by, you only knock 1% of the renewables target. That means that a developer will only be prepared to spend 10% as much on energy efficiency as they will on renewables.

    I’m all for monitoring of renewables. If we don’t know what works in the real world then how are predictions ever going to improve? However there is a question over whether there is any grounds for punishing developers / consultants for any shortfall. Estimates can only be made based on averages, in the same way that SAP is based on standard occupancy. It wouldn’t be fair to punish a developer for the energy consumption of the home-buyers. Equally it wouldn’t be fair to punish them for a particularly overcast year, or for an unexpectedly poor wind resource.

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