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Should the RHI aim to raise performance of renewable heat technologies?

Posted by Cathy Debenham on 30 October 2012 at 8:58 am

If the renewable heat incentive (RHI) is to meet its stated goals of generating more energy from renewable sources and reducing carbon emissions, it is important that the installations subsidised by it are efficient and high performing. This requires good design and installation and owners who know how to get the best out of their system.

Field trials carried out by the Energy Saving Trust on heat pumps and solar thermal found that this wasn't the case in many of the installations included in the trials. Since the heat pump trial, the MCS standards for installers has been extensively revised. Early figures from the renewable heat premium payment scheme (RHPP)  indicate that there has been a modest improvement - although it's likely that the results will still be a long way off the high performing systems that are consistently measured in Germany.

To ensure value for money both for tax payers who fund the incentive and for people who invest in renewable heat systems DECC is consulting on whether a range of measures would be effective in delivering continual improvements in the performance of renewable heat installations in the UK. Whether any, all or a combination of some of them are included will depend on responses to the consultation.

1. Additional financial support for systems that are metered and monitored

People would be offered extra financial support (an enhanced tariff or bonus payment) if they agreed to their system being monitored and metered at a higher level than generally required by the scheme. This would only be open to a limited number of installations to control costs.

One benefit would be that it will enable the householder, installer (and manufacturer) to identify lower than expected performance and do something about it.

The extra financial support would be paid whatever the measured efficiency of the system, on the assumption that if performance is lower than expected, the owner, installer and manufacturer will take action.

2. Linking the tariff level for heat pumps to the SPF measured in the metering programme

This proposal would operate in addition to the one above, using seasonal performance factors (SPF) based on in-situ performance (rather than factory trials). It would only apply to those systems metered and monitored under option one. It would pay a higher tariff rate, the higher the SPF. On the one hand, this would introduce an element of risk for consumers - if their system performed worse than predicted, the return would be lower. On the other, it is a strong incentive to installers not to over-claim for their products.

3. Introducing a higher seasonal performance factor (SPF) for heat pumps as an eligibility requirement for the RHI

The EU has set a minimum performance level for heat heat pumps to be classified as renewable. This is currently 2.5. It means that when performance is averaged across the whole year, you must get 2.5 units of heat for each unit of electricity used.

DECC is asking whether it should require a higher SPF for heat pumps to be eligible for the RHI. Many manufacturers claim higher SPFs for their products. Germany is currently running a heat pump stimulus programme that requires SPFs of 3.5 for air source heat pumps and 3.8 for ground source heat pumps.

DECC wants is seeking views on what might be a suitable SPF figure, and on whether the minimum standard should rise steadily over time as the market develops in the UK.

4. Enhanced monitoring of installations for evaluation

The aim of this proposal is twofold: for DECC to have access to good evidence on what renewable heat is being generated, and what carbon savings are made; and to increase consumer confidence in installers.

All domestic installations  of heat pumps, biomass boilers and solar thermal would have to be installed 'meter ready' (this is currently already the case for the second phase of the RHPP scheme), so that if that installation was chosen for the metering programme, the team would have access to the pipework, and the system wouldn't have to be drained down.

The idea is to make sure that at least one installation from each active MCS installer is metered and meets the appropriate standard. DECC is also consulting on what would be an appropriate penalty for consumers who don't make their installation 'meter ready'. It is suggests either a 20% cut in the RHI rate, or losing the first year's payment.

Do let us know what you think about these proposals. I have an opportunity to make your thoughts heard as I am speaking at the Westminster Forum on the domestic RHI in November.

You can download the full consultation document and respond to the consultation here.

Photo by Brenda Clarke


If you have a question about anything in the above blog, please ask it in the comments section below.

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3 comments - read them below or add one


albaComment left on: 1 November 2012 at 10:26 am

I think its all well and good putting in an efficient system but I think people are all trying to save money in the long run, I have done a few quick calculations for this based on a heat pump of 2.5 SPF;

Cost of electricity/kWh= 16p/kWh

So for a heat pump of 2.5SPF=   6.4p/kwh

This is very similar to the cost of oil and with rising electricity costs you could end up putting in a system that might pay back to zero net benefit over the term of the RHI then be left with a heating system that is more expensive to run than the one you took out, or am I missing something here? 

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ChrisDavis from Comment left on: 31 October 2012 at 10:19 pm

Bob, heat pumps are all tested to a European standard for their performance and efficiency and have to meet a minimum standard to be classified under MCS.

As one of the You Gen Energy Experts on heat pumps, I'm very keen to see the RHI tariff reward better performing systems, indeed it is crucial for the success of the scheme that it does so. 

One area that needs to be remembered is with heat pump systems, owners will not only have to purchase a good quality heat pump, but also have to invest more in their heat distribution system to achieve higher levels of efficiency (or SPF as mentioned by Cathy above).  By this I mean ensure that radiators are either sized correctly to allow the heat pump to operate at lower water temperatures, or alternatively consider installing fan assisted radiators.

The improvements that can be made through reducing the flow temperatures are already well documented in the Heat Emitter Guide and linked to a Temperature Star Rating that must be declared to the homeowner by the installer at the point of sale under the requirements of MCS.

I would like to see the RHI tariff linked to this Star Rating, both to recognise and cover the extra costs that homeowners wishing to install a more efficient system will incur, but also to reward them at a higher rate of return for doing so.  So for instance, you might be able to get a very basic tariff for just installing a heat pump that meets the minimum SPF requirement of 2.5, but the tariff would be much higher if I design and install a system to perform more efficiently than this.  Because I can use the Star Rating system which is required under MCS, potentially this means there is no need for complex and costly metering.

Going back to the point raised by Bob however, while there is a minimum performance standard that heat pumps must achieve to be MCS approved, this is not currently aligned with the requirements under RHI for a minimum SPF of 2.5. Ie, just because a product is MCS approved, it does not mean it will automatically deliver the efficiency levels that RHI is asking for. The MCS product performance standard therefore will need to be improved to ensure that any MCS approved product would be capable of achieving the efficiency levels required by RHI.

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Bob Irving

Bob IrvingComment left on: 31 October 2012 at 11:17 am

I agree with principle of these points, but only one of them provides an incentive to improve the actual performance of h-p's pre-installation. In choosing a system, surely authoritative information is important. As yet, I don't think we have any standard testing of h-p's in the UK, as per SEDBUK. Shouldn't this be provided so that choice is clearer?

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