How to get the most from the RHI

2 September 2014
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2 September 2014, Comments: 0

After five long years of waiting, the domestic RHI scheme finally launched this year. Details of tariffs and links to more information can be found on our Incentives page but what follows is a brief description of the essentials and also a few pointers on how to get the most out of the scheme.

Part of the eligibility criteria for the scheme is that you have a Green Deal Assessment done (or just an EPC for self builders) and the reasoning for this is to ensure that your building meets a minimum standard in terms of energy efficiency and also so that an independent figure can be produced for the amount of energy you will need to heat your building each year. The minimum efficiency standards are 250mm of loft insulation and cavity walls filled (if viable). It makes sense to ensure that you meet this minimum standard before you get an assessor in so as to avoid having to get a second assessment done once the insulation is in place. The annual energy usage figure is plucked from page 4 of your EPC (included in the Green Deal Assessment) and this figure, combined with your system’s SPF (seasonal performance factor) is what will determine how much your annual RHI payments will be. At this point you can see that the performance of the system is one of the things that you have some control over and therefore you will want to do whatever you can to maximise this. The document that all MCS (Microgeneration Certification Scheme) installers must work to is called the heat emitter guide and can be found here. Ultimately there are three factors that affect the SPF and they are the “Room specific heat loss” in W/m2, the size of the heat emitter (radiator, fan coil or convector size or UFH pipe spacing) and when using UFH the floor construction type and coverings. Obviously you should do all you practically can to reduce the the heat loss of each room which then leads us on to the heat emitter. By this we simply mean the thing that puts heat into each room such as radiators or UFH (under floor heating). The large the heat emitter the lower the required flow temperature is and the better the SPF is. So if you have radiators you may want to look into the value of upgrading these to ones with higher outputs in order to get to a better SPF. This can often be done quite easily and cost effectively by replacing a single panel with a double paneled radiator and the effect on RHI payments can be quite dramatic. The Heat Emitter Guide details the extent to which you need to oversize to achieve different SPF levels. When selecting a UFH system a good supplier will always tell you that the more pipe you use the lower the required flow temperature will be (and therefore better SPF and RHI payments) so closer pipe spacings equates to better performance. When using UFH, solid screeded floors are always better than aluminium spreader plates so if you have the choice a block & beam first floor will be more advantageous not just in terms of SPF and RHI payments but also for sound insulation. When choosing floor coverings to go over areas with UFH it makes sense to limit the use of timber and carpets as these do limit the heat output. Ceramic tiles are by far the best material for use with UFH as the “thermal resistance” is practically zero and the Heat Emitter Guide does reflect this.

Hopefully this has given you a bit of an insight into the scheme and its requirements and also some ideas of what you can do to get the most from it. Some of our clients have used our knowledge of the scheme to help with selecting radiators in order for them to achieve higher SPFs and larger RHI payments and the benefits for them have been quite significant. If you would like to find out more about how JKN can help you, then please get in touch.

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