With the soon to be launched domestic RHI set to offer consumers a good incentive to make the switch to renewable technologies, demand for ground source heat pumps is set to rise. Chris Davis, Commercial Director at Kensa Heat Pumps, sets out the acase for GSHPs.
With the stormy weather, some of the worst floods in living memory and the ‘winter that never was’ now seemingly behind us, spring is on the way and with it at last comes the long anticipated launch of the Domestic RHI” four and half years after originally being announced.
At the time of writing, Ofgem has just published the first batch of its domestic RHI fact sheets, proof positive for the cynics that yes, at long last, the finer details of the long awaited and long-time needed stimulus to the domestic renewable heat market are about to be revealed.
With the tariffs for ground source heat pumps confirmed at an attractive 18.8p/kWh, there will be huge growth opportunities for contractors and heating engineers operating in the domestic sector, particularly those operating in rural areas, away from the gas grid.
The recent furore over double digit energy price increases coupled with news that the typical UK household heating bills are now well in excess of £1000 per year, has certainly given many householders food for thought when it comes to the costs of domestic heating.
The challenge for installers then is to identify the best pockets in the market that would benefit most from renewable technologies. Certainly in scenarios where customers are faced with potentially having to upgrade an aging oil boiler, the certainty of a guaranteed payback on investment of under five years”“ thanks in part to the Renewable Heat Incentive” means ground source heat pumps are a particularly compelling solution.
For example: with the combined benefit of fuel costs savings against oil heating and the RHI income, a ground source heat pump retro fitted into a 120m2, four bedroom property can pay for itself in as little as five years:
Ambitious target
The financial stimulus the RHI will bring not only aids private householders, but also creates real business opportunities for heating installers in the private sector” all intended to help achieve the Governments target of 4 million heat pumps by 2030. This ambitious target is proof of the Governments conviction in heat pump technology and its capacity to deliver wide scale and long term carbon and cost savings across both domestic and commercial sectors.
By their nature, ground source heat pumps suit properties with available land area, with horizontal ” or more commonly in our experience” slinky ground collectors being the most cost effective means of extracting the heat from the ground. For single domestic installations, boreholes are likely to be cost prohibitive.
Properties with a reasonable land area available tend to be somewhat larger than average, subsequently with a higher peak heat load. However, larger domestic dwellings on single phase electricity supplies are notoriously tricky to deal with using heat pumps. This is principally because typically the largest single phase heat pumps available offer around 12-14kW output, above which only three phase units are available.
Air drop
For air source heat pumps, this problem is exacerbated, as typically the output of the unit is rated at optimum water heating temperatures (35ºC) and benevolent outside air temperatures (7ºC). By their nature, the majority of air source heat pumps on the market will see their output reduce as the operating conditions become more testing i.e. lower typical winter operating air temperatures and higher heating system flow temperatures in retro-fit situations. And with the MCS sizing rules now requiring the heat pump to provide 100% of the required building heat load at an outdoor temperature in the region of -1 ºC to -4ºC (based on the CIBSE Guide A), this limits the maximum heat load that can be covered by an individual air source heat pump in many cases to around 10kW.
So what is the solution for larger private dwellings on single phase with high peak heat loads looking to replace an oil boiler? Ground source heat pumps suffer far less from the issue of reduced performance when the weather turns cold, principally because the heat source (the ground) isnt directly affected by the ambient air conditions, remaining stable year round. As a result, GSHPs lend themselves to supporting higher heat loads than air source systems.
Better still, Kensa ” with our focus entirely on the needs of the UK market and the peculiarities of our electricity infrastructure and housing stock ” has a range of single phase ground source heat pumps able to provide outputs of up to 24kW, expanding the scope of opportunity for customers with larger homes off the gas grid, where the previous costly and unrewarding alternative was oil or LPG.
Oil installers will be acutely aware of the impact seasonality and fluctuations in oil prices can have on their market. Lets be under no illusion that the mild, albeit wet, winter will have affected the running costs of oil based systems. Furthermore, with oil prices currently falling, the question must be asked if customers are more likely to remain with oil based systems now, rather than had we experienced a far harsher winter and oil price hikes?
The point here is to look at the bigger picture. The Renewable Heat Incentive by its very name offers an excellent financial incentive to the market to switch to a more sustainable form of heating, and to address the additional financial outlay required for renewable technologies. But to encourage a householder to change its habits and make the leap to a cleaner, greener technology, more than a financial encouragement is needed, particularly if the current perception is that oil prices are falling and will continue to do so.
Long running
Ground source heat pumps have an expected lifetime of 25 years, and the ground array an impressive 100 year design lifetime” with minimal maintenance required. Compare this to the average lifetime of a new condensing boiler at just 10 – 12 years, and the necessary ongoing maintenance costs. Now consider the price of oil over a 10 year lifetime of a boiler ” it may currently be experiencing a welcomed drop, however over the past 10 years the price of oil has experienced an average year on year increase of 10.77% (Source: ONS 2014). Compare this to gas which has had a year on year increase of 10.51% over the past 10 years, and electricity that has experienced an average increase of 6.05%.
If these patterns continue, the long term outlook for fuel costs is an accelerating disparity between heating oil costs and electricity. Add to this the ‘greening’ of the national grid, and the bigger picture is now far more compelling for householders to replace their consumption of heating oil with efficient electricity-supported renewable technology, that not only lasts longer, but is more affordable, resilient to price hikes, and clean.
Of course to address the immediate cost differences, the efficiency of a ground source heat pump comes to the fore”“ the more efficient the heat pump, the lower the fuel costs. Furthermore, as with any renewable technology” and particularly so with heat pumps” sizing and installation are critically important in ensuring a well performing and sustainable system. To this end, it is strongly advised that oil installers access the wealth of training available through manufacturers and the Governments training incentive administered by GTEC, under which 75% of the cost of renewables training can be saved.