A heating solution worth shouting about
With more and more engineers realising the potential of renewable energy, heat pumps are becoming an increasingly attractive option for commercial buildings, says Chris Davis, Business Development Director for Dimplex Renewables.
It has never been more evident that we need to look at lower carbon energy solutions if we are to meet ambitious Government targets of an 80% cut in greenhouse gas emissions by 2050.
The increasing price of fossil fuels particularly in off-gas areas, more stringent legislation on emissions and the coming of age of new technologies are all contributing to a shift towards renewables solutions which should not be ignored – especially in the commercial sector, which generates 40% of all CO2 emissions in Europe.
This focus on lower carbon energy, together with growing support from Government incentive schemes, makes renewable heat a viable solution for many organisations which can save money, cut emissions and pay back sooner than you might think.
As businesses strive to hit carbon reduction targets within increasingly challenging building regulations, heat pump technology (when applied correctly and to the right specification) can provide a cost effective heating solution which ticks all the boxes.
Dimplex has already had a lot of success with both air source and ground source heat pumps in the commercial new build sector where building regulations demand higher levels of efficiency and zero carbon buildings by 2019. Heat pumps are a proven solution for new build projects, increasingly specified to help meet the latest regulations and contributing significantly to high BREEAM scores for those buildings with additional sustainability targets. We have seen some fantastic results on construction projects for schools, offices, retail and leisure buildings amongst others.
However, there is also a huge opportunity for heat pumps in retrofit projects – particularly air source technology which is less disruptive to install than ground source. Despite cost saving benefits, the opportunity to install an air source heat pump as a replacement for oil or LPG systems in off-gas areas is often overlooked – and part of the reason for this is the glaring omission of air source heat pumps from the non-domestic Renewable Heat Incentive (RHI).
Despite the lengthy delays to the domestic RHI, the non-domestic scheme has been in place since November 2011 offering financial support for ‘green’ heating technologies including ground source heat pumps, biomass and solar thermal water heating – but not air source heat pumps.
Unfortunately, take-up has been disappointing and at just 50% deployment rate according to the latest Ofgem report (predominantly biomass), DECC has said itself that overall take up of the RHI is ‘lower than expected’. The general feeling is that many of the tariffs were based on inaccurate assumptions and subsequently set too low, which is why the Government has just completed a consultation with a view to increasing tariffs for some technologies, but there has also been pressure from the industry to include air source heat pumps.
Now, with the Government striving to meet its target that 12% of the UK’s heating will be provided by renewable sources by 2020, changes are set to be made.
Recognising that air source is a relatively easy-to-apply technology which can contribute significantly to carbon reduction targets, DECC has announced its intention to finally include air source heat pumps with a tariff of 2.5p per kWh – which is great news for building services engineers looking to reduce heating bills and carbon emissions.
As figure 1 shows, the latest high efficiency air source heat pumps such as the new Dimplex A Class can offer considerable running cost savings – even before you take into account the inconvenience of bulk oil buying, storage, system maintenance and rising oil prices. With additional funding under the non-domestic RHI, it gives figures which simply cannot be ignored with an annual benefit of more than £5,500 compared to an ageing oil boiler.
What’s more, DECC is set to increase the tariff for ground source heat pumps from 4.8p to 8.2p per kWh which will help to make ground source a far more competitive option for new build projects compared to biomass boilers, which has enjoyed a surge under the non-domestic RHI thanks to some attractive looking tariffs.
However, whilst the appealing RHI tariffs for biomass make it an attractive proposition on paper, it is important to consider the long term implications. The figures include a subsidy for the fuel, which is already more expensive than oil, and requires bulk purchase, storage and drying – all at additional cost and inconvenience. The system itself will require regular maintenance too and the unfortunate truth for many organisations is that they are now starting to face the expensive reality of biomass systems.
Compare this to ground source heat pumps, which require little maintenance and offer a future-proof solution in line with energy policy. They are easier and cheaper to run than biomass systems and with increased tariffs from the non-domestic RHI, the payback can be rewarding for new build projects.
The changes to the non-domestic RHI will open up new opportunities for air source and ground source heat pumps, both proven technologies which can provide cost effective heating and help meet carbon reduction targets. Now is the time to make sure you don’t get left behind.
Heat pumps in action
A new building at one of the UK’s leading centres for technology and science businesses is benefitting from low carbon heating and passive cooling, thanks to a Dimplex ground source heat pump system.
Vanguard House, a three-storey office and laboratory facility at Sci-Tech Daresbury in Cheshire, was designed to achieve a BREEAM Excellent rating, and no fossil fuels such as natural gas or oil are used anywhere in the building, so highly efficient Dimplex heat pumps offered a low carbon alternative for the delivery of both heating and cooling.
Designed and installed by Ecovision Systems Ltd, the system uses two Dimplex SI 130 TUR+ heat pumps to provide 260kW of heating capacity, running at a maximum temperature of 60°C. These heat pumps are reversible, so they also provide passive cooling during the summer months. In cooling mode, a flow temperature of 18°C is sufficient to gently cool the building, so no active chilling is necessary. A Dimplex SIH 40 TE 40kW high temperature heat pump provides all the domestic hot water for the building, achieving a flow temperature of 70°C.
Ecovision’s innovative system design takes full advantage of the geography of Vanguard House’s location, standing as it does above one of the largest natural aquifers in the UK – the Permo-Triassic sandstone. This yields a plentiful groundwater supply, which allowed Ecovision to develop an open loop system, drawing water from a depth of 65m and passing it through a heat exchanger before re-injecting it into the ground at depths of up to 150m, removing any risk of groundwater flooding into service channels and basements.
The average temperature of water from the aquifer is around 10-12°C, allowing the heat pumps to operate extremely efficiently. Taken over the year, the Dimplex heat pumps can achieve a CoP of 4.2. Heating and cooling is delivered to the building’s offices and laboratories by use of a concrete core activation system, consisting of pipes embedded into the pre-cast concrete planks that form the floors.