Rob Berridge, a Heating Design Consultant and Director of Heat Engineer Software, looks at whether gas will have a place in the future energy mix:
When I started this train of thought I shuddered at the thought of my beloved fuel (gas) becoming obsolete. I say obsolete but in reality, I am only referring to the efficiency of its usage in certain buildings for heating purposes. Having worked with it for most of my career, I would be sad to see it go, but for the last five or six years since my career was forced to take an alternative path, I have come to understand more about its efficiency and suitability than I could ever have dreamed possible.
Do you agree with government that fossil fuels should be banned within new builds from 2025? In principle, I agree but as always, the subject is much more complicated than a blanket approach.
We currently have amazing manufacturers all over the world sharing technology (they buy each others boilers you know). Each of them spends vast sums on R&D each year in the hope of making their product more efficient, cost competitive and suitable for a range of kW requirements. It is my understanding now that gas burners have a limit (at present) of kW output that they can modulate down to, and I believe that this is due to the difficulty of getting the air/gas ratio stable enough to maintain a safe spread of flame across the low output heat exchanger? I’m sure there are other contributing factors far above my pay grade but it is abundantly clear that after nearly five years of talking about oversized boilers, I cannot get an answer as to whether they can indeed be made smaller.
We currently have the ability to modulate down to around 1.7kW and that is the lowest on the world market as far as I’m aware, and I would now argue that even this is inappropriate for new builds after 2025. But……
Government must firstly tackle the unaccountability and free-running of the building industry to ensure that every building is performance tested to match design criteria. I’ve said it many times but our housing industry is the least regulated in the modern world and after some research in the last few weeks, I now understand that building control actually very rarely visit sites any more and indeed will accept photographic evidence of building compliance? Really? Building control has been systematically taken away from local authorities, in favour of privatisation and I have to say, I have first hand experience of this second rate approach to build quality. What can you possibly tell from a photograph in this example? I remember dealing with and building good relationships with local authority building inspectors throughout my career and they were always a resource that instilled confidence and learning. Indeed, I used to service the boilers for two of them as our relationships had attained mutual respect.
If indeed, 1.7kW is the lowest modulation output we can achieve, then I absolutely agree that gas has had its day in most modern buildings in its present format and when the, ‘Future Homes Standard’ (Part L & F from October 2019) finally gets the anticipated amendments/extensions later this year, we should see drastic changes to the allowance of heat loss in buildings. It has to be said that if we don’t see these drastic changes and limiting the heat requirement to at least 30 W/sqm (Watts per square metre), I simply cannot see how the new rush towards heat pumps can ever be truly viable or achieve the UK efficiencies that we must adopt if we are to drastically reduce our energy wastage.
Let’s take an average 100 sqm new build, typically a 2 bed house at 30 W/sqm heating allowance under (hopefully) the new regulations. This equates to a typical total heating load of just 3 kWs. To be clear, if this 30 W/sqm limit is to be rolled out across the UK, different regional building practices will need to be enforced based on outside mean temperatures and Delta T (London is -1.8c for example). Just how many times in the year do you think we will require 3 kW to heat our new regulated house, or how many times is it actually -1.8c outside in London?
At Heat Engineer Software Ltd, great effort was made to compile regional and monthly degree data information and implement it into our, ‘Bivalent Design’ tool. Typically, if the outside temperature was at a rather more common 7c for example, this new house would only have a heat requirement of approximately 2kW and if it was at 15c, you would only require around 1 kW to maintain your very comfortable 21c inside temperature.
As I have stated above, gas has been my life and I see absolutely no reason for it not to have a place in our future but we simply have to face facts and use it more efficiently. I would suggest that any property with a heat loss requirement of 10kW or below (and that is a HUGE building), must therefore be part of a more efficient district heating system, serving at least three or four properties. This would seem logical and could at least assure the maximum efficiency of this still great and abundant fuel. The exact same would apply for oil but I’m assured that this technology can currently only modulate down to around 4 or 5 kW and so pro-rata district schemes could apply on close proximity buildings.
We absolutely must embrace new heat pump technology for all independent heating requirements but also not rule out district heating circuits. Bore hole technology for example, pretty much guarantees around 12c from the ground, 365 days a year. I have been lucky enough to design a few of these downstream systems and they are utterly brilliant! Again, another BUT….
Heat pump, hydronic technology is nowhere near as forgiving as a standard gas boiler installation, where the typical shopping list comprises of, ‘a bundle of 22 and 3 bundles of 15 please guvnor’. It is crucial that hydronic system design is accurate for this excellent, new technology and yet we have all heard of running cost disasters from unscrupulous or unaware installers/installations that put the fear into consumers by installing Heat Pumps onto existing systems. The fact is, they simply will not work efficiently without very careful planning of both primary and circuitry pipework and emitters.
This is now the area that training absolutely has to focus on! The knowledge is not yet widespread but it is agreed, engineering physics. The task of this is vast and so we must therefore, join together to train this new approach to system design as the basic hydronic principles apply across all manufacturers. We need to forget the, ‘cloak and dagger’ mystery of information and freely share the knowledge within our own (revenue earning) classrooms and approaches. The single, most important point, is that we have to agree on the hydronic principles and sing from the same sheet, as confusion has been proven to breed mis-trust.
Once again, I find myself calling for industry unity and cohesion between all levels. A ‘one voice’ that supports and includes the least knowledgable, to help them achieve the skills to deliver the energy savings and system designs that are truly worthy of a national and proud heating industry. #BeaPro