A thing of beauty: the Danish heat network experience
I’ve been involved in the people side of heat networks for several years now. The work I've been doing at Southern Housing Group on their communal heating schemes has put me at the sharp end of the processes involved, giving me the opportunity to get some district heating dirt under my fingernails and see at first hand the ways in which UK housing providers are trying their very best to make the systems work. It's a tough gig though. Many of my social housing colleagues are dealing with many of the same issues as we are - everything from heat agreemenets and tariff setting, to system design, maintenance and operation.
Knowing how the systems work is clearly an advantage, which why I was thrilled when I was invited to join a district heating study-tour to Denmark for social housing providers last month. It was a whirlwind couple of days taking in new and retrofitted schemes, a district heating plant, and CHP, HIU and energy meter factories (as well as a good deal of Danish hospitality along the way!) Many thanks to SAV Systems for hosting the tour and to Guru Systems and Fairheat for inviting me along!
The trip was certainly thought provoking, and all of us left with heads full of ideas of if/how/when we can apply the Danish experience to our own heat networks. My five top take-aways from the trip are below – as much for my own benefit as for yours, so I can use them as a touchstone going forwards to see how we’re doing:
- Sense of community: communal heating really does mean just that. There is a much stronger sense of community in Denmark than in the UK, with an appreciation of everyone’s small part they play in the whole. The idea of not paying your bill – though not entirely unheard of – seems to be rare. Why would I not do that?
- Delta-T is king. Definitely my number 1 take-home message (thoroughly drummed in at all stages!) Delta-T is the difference between the flow and return temperatures on a heat network – the bigger the difference the better as this means more heat is being demanded as the water flows round the system (rather than it returning just as hot as when it went out, which is a waste on so many levels). On some schemes I’ve seen in the UK the Delta-T is very low – even 0 in one case. In Denmark, if it drops below 30 they think something is wrong.
- What’s more – consumers understand Delta-T! Because of the way the tariff is set up (taking into account water volume as well as gas price and system efficiency), they understand that the more they can improve their Delta-T – or the lower they can make their return temperature – the less they will pay. They actually understand this.
- This in turn means that consumers will happily let operatives into their homes to help maintain and improve their HIUs. What’s more, because district heating is so common (64% of all heat/homes), general plumbers can fix HIUs – specialists are not required.
- Direct district heating is more efficient. The schemes in the UK that I’ve been involved with (and I don’t think it’s that unusual) are indirect. This means the heat is transferred from the primary system to the secondary system via a heat exchanger: the water in the primary system doesn’t go into the radiators. In a direct system it does, which means less opportunity for heat loss in the HIU! (Hot water is still indirect – the primary system water is treated, I’m not sure I’d like to shower in it…)
Just as interesting however, was finding out what they’re not quite so good at – and that seemed to be data. Although their energy systems were way better than ours, the way they handle, manipulate and use data seems way behind what we’re doing in the UK. Their databases felt clunky and manual, whereas ours are automated, flexible and responsive.
There’s ample opportunity for an exchange of ideas, skills and approaches it seems, and lots that we can aspire to for UK heat network - from straight forward good housekeeping to more complex interventions that need higher levels of investment. And of course we need to get the design right in the first place... I’d love to know your thoughts – drop me a line at rachael.mills@se-2.co.uk or reach out on Twitter @se2rachael