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The evolving market for small to medium scale district heating
The introduction of the Non-Domestic RHI in November 2011 helped to trigger significant growth in small scale district heating. REHAU realised this potential and it was one of the drivers in our decision to invest in UK district heating pipe production in the Spring of that year.
Since then, a small scale district heating market which has been until now, dominated by sub 200kW biomass boilers has recently broadened to include CHP solutions (gas and renewable), anaerobic digestion and heat pumps as well, showing just what a wide range of heat source options are possible.
Moving forward, the likely reduction in the 200kW small biomass tariff on 1st July 2015 may actually have a positive effect on best practice system design, discouraging possible over/under sizing of the plant. I’m certainly hoping to see more projects sized more appropriately in the future regardless of the heat source chosen, with the emphasis shifting from tariff banding to optimum efficiency.
Polymer district heating pipe can easily accommodate up to ca. 2MW in a single 160mm pipe, making it the material of choice for many of these small to medium scale schemes. Steel pipes are ideally suited to large, city-wide projects which require bigger pipe diameters (eg 500-1000mm), whereas polymer pipes offer significant installation savings on the small to medium sized projects.
The emphasis needs to be on reducing flow/return temperatures since this is what makes schemes more efficient in terms of heat losses, and reduces capital costs because it allows the smaller pipe sizes to be used. This message was reinforced recently in the CIBSE Code of Practice which encouraged specifiers to focus on the importance of good system design. Training courses on this Code of Practice and manufacturer-led training such as CPD courses and design courses are key to ensuring best practice in this growing industry.
Personally, I hope that more community-based heat pump schemes are installed as they are ideal in terms of efficiency and pipe sizing because of the lower flow temperatures which heat pumps demand.
Obviously, there is understandable concern in the industry about the possible changes to the RHI after 2016 and what impact they might have on future deployment of district heating in the UK, but I remain confident that, with the right focus on efficiency and cost effectiveness, it will still have a major role to play in the UK heat market.