1. BEST PRACTICE IN HEAT NETWORK DESIGN Steve Richmond – Head of Marketing & Technical – FES Conference, Warwick 10th Oct 2016

2. / 20,000 employees worldwide – experts in polymer manufacturing. Founded in 1948 in Germany. 5 divisions in the following sectors: -Window solutions -Building solutions -Industrial solutions -Furniture solutions -Automotive solutions The REHAU Group 2 October 2016 / Rowy 2642/ BT GB

3. / UK production: Only UK manufacturer of PE-Xa district heating pipes. REHAU - Your expert partner in district heating 3 October 2016 / Rowy 2642/ BT GB Quality: The renowned REHAU Everloc™ jointing system has been used over 850 million times. Local UK sales & technical teams: On- site support from specialist DH sales team (4 regional offices + UK head office) Design service: Experts in heat network optimisation and design. Largest UK stock & full cutting service: No 4-6 week wait for an urgent fitting. BIM: REHAU’s district heating pipes have BIM models ready for download.

4. REHAU are the only UK- manufacturer of PE-Xa district heating pipe. Production started in May 2012. Est. 30% reduction in CO 2 from UK manufacturing.

5. / District heating pipe materials: steel (EN 253) or polymer (EN 15632) Steel pipe with PU foam Polymer pipe with PU foam Polymer pipe with PEX foam (bonded) (bonded) (non-bonded) 5 October 2016 / Rowy 2642/ BT GB

6. / Advantages: - Very large diameter sizes available - Capable of withstanding higher temperatures / pressure than polymers - Strong material – resistant to impact damage Disadvantages: - Only straight lengths possible - Joints required every 6-12m - Expansion/contraction joints required - High installation costs - Corrosion problems (therefore warning systems are required) - Specialist welding required λ ≈ 0.022 W/mK Steel district heating pipes 6 October 2016 / Rowy 2642/ BT GB

7. >75% of the failures in steel district heating pipes were due to on-site welding. Source: German CHP & District Heating / Cooling Association, 2013

8. / Advantages: - More flexible compared to steel -No water ingress if outer jacket punctured - No thermal expansion (self-compensating) - Long coil lengths possible (less joints) Disadvantages: -Steel has higher temperature / pressure limits - Less flexible compared to non-bonded polymer pipes λ = 0.0216 W/mK Polymer – PU insulation (bonded) 8 October 2016 / Rowy 2642/ BT GB

9. / Advantages: - Highly flexible - Ideal for house connections / congested installations - Long coil lengths possible (less joints) Disadvantages: -Steel has higher temperature / pressure limits - Lower insulation performance compared to PU foam λ = 0.043 W/mK Polymer - PEX insulation (non-bonded) 9 October 2016 / Rowy 2642/ BT GB

10. / Optimising heat network design – a balancing act Total costs Heat loss costs Investment costs Pump & pumping costs Costs Pipe diameter October 2016 / Rowy 2642/ BT GB

11. / 4 key design areas to focus on 11 October 2016 / Rowy 2642/ BT GB Correct heat loads Diversity Installation costs Pipe sizing

12. / 1. Calculating the correct heat load 12 October 2016 / Rowy 2642/ BT GB Only roughly estimated or the old boiler load is used Pipes & plant will be oversized leading to higher heat losses Income from selling the heat is less

13. / It is unlikely for every heat customer to use their peak load at the same time. This is described as diversity. The diversity factor is the ratio / percentage of the peak load really used. For a heat load of 1MW, a diversity factor of 0.7 means you only need a 700 kW plant. 1000kW x 0.7 = 700 kW 2. The impact of diversity 13 October 2016 / Rowy 2642/ BT GB Diversity factor in the example on the left

14. / 14 June 2016 / Rowy 2642/ BT GB Coldest days Original – no diversity (1) = 2,540 kW Designed diversity of 0.85 = 2,160 kW Feb 2012April 2012 Real life measurement of diversity from a German DH network with 80 connections Actual = 1,600 kW => diversity 0.63 = 1600/2540

15. / - Installing in soft-dig areas saves time & cost - Polymer pipes reduce the installation costs due to number of joints and time taken per connection - Innovative use of tees / secondary spines - Twin pipes instead of single pipes (where possible) 3. Reducing installation costs 15 October 2016 / Rowy 2642/ BT GB

16. / Trench routing optimisation 16 October 2016 / Rowy 2642/ BT GB - Less big tees off header pipe - More opportunity to use DUO

17. / 2x UNO 25 = 10.9 W/mDUO 25 = 7.6 W/m Heat loss reduction with DUO  30% 2x UNO 40 = 16.6 W/mDUO 40 = 11.6 W/m Heat loss reduction with DUO  30% 2x UNO 63 = 19.5 W/mDUO 63 = 13.1 W/m Heat loss reduction with DUO  33% Data at 80/50 ° C using RAUTHERMEX pipe. Benefits of using twin DH pipe 17 October 2016 / Rowy 2642/ BT GB

18. / 4. Optimising the flow / return temperatures Modern DH systems typically use a flow temperature of ca. 70-80 ° C. 18 October 2016 / Rowy 2642/ BT GB Flow / return temperatures ( ° C) Heat loadPressure loss (Pa/m)Pipe size required 82/711.1MW161160mm 80/601.1MW183125mm 80/501.1MW161110mm 70/401.1MW166110mm 60/201.1MW28090mm

19. / F/R temperatures ( ° C) Heat loadPipe sizing OD (mm) Heat losses (vs 82/71 ° C) PE-Xa lifespan (24/7 operation) 82/711.1 MW160<25 years 80/601.1 MW12510% lower>25 years 80/501.1 MW11019% lower>25 years 70/401.1 MW11034% lower>50 years 60/201.1 MW9069% lower>50 years 19 October 2016 / Rowy 2642/ BT GB Heat loss assumptions: 10°C soil temperature 1km distance 0.8m installation depth 1.0 W/m*K soil conductivity CIBSE Code of Practice: Best practice would aim to achieve return temperatures <55°C for existing buildings and <40°C for new buildings. 4. Optimising the flow / return temperatures

20. / Flow / return temperatures ( ° C) Max. heat load via 160mm pipe 82/711.12 MW 80/602.05 MW 80/503.07 MW 70/403.07 MW 60/204.10 MW 20 October 2016 / Rowy 2642/ BT GB 4. Optimising the flow / return temperatures 80/60 > 80/50 = 50% additional heat capacity 80/60 > 60/20 = 100% additional heat capacity

21. / Project details: 75 connections 20kW per house = 1,500kW Total network length = 950m Flow / return temps = 82/71 ° C No diversity applied All UNO pipes List price = £313k Heat network optimisation – original design 21 October 2016 / Rowy 2642/ BT GB 160mm (12m lengths)

22. / Project details: 75 connections 16kW per house = 1,200kW Total network length = 950m Flow / return temps = 82/71 ° C No diversity applied All UNO pipes List price = £267k Heat network optimisation – correct heat loads 22 October 2016 / Rowy 2642/ BT GB 125mm > 110mm 160mm > 140mm

23. / Project details: 75 connections 16kW per house = 1,200kW Total network length = 950m Flow / return temps = 82/71 ° C Diversity applied of 0.8 All UNO pipes List price = £218k Heat network optimisation – using diversity 23 October 2016 / Rowy 2642/ BT GB 160mm > 140mm 125mm > 110mm 110mm > 90mm 75mm > 63mm

24. / Project details: 75 connections 16kW per house = 1,200kW Total network length = 950m Flow / return temps = 70/40 ° C Diversity applied of 0.8 All UNO pipes List price = £134k Heat network optimisation – optimising flow / return temperatures 24 October 2016 / Rowy 2642/ BT GB 140mm > 90mm 110mm > 75mm 90mm > 63mm House connections - 32mm > 25mm

25. / Project details: 75 connections 16kW per house = 1,200kW Total network length = 950m Flow / return temps = 70/40°C Diversity applied of 0.8 Route optimised All UNO pipes List price = £128k Heat network optimisation – route optimisation 25 October 2016 / Rowy 2642/ BT GB

26. / Project details: 75 connections 16kW per house = 1,200kW Total network length = 950m Flow / return temps = 70/40°C Diversity applied of 0.8 Route optimised Use DUO pipes if possible List price = £123k Heat network optimisation – use of DUO pipes 26 October 2016 / Rowy 2642/ BT GB ALL DUO

27. / From these simple steps: 1)Heat load correction from 20kW to 16kW 2)Optimising the route and using DUOs 3)Changing flow temperature from 82/71°C to 70/40°C 4)Diversity factor of 0.8 Cost saving of 60% from the original design. Heat losses reduced from 23.53kW to 8.98kW which is 63% heat loss reduction. Heat network optimisation – conclusion 27 October 2016 / Rowy 2642/ BT GB

28. Can polymer be used for a large scale heat network? REHAU supplied 80km of RAUTHERMEX to the bioenergy village of Lathen in Germany of 11,000 residents.

29. / UK Case studies 29 October 2016 / Rowy 2642/ BT GB - Gaunts Estate – AD plant – 1.6km network - Soho luxury cottages – Biomass – 7km network - Eleanor Social Housing – Gas CHP – 2km network - Tattenhall Retirement Village – Gas – 2km network - Dundee Social Housing – Gas CHP – 2.5km network - Portmeirion Village – Biomass – 3km network

30. THANK YOU FOR YOUR ATTENTION Any questions? Contact details: steve.richmond@rehau.com 07921 405948