1. District Energy Networks
Lowering return temperatures as the key to lower flow temperatures in DH systems.
What effect this creates for energy efficiency, material selection and whole life cost efficiency
Andy Watts - Flexenergy Ltd
District Energy Networks

2. Why lowering network temperatures?
Low Flow temperatures (max 70°C) allow much more useage of renewable energy as well as residual heat from industry

3. Low temperature solution for Hot water
Typical flow below 55°C
Typical flow (UK) 80°C +
Reason why DH schemes perceive they can’t go lower than 40⁰C return temperatures is because they operate at higher flow temperature and they usually have a bypass built in, so if there is no demand the flow goes over the bypass into the return subsequently maintaining it at a higher temperature

4. What does it mean 98 YEARS Material selection opportunities
Life Expectancy
For plastic materials, lower temperatures are key to enhancing the life of systems. Plastics operate better at lower temperatures so this significant change promotes longevity in use. Eg;
Where 70⁰C is used as the optimum flow temperature
PB (Polybuteleyne),will provide a life calculation even based on 24hrs/ 365days
98 YEARS
Describe how variable flow and continuous now most common because of HW at lower temperature

5. What does it mean Reduce investment costs (Low lifetime costs)
Reduce energy losses (Improve energy efficiency)
Smaller pipe diameters (improve installation time)
Less repairs/maintenance
Plastics do not rust or corrode. Bore remains the same through the life of the product
Reduced energy through the life of the system
Higher ΔT

6. Mayor of London Study
At 70°C Flow temperature the entire heat demand (66 TWh/a) of London can be covered with Heat Pumps

7. Hengelo Street in a day 10 house connections within 1,5 hours
Watch our Street in day clip on our youtube channel by clicking on the play button
Experience the significant lower impact on citizens.
Street with 10 houses connected within 1.5 hours
Watch our Street in a day clip on our youtube channel by clicking on the play button!

8. Questions
Andy Watts