Heat networks:

Code of Practice

for the UK

Rehau Seminar

4th November 2015

Paul Woods Concessions Director Cofely Energy Services paul.woods@cofely-gdfsuez.com

• Leicester District Energy • Birmingham District Energy • Coventry District Energy

• Olympic Park & Stratford

City

• Bloomsbury Heat & Power

• ExCeL Exhibition Centre

• Southampton Geothermal

• Eastleigh

£3.1bn revenue stream over the concessions

77,000 tonnes CO2 saved per annum 270 GWh energy sales per annum

London

Midlands

South coast

Cofely’s Heat Network Projects

www.cibse.org/CP1

Why use heat networks/district heating?

• Lower CO2 emissions – limiting climate change

• Lower running costs – combating fuel poverty

• Delivers high reliability from diverse heat supplies

• Above has led to:

• Requirements for heat networks from local planning policies

• Development of Government policy to support Heat Networks

• EU Energy Efficiency Directive encourages heat networks

www.cibse.org/CP1

The need for standards

• Heat networks not always delivering on promises

• ADE market research and anecdotal evidence revealed the following

problem areas:

• High heat losses from • Poor pipework specification

• Lack of insulation continuity

• High operating temperatures

• Poor pipework layout

• High capital costs • Oversizing of network and plant

• CHPs not operating well

• High operating and maintenance costs

• Poor commissioning

• A threat to the sector’s future – main weaknesses in the areas of design

and commissioning

www.cibse.org/CP1

A fragmented supply chain

Feasibility Outline design Detailed design Construction

and Commissioning

Operation

Suppliers

Energy services company (ESCo)

www.cibse.org/CP1

www.cibse.org/CP1

• Require CoP to be followed in briefs and specifications

• Ensure any deviations from CoP are documented

• Monitor project against the minimum requirements

• Manage handover between stages

• Ensure project team is experienced and qualified in heat network

• Provide feedback to CIBSE on the experience of using the Code to enable progressive improvement

• Best Practice – employ an independent auditor to check compliance with the Code

Objective 1.1 – Aimed at Clients

www.cibse.org/CP1

Key goals that run across all stages of

the plan of work

A. Correct sizing of plant

and network

B. Low heat losses

C. Low return temperatures

D. Use of variable volume

control

E. Use low carbon heat

supply

F. Safe, high quality, low

environmental impact

systems

But these goals are linked!

www.cibse.org/CP1

Correct sizing of plant and network

1. Main concern was diversity

factor for instantaneous

domestic hot water heating

2. Typical peak seen in practice

is <5kW per dwelling for new

flats

3. CHP heat capacity typically

one third of peak

4. For the majority of time

systems operate at 10% to

25% of peak

5. Oversizing of network leads

to higher heat losses

www.cibse.org/CP1

Achieving low heat losses from network

1. Code requires calculation on heat

losses and economic evaluation – no

fixed maximum loss

2. Avoid oversizing

3. Minimise length of network

4. Insulation type and thickness

5. Low mean network temperature

• But is a 90/40 system worse than a 65/40

system? – use of variable network

temperatures

6. How important is it?

• A typical CHP-based system with 30% heat

losses has 10% higher emissions than one

with a 10% heat loss – as the low carbon

CHP will supply the extra heat loss

www.cibse.org/CP1

Low return temperatures (and low flow

temperatures)

1. Low return temperatures result in:

• Less volume of water

• Smaller pipes – lower cost

• Lower heat losses

• More efficient central plant

• More cost-effective thermal storage

Requirement for new radiator circuit is a return temperature < 40°C – achieved with pre-settable TRV designed for low flow rates

The building services design governs return temperatures!

2. Lower flow temperatures

result in:

• More efficient central plant

• Lower heat losses

• But larger pipes offset this

benefit and add to cost –

need to consider impact of

smaller delta T (Tflow-

Treturn)

3. Minimise bypasses,

minimise no. of heat

exchangers, and use

variable volume control

www.cibse.org/CP1

Variable volume control

1. Variable volume control using two-port control valves results in:

• Falling return temperatures under part-load

• Lower pumping energy*

• Lower heat losses

• Better use of low carbon plant

2. Need controlled bypass flow to maintain temperatures in the network and meet minimum pump flow requirements

*For a 50% drop in demand pump energy drops to 12.5%

0.00

5.00

10.00

15.00

20.00

25.00

30.00

0 500 1000 1500 2000 2500 3000 3500 4000

Ave

rage

dT

MWh/year

www.cibse.org/CP1

Use of low carbon heat sources

1. Optimal sizing

• 60% to 80% from low carbon plant

• Delivered CO2 content <150g/kWh

2. Use of thermal store

3. Maintain low return temperatures

4. Location of peak boilers

www.cibse.org/CP1

Safety, quality and environment

1. Safety

• Trenching work remains a high risk area

2. Quality

• Inspections of heat network installations

• Commissioning of buildings

3. Environment

• Visual impact

• Air quality

• Noise

• Construction impact

Page 14

www.cibse.org/CP1

www.cibse.org/CP1

• Clear and transparent statement on heat tariffs and charges and how these may be indexed over time – compliance with the Heat Trust scheme

• Choice of paper or electronic bills

• Pre-payment option

• Annual statement showing comparison of costs with an individual heating system

• Annual statement on heat sources used, CO2 emissions, heat losses, pumping energy

Objective 7.1 – Billing of customers

www.cibse.org/CP1

• Information pack for residents when they move in

especially around controls and metering

• Annual newsletter about the scheme

• Provide advance notice of any planned shutdowns

• Vulnerable customers

• Helpline and emergency calls

• Complaints procedure

• Best Practice – customer representative committee

Objective 7.2 – Communications to customers

www.cibse.org/CP1

The Code of Practice – training and certification

One day course – aimed at developers, clients, Local Authorities etc.

Next date:

• 11 November 2015 (London)

Two day course – detailed technical content and exam/certification

Next dates:

• 18-19 November 2015 (Birmingham)

• 30 Nov-01 December 2015 (London)

IN HOUSE TRAINING AVAILABLE – 6 or more people

www.cibse.org/CP1

Purchase or download the Code (free pdf for

CIBSE members) at www.cibse.org/CP1