1. Ground Source Heat Pumps in low-income housing
Presented by Denys Stephens
Sustainability Manager, Penwith Housing Association
A member of the Devon & Cornwall Housing Group

2. Penwith Housing Association
A member of the Devon & Cornwall Housing Group
� Manages 6000 homes throughout Cornwall
� Has pursued best practice in energy efficiency
since stock transfer in 1994
� First RSL to install GSHP in newbuild 1998
� First RSL to retro-fit multiple GSHPs in 2004
retro-

4. Ground Source Heat Pump Heating
� Uses closed loop ground source heat pump
technology to access mainly solar energy
� The ground absorbs solar heat and maintains a
relatively constant temperature
� Usable almost anywhere in the U.K.
� Very low CO2 emissions
� Backup heating is not necessary if you choose a
well designed system
� Runs on electricity
� 1 kW electricity generates about 3.2 kW heat
(Coefficient of performance 3.2 – radiator system)

5. Why use Ground Source Heat Pumps?
� Many rural areas are off the gas network
� Difficult to achieve Affordable Warmth with
conventional electrical heating
� Cost & unsustainability of oil & LPG fired central
heating.
� GSHPs provide affordable heating with very low
CO2 emissions & low maintenance
� Currently one of the most accessible renewable heat
technologies
� Will benefit from Renewable Heat Incentive in 2011

6. Grid electricity as a heating fuel
� It has a carbon consequence (0.517 kg/kW hr), BUT
� GSHPs reduce that by 60 – 75%
� CO2 content of the grid will reduce
� GSHPs zero carbon when run on green electricity
� Insufficient supplies of biomass fuel for general use
� Gas supplies are depleting and reliance on foreign
supply is increasing – the carbon footprint of gas
increases when it’s shipped further
� Electricity available almost everywhere, hence
importance of heat pumps in off gas areas

7. Effect of Fuel Price Increases 2005 - 2009
100m2 house annual heating costs
Effect of Fuel Price Increases on Annual Heating & HWS Costs for 100m2 L.A. House
[2005 - 2009]
1700
1600
1500
1400
1300
1200
GSHP
Cost (£)
1100
1000 Gas
Annual Fuel C
900 Oil
800 Electricity
l
700 Coal
600 Lpg
500
400
300
200
100
0
01/01/05 01/01/06 01/01/07 01/01/08 31/12/08 31/12/09

8. Features of a GSHP System
Hot water cylinder
Heat distribution system –
radiators or under-floor
Heat pump & circulating
pump – can be inside
or in external enclosure
Ground loop – (not to scale)
can be vertical or horizontal

9. Ground source heat pump system
with horizontal ground loop

10. Ground source heat pump system
with vertical ground loop

11. Specifying GSHPs – key issues
� Engage the interest & support of tenants
� Pick dwellings that are (or can be) well insulated
� Choose a reliable GSHP that can comfortably meet the heat
loss levels of the dwellings.
� An expert installer is needed, particularly to correctly design
the ground loop.
� Pay attention to design for noise reduction
� M&E contractor who installs heat distribution system must
understand GSHPs.

12. Design Issues - Drilling Work
� Need to avoid underground services
� Location as close as possible to dwelling
� Need to avoid damage to gardens
� Disposal of any ground water

13. Design Issues – location of heat pump
� Preferably close to ground loop
� Internal or external?
� Ground loop condensation
� Sound insulation
� Connection of flow & return to plumbing
� Connection of electricity supply

14. Design Issues – heat distribution
� Underfloor - very difficult in retrofit
� Warm air - availability? Popularity?
� Radiators - can be retrofitted
� Radiator sizes need not be excessive
� High water content radiators for thermal storage
� TRV’s in bedroom/s & kitchen only
� Hot water storage – simultaneous space & hw
heating not possible

15. Design Issues - controls
Room thermostat Programmer Heat Pump Control
� Diverter valve or dual pump?
� Conventional 2 channel programmer
� Conventional room thermostat
� Probe thermostat in h/w tank

16. 4 Bungalows at Bodinnar Close Newbridge
Grant Aided by the Low Carbon Buildings Programme & Cornwall CC
Penwith HA’s Fourth GSHP retrofit project – April 2008
An E.ON HeatPlant Project – GSHP Installer EarthEnergy

17. Project Details
� 4 bungalows fitted with 3.5 kW systems
� Retrofitted to existing buildings
� Bungalows already fitted with cavity fill, double
glazing & loft insulation
� GSHP installer EarthEnergy
� Plumbing systems by local contractor MV Clatworthy

18. Drilling rig in action

19. Protecting garden areas

20. Inserting the ground loop

21. Installed ground source heat pump
Flow & return to
heating system
Ground loop
circulating pump
Heat pump
Ground loop pipes
Pre-formed enclosure

22. Plumbing Completed

23. GSHP performance
PHA GSHP heated property – performance 28th – 30th November 2010
Hot water
temperature
Internal air
temperature
External air
temperature

24. GSHP performance
PHA GSHP heated property – March 2010 – February 2011
Hot water
temperature
Internal air
temperature
External air
temperature

25. Annual fuel costs and CO2 Emissions
comparison with other systems
2 bedroom 3 person house (60 m2)
� GSHP - £ 307 1.1 tonnes CO2/yr
� ASHP - £ 412 1.5 tonnes CO2/yr
� HE Gas boiler - £ 442 2.0 tonnes CO2/yr
� LPG boiler £ 884 (47 kG bottle) 2.4 tonnes CO2/yr
� Oil boiler £ 442 (28 sec, 899 litre drop) 2.7 tonnes CO2/yr
� Electricity £ 728 (storage heaters) 3.4 tonnes CO2/yr
� Smokeless coal £ 1056 (back boiler) 6.4 tonnes CO2/yr
GSHP data based on 5 years monitored performance in HA homes
Fuel costs November 2009. Dwelling heat loss 2.1 kW

27. HeatPod Project
Penwith HA’s Retrofit for the Future Project – 2 bed end of terrace house
Project partners John Parker Consulting & EarthEnergy
� ‘Passivhaus’ approach not suitable for all housing, e.g. for
Passivhaus’
vulnerable, elderly & special needs groups needing greater warmth
� HeatPod offers a dynamic solution – very good fabric standard
coupled with an innovative GSHP system – a Ground / Air / Solar
Source Heat Pump coupled with an air handling unit
� Energy from exhaust air & HeatPod solar gain reduces GSHP
ground loop size (and cost) and enhances system performance
� System designed to utilise thermal storage capacity of the ground

28. HeatPod Project - Plans
High performance
External doors
100 mm external
Wall insulation
Softwood triple
glazing
Wood pellet
stove

29. HeatPod Vertical Section
Exhaust air heat pump system augmenting
GSHP performance
Pressurised hot water cylinder
Ground source heat pump
Ground loop circulating pump

30. HeatPod Project – CO2 emissions
Comparison of HeatPod Annual CO2 Emissions - [kgCO2/m2 p.a.]
150.0
140.0
130.0
120.0
1 0.0
1
100.0
Co o king
90.0
A ppliances
80.0 Lighting
70.0 Fans & P umps
60.0 Hws
Heating
50.0
40.0
30.0
20.0
10.0
0.0
Existing (co al) Sto rage heaters Std. gshp Enhanced gshp HeatP o d
Data modelling by John Parker Consulting

31. Acknowledgements
Thanks to the following for making this work possible:
The Technology Strategy Board
The Low Carbon Buildings Programme
Cornwall Council
John Parker, John Parker Consulting
Dr Robin Curtis, EarthEnergy Ltd.
Mike Newell, E.ON
Calorex Heat Pumps