Tipperary Energy Agency CEO Paul Kenny speaking at 2018 IEA Heat Pump Research Seminar, 25th September, BEIS Conference Centre. Paul discussed the performance of heat pumps in cold weather and asks "Do we really need a backup heater or boiler?

1. Tipperary Energy Agency
Cold weather performance of Heat pumps in Irish homes – Do we really need back up
heat?
Presented by Paul Kenny
September 2018 | London

2.  Tipperary Energy Agency – Local Energy Agency established under
SAVE (20 years ago)
 Established the Superhomes Program to test, demonstrate and scale up
deep retrofit with heat pumps
 150 homes completed to date (80% with metering).
 Significant communications & Market development actions
 Monitoring of most homes to date – Heat & Elec
 Parallel R&D project Superhomes 2.0 testing:
 Validation of ASHP building integration
 Optimisation of ASHP
 Experimental ToU tariffs; PV integration;
 Aiming to provide smart grid and financing
 Just submitted my MSc Dissertation on HP optimisation
About Us

3. How we design Heat pump Installations
 Radiators predominantly
 High volume mass produced steel radiators (Stelrad/
Quinn etc)
 Cheapest heat transfer area per €uro invested.
 Usually on existing radiator pipe spacing
 Only replaced if required (<80% of design load)
 Generally replace sitting room/ kitchen radiators
 Sized for -3/21 at 43 Mean water temperature MWT (about
15-20% larger than condensing boilers)
 Room by room heat load calcs
 Allow 2hours per day for DHW.
 Demand Curve (flow temperature)
 34 Degrees 7 to 15 degrees C. (operational hours
increase as temp. drops)
 46 Degrees -3
 Engineer.

4. Retrofit Results
0
100
200
300
400
500
600
700
800
900
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77
kWh/M2/Annum
Pre & Post BER (Energy Certificate)
 26kWh / m2 delivered energy per annum average
 Energy certificate of 67 KWh/M2 Primary energy
 65% - 80% cost savings from buildings.

5. The Beast from the East
 1st March 2018 significant weather event
 7 days below zero
 300mm snow
 Not a single complaint – several positive emails & texts.

6. -6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
20-Feb 22-Feb 24-Feb 26-Feb 28-Feb 02-Mar 04-Mar 06-Mar 08-Mar 10-Mar
Temperature(°C)
COP
Day
SH001 - COP vs Outside Temperature
Overall COP Average Outside Temperature COP required to equal Oil Cost

7. Deep dive into one house
-6
-4
-2
0
2
4
6
8
10
20-Feb 21-Feb 22-Feb 23-Feb 24-Feb 25-Feb 26-Feb 27-Feb 28-Feb 01-Mar 02-Mar 03-Mar 04-Mar 05-Mar 06-Mar 07-Mar 08-Mar 09-Mar 10-Mar
€0.00
€0.50
€1.00
€1.50
€2.00
€2.50
€3.00
€3.50
Temperature(°C)
Day
CostSavingsperday(€) SH001 - Cost Savings vs Outside Temperature
Savings Average of OutsideTemperature

8. Deep dive into one house
0
10
20
30
40
50
60
70
80
90
100
20-Feb 21-Feb 22-Feb 23-Feb 24-Feb 25-Feb 26-Feb 27-Feb 28-Feb 01-Mar 02-Mar 03-Mar 04-Mar 05-Mar 06-Mar 07-Mar 08-Mar 09-Mar 10-Mar
Energy(kWh)
Day
SH001- Energy Consumed per day (ASHP actual, Fossil Estimation @85%)
Oil Energy Consumption ASHP Energy Consumption

9. 1-Feb 22-Feb 23-Feb 24-Feb 25-Feb 26-Feb 27-Feb 28-Feb 01-Mar 02-Mar 03-Mar 04-Mar 05-Mar 06-Mar 07-Mar 08-Ma
OIL COST ASHP COST

10. 0.00
0.50
1.00
1.50
2.00
2.50
3.00
0 2 4 6 8 10 12 14 16 18
COP per house - Worst Day

11. 0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
COP per house - 2 weeks of cold weather

12. 0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
2
4
6
8
10
12
14
16
18
COP
COP Oct ‘17- May ‘18 for 16 Superhomes
Overall Average = 3.1

13. 0%
5%
10%
15%
20%
25%
30%
35%
0 2 4 6 8 10 12 14
%ofheatinghours
kW load
Hourly 2-Hourly 4-Hourly Daily average
kW Hourly 2-Hourly 4-Hourly
Daily
average
1 6.5% 12.7% 15.0% 20.6%
2 8.0% 13.7% 16.9% 27.1%
3 14.1% 14.4% 16.9% 30.4%
4 15.1% 17.1% 18.9% 19.0%
5 22.0% 20.7% 17.0% 2.4%
6 17.7% 15.7% 12.0% 0.4%
7 8.0% 4.3% 2.6% 0.0%
8 3.1% 0.7% 0.4% 0.0%
9 2.4% 0.3% 0.2% 0.0%
10 1.7% 0.2% 0.0% 0.0%
11 0.9% 0.1% 0.0% 0.0%
12 0.3% 0.1% 0.0% 0.0%
 150 homes – no backup heater
 No immersion
 Some stoves – but largely unused
 Histogram of heat loads is
surprisingly low.
 Minimising cycling by sizing
correctly.
 Extra Cap-ex into radiators
instead.
Backup heater – Can’t fathom why?

14.  Decreasing Flow => increasing
performance
 Floor is minimum compressor
output
 Cycling an issue at milder
temperatures
 Commissioning setpoints =>
steady state dissipated heat ~
70% compressor minimum load
0
0.5
1
1.5
2
2.5
3
3.5
4
0 5 10 15 20
COP
Run Time (min)
2
3
4
5
6
7
8
32 34 36 38 40 42
Heatoutput(kW)
Flow Temperature (°C)
Radiator load by Temperature Heat pump Minimum Capacity
Linear (Radiator load by Temperature) Linear (Heat pump Minimum Capacity)
Careful of Cycling

15. Summary and Key Take-Outs
 Well sized and designed Heat pumps perform wonderfully in cold
weather
 Savings go up as temperature drops
 Average -4 degrees performance 2.5; 0 degrees 2.75
 Typical electrical loads from 1.5kW to 2.5kW (150kWh heat).
 Size emitters large and all* other problems disappear
 DT23 Vs DT30 ~ 18% increase in cost (€400 for 200m2
home)
 Increases HP performance by c. 15% - 20%
 Decreases cycling & lowers operational temperatures
 3-5 year payback.
 Improves comfort levels through faster response.