BPA RTU Winter OperationPresented to:

RTUGAugust 2010

Presented by:Kathryn Hile, The Cadmus Group

Howard Reichmuth, New Buildings Institute

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Winter Analysis Overview

Improvements to analysis template

Downloading and organizing data

Fan operation – schedules

Gas pack operation

Heat pump operation

Winter economizing (or cooling)

Additional opportunities

Lessons learned

2

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Winter Sample

45 serviced RTUs

– 32 at 3 sites in Puget Sound area

– 13 at 3 sites in Tri-Cities area

4 baseline RTUs in Tri-Cities: serviced spring 2010

3

RTU Type Number of Units Subtractions Units Analyzed

All Electric 1 1

Gas Pack 34 5 29

Heat Pump 10 0 10

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Analysis Template Improvements

All winter data in one spreadsheet (at hour level) Much smaller analysis files Automation with SAS and VBA Time series dynamic graph Both SA min and SA max plotted in time series

4

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

5

Downloading and Cleaning Data HOBOlink

Excel

Visual Basic

SAS

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Data Preparation Process

Download zip file from HOBOlink with data from all HOBOs

Organize by HOBO Create one file for each HOBO, based on power,

one sheet for each two-week period Import to SAS with keys for CT size, WattNode

scale factor, fan low and fan high

6

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Data Preparation

Calculate hourly and daily minimums, maximums, totals and averages

Export to Excel Only full 24 hour days used to create energy

signature View data in hourly compressor map, dynamic

time series and energy signature

7

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Data Collection Issues

Some (not many) sensors failed last winter, and four sites required troubleshooting to fix– Splitters– AC adapter – battery failure

Downloaded data– One site: two units had nonsensical data– One site: three sensors just disappeared from

HOBOlink – result of the AT&T upgrades last fall?

8

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Calculating Percent Outside Air

9

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Winter Operation

Schedules – fan ON or AUTO

Fan kW, duty, base load

Typical signatures

10

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Fan Mode = ON Winter numbers similar to pilot data

11

Winter Data Summer Pilot Post-Servicing DataRTU Fan kW Fan Duty Base Load Fan kW Fan Duty Base Load

RTU6 0.69 91% 15.11 0.65 88% 13.68 HP15 0.65 100% 15.66 0.63 100% 15.06 HP17 1.40 100% 33.51 1.48 87% 30.96 GP5 0.96 99% 22.90 0.87 96% 20.13 GP6 2.69 99% 63.73 2.63 99% 62.53

AC10 0.89 100% 21.38 0.92 100% 22.19 AC6 2.66 38% 24.13 2.94 25% 17.42

RTU1 1.49 99% 35.28 1.46 93% 32.82 RTU3 0.93 100% 22.35 0.91 94% 20.35 RTU6 1.73 40% 16.43 1.73 35% 14.43

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Fan Mode = AUTO Small sample Fan kW very close; fan duty and base load differed

12

Winter Data Summer Pilot Post-Servicing DataRTU Fan kW Fan Duty Base Load Fan kW Fan Duty Base Load

RTU5 1.84 76% 33.48 2.12 85% 43.40

RTU3 2.06 5% 2.68 2.01 28% 13.50

HP2 0.60 8% 1.20 0.69 100% 16.45

GP7 1.28 26% 7.86 1.29 61% 18.71

GP8 1.35 2% 0.76 1.23 14% 4.07

AC9 1.22 5% 1.46 1.22 100% 29.31

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Gas Pack Signatures

24 of 32 energy signatures were as expected 8 needed more investigation to understand

performance

13

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Gas Pack Typical Signature 1

14

0 10 20 30 40 50 60 70 80 90 100 1100

10

20

30

40

50

60

70

80

90

Energy Signature

Average Daily Outside Air Temperature (F)

To

tal

Da

ily

En

erg

y (

kW

h)

Operates same set schedule each day

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Gas Pack Compressor Map

Same RTU as previous slide

15

10 20 30 40 50 60 70 800

0.5

1

1.5

2

2.5

3

3.5

4

RTU Hourly Avg kWh and Max kW

RTU2_Hourly_kWh_Graph RTU2_Max_Hourly_kW_Graph

Average Hourly Outside Air Temperature (F)

Ho

url

y k

Wh

an

d M

ax

kW

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Gas Pack Time Series

16

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Gas Pack Typical Signature 2

17

0 10 20 30 40 50 60 70 80 90 100 1100

20

40

60

80

100

120

Energy Signature

Average Daily Outside Air Temperature (F)

To

tal

Da

ily

En

erg

y (

kW

h)

Operates slightly longer at lower temperatures

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Compressor Map Same RTU, compressor map

18

0 10 20 30 40 50 60 70 80 90 1000

1

2

3

4

5

6

7

RTU Hourly Avg kWh and Max kW

RTU2_Hourly_kWh_Graph RTU2_Max_Hourly_kW_Graph

Average Hourly Outside Air Temperature (F)

Ho

url

y kW

an

d k

Wh

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Gas Pack Typical Signature 3

19

0 10 20 30 40 50 60 70 80 90 100 1100

20

40

60

80

100

120

140Energy Signature

Average Daily Outside Air Temperature (F)

To

tal

Da

ily

En

erg

y (

kW

h)

Two signatures – Monday – Saturday, and Sunday Unit may have reached setback temperatures when average daily

temperatures below 40

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Gas Pack Findings

Fan power calculated this winter was close to metered pilot data in almost all cases

Fan duty was close to metered pilot data in units with fan scheduled ON

Fan duty and base load were difficult to predict from summer metered data when fan ran in AUTO mode

20

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Winter Heat Pump Operation

Heat pumps were trickier Smaller sample, all at a notorious site Units served either offices or fabrication

(manufacturing) spaces Four units did not have economizers

21

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Heat Pump Typical Operation Energy increases as temperatures decrease Steeper slope than for cooling

22

0 10 20 30 40 50 60 70 80 90 1000

10

20

30

40

50

60

70

80

90

Energy Signature

Average Daily Outside Air Temperatures (F)

To

tal D

aily

En

erg

y (

kW

h)

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Heat Pump Compressor Map Same unit as previous slide

23

0 20 40 60 80 1000

5

10

15

20

25

RTU Hourly Avg kWh and Max kW

HP15_Hourly_kWh_Graph HP15_Max_Hourly_kW_Graph

Average Hourly Temperature (F)

Ho

url

y E

ne

rgy

(k

Wh

)

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Heat Pump Time Series

24

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Heat Pump Findings

Typical heat pumps will have a second sloped line

Need summer data (spring was not warm enough) to connect winter and summer usage

Will use that to calculate and predict total annual energy use, not just cooling and fan

25

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Winter Economizing Some units modulate dampers to take advantage of free cooling. SA min and SA max track OAT Three speed fan?

26

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Heating to Economizing Fan operates at different power when heating or

economizing

27

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Atypical Performance

Balance point below the range of monitored temperatures

Cooling at low temperatures Units serving the same space Two units with bad data

28

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Low Balance Point

29

0 10 20 30 40 50 60 70 80 90 100 1100

20

40

60

80

100

120

140

160Energy Signature

Average Daily Outside Air Temperature (F)

To

tal D

aiy

En

erg

y (

kW

h)

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Cooling at Low Temperatures

Mechanical cooling at 25 degrees

30

0 10 20 30 40 50 60 700

2

4

6

8

10

12

RTU Hourly Avg kWh and Max kW

GP6 Hourly kWh GP6 Hourly Max kW

Average Outside Air Temperature (F)

Ho

url

y kW

h a

nd

kW

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Cooling at Low Temperatures

31

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Heating a.m., Cooling p.m. Two different max kW, at 3.5 kW, cooling (SA min

at 55) and heating 4.5 kW (SA max at 90)

32

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Someone’s Been in my RTU…

33

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

…Twice!

34

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Economizer Findings

Cooling at temperatures below 40 degrees. Why? Controls? Or dampers didn’t modulate because broken? Bad sensor? Comments? Significant savings opportunity?

Cooling in the 50-60 degree F. Could economizer changeover temperature be increased for additional savings?

Winter is a good (better than summer?) candidate for economizer savings

35

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Preliminary Annual Signature

Winter:– Standard, flat gas pack– Standard, sloped – but could we just take an average

and keep slope at 0?– Gas pack with two occupancy schedules– Heat pump – is this signature messier than it would be

during summer cooling? TBD.

Atypical.

36

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Ex: AC w/Elect Resistance Heating

37

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

AC Compressor Map

38

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

AC Time Series

39

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Next Steps in Research

Draft annualized savings methodology with separate characterizations of annual operation for summer and winter

Data block interval analysis Recommendations regarding fan schedule persistence Additional persistence analysis Measure life implications from the data Updated M&V protocol recommendations

40

B O N N E V I L L E P O W E R A D M I N I S T R A T I O N

Web-Enabled Thermostats

Test the web-enabled thermostat as an M&V tool as a substitute for data-loggers– Data-friendliness?– How complete is it?– What does it look like?

Use the current analysis protocol and modify it for these data

41