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
Variable Capacity Heat Pump RTF Sub-Committee
November 16, 2011
Mira Vowles, P.E., CEM Emerging Technology Project Manager
BPA Energy Efficiency
Slide 1
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
Meeting Agenda
1. EnergyPro Correction
2. Small Office Baseline Model Differences
3. Small Office VRF Heat Pump Model Differences
4. VRF Model Best Practice
5. Revised Definitions
If we have time:
– Discuss M&V best practice & standard protocol
– Discuss compiling list of PNW VRF installations
Slide 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
Seattle Small Office Energy Use
Correction
Energy Solutions Small Office
SEATTLE
RTU
(kWh/SF)
RTU (%)
VRF
(kWh/SF)
VRF (%)
Fan
(kWh/SF)
6.4
73%
0.7
27%
Cooling
(kWh/SF)
1.0*
11%
1.2
46%
Electric
(kWh/SF)
7.4
84%
1.9
73%
Heat
(kBtu/SF)
4.7
16%
2.4
27%
Total
(kBtu/SF)
29.9
100%
8.9
100%
* Corrected to include duct loss adjustment
Slide 3
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
Energy Solutions Small Office Model
7,200 square foot office modeled using EnergyPro 5
• Baseline: Packaged rooftop air conditioner with
gas furnace and constant volume fan
• ASHRAE system type 3
• 4 units, 6-8 tons each, fixed temp economizer,
1,080 cfm of OSA
• Included 28% cooling increase to account for
conductive duct losses
• Included 37% fan energy increase to
compensate for duct leakage
• VRF heat pump system with DOAS
• 2 Mitsubishi units, 10 to 12 tons each, no
economizer, 1,080 cfm of OSA
Slide 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
Energy Solutions & PECI Small Office
RTU Gas-Pack Model Differences
1. Energy Solutions used EnergyPro and PECI used
eQuest
2. Energy Solutions included significant Baseline duct
losses
3. PECI included two-speed fans (fan at 35% when no
heating or cooling loads)
4. PECI included server room which requires minimal
heating
Slide 5
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
Energy Solutions & PECI Small Office
VRF Heat Pump Model Differences
1. Energy Solutions used EnergyPro Mitsubishi VRF
performance modules
2. PECI used the eQuest “BSUG method” (PVVT model
with compressor VSD and post processing heat
recovery analysis)
3. PECI’s model doesn’t include refrigerant pipe losses
4. PECI included ventilation fan with 2.5” static pressure,
while Energy Solutions used DOAS with unknown static
pressure
Slide 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
Seattle RTU Fan Energy Use Summary
Slide 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
Small Office RTU Gas-Pack
Modeled HVAC Energy Use Comparison
SEATTLE RTU Gas-Pack Modeled HVAC
Breakdown Comparison
kBTU/SF
40.0
30.0
20.0
10.0
0.0
Fan
Cooling
PECI eQuest Model
Heat
Total
Energy Sol'ns EnergyPro Model
Slide 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
Small Office RTU Gas-Pack
Modeled HVAC % Use Comparison
SEATTLE RTU Gas-Pack Modeled HVAC
Breakdown Comparison
80%
60%
40%
20%
0%
Fan
Cooling
Heat
PECI eQuest Model
Energy Sol'ns EnergyPro Model
Slide 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
Small Office VRF HP
Modeled HVAC Energy Use Comparison
SEATTLE VRF Heat Pump Modeled HVAC Breakdown
3.0
2.3
kWh/SF
2.5
2.6
2.0
1.5
1.0
1.1
0.7
1.2
0.7
0.5
0.7
0.5
0.0
Fan
Cooling
PECI eQuest Model
Heat
Total
Energy Sol'ns EnergyPro Model
Slide 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
Small Office VRF HP
Modeled HVAC % Use Comparison
SEATTLE VRF Heat Pump Modeled % HVAC
Breakdown
120%
100%
80%
60%
40%
20%
0%
Fan
Cooling
PECI eQuest Model
Heat
Total
Energy Sol'ns EnergyPro Model
Slide 11
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
Building Simulation Program Issues
 Due to the complexity of VRF systems (both VRF HR
and VRF HP), building simulation programs are needed
to estimate site-specific savings;
 How can the accuracy of the building simulation
programs be verified?
 What are the important metrics?
 Monthly energy use and average monthly
temperature
 Other?
 Can building simulation programs provide these
important metrics for verification purposes?
Slide 12
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
VC HP Building Simulation Model
Best Practices
– EnergyPro
– TRACE
– eQuest
– Other?
Slide 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
Modeling VC HP with TRACE
TRACE can explicitly model VC HP, both heat pump and heat recovery
systems:
– Algorithms are based on Daikin empirical model
– Inputs based on first generation Daikin VRV equipment
•
modify to match current generation equipment or other manufacturer
•
Heating COP or Cooling KW/ton
•
Condensing Fan power consumption KW/ton
•
Select unloading curve, compressor power consumption curve,
condensing fan curve and cycling point as appropriate
Based on April 15, 2009 BSUG meeting presentation
Slide 14
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
Modeling VC HP with TRACE continued
TRACE airside simulation
•
When space temperature rises above the cooling setpoint, the cooling
coil supplies air at a constant, cooling-supply-air-temperature until the
setpoint is met; rejected heat is supplied to the refrigerant condenser
loop.
•
When space temperature drops below the heating setpoint, the
heating coil supplies air at a constant, heating-supply-air-temperature
until the setpoint is met, and the heat is removed from the refrigerant
condenser loop. The default minimum reheat is 10%, or it can be
entered on a room by room basis.
•
When the heating and cooling coils are inactive, the minimum supply
airflow at the mixed-air temperature is assumed; fan heat is , included.
Based on April 15, 2009 BSUG meeting presentation
Slide 15
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
Modeling VC HP with eQUEST
Model as PVVT Water Source Heat Pump system
•
Zone the building in the same manner as the design for representative
heat recovery modeling
•
Select a water cooled condenser with a condenser water loop
•
Create one system per zone
•
Create separate condenser water loops for each VRF condenser and zero
out the pump energy
•
Change the fan efficiency ratio and electric boiler EIR to reflect VRF
efficiencies
Based on April 15, 2009 BSUG meeting presentation
Slide 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
Modeling VC HP with eQUEST continued
Model as PVVT Air Cooled Heat Pump
•
Create one system per zone
•
Change to variable compressor speed
•
Label systems and zones to according to which condenser each zone is
connected to
•
Create hourly reports with total heating and cooling energy use for each
system
•
Use spreadsheet to find simultaneous heating and cooling for each
system, and sum the savings
–
This methodology is felt to be a conservative approach, which has been
accepted by the USGBC on the Portland Mercy Corp LEED building
–
DOE-2 VRF system curves need to be developed
Based on April 15, 2009 BSUG meeting presentation
Slide 17
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
How Accurate are Baseline and VC HP
Models?
– PNW EUI’s
– EnergyPro EUI’s
– eQuest EUI’s
– How can we verify model accuracy?
Slide 18
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
Slide 19
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
Slide 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
Small Office Baseline EUI Comparison
90
80
83
84
77
70
57
60
Energy Solutions
(EnergyPro -Seattle)
2007 CBSA
50
2003 CBECs
40
30
PECI (eQuest)
20
10
0
EUI (kBtu/SF)
Whole building Mean EUI = 75 (kBtu/SF),
with a Standard Deviation of 13 (kBtu/SF)
Slide 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
Medium Office Baseline EUI Comparison
120
106
Energy Solutions
(EnergyPro -Seattle)
100
2007 CBSA
74
80
63
52.9
60
2003 CBECs
41
40
PECI (eQuest)
20
Mitsubishi (EnergyPro Seattle)
0
EUI (kBtu/SF)
Whole building Mean EUI = 67 (kBtu/SF),
with a Standard Deviation of 25 (kBtu/SF)
Slide 22
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
Small Office VRF HP & Getting to Fifty
EUI Comparison
70
63
60
52.9
46
50
Energy Solutions
(EnergyPro)
PNW GT50 Low (NBI)
40
32
PNW GT50 High (NBI)
30
20
PECI (eQuest)
10
0
EUI (kBtu/SF)
Whole building Mean EUI = 48 (kBtu/SF),
with a Standard Deviation of 13 (kBtu/SF)
Slide 23
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
Small Office VRF HP
HVAC EUI Comparison
9.4
9.2
9.2
9.0
8.8
Energy Solutions
(EnergyPro)
8.6
8.4
8.2
PECI (eQuest)
8.0
8.0
7.8
7.6
7.4
HVAC EUI (kBtu/SF)
HVAC EUI Mean = 9 (kBtu/SF),
with a Standard Deviation of 1 (kBtu/SF)
Slide 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
Medium Office VRF EUI Comparison
60
54
47
50
40
39
34
Energy Solutions
(EnergyPro)
GT50 Ave (NBI)
30
Mitsubishi (EnergyPro)
20
PECI (eQuest)
10
0
EUI (kBtu/SF)
Whole Building EUI Mean = 43 (kBtu/SF),
with a Standard Deviation of 8 (kBtu/SF)
Slide 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
Small Office VRF Savings Comparison
25.0
21.0
20.0
Energy Solutions
(EnergyPro)
15.0
PECI (eQuest)
10.0
5.0
4.2
0.0
savings EUI (kBtu/SF)
Savings EUI Mean = 13 (kBtu/SF),
with a Standard Deviation of 12 (kBtu/SF)
Slide 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
Medium Office VRF Savings Comparison
16.0
13.6
14.0
12.0
10.0
8.9
8.0
Energy Solutions
(EnergyPro)
PECI (eQuest)
6.0
4.0
2.0
0.0
savings EUI (kBtu/SF)
Savings EUI Mean = 11 (kBtu/SF),
with a Standard Deviation of 3 (kBtu/SF)
Slide 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
Office Building Definition
 A building used primarily for office functions, including
desk-work, reading and light equipment (computer,
copier, printer, telephone, etc.) use.
 Office occupancies are further defined by
 overall occupant densities between 50 and 300
square feet per person,
 overall lighting power densities up to 1 watt per
square foot, and
 overall equipment plug loads up to 1.5 watts per
square foot.
Slide 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
VRF System Definition
Variable refrigerant flow (VRF) systems, either heat-pump
or heat-recovery styles, providing heating and airconditioning, and typically consisting of:
1. Outdoor unit(s) with inverter driven compressor(s) and
condenser fan providing improved part-load and lowambient performance,
2. Multiple indoor units with multi-speed fans, electronic
expansion devices, integrated zone temperature
controllers and no electric resistance heating capacity,
3. Refrigerant piping between the outdoor and indoor units,
5. Ventilation provided by either natural ventilation or a
dedicated outside air system (DOAS).
Slide 29
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
VRF System M&V Best Practice?
– Meter baseline and VRF system electricity use for
representative period, project to annual savings
– Use calibrated Building Simulation model to predict
annual savings and monthly electricity use
– Verify savings by comparing actual monthly electricity
use to predicted monthly electricity use
Slide 30
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
VRF System M&V Standard Protocol?
– Use whole building regression analysis spreadsheet with
representative period pre- and post- monthly electricity
billing data and hourly average OSA temperature,
– if savings are temperature dependant, over 15% of
whole building electricity use and there are no other
significant changes to electricity use, the whole building
regression analysis spreadsheet can provide an 80-20
confidence interval for savings
Slide 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
Small Office Monthly Electricity Use and Savings
30,000
20,000
Monthly Savings (kWh)
15,000
Proposed (kWh)
10,000
Adj Baseline (kWh)
5,000
No
v
p
Se
l
Ju
ay
M
ar
M
n
0
Ja
(kWh)
25,000
Based on Energy Solutions EnergyPro model
Slide 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
Percent Monthly Electricity Savings
33% 32%
35%
(%)
33%
31% 31%
27%
30%
25%
30% 31% 32%
28%
25%
21%
20%
15%
10%
5%
0%
Jan Feb Mar
Apr
May Jun
Jul
Aug Sep Oct
Nov Dec
Based on Energy Solutions EnergyPro model
Slide 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
Use Whole Building Analysis for VRF ROB
Electricity Savings M&V?
– Energy Solutions EnergyPro model predicts monthly
electricity savings ranging between 21 and 33%
– For the Small Office (7,200 SF) the monthly electricity
savings ranging between 1,900 and 2,200 kWh
Next Step: use whole building regression analysis
spreadsheet, using EnergyPro model predicted monthly
electricity use and Seattle hourly average OSA
temperature
Slide 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
Next Meeting
– Scheduled for 12/21/11 at 9 am
– Move to 12/14/11 at 9 am?
Potential Topics:
– Compare actual RTU annual fan kWh/SF to models
– Develop VRF savings estimates (IEER plus fan?)
– Compile list of PNW VRF installations & brainstorm how
to “mine” for useful information
– Develop M&V best practice and standard protocol
– Develop research plan to verify model accuracy
– NEEA RTU Replacement Discussion
Slide 35