Proposed Mandatory Building Energy Codes Do they Go Far Enough?
Best Practice – ASHRAE 90.1
Philip C.H. YU PhD RPE CEng Trane Environmental & Applications Engg Chair, TWG – Energy, ASHRAE HK Chapter
Acknowledgement ENERGY • ASHRAE Hong Kong Chapter TWG-Energy – – – – – –
Philip Yu (Chair) Vincent Chu TW Fung Jacob Yiu David Fan JH Wang
• References – ASHRAE Standard 90.1 – GB 50189
2
Standard Rating Conditions • Lack of equipment rating standard, e.g. ARI 550/590 for chiller performance • Water-side Fouling Factor: – 0.0001 h⋅ft2⋅ºF/Btu or 0.000018m2⋅ºC/W for the evaporator – 0.00025 h⋅ft2⋅ºF/Btu or 0.000044 m2⋅ºC/W for water-cooled condenser
3
Standard Rating Conditions • To catch up with current technology: change “chilled water temp - IN ” to chilled water flow rate, e.g. 2.4 gpm/ton or 0.043 L/s per kW change “condenser water temp – OUT” to condenser water flow rate, e.g. 3.0 gpm/ton or 0.054 L/s per kW • Ref. Standard: ARI 550/590, GB/T 18430.1 4
Minimum Energy Efficiency • -
Compressor technology: recip being phased out by scroll for small equipment, by screw for large equipment - air-cooled centrifugal is no longer existing due to the efficiency improvement of screw - Open-type compressor: extra energy for motor cooling shall be estimated and included in calculating the equipment COP 5
Minimum Energy Efficiency Compressor Type Water-cooled scroll Air-cooled
Water-cooled screw Air-cooled
centrifugal
Water-cooled
Cooling Capacity (kW)
PRC
USA
HK
≤527
3.80
4.20
4.00
527～1163
4.00
4.20
4.50
＞1163
4.20
4.20
5.20
≤50
2.40
2.80
2.70
＞50
2.60
2.80
2.70
≤527
4.10
4.45
4.60
527～1163
4.30
4.90
4.60
＞1163
4.60
5.50
5.50
≤50
2.60
2.80
2.90
＞50
2.80
2.80
2.90
≤527
4.40
5.00
4.00
527～1163
4.70
5.55
4.50
＞1163
5.10
6.10
6 5.70
Variable-Speed Technology • VSD for VAV fan control, motor size >15 HP 3 N2 • Variable flow pump system P2 = P1 power >10 HP N1 • VSD-chiller not energy-saving unless – cooling load varies significantly with long operating hours at low-load; or – cooling water temperature reduces significantly at part-load ( 100 people per 1000 ft² or fresh air intake > 3,000 cfm] – Shut-off when when unoccupied – Occupancy sensor – CO2 demand control 12
Advanced System Controls • Chiller-tower energy optimization • Variable-primary-flow (re: ARTI 2004) – Total annual plant energy 3~8% – First cost 4~8% – Life cycle cost 3~5% more
13
Lighting Power Density Interior LPD, W/m² Space type
PRC
USA
HK
Library
9
13
17
Hotel
13
10
17
Office
9
10
17
Retail
10
15
20
School
9
12
17
14
Lighting Power Density Tradable exterior surface
Maximum LPD
Parking lots and drives
0.15 W/ft²
Building main entries
30 W/lin ft of door width
Canopies
1.25 W/ft²
Outdoor sales open areas
0.5 W/ft²
Source: ASHRAE Standard 90.1-2004 15
BEC vs. Green Building Building Market Proportion of Market Attaining
0.12
0.1
0.08
0.06
Typical Practice The Majority
0.04
75%
Green Buildings 25% Certified Silver
0.02
Law Breakers
Gold Platinum
Innovators/ Risk-takers
0 0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Green Standards
16
Go far enough?
30% 90.1 AEDG
50% AEDG
Net Zero Energy Building
17
Knowing is not enough; we must apply. Willing is not enough; we must do. THANK YOU
Dr. Philip Yu,
[email protected], 2594-9741
18
Variable Frequency Drive Centrifugal Chiller IPLV comparison 0.55 Lowest-std Highest-std Highest-VFD Lowest-VFD
Energy Efficiency, kW/ton
0.5
0.45
Standard Chillers 0.4
0.35
Chillers w/VFD 0.3 0
500
1000
1500 Nominal Cooling, tons
2000
2500
VFD=Efficiency? 0.8
kW/ton
0.7
Standard Unit
0.6 0.5 0.4
Std. Unit with VFD
0.3 20%
30%
40%
50%
60%
70%
80%
90%
Load
Performance at ARI conditions
100%
VFD=Efficiency? 1.100 - Std. Eff. Unit w/VFD - Std. Eff Unit
kW/ton
0.900 0.700 0.500 0.300 15%
25%
35%
45%
55%
65%
75%
85%
95%
% Load
Performance at Constant water temperature
Performance vs ECWT 85ºF (29.4ºC) ECWT 350 300
kW
250
- High Eff. Unit - Std. Eff. Unit w/VFD
200 150 100 50 0
20% 30% 40% 50% 60% 70% 80% 90% 100%
Load
ECWT = Entering Condenser Water Temperature
80ºF (26.7ºC) ECWT
350 300
200 150 100 50
90 %
10 0%
Load
80 %
70 %
60 %
50 %
40 %
30 %
0
20 %
kW
250
- High Eff. Unit - Std. Eff. Unit w/VFD
ECWT = Entering Condenser Water Temperature
70ºF (21.1ºC) ECWT 300 250
150 100 50
10 0%
90 %
80 %
70 %
60 %
50 %
40 %
30 %
0
20 %
kW
200
- High Eff. Unit - Std. Eff. Unit w/VFD
Load ECWT = Entering Condenser Water Temperature
60ºF (15.5ºC) ECWT 250
150 100 50
10 0%
90 %
Load
80 %
70 %
60 %
50 %
40 %
30 %
0
20 %
kW
200
- High Efficiency Unit - Std. Eff. Unit w/VFD
ECWT = Entering Condenser Water Temperature
Chiller-Tower Optimization Optimum Temp. Total Chiller only
Cooling Tower only
How do chiller reacts to variable flow? 1 30
1 ,500 .00
C a p a c ity C o n tro l w /o W a te r F lo w C o m p e n s a tio n
1 ,300 .00
1 10
1 ,100 .00
1 00
9 00.0 0 E va po ra tor W ate r F lo w
90
80
70
7 00.0 0
5 00.0 0
Change Too Fast can be a problem
3 00.0 0
60
1 00.0 0 E va p E nte ring W a te r T e m p
-1 00.0 0
50
40
-3 00.0 0 C hille r o n E va p L e avin g W a ter T em p
30 0 :00:00
0:10 :00
C h iller off
0:2 0:00
C hille r off
0:3 0:00
T im e (h o u r:m in :s e c )
0:4 0:00
-5 00.0 0 0 :50:0 0
Water Flow [gpm]
Water Temp [degF]
1 20
Newer Technology Can Eliminate all Concerns 1,500.00
130
C apacity C ontrol w ith W ater Flow C om pensation
1,300.00
110
1,100.00
100
900.00
90
80
70
700.00
E vaporator W ater F low
No Problem!
60
500.00
300.00
100.00
E vap E ntering W ater T em p
-100.00
50
-300.00
40 E vap Leaving W ater T em p
30 0:00:00
0:10:00
0:20:00 0:30:00 Tim e (h o u r:m in :sec)
0:40:00
-500.00 0:50:00
Water Flow [gpm]
Water Temp [degF]
120
