Building Performance and Efficiency_Project_Regenerative Lifts

Energy Efficient Elevators: A Study of Regenerative Drive Group Members Shaheen Mistry Htet Eint Phoo Shruti Srinivas Vaishali Parmar

Introduction Context • BCA has targeted 80% of all buildings in SG to be GM certified by 2030. installation of regenerative lifts is a prerequisite for Green Mark Certification.

•

Regen is a green technology. It produces clean & safe energy that does not damage the network

Significance Buildings account for 38% of total electricity consumption in SG and out of this 3% to 10% is consumed by elevators.

• Taking into account demographic trends as well as a growing need for convenience, it is expected that the number of lifts and escalators will be rising worldwide.

• Further urbanisation in developing countries and a growing awareness of accessibility issues due to an aging population s will foster the need for more of this equipment.

• Understanding energy usage and costs is becoming increasingly important to clients of the elevator industry. Thus it is necessary to be able to predict, with reasonable accuracy, the energy usage of a new elevator installation and of an existing installation post modernization.

The Principle of Regenerated Energy in a Lift system • Potential energy is constantly being transferred while the car is moving.

• If, a lift is travelling down full and the load weight (people inside) is larger than the counterweight, then the motor torque is opposite direction to the speed i.e., the motor is braking • In the same way, when the lift is going up with light load, the motor is braking to prevent the car from coming up very fast due to heavy counterweight.

• This braking energy is the regenerated energy which is typically dissipated in a resistance and it can be saved if the motor is controlled with a regenerative drive.

• It is possible if the motor acts as a generator and is directly connected to the grid or depending on the typology allows the braking energy to be injected back to the power network

Lift motor operating modes (fM ‐ Motor force ; v ‐ Speed ) (source: ISR‐UC

The Principle of Regenerated Energy in a Lift system

Regenerative operation of a lift equipped with a regenerative inverter (source: Mitsubishi) Theoretically, if there were no losses, the regenerated energy would be equal to the motoring energy.

Total Energy= Mechanical Energy+ Auxiliary Energy- Regenerative energy However, there are still losses due to the existence of • friction losses (e.g. friction in the guide rails, air resistance), motor losses (e.g. the copper • losses, the iron losses) • and, in geared systems, losses in the gearbox (this is especially significant in systems equipped with worm gears where the efficiency in the reverse direction is considerably • lower than in the forward direction).

• Illumination circuit, car illumination, socket on car roof, car fan, emergency call and telephone monitoring, backup power supply.

Hence we can represent the energy regenerated as

Total Energy= Mechanical Energy+ Auxiliary Energy+Losses -Regenerative energy

Manufacturer’s Claims For • lifts capacity ranging from 650-2500 kg • lift speeds 1.5m/s to 2.5 m/s • Number of starts 1000-1500 / day • Condition: fully loaded

S. No.

Manufacturer

Low rise (below 30 stories)

Mid rise (30-80stories)

High rise (80 and above)

1.

OTIS

60%

50%

75%

2.

Mitsubishi

60%

50%

70%

3.

Kone

60%

65%

75%

Hypothesis

1.

Lifts having high capacity will have more energy consumption. These will also produce more regenerative energy.

2.

Regenerative drive will be more efficient in high rise buildings compared with low-rise buildings.

Methodology

Literature Review and comparative study based on OTIS data

Live case study 1: NHC towers by Kone- understanding the regenerated energy- new construction

Live case study 2: Fuji Xerox towers by Mitsubishi – retrofit construction

Comparative analysis

Conclusion and hypothesis validation

History of Elevators

Type of Elevator

Year

Speed

Load

Steam-powered-1st 1857 Passenger elevator

0.2 m/s

450 kg

Hydraulic Power

1867

2.5 m/s

Direct connected Geared Elevator

1889

Traction

1903

2.5 m/s

Gearless

1922

7 m/s

675 kgPassengers 1125 kg-Freight

Calculation of energy consumption using Doorlard and Schroeder’s Method Doolard’s method • •

Energy consumed by each elevator when it makes a round trip is considered.

Comparison between the different elevator drive technologies.

Schroeder’s method •

An estimate for the daily energy consumption of the elevator can be made.

The daily energy consumed (Ed) is: Ed = R x ST x TP /3600 where: R is motor rating ST is daily number of starts TP is trip time factor

Drawbacks of Doolard and Schroedar methods • • •

Proven to be inconsistent by almost a factor of two.

These methods are only suitable for rule of thumb calculations, and for making comparative assessments between different configurations.

They cannot assess the benefits of regenerative drives, different roping arrangements, different efficiency motors or gearboxes, and so on.

Calculation of energy consumption using ISO formula ISO FORMULA E(total) = Z x k1 x k2 x hmax x Pm / v x 3600 + Standby Energy E = Annual Energy Consumption Z = Number of starts k1 = Average Load factor K2 =Height factor Pm=Motor Power v= Speed of lift

SCOPE OF ISO METHOD OF CALCULATION a) a method to estimate energy consumption based on measured values, calculation, simulation on an annual basis for traction, hydraulic and positive drive lifts . b) energy classification system for new, existing, and modernized traction, hydraulic .

DRAWBACKS OF THE ISO METHOD ISO doesn’t take the following into consideration : a) hoistway lighting; b) heating and cooling equipment in the lift car; c) machine room lighting; d) machine room heating, ventilation, and air conditioning; e) non-lift display systems, CCTV security cameras, etc.; f) non-lift monitoring systems (e.g. building management systems, etc.); g) effect of lift group dispatching on energy consumption; h) environmental conditions; i) consumption through the power sockets; j) lifts whose travel includes an express zone.

Hypothetical Cases Considered to arrive at the energy consumption of lifts and the possible regenerated energy Assumptions Standby power considered = 0.6 Kw Speed of Hydraulic lift = 1m/s Speed of Gear lift =1.3m/s Speed of Gearless lift =2m/s Percentage of Regenerated Energy considered = 20% to 40%(Source: OTIS)

CASE 1 Height of building :60m

OFFICE Hydraulic = 147600 x 0.3 x 0.5 x 60 x 16.7 / 1 x 3600 = 2,21,84,280/ 3600 = 6162.3+ 5256 = 11418.3 kWh Energy Regenerated =2283.33 kWh

Gear

= 147600 x 0.3 x 0.5 x 60 x 12.7 / 1.3 x 3600 = 17265960 / 4680= 3689.3 + 5256 = 8860.84 kWh Energy Regenerated =3544.33 kWh

Gearless = 147600 x 0.35 x 0.5 x 60 x 11.7 / 2 x 3600 = 1,81,32,660 / 7200= 2518.42 + 5256 = 7774.42 kWh Energy Regenerated = 3109.76 kWh

OFFICE

Type of elevator

Annual energy consumption (in kWh)

Energy Regenerated(in Kwh)

Hydraulic

11418.3

2283.33

Gear

8860.84

3544.33

Gearless

7774.42

3109.76

Type of elevator

Annual energy consumption (in kWh)

Energy Regenerated(in Kwh)

Hydraulic

11774.9

2354.98

Gear

10072.59

4029.03

Gearless

8233.10

3293.24

RESIDENTIAL

Constants: Standby power considered = 0.6 kW

CASE 2 : HEIGHT OF BUILDING : 90M OFFICE Type of elevator

Annual energy consumption (in kWh)

Energy Regenerated(in Kwh)

Hydraulic

14,499.45

2899.89

Gear

10,663.26

4265.30

Gearless

9033.63

3613.45

Type of elevator

Annual energy consumption (in kWh)

Energy Regenerated(in Kwh)

Hydraulic

15,034.35

3006.87

Gear

12,480.89

4992.35

Gearless

9,721.66

3888.66

RESIDENTIAL

ELECTRICITY COST Type : Residential Height of building : 60 m Type of elevator

Energy Consumption by 1 lift (in kWh)

Energy Regenerated ( in kWh)

Cost Before Regeneration (SGD)

Cost After Regeneration (SGD)

Savings per lift (SGD)

Hydraulic

11,774.9

2354.98

2000

1665.45

334.55

Gear

10072.59

4029.03

1780.80

1068.5

712.30

Gearless

8233.10

3293.24

1455.61

873.36

582.25

Height of building : 90 m Type of elevator

Energy Consumption by 1 lift (in kWh)

Energy Regenerated ( in kWh)

Cost Before Regeneration (SGD)

Cost After Regeneration (SGD)

Savings per lift (SGD)

Hydraulic

15,034.35

3006.87

2658.07

2126.45

531.62

Gear

12,480.89

4992.35

2206.62

1323.97

882.65

Gearless

9,721.66

3888.66

1718.78

1031.27

687.50

Live Case Study 1 National Heart Centre, Singapore

Project Detail GFA No. of storey Year of Completion Building use Total no. of Lifts

– 48,000 sq. m – 12 storey – 2014 – Hospital – 12 no. (10 are regenerative lifts, served from Basement 3 to Level 12)

Live Case Study 1, NHC Six months data from NHC Type of Lift

Passenger Lifts

Service lifts

Capacity

Speed (m/s)

Sep-2015 (kWh)

Oct-2015 (kWh)

Nov-2015 (kWh)

Dec-2015 (kWh)

Jan-2016 (kWh)

Feb-2016 (kWh)

PL1

24 Persons (1630 kg)

2.5

270.309

297.666

274.013

280.448

234.088

215.557

PL2

24 Persons (1630 kg)

2.5

314.498

352.751

303.433

297.985

278.837

244.236

PL3

24 Persons (1630 kg)

2.5

226.034

248.874

219.127

218.302

194.862

156.439

PL4

18 Persons (1225 Kg)

2.5

175.689

199.471

178.624

189.916

176.986

161.681

SL1

35 Perons (2400 kg)

2.5

818.056

879.04

796.705

792.208

789.682

689.432

SL2

35 Perons (2400 kg)

2.5

804.366

881.428

783.608

832.012

762.033

743.654

SL3

24 Persons (1630 kg)

2.5

482.108

536.809

512.931

500.654

527.484

441.987

SL4

24 Persons (1630 kg)

2.5

591.638

624.33

582.021

599.463

656.018

610.763

Comparing energy consumption on six months

900

Energy Consumption (kWh)

800 700

When the capacity is bigger (the speed = constant), the energy consumption of lifts become larger.

600 500 400 300 200 100 Sep-15 PL1

Oct-15 PL2

PL3

Nov-15 PL4

Dec-15

Month SL1

SL2

Jan-16 SL3

Feb-16 SL4

Live Case Study 1, NHC Manual calculation to determine the energy regenerated

Type of Lift

Capacity

Speed (m/s)

Energy Consumed

Total Energy Consumption = Mechanical Energy + Auxiliary Energy –Regenerative Energy

PL1

24 Persons (1630 kg)

2.5

For Passenger Lifts (PL 1) calculation

PL2

24 Persons (1630 kg)

2.5

PL3

24 Persons (1630 kg)

2.5

PL4

18 Persons (1225 Kg)

2.5

SL1

35 Persons (2400 kg)

2.5

SL2

35 Persons (2400 kg)

2.5

SL3

24 Persons (1630 kg)

2.5

SL4

24 Persons (1630 kg)

2.5

For peak hours NHC Operation Hours (8am – 5pm) (Assuming for the people who wants to consult with doctors, 9:00am to 9:30am // 3:00pm to 3:30pm) Visiting hours – (12:00pm to 2:00pm // 5:00 pm to 8:30 pm) (Assuming for the people who visit their patient in NHC, 12:00pm to 12:30pm // 7:00pm to 7:30pm)

Service and Staff lifts

Jan-2016 (kWh) 234.088

278.837 %

Energy Regenerated Energy Consumed

194.862 %

Energy Regenerated Energy Consumed

176.986 %

Energy Regenerated Energy Consumed

789.682 %

Energy Regenerated Energy Consumed

762.033 %

Energy Regenerated Energy Consumed

527.484 %

Energy Regenerated Energy Consumed Energy Regenerated

% of saving %

Energy Regenerated Energy Consumed

Passenger Lifts

Traffic Patterns (considering diversity factor)

Item

656.018 %

For low traffic (at night) (8:30pm to 8:00am) (50% of the full load ) For normal hours – 70% of the full load 

ME = KE + PE = ½ mv2 + mgh

• 100% full load capacity (peak 2 hours) Mechanical Energy = ½ x 1630 x 2.52 + 1630 x 9.81 x 60 = 964511.75 Nm = 0.27 kWh (1kWh = 3600,000 Nm) = 0.54 kWh/day (x2) = 14.04 kWh/ month (x26)

• 70% of the full load capacity (normal 10:30 hrs) Mechanical Energy = ½ x 1141 x 2.52 + 1141 x 9.81 x 60 = 4108855.1 Nm = 0.18kWh = 1.89 kWh/day (x10.5) = 49.14 kWh/ month (x26)

• 50% of the full load capacity (11:30 hrs at night) Mechanical Energy = ½ x 815 x 2.52 + 815 x 9.81 x 60 = 482255.875 Nm = 0.13 kWh = 1.495 kWh/day (x11.5) = 38.87 kWh/ month (x26)

Live Case Study 1, NHC  Auxiliary Energy = =

Energy consumed by lighting + circuit (data from the supplier) 1 kWh + 3kWh = 4kWh/ month

Total Energy Consumption = Mechanical Energy + Auxiliary Energy – Regenerative Energy 234.088 = 102.05 + 4 – RE RE = -128.038 kWh % of saving

= 35%

For Staff and Service Lifts (PL 1) calculation For peak hours NHC Operation Hours (8am – 5pm) Morning (8:00am to 8:30am), before lunch (12:00pm to 12:30pm), after lunch (1:00pm, 1:30pm), Evening (5:306:00pm) For low traffic (at night) (9:00pm to 6:00am) (50% of the full load ) For normal hours – 70% of the full load • 100% full load (peak 2 hours) Mechanical Energy = 20.28 kWh/month

Regenerative Energy

=

% of saving

=

-626.302 kWh

44%

• 70% of full load capacity (normal 13 hrs) Mechanical Energy = 94.64 kWh/ month (x26)

• 50% of full load capacity (9 hrs at night) Mechanical Energy = 44.46 kWh/month

Live Case Study 1, NHC Capacity

Speed (m/s)

PL1

24 Persons (1630 kg)

2.5

PL2

24 Persons (1630 kg)

2.5

PL3

24 Persons (1630 kg)

2.5

PL4

18 Persons (1225 Kg)

2.5

SL1

35 Persons (2400 kg)

2.5

SL2

35 Persons (2400 kg)

2.5

SL3

24 Persons (1630 kg)

2.5

SL4

24 Persons (1630 kg)

2.5

Type of Lift

Passenger Lifts

Service and Staff lifts

Item Energy Consumed Energy Regenerated Energy Consumed Energy Regenerated Energy Consumed Energy Regenerated Energy Consumed Energy Regenerated Energy Consumed Energy Regenerated Energy Consumed Energy Regenerated Energy Consumed Energy Regenerated Energy Consumed Energy Regenerated

Jan-2016 (kWh) 234.088 128.038 278.837 172.787 194.862 88.812 176.986 94.466 789.682 626.302 762.033 602.653 527.484 418.184 656.018 546.718

% of saving 35%

Percentage of Saving

38%

31%

SL

35%

4

44%

3 2

44%

1

PL

44% 46%

0%

10%

20%

30%

40%

50%

Energy saving of eight lifts on Jan-2016 900

Energy (kWh)

800

•

Compared with passenger lifts, the service and staff lifts have high capacity and seems to have heavy traffic. More savings are found in service lifts.

•

Energy consumption and energy regenerated is most influenced by the traffic flows.

700 600 500

400 300

The savings of eight regenerative lifts are within 31% - 46% (Kone claim that energy consumption of lifts with regenerative drive can be reduced to 60%) •

200 100 0 PL 1

PL 2

PL 3

PL 4

SL 1

SL 2

Type of lifts Energy Consumed Energy Regenerated

SL 3

SL 4

Live Case Study 2 – Fuji Xerox Tower

Car Park Lift 1 (B3-2flr)

Car Park Lift 2 (B3-2 flr)

Low Rise Zone (3-15 flrs)

High Rise Zone (15, 29-38 flrs)

Service Lifts (B3-15 flr)

Mid Rise Zone (15, 24-28 flrs)

Note: 15-24 flrs - void

Floor Plan Retrofitting – Lift Modernization with Regen Drives GFA – 47,000 sqm Height – 38 storeys Commissioned – 1987 No. of Lifts - 16 (12 with Regen) Original & Retrofit – Mitsubishi Elevators Retrofitting Period - Jun 2012 – Oct 2014 Developer – CDL Major Tenants – Fuji Xerox / Prudential / Watsons

Lift Zoning: Low Rise Zone – 3rd to 15th floor Mid Rise Zone – 3rd, 15th, 24th to 28th floor High Rise Zone - 3rd, 15th, 29th to 38th floor Car park Lifts – B3 to 3rd flr (no regen) Service Lifts - B3 to 15th flr (no regen)

Live Case Study 2 – Fuji Xerox Tower Zone

No. of Lifts No. of Stops

Motor

Capacity

Speed (m/s)

Before

After

Regen Drive

Low Rise (Upto 15 flrs)

4

14

1155 kg (17 persons)

3

Thyristor

VVVF

Yes

Mid Rise (Upto 28 flrs)

4

6

1155 kg (17 persons)

5

Thyristor

VVVF

Yes

High Rise (Upto 38 flrs)

4

12

1155kg (17 persons)

7

Thyristor

VVVF

Yes

Car Park Lifts (Upto 2 flrs)

2

6

815 kg (11 persons)

1

AC-Geared

VVVF

No

Service Lifts (Upto 15 flrs)

2

17

1600 kg (20 persons)

1.5

AC-Geared

VVVF

No

18,000.00

Jul 2012 to Oct 2014 – Lift Modernization

•

Observed that the energy consumption is reduced after introduction of modern technology in lifts.

Lift Modernization Period

16,000.00

12,000.00 10,000.00 8,000.00

6,000.00 4,000.00 2,000.00

Car Park (kWh)

Car Park (kWh)

Service Lift (kWh)

Low Rise Zone (kWh)

High Rise Zone (kWh)

Mid Rise Zone (kWh)

Feb '16

Jan '16

Dec '15

Nov '15

Oct '15

Sep '15

Jul '15

Aug '15

Jun '15

May '15

Apr '15

Mar '15

Feb '15

Jan '15

Dec '14

Nov '14

Oct '14

Sep '14

Aug '14

Jul '14

Jun '14

May '14

Apr '14

Mar '14

Feb '14

Jan '14

Dec '13

Nov '13

Oct '13

Sep '13

Aug '13

Jul '13

Jun '13

May '13

Apr '13

Mar '13

Feb '13

Jan '13

Dec '12

Nov '12

Oct '12

Sep '12

Aug '12

0.00 Jul '12

Energy Consumption (kWh)

14,000.00

Live Case Study 2 – Fuji Xerox Tower • Jul 2012 to Oct 2014 – Lift Modernization • Oct 2013 to Oct 2014 – Regen Drive Activation

18,000.00 16,000.00 14,000.00

10,000.00 8,000.00 6,000.00 4,000.00 2,000.00

Lift Modernization Period

Low Rise Zone (kWh)

Phase-wise Activation of Regen Drive

Jan '16

Nov '15

Sep '15

Jul '15

May '15

Mar '15

Jan '15

Nov '14

Sep '14

Jul '14

May '14

Mar '14

Jan '14

Nov '13

Sep '13

Jul '13

May '13

Mar '13

Jan '13

Nov '12

Sep '12

0.00

Jul '12

Energy Consumption (kWh)

12,000.00

High Rise Zone (kWh) Mid Rise Zone (kWh)

Live Case Study 2 – Fuji Xerox Tower Comparing Annual Energy Consumption from 2013 to 2015

Reduction in Energy Consumption for three zones 16000

35000

14000

30000

12000

25000

10000

20000

2013

max kWh

8000

min kWh

2014

15000

2015

6000

10000 4000 5000

2000

0

0 High Rise

Mid Rise

Jan Feb Mar Apr May Jun

Low Rise

Maximum Energy Consumption (kWh)

Minimum Energy Consumption (kWh)

% of reduction

High rise

15236.47

5564.60

63%

Mid rise

9570.87

3956.56

59%

Low rise

5649

3617.94

36%

Obviously, Regenerative drive is more efficient in high-rise buildings compared to low rise as expected.

Jul

Aug Sep Oct Nov Dec

From 2013 to 2015, there is a 57 % decrease in energy consumption.

As 3-10% is the lift energy consumption in a building, assuming 8% is this energy, with the application of regen drive, total lift energy consumption in a building shall reduce by 4.56%

Case Study Results 1. Literature Review. Different heights (60m and 90m) %Regenerated energy specified by Otis for various heights 2. NHC. different load conditions. Speed and height constant (60 m) Capacity

1630 kg

2400 kg

Energy saving 30%-38%

45%

3. Fuji Tower. different height and speed conditions. Load is constant (1155kg) Height Energy saving

Zone1 (42m) Zone 2 (84m)

Zone 3 (114m)

36%

63%

59%

Result Interpretation 1.

2.

3.

78-86 % more energy regenerated when number of floors increased from 20 stories to 30 stories There is 10%-15 %increase in energy saving as the capacity increases by 700-800 kg There is 20% increase in energy saving as the height goes up from low rise to mid rise and further increase in 5% as the height goes up from mid to high rise

Conclusion • Regenerative drives are considerable more efficient in high to super high structures with high capacity and high traffic.