ENERGY EFFICIENT ELEVATORS ESCALATORS AND REGENERATION

The energy has become essential, but its high costs should motivate us to save wherever is possible. In particular, in Europe today there are nearly five million elevators and escalators, so 5 million of opportunities for action that could affect energy efficiency, energy recovery and the possibility of reducing the emission of carbon dioxide in the atmosphere (CO2) during the operation. It is therefore important to keep in mind that the less we consume, the less it pollution.

MSEE Ibrahim GULESIN

Introduction
Italy is the European country that emits carbon dioxide into the atmosphere about 10 times higher than Switzerland and much of that wasted energy that could easily be recovered for example, installing solar panels for hot water, photovoltaic panels to produce electricity or thermal insulation in external walls and roofs of buildings and produce elevators, high efficiency and low consumption or with energy recovery. It can even have energy savings totally consumed in the building up to more than 50%. Considering that the less you consume, pollute less, if we want to respect the Kyoto protocol is necessary to implement something concrete even in the elevator industry. Why, considering the table below:

COUNTRY

No. of lifts installed (2010)

No. of lifts sold annually (2010)

Spain

910.563

33.836

Italy

850.000

13.400

German

650.000

9.984

Turkiye

232.700

7.400

In Europa

4.752.233

116.226

There is already about 4,8 million lifts, as well as about 75 thousand escalators and moving walks installed in the EU-27. Their energy consumption adds up to 3 to 5 % of the overall consumption of a building. About one third of the final energy consumption in the European Community occurs in the tertiary and residential sector, mostly in buildings. Due to the increasing comfort requirements, energy consumption in buildings recently experienced a significant raise, being one of the leading reasons for a growing amount of CO2 emissions. High untapped saving potentials exist with respect to energy-efficient equipment, investment decisions and behavioral approaches, in these sectors.

Simulations indicate that on average a hydraulic lift at low load, running 100,000 starts a year, would use 1,900 kWh / year. On the other hand power consumption in standby can get a lift to 2 kW, which would translate into 10,000 kWh / year for 5000 hours of standby time in a year. This represents a substantial share of total annual electricity consumption of the elevator, which is between 25 and 80%.

The elevator systems have been designed individually for each specific application. Each of its parts contribute differently to the overall efficiency of the lift. All elevator systems have common elements, regardless of their principle of operation, including: a cabin, doors, lights and ventilation systems, a motor and a control device (said control panel) with shaft,(an enclosed area where the car travels). There are two main classes of systems: hydraulic lifts and electric traction. Electric traction can be further divided into two categories: motor with gearbox (geared) and gearless.

The hydraulic elevators are typically have no counterweight, are the most inefficient and consumes an amount of energy three times greater than an electric elevator. The energy is dissipated as heat when it goes down. Hydraulic elevators traveling at low speeds, typically less than 1 m / s. The maximum stroke for this type of plant is about 20 m. This is due to the fact that increasing the height of travel, the pistons of larger diameter should be used to withstand the greater forces of instability. This increases the cost of the equipment that makes the systems less attractive.

The technological choice between the 2 types of lifts (hydraulic or electric) is based on a ratio of 3:1 of difference of energy consumed. Within the same category, the difference in energy consumed between the most efficient and least can get to 30-40%. Anyway, we must remember that at least two thirds of all systems installed today are hydraulic elevator, however, limited to no more than seven stops, the rest are called elevators that use electric traction rope guided by pulleys driven by a motor and are fitted with a counterweight that reduces the weight to be lifted.

Dynamical systems are driven by motors with large rotating masses or used to move large loads of weight, build up high levels of kinetic energy or potential energy and this means that when there is a slowdown or shutdown may present a problem. Is thus required the motor to work in reverse and the motor behaves as a generator of electrical energy that must be diverted or dissipated. An easy way to do this is to provide a surplus of electricity to a resistor which converts it into thermal energy. Examples of systems that store kinetic energy are centrifuges, press brakes, wind generators, large fans and trains, while examples of potential energy sources are adapted elevators, escalators and cranes.

Between the drive systems of the motor of these lifts we can find DC motor with generator (MDC-G) that has the lowest efficiency because of the large energy loss in the motor and the generator, which converts electrical energy into mechanical energy and finally back into electrical energy. Another reason for the low efficiency of the drive motor MDC-G is that the engine must be kept running when the elevator is idle.

Similarly, even AC motors to 1 or 2 speeds are considered less energy efficient. These motors usually one or two speeds, especially during acceleration and deceleration, consume electricity 4 or 6 times more than normal which is dissipated as a result of overheating in the motor winding. The gearbox and flywheel iron / cast iron contributing to the low efficiency of the system.

These types of electric motors AC-1, AC-2 or VVVF are also used for escalators and moving walkways in such a drive system (control panel) moves steps and handrails. Other elements that compose them are steps in addition to the drive, sensors, brakes and chain. The escalators typically traveling at a speed of about 0.5 m / s which is fast enough to provide a rapid shift without neglecting the comfort and safety. Escalators and moving walkways are used especially in commercial centers, airports and metro and its drive system of the engine is running all the time regardless of the loading condition of the stairs or escalators. Thus the electricity is continuously consumed even when there are no passengers on them. Much energy is therefore wasted if the number of passengers is widely fluctuating such as railway stations, commercial centers and places like public transport and metro.

The hydraulic elevators dominate the market for buildings are not very high, because they have substantially lower purchase prices. The market for buildings and buildings traditionally makes use of elevators with electric motor (geared), while those without direct electric motor (gearless) are predominant in high-rise buildings and skyscrapers. The oldest and least efficient elevators use electric motors or induction as DC drive motor and electromechanical relays for control. Currently, the control system with the relay has been abandoned and replaced with electronic control panels. Parallel to the drive units for lifts to one or double speed, are giving way to the systems of compact motors with permanent magnets and drive VVVF With PWM converter that will become an efficient use of equipment with a braking system capable of regenerating electric energy .

Fig.2. Control panel VVVF                                                                                                                             Fig.1. PWM Converter

A recent Canadian study on total energy consumption can be up to 3,000 GWh / year. There are about 150,000 lifts in Switzerland who consume about 300 GWh, equivalent 0.5% of electricity needs of the country. The standby power lifts is about 160 GWh.

Technological development in the elevator industry was mainly driven by factors other than energy efficiency. Travel speed, acoustic noise, ride comfort and space are the main concerns of the lift design. However, the demand for energy efficient and greener buildings has increased in recent years and the elevator industry has responded accordingly, presenting its customers with solutions to meet these growing needs.
The increase in electricity prices has also made an important contribution to the demand for more efficient energy solutions. In most applications, electricity costs are often higher than the same cost of equipment purchased, which is why it is so convenient to invest in an elevator with high energy efficiency.
The energy is used for efficient technological developments that take different approaches addressing several sources of inefficiency in vertical transportation systems. These causes can be divided into two main groups: direct and indirect. The direct causes are those that can be directly connected to the device, while the underlying causes are related to the operation of the equipment. The most common direct causes are: frictional losses, transmission losses, motor losses and losses on the brake resistor and brake.

The energy consumption of an installation of an elevator is a significant percentage of the total electrical load of the building. Estimates range from 5 to 15% depending on other services installed in the building. The understanding of energy use and costs is becoming increasingly important for customers of this industry. Therefore it is necessary to predict, with reasonable accuracy, the use of energy in a new installation and modernization of already existing plants.

If the objective is to recognize the energy efficiency of the lifts, the most important consideration is that they must be regarded as the best engineering systems, once installed the basic elements (cab compartment) these will be used for the life of ‘building (in many cases 30 to 100 years). However, during this life of service, many factors that can affect energy consumption, they may still be replaced.
Spain is home to the world of elevators, followed by Italy and Germany. Italy is the country that has the highest number of elevators, after Spain, which is about 850,000, the rate of growth and new facilities are impressive. Install each year from 10,000 to 20,000.

As we know, the life cycle of a plant is 10-30 years where it is undergoing major renovations that would correspond to about 20.000-40.000/anno. On average,  in Italy, there are approximately 50,000 new plants and renovated facilities.

In Europe you have then about 5 million of opportunities for action on energy efficiency of elevator. Most major manufacturers of elevators currently producing sytems can produce energy savings of 20-30% compared to traditional systems, which Delbo SpA, the market offers systems that can produce energy savings of 30% -80% with DB-EcoGen, DB-ReGen, and DB-6ReGen DB-HydroGen and 93% with DB-StByGen standby applies to new installations or existing installations for all types of elevators, escalators and moving walkways.                                                                                                

MSEE. Ibrahim GULESIN

Energy Transfer
A rope(electric traction) elevator, and counterweight, serves as a storage device for energy. In an ideal world without friction losses, energy is never consumed in an elevator, is borrowed and then returned. Taking as an example only of a building that houses offices, all passengers who take the elevator upward in the morning, will resume in the afternoon to go down. The potential energy that has been “stored” in the morning it will be returned to the system in the afternoon. The inefficiency of the system to cause the loss of energy. The system of the lift substantially converts electrical energy into mechanical energy input in the output, with losses in the form of heat. Taking a simplified diagram that represents the flow of energy in and out (see Figure 3), there are three active phases in the flow of energy during acceleration, constant speed and deceleration phase.

Fig.3 Diagram representing the Idea flow of energy use when the various phases of a journey of elevator

  1. When the elevator is at rest before the trip, the only energy consumed is that necessary to maintain the controller running.
  2. Once the elevator starts to accelerate, the system absorbs energy to deliver kinetic energy to the masses in motion. It will also be consumed or returned, as in the following phase the potential energy.
  3. At the end of the acceleration phase, the kinetic energy is no longer necessary because the velocity is constant. During the movement to the top: if the car is loaded with its load exceeds the acceleration phase to the constant speed and deceleration. The potential energy is required to move the masses unbalanced while the kinetic energy is stored / dissipated in the masses in motion (the weight of the car and the weight of the counterweight).
  4. The system is therefore designed to store potential energy. If the counterweight is heavier, the system returns potential energy. Similarly in the cars traveling to the bottom, the potential energy can be saved or restored.
  5. At the end of the constant speed, the elevator begins to slow down and is returned to the kinetic energy stored in moving masses. The potential energy will be drawn or returned as the final stage. From the moment the elevator stops at the floor, back to the first phase where the only energy consumed is needed to keep the controller running (standby).
  6. When the net energy required is negative, the unit will return regenerative energy in the distribution network, or consumed as a heat engine or as a heating resistor.

Fig.4 Diagram representing the flow of real power during the different stages of a journey of elevator

  1. When the elevator is at rest before the trip, the only energy consumed is that necessary to maintain the controller running.
  2. Once the elevator starts to accelerate, the system can absorb energy 3-6 times greater than the rated current of the motor or pump (if Example. Current Rating = 10 Amps can be up to 60Amper Power = 26 kW  and drops with oscillation in 2-3 seconds at the nominal current and power kW = 7kW) to provide kinetic energy to the masses in motion. It will also be consumed or returned, as in the following stage, the potential energy.
  3. At the end of the acceleration phase, the kinetic energy is smaller but still useful because the velocity is constant (depends on the type and installation of the installation and performance of the motor). During the run toward the cabin is high load and with its load exceeds the acceleration phase, that of constant speed and deceleration. Potential energy is required to move the masses unbalanced. The potential energy is required to move the masses unbalanced while the kinetic energy is stored / dissipated in the masses in motion (the weight of the car and the weight of the counterweight).
  4. The system is therefore designed to store potential energy. If the counterweight is heavier, the system returns potential energy. Similarly in the cars traveling to the bottom, the potential energy can be saved or restored.
  5. At the end of the constant speed, the elevator begins to decelerate to slow down and is returned to the kinetic energy stored in moving masses. The potential energy will be drawn or returned 3-4 times more than the rated current of the motor or pump (if Example. Current Rating = 10 Amps can be up to 40Amper Power = 18 kW with a drops down in 2-3 seconds at rated current Power =1,5 kW as in the last phase. At the moment when the elevator stops at the floor, returns to the first phase where the only power consumed is necessary to maintain the controller running.
  6. When the network energy required is negative, the unit will return regenerative energy in the distribution network, or consumed as a heat engine or as a heating resistor.

The method of Schroeder
Schroeder has developed a simple method to calculate the energy consumption and using a table of basic formulas. The table estimates the typical duration of a trip of a elevator according to the number of floors of the building and the speed of the lift. Using the number of start movement per day, and assuming that the motor has been used at full capacity during execution, has made an estimate of daily energy consumption of the elevator. Multiplying this by the number of days worked per year and then dividing by the area the building, is the possibility of calculating a figure of merit for evaluating the energy consumed by the building’s elevators per m2 per year. For the first time has taken the average for an engine rubric m% (see Table 1) He then proceeds to another factor – the typical time travel – TP, which depends on the number of floors of the building, the type of actuation and consequently the speed of year. Table 2 shows the values calculated by Schroeder for several drives.

Tabella 1                                                      

azionamento

piani edificio

m%

Campo

Media

Oleodinamico Senza contrappeso

3-4

22-28

25

Con riduttore AC 2 velocità

4-8

37-50

44

ACVV(peso basso)

6-12

29-33

31

ACVV(peso alto)

6-12

21-23

27

Senza riduttore Motore- generatore

12-18

17-25

21

Tiristori

12-18

12-21

17

Tabella 2

azionamento

piani edificio

TP[sec.]

Campo

Media

Oleodinamico

Senza contrappeso

Meno
di 6

5-7

6

Con riduttore

AC 2 velocità

6

9-12

10.5

ACVV(peso basso)

12

7-10

8.5

ACVV(peso alto)

12

5-8

6.5

Senza riduttore

Motore‑ Generatore

18

4-6

5

Tiristori

18

3-5

4

The factor TP is inserted into the following formula:

where:
And – the daily energy consumption in kWh / day
R – motor power in kW
ST – the number of departures per day
The parameter “ST” is to be esteemed or measured, which affects the accuracy
of estimation.

The value of “E” is used to calculate the annual energy consumption

Instead (e) per unit surface:

Example 1:
A building is equipped with four elevators, each having the operating speed of 1.52 m / s, 10 passengers and a drive motor-generator. TP is the factor from the tables be 5 seconds (mean value). The power of an engine is 18.5 kW. To determine the daily energy consumption of the only parameter that is missing, and that has to be estimated, is ST the number of departures per day. A simple method to estimate the number of starts is consider two peaks of two hours each, during which we obtain the maximum value of 240
times per hour. We consider then another eight hours of regular traffic of 40 departures per hour
(so we considered 12 hours a day 7:00 to 19:00). We have as a result the number total starts a day:

S= 2 × 240 + 2 × 240 + 8 × 40 = 1280 start per day

So the total consumption per day for each lift:

Eday=(18,5  x 1280 x 5) / 3600 =32,9 kWh/day  per lift

For all four elevators: 32,9×4=131,6 kWh/day

The annual energy consumption for 269 days:

Eyear=131,6 x 269 =35407,5 kWh

emissions of carbon monoxide CO2=27618 kg/year

Estand-by = 4,7 x 24 x 365 = 41172 kWh/year

emissions of carbon monoxide CO2=23468 kg/year

annual cost: €.18.380

Considering 600 people in the building and 20 m2 for each person, you get:

 eanno=131,6 x 269 x 0,85 / 600 x 20 =25,07 kWh/m2 year


The measurements of Doolard
Doolard has performed a large number of measurements on thirty elevator. He measured the energy consumed by each lift when performing a round trip of three floors. The elevators were empty. The results were normalized with respect to the mass of the car and plotted with respect to the nominal speed. In itself, the measurements of Doolard were not a means to calculate the energy consumption of other installations of lift, but a comparison indicative between the different types of lifts. CIBSE Guide D Systems transport in buildings provides a method for the use of the results of Doolard so that the data can be applied to other plants.

Of which is seen that hydraulic elevators consume the most energy of a rope type 2 speed elevators and VVVF system consumes less.

Calculating the motor power required to lift the load

where:
T = load to be lifted (traction difference in Kg) (The traction difference depends on the balance of the plant and by the weight of the ropes (in the absence of compensation ropes).
V = speed of the car in m / s.
ηa = Efficiency of motor (0.6 to 0.75 with endless gears in 1 principle, 0.8 to 0.9 with endless gears in 2 principle or more active principle).
ηv= Efficiency of the shaft (0.9 to traditional arcades, arches 0.8 per embossed)
ηp = Efficiency of pulleys (usually 0.98 each pulley).
N = Number of pulleys
χ = Safety factor for possible overload (typically 1.1).

Example: a system capacity of 4 people with capacity 320 kg, speed 1.2 m / s, stroke 30 m, 3 ropes 10mm diameter, without compensation ropes and 1 pulley;
Eficency are ηa  = 0.8  ηv= 0.9 and ηp = 0.98.

Balance type:
1) Balance at 50% The difference in draft with moving to upward at full load will be:

T = Capacity – (Range * 0.5) + Ropes Weight = 320 – 160 + (0.37 * 30 * 3) = 193 Kg

The motor power required, using the formula written above, will be:

P = (1.1 x 1.2 x 193) / (0.8 x 0.9 x 0.98 x 1 x 102) = 3.6 kW

2) Balance 35%
The difference in draft with moving upward at full load will be:

T = Capacity – (Capacity * 0.35) + Ropes Weight = 320 to 112 +33.3 = 242 Kg

The motor power required will be in this case:

P = (1.1 x 1.2 x 242) / (0.8 x 0.9 x 0.98 x 1 x 102) = 4.44 kW

Energy consumption electric motor with inverter

where:

E inv: energy consumption kWh/day

P : power of motor kW

ST : daily running with people

TP: travel time

Example: Motor power 4.4 kW, speed of the elevator 1m / s, running daily start 100, TP (door open + door close  + departure + arrival + time to travel + arrival + door open +door close) is 12 seconds for 360 days

Einv = 0.52 x 4.4 x 100 x 12/3600 = 0.762 kWh / day

Eanno = 0.762 x 360 = 275 kWh / year

Estand-by = 0.500 x 24 x 365 = 4380 kWh

Annual cost: 0.24 x 4655 = € .1117,00

Energy consumption for permanent magnet motor with inverter

where:

E pm: energy consumption kWh/day

P : power of motor kW

ST : daily running with people

TP: travel time

Example: Motor power 2.8 kW, speed of the elevator 1m / s, running daily start 100, TP (door open + door close  + departure + arrival + time to travel + arrival + door open +door close) is 12 seconds for 360 days

Einv = 0.3 x 2.8 x 100 x 12/3600 = 0.28 kWh / day

Eanno = 0.28 x 360 = 100 kWh / year

Estand-by = 0.500 x 24 x 365 = 4380 kWh

Annual cost: 0.24 x 4480 = € .1075,20

Energy consumption for hydraulic drive

where:

E pm: energy consumption kWh/day

P : power of motor kW

ST : daily running with people

TP: travel time

Example: Motor power 15 kW, speed of the elevator 1m / s, running daily start 100, TP (door open + door close  + departure + arrival + time to travel + arrival + door open +door close) is 12 seconds for 360 days

Einv = 1,7 x 15 x 100 x 12/3600 = 8,5 kWh / day

Eanno = 8,5 x 360 = 3060 kWh / year

Estand-by = 0.500 x 24 x 365 = 4380 kWh

Annual cost: 0.24 x 7440 = € .1785,60

The method of ISO

standards of energy consumption of elevators and calculated using the following formula:

where:
E-Annual energy consumption
k2-compartment height factor (two levels: 1, other: 0.5)
k1-average load factor (tension: 0.35; regenerative traction +: 0.21; hydraulic: 0.3)
Pm – motor power [kW]
v-speed lift
hmax-height bay
Z-number of cycles per year of racing

Example 2:
A building had a hydraulic system, range 4 persons, motor power 11 kW, speed 1m / s, height of room 20m
ST the number of departures per day. A simple method to estimate the number of starts is
consider two peaks of two hours each, during which we obtain the maximum value of 50
times per hour. We consider then another eight hours of normal traffic of 20 per hour starting
(so we considered 12 hours a day 7:00 to 19:00), but another 10 from 19:00 to 00:00 starting time.
We have as a result the total number of departures per day:
ST = 2 x 50 + 2 x 50 + 8 x 20 + 5 x 10 = 410 starts
Number of cycles per year of racing:
Z = 410 x 360 = 147,600 annual starting.
Annual energy consumption:
E = (147 600 x 0.3 x 0.5 x 20 x 11) / (1 x 3600) = 1353 kWh

Power stand-by;
E = 1.5 x 24 x 365 = 13,140 kWh (which includes consumption of switchgear, relays, contactors, cab light, display, buttons … etc..)
Annual cost: 0.24 +0.24 x1353 x13140 = € .3478,4

Fig.9 consumption of energy and stand-by operating according to the number of cycles of runs

Fig.10 Percentages of energy consumption stand-by mode based on the type of building It may be noted that the energy consumption in standby generally vary between 20% and 85%

Fig.11 Amount of energy consumption of an elevator during the stand-by

1 – Electronic control panel
2 – Display of plan
3 – Buttons plan
4 – booth Buttons
5 – Network of photocells for the car door
6 – Inverter
7 – Cabin Lighting
8 – Door Operator

Methodology

For the measurement of the energy consumption of the lifts and escalators audited, and to ensure the repeatability of the measurements throughout the campaign, a methodology was developed, based on the following documents:

  • Draft International Standard ISO/DIS 25745-1 Energy Performance of Lifts and Escalators – Part 1: Energy Measurement and conformance, 2008 [1];
  • EN 60359:2002 Electrical and electronic measurement equipment – Expression of the performance [2];
  • Nipkow J. Elekrizitaetsverbrauch und Einspar-Potenziale bei Aufzuegen, Schlussbericht November 2005, Im Auftrag des Bundesamtes fuer Energie [3];
  • Lindegger Urs, Energy estimation: Document for E4, ELA, VDI & ISO, 11 June 2008 [4];
  • Gharibaan Esfandiar, Load Factor for Escalators, EG (09/05/2008) [5].

Only a brief description of the methodology is made in this report, to help readers understand the basic procedures behind the measurements made. A detailed description of the methodology can be found on the project’s website (www.e4project.eu).

The aim of the measurements was to determine the direct energy consumption of the installation itself – in the case of a lift this includes the direct electrical power consumption of

62

the lift, but does not include additional equipment such as the machine room ventilation or shaft lighting. Thermal losses in buildings from shaft ventilation are also not part of the audits.

The electrical power demand of both the 3-phase power coupling for the drive circuit and the single phase power coupling for the lift ancillary circuit were monitored. Figure 5-3 shows the measuring points used for the German monitoring campaign. For some lifts it was not possible to differentiate between the two branches of power supply, e.g. for reasons of accessibility; for these installations, the energy consumption was measured before the splitting point (see Figure 5-1, Figure 5-3).

The methodology considers energy measurement relating to the normal operation of the lift, escalator and moving walk including: Main energy – elevating/escalating/moving walk equipment such as: motor, frequency converter, controls, brake and door.

Ancillary energy – car auxiliary equipment such as: light, fan, alarm system, etc. Other consumption such as hoistway and machine room illumination, heating, ventilation and air conditioning were excluded from the measurements.

The reference measurement cycle for lifts, starting at the bottom landing, consists of:

  • Opening the Door
  • Closing the Door
  • Driving the car from the bottom landing to the top landing, without passengers
  • Opening the Door
  • Closing the Door
  • Driving the car from top landing to the bottom landing, without passengers
  • Opening the Door
  • Closing the Door

The total running energy consumption per one cycle is calculated using the recorded values of

The total running energy consumption per one cycle is calculated using the recorded values of

active power and time

The  measurement  of  the  standby  energy  consumption  starts  5  minutes  after  the  last movement of the car.  Both  values,  running  energy  and  standby  energy,  are  combined  with  usage  patterns  to estimate the annual energy consumption, in kWh, of the installation.

Where,

Elift   Energy used by the lift in one year [kWh/year]

caml    Average motor load factor.

catd   Average travel distance factor (1; 0,5 or 0,3)

h   Rise height  [m]

ntrip   Trips per year [1/year]

Estandby   Standby Energy used in 1 year [kWh/year]

Ecycle   Energy for a cycle trip [Wh]

cbal  Balancing factor

The annual standby energy used is calculated in the following way:

Where,

Estandby   Standby Energy used in 1 year [kWh/year]

catd   Average travel distance factor (1, 0.5 or 0.3)

h   Rise height  [m]

ntrip   Trips per year  [1/year]

Pstandby   Standby Power [W]

v   Speed of lift [m/s]

All measurements are made with an empty car. Since lifts do not run empty all the time under real conditions, adjustments via a typical load collective2  were done. The average motor load factor Caml, as shown in Table 5‐2 is used for this calculation.

Fig.12 shows a typical cycle of an elevator traction. (source E4-WP6)

The initial transient, typical of a direct starting of an AC motor, it is evident. In this case, in the starting phase in downward (empty car) the power active energy is 145% (7 times) more than the rated engine power. This value can vary with the load and the balance of the system with the counterweight and during the “trip down” is necessary to overcome the difference in weight between the car and counterweight. When “travels up”, as the counterweight is heavier than the cabin, the active power required is quite reduced. Arrived at the end of each trip, there is a peak in the active power corresponding to the braking power of the motorized system.

Figure 13. Typical cycle of a hydraulic lift. (source E4-WP6)
When the elevator “travels down”, the total active power required by the hydraulic lift system is practically nothing compared to the consumption of standby. this small consumption is mainly due to the maintenance of hydraulic fluid pressure because the descent valve allows the flow of hydraulic fluid to move towards the tank. The real energy consumption high as the entire weight of the car must be raised, requiring high electrical power and power as you move upwards as shown in the graph. The consumption of the entire cycle of the lift stroke is highly dependent on the number of floors.

Figure 14. Percentage of standby mode and race to the overall energy consumption of elevators in the residential sector. (source E4-WP6)

It ‘clear that the standby power lift is a very important issue. The stand-by consumption is between 4.2% and 90.2% of the total consumption of the lift. It is important to note that among the models used has an important influence the relationship between power and running in standby energy consumption of lifts which is greater in the installation as a whole. The figure below illustrates the various states of operation of a scale Mobile features a variable speed drive..

Figure 15. Active power of an escalator in different operating modes (source E4-WP6)
Typically, three modes of operation are provided by a variable speed escalator. Determined period of inactivity, these escalators reduce their speed and reach the so-called mode “reduced speed”. The consumption in this phase is more or less half of the consumption in the normal operation mode. After reaching this mode of operation, and After another interval of time, the scale is put in a stop mode. At this point, only the control system and the passenger detection system (pressure sensor on the stairs, photocells or infrared rays), are kept running. When a passenger is detected, the escalator slowly begins to move again, slowly speeding up to reach the rated speed. According to a methodology developed, the standby consumption is considered to be the sum of the low speed and consumption in shutdown mode.

Figure 16. Annual electricity consumption of escalators monitored (source E4-WP6)

The electricity consumption of lifts in Europe

According to statistics of the equipment installed as part of Work Package 2 of project E4, there are approximately 4.8 million elevators installed in the 19 countries surveyed. The data obtained through the investigation of WP2, for 19 countries, were adjusted to EU-27 plus Switzerland and Norway. Using the methodology previously described, the total electricity consumed by plants trucks is estimated at 18.4 TWh, of which 6.7 TWh in the residential sector, 10.9 TWh in the tertiary sector and only 810 GWh in the industry.

Solutions for increased efficiency with the modernization of elevators
The efficiency of the engine has a significant effect on energy efficiency. The motors that can be used in installations elevators are: DC motor with power factor 0.5 to 0.7, asynchronous motors with alternating current power factor from 0.7 to 0.85 and synchronous motors with permanent magnets with power factor 0.85 -0.98. The DC motors have good control characteristics, however, are expensive and produce noise in the power network and the efficiency of the engine is less than 60%. The asynchronous motors do not have a good power factor (power factor) but the efficiency of the engine and less than 70%. Due to the development of magnetic materials, modern elevators are starting to use the permanent magnet synchronous motors of small size. Due to the low inertia, are easier to control, and have a very high power factor and efficiency of the engine greater than 85%.

Technological development in the elevator industry was mainly driven by factors other than energy efficiency. Travel speed, acoustic noise, ride comfort and space are the main concerns of the lift design. However, the demand for energy efficient and greener buildings has increased in recent years and the elevator industry has responded accordingly, presenting its customers with solutions to meet these growing needs.
The increase in electricity prices has also made an important contribution to the demand for more efficient energy solutions. In most applications, electricity costs are often higher than the same cost of equipment purchased, which is why it is so convenient to invest in an elevator with high energy efficiency.
The energy is used for efficient technological developments that take different approaches addressing several sources of inefficiency in vertical transportation systems. These causes can be divided into two main groups: direct and indirect. The direct causes are those that can be directly connected to the device, while the underlying causes are related to the operation of the equipment. The most common direct causes are: frictional losses, transmission losses, motor losses, losses on the brake resistor and brake heat and heat losses.

General principles for achieving energy efficiency
In general, the principles for the achievement of energy efficiency for plants lifts / escalators are the following:
1. Define the equipment or device for energy efficiency.
2. Do not change the design of existing systems.
3. Place items in a suitable area.
4. Appropriate control and energy management of lifting equipment.
5. Use lightweight materials for the coating of the cab
6. Frequent maintenance for proper seal.

As established above, one of the energy losses of the lifting equipment are the friction during its operation. In modern installations of an elevator, various methods are employed to reduce the loss of these friction. Some of these measures to be taken are:

1. The use of transmission gears with high efficiency to reduce the transmission loss.
2. The use of bearings for the shaft of the pulley.
3. The suspension of the car from a point above its center of gravity instead of the geometric center of the crosspiece so as to reduce the lateral thrust on roller rubbing of the guide.
4. The use of roller guide shoes instead of skates rubbing.
5. The reduction in the number of pulleys. The smaller the pulley consequently less friction will result. If the engine is mounted under (lower level), it is more efficient to locate the traction sheave in the hoistway to have two additional pulleys to divert the ropes from the machine room in the hoistway.
6. The use of pulleys of large diameter. The greater will be ildiametro of the pulley, the lower the tensile force required for the rope to overcome the moment of friction of the bearings.
7. The use of ropes and pulleys suitable plant itself to improve the performance of work.
The energy efficiency of hydraulic lifts
The hydraulic lift in itself is not fundamentally a machine with high efficiency
compared with an elevator rope. The energy is discharged in the following ways:
1. Energy loss in the motor (drive of the hydraulic pump) during the conversion of electrical energy into kinetic energy.
2. Energy loss in the same hydraulic pump.
3. Energy loss in the valve assembly due to pressure drop.
4. Energy loss in the transmission of the hydraulic fluid.
5. The engine has no feature of regenerative energy.
6. Loss of energy, as the heat dissipation of the hydraulic fluid.
7. The system usually is not equipped with a counterweight to compensate for potential energy demand of the cabin.
8. The pump always has a flow and a constant speed in spite of the various weight to lift. If the speed is lower than the nominal speed (such as during acceleration and deceleration), part of the hydraulic fluid is returned to the reservoir through by-pass. The loss is significant when the car accelerates and decelerates.
9. In some cases, extreme separate arrangements of cooling (for example cooling coils) are required to avoid excessive heating of the hydraulic fluid.
10. With friction of moving parts like the cylinder, pads, leads, etc..
11. During acceleration and deceleration consumes electricity 4 or 6 times more than the nominal that is dissipated as a result of overheating of the oil.

Factors that affect the consumption of energy in the system of elevators and escalators

Generality
The mode of vertical transportation in buildings can be classified in three main ways:
1. Frequent use (traffic) on the scale
2. Frequent use (traffic) of the lift
3. Frequent use (traffic) of the escalator
Each of these modes of vertical transport has its own characteristics and limitations. Despite the extensive use of different lift, there are basically two main categories of lifting equipment, ie the electric and hydraulic lift.
From the point of view of energy efficiency, the electric elevator rope has more energy efficient of the hydraulic lifting system. Once installed the hydraulic lift, it uses a considerable amount of energy that is wasted in heating the hydraulic fluid through hydraulic pressure. Some installations do not even have to separate chillers to cool the fluid to prevent overheating. In addition, hydraulic elevators are not usually provided with a counterweight, therefore, the lifting motor must be large enough to lift the rated load plus the dead weight of the cab. Electric elevator, the maximum weight to be lifted under normal conditions is only about half of its rated load. Therefore, designers must navigate the search materials and systems more energy efficient systems for ascensoristici and escalators.

Energy is consumed by the elevator and escalator mainly with:
1. Losses due to friction incurred during the trip.
2. Dynamic damage losses during starting and stopping.
3. The potential transfer of energy when moving uphill or downhill.
4. Regenerative energy recovery, or the fuel system.
5. The general approach to energy efficiency in air lifts and escalators
only to minimize frictional losses and losses of the system dynamics.

There are many factors that influence these losses to a system of elevator and escalators:

Characteristics of equipment used
1. The type of control system (panel Maneuver) to operate the motor and the machine.
2. Inner lining of the cab.
3. Means for reducing friction in the moving parts (eg guide pads).
4. The type of elevators and escalators.
5. The speed of the elevator / escalator.
6. The pulley apparatus.

Characteristics of local
1. The distribution of local machines.
2. The type of premises.
3. The height of the premises.
4. Type of structure that maintain the local machines.

The system configuration of lift / escalator.

1. The zoning of the lifting system.
2. The combination of the components of elevators and escalators.
3. The strategies for the vertical transport.
4. The degree of service required of the system.

The major producers of elevators What are doing?

SCHINDLER

The leader in elevators and escalators, today, thanks to the project Schindler energy. You can save on energy costs by producing clean energy lift. The news was in Florence turned to condominiums, hotels and businesses. It should be noted that the annual expenditure for the electricity consumed is greater than the elevator to the annual fee for maintenance of the facility. In contrast, for those who adhere to the project, will be sufficient to install photovoltaic solar panels that store energy from the sun, will transmit the electricity grid. The lift will work thanks to this energy, clean and cost. Also, you will need to anticipate any amount of money. The investment required for the supply and installation of solar photovoltaic panels can be reimbursed through state subsidies, which encourage the production of clean energy. Specifically Schindler is committed to implementing responsible use of resources, limiting the effect that the materials purchased and delivered may have on the environment throughout their life cycle where possible and replacing them with eco-friendly materials, to continue in all the locations saving energy, reducing CO2 emissions and electricity consumption.

KONE

It ‘a technology used to convert mechanical energy into electrical energy when the elevator shaft acts as a generator. When an empty car or a full salt down. The counterweight or the cab itself act as a motor and the KONE EcoDisc becomes a generator. The regeneration system recovers energy and converts it into electricity, which can be used for example to illuminate the building. You can convert up to 25% of the total energy used by the elevator.
Economical operation with regeneration energy KONE: The elevators are moving within the compartment is filled with that empty cabin. The energy consumption is higher when a full or empty car down salt. But when a car goes full or empty room is higher than that generated energy consumption: it creates so the braking energy. In systems with traction power is dissipated by braking resistors: the energy is converted into heat and dissipates, often making it necessary to use more energy to cool or ventilate the space where the braking resistors are placed. With KONE regenerative solutions for medium to low buildings, the elevator converts this energy into electricity ready for reuse within the building. With the engine operating as a generator, it converts the braking energy into electricity that can be used for other applications within the building or to move other elevators. Electromagnetic interference and harmonic distortion are kept well below the allowable values. The regenerated energy, with low harmonic distortion is clean. Up to 20% of the total electricity used in the lift can be recovered. The result is a reduced net power consumption of the building. You get so considerable savings during the life cycle.

 

OTIS

Generating clean energy, so they shared empty elevator that goes up and down an elevator load?. An amount of excess energy, which often is dissipated as heat. The drive ReGen converts this energy into electricity and returns it to the electricity network of the building for reuse by other loads such as lighting. It produces clean energy.
GeN2 Comfort can be equipped with the drive ReGen, a new technology efficient from the point of view of energy that can provide savings of up to 75% compared to the conventional elevator systems. (hydraulic). When the cabine is full capacity, used gravity to make the ride down, enabling the machine to produce instead of consuming energy, just like a generator. The same occurs when a cabin empty or lightly loaded makes its upward running, the counterweight is heavier and moves downward due to gravity, thus generating energy. ReGen Drive, exclusive of OTIS, is able to use this energy and making it available to the electrical network of the building, where it can be used to power other electrical components.

ThyssenKrupp Elevator

ThyssenKrupp Elevator has started since last March in Germany, the marketing of an elevator that takes advantage of all the passive energy during deceleration or braking, reimmettendola in the circuit with a recovery of 30% of electricity, although it is still premature to determine the date entry into the market, is determined by its Italian division to launch this type of ecological lift in our country. And ‘a’ holding our local ECO SUN POWER instead patent ERS (Energy retrive System). That is a system that can retrieve and store the kinetic energy caused by the movement of ascent and descent of the elevator and use it to power lights of stairs, door opening, intercoms and more as part of a building that functions electronically.

Considerations for Energy Recovery Project

  1. When a system is used in energy recovery must take special precautions to ensure that the quality of the regenerated power is of sufficient quality to be accepted by the network and the network is fully protected against short circuits and disorders.
  2. The values of capacitance of the capacitors for the removal of harmonics must be carefully calculated to make sure that together with the distribution transformer capacitors do not create a resonant circuit.
  3. The variable frequency drive type VVVF and hardware (electrical and electronic components), may influence the choice of filter components and each of the following points must be taken into consideration:
  • the type of modulation and the modulation factor of the drive
  • the switching frequency for the regeneration
  • the impedance of the drive and power supply
  • the length of cables
  • special characteristics of the drive (circuit to raise the voltage of the DC link)

E ‘is also important to remember that the power distribution network may not always be free to accept regenerated energy, due to unplanned power outages or other unforeseen problems. Thus, a braking resistor will almost certainly be required for dynamic braking or reserve for emergency situations.

DB-EcoGen Energy from the sun to lift or escalator

Fig.17 DB-EcoGen a typical photovoltaic generating system connected to the network of lifts

A solution for every situation: energy from the sun. The solar photovoltaic technology. This technology enables the direct conversion of solar energy into electricity. The base unit is “the photovoltaic cell,” which consists of a small slab of semiconductor material (almost always silicon) that treated in the appropriate way, creates the potential difference between the upper surface (-) and lower (+). The solar radiation that hits the cell starts to move the electrons inside the material, which move from the negative to the positive. This movement generates current. The cells are connected together and coated in a manner to form larger surfaces of the said “modules”. The photovoltaic modules in turn are connected to each other to form the “Photovoltaic Generator”, able to generate substantial electrical energy thus produced by the generator Photovoltaic during the hours of the day must be accumulated before they can be used at night.
The photovoltaic systems are divided into two main categories according to the type of storage used
1. In photovoltaic systems where there is no electricity grid (remote rural, mountainous and inaccessible), accumulation is done through the use of Batteries: PV-grid installations
2. In systems of cities and urban areas of the DC current is converted to AC (via an inverter) and then fed into the grid. In this way the current can be taken at the time of need and is the same network that functions as an accumulator: photovoltaic systems on the network. This type can be used to supply elevators, escalators and moving walkways. You can save on energy costs of the lift through the production of clean energy. The lift will work thanks to this energy, clean and zero cost.

DB-ReGen Energy Recovery

Fig.18 DB-Regen a typical energy recovery system connected to the distribution network

The efficiency of the engine has a significant effect on energy efficiency. Electrical energy is consumed directly from the drive system (Control panel) and the motor. In this way the motor is able to convert electrical energy into kinetic energy. The history of technological development has changed enough for the equipment of a lift especially the engines.
Some of these engines were / are in the elevator system:

  1. Motors with DC generator (MDC-G).
  2. DC motors with solid-state regulator (DC SS).
  3. 1 or 2 speed AC motors.
  4. AC motors with variable voltage regulator (ACVV).
  5. AC motors with variable frequency and voltage controller (ACVVVF).

Between the drive systems of the above, MDC-G has the lowest efficiency because of the large energy loss in the motor and generator, which converts electrical energy into mechanical energy and finally back into electrical energy. Another reason for the low efficiency of the drive motor MDC-G is that the engine must be kept running when the elevator is idle.

 

Infrared picture of running electric motor (Source: Future Energy Solutions, 2009)

 

Similarly, even AC motors to 1 or 2 speeds are considered less energy efficient. These motors usually one or two speeds, especially during acceleration and deceleration, consume electricity 4 or 6 times more than normal which is dissipated as a result of overheating in the motor winding. The gearbox and flywheel iron / cast iron contributing to the low efficiency of the system.
Combining a certain type of engine and a certain type of control system can be obtained consistent reductions as concerning the energy consumption of the lift than the old hydraulic elevator. For example, a revolutionary solution consists in the use of the permanent magnet motor without a reduction gear (GEARLESS). This solution increases the energy efficiency of 40% over the traditional system with traction and 60% compared to the hydraulic system.

Today, electricity is becoming an increasingly precious commodity and it is therefore essential that most of this energy can be recycled back into making the power source – a process known as recovery. However, braking resistors may still be required as a backup system when the power supply network is not able to receive power recovered, as in the case of absence of current, voltage levels incompatible or situations critical to safety.

With the introduction of new Community legislation such as the European Directive 2005/32/EC EuP (Eco Design of Energy-using Products) is the responsibility of designers and manufacturers to ensure that products are energy efficient.

Fig.19 a cycle of consumption of an elevator. Stored energy is recovered.

DB- ReGen  Regenerative and a converter (converter energy recovery) as shown in figura.14. Kinetic energy stored in moving masses is recovered.
A more concrete example was done on an elevator system that has the following characteristics;
Elevator has capacity: 1200kg
Capacity: 16 people
Size: 2:1
Vana stroke: 45m
Motor: Permanent Magnet Wittur (Gearless)
Poles: 22,
Power: 17.6 kW,
Nominal Current = 43Amper,
Rpm = 153 rpm,
Sheave diameter: 400mm
In an hour moving the elevator consumes active power: 13.8 kW
Energy recovered during deceleration: 6.2 kW. This means 45% of energy is recovered.
Harmonics THD = 8.6%,
Power factor and efficiency = 0.97%
Total energy consumption of the lift in 8 hours: 110.4 kW,
Energy recovered in 8 hours = 49.6 kW
The annual energy cost recovered: 49.6 x 0.24 x 360 = €. 4285.44
Energy recovered in a year: 49.6 x 360 = 17.856kW
The annual cost of energy consumed: 110.4 x 360 x 0.24 = €. 9538.56
Total energy consumption per year = 110.4 x 360 = 39,744
Reducing CO2 emissions to the atmosphere, 17,856 kg x 0.57 = 10177kg/anno

DB-Regen as shown in figura.18 composed of four main components that are connected between the mains and the converter, which is connected to the load, connected to AC1-2-speed induction motors or synchronous motors (permanent magnets) in this case a asynchronous motor. A back-to-back inverter was chosen to recover energy from the network. Connection to the public supply network via a standard EMC filter for removing conducted disturbances, resistors which are connected to the precharge circuit when the inverter is first put under tension, to reduce the peak current and protect the capacitors of the DC link during the charge, filter for the removal of harmonic frequencies in the wave sinusoidal current when the power is recovered from the load to the distribution network. BOOST separate reactor that raises the voltage of the DC link, thus allowing current to flow to the distribution network.

DB-StByGen standby energy production

Fig.20 DB-StByGen a typical power system operating under the lift and accessories

The developments in microelectronics technology have also started to be used in systems and control panels for lifts was relay and contactor have been abandoned and replaced with electronic control panel. The advantages derived from the electronic control system have made neglecting the increased use of energy during the stand-by mode. With the start of the use of security systems of the doors and of variable speed drives, which have been developed in successive periods, together with the illuminated buttons, display inside and outside of the cabin, warning systems and security and other electronic equipment, the energy requirements during the stand-by are increased in order to keep active all these systems.

Elevator motors at one speed or double speed, which were intensively used in earlier periods, have given way to the VVVF drive systems. With MRL (machine room less) systems, the size of the motor reduced, with permanent magnet motors the traveling comfort is increased and reduced power consumption by up to 50% compared to traditional traction elevators. This application is also used as an alternative energy-efficient. Although an additional power consumption with the inverter is wrong with the overall power consumption of elevators, drive units with inverters have been presented as an energy efficient solution for all .. These systems were then imposed on consumers as the only energy-efficient solutions regardless of the use of the lift. Then, a new marketing strategy supported by a discourse on ecology impernianti increase in unit sales ascensoristiche inverter.
It ‘was supported in a study supported by the Swiss Agency for Energy Efficiency (SAFE) on 33 different lifts, the amount of energy consumed by the elevators in stand-by has reached 80% of total energy consumption. SAFE in research, is also indicated that lifts a lot of the solutions used with hydraulic drives have the same energy efficiency of electric MRL. The same conclusion was deduced from Leeds in his MSc thesis. These results do not support a general conclusion, which indicates that the hydraulic elevators consume more energy than the electrical MRL.
In the study of Leeds also stipulates that lifts with low use, the use of inverters increases the power consumption during stand-by and then, the traditional hydraulic lifts are still a good choice. It was also noted that if an elevator is in standby mode for 80%, the inverter consumes an amount of energy equal to 222 kWh / year for a lift. This means that the poor use of elevators, energy consumption would increase despite the use of newer technologies that aim ascensoristiche energy efficiency. Another similar example could be the hydraulic systems with accumulators. Although these systems are not used frequently because of initial costs, it is indicated that the system would consume more energy when these types of lifts are used continuously at low loads. The uses that affect energy consumption in stand-by mode are shown in Fig. 20. As can be seen in the cabin lighting always on, and the sealing system of the doors indicates the maximum use. These are followed by the control panel (QDM) and the inverter.
DB-StByGen produces electricity from solar panels and converts direct current into alternating current and at the same time charging the battery backup for use in the evening with a range of minimum two hours. And with Intelligent Controller is totally off the power of the QDM (sleep mode). Just get a call or a door opening / closing operation by the photocell receives a wake-up signal and the QDM rialimenta

DB-StByGen is a kit consisting of photovoltaic module No. 2, No. 2 backup battery, intelligent controller No. 1 and No. 1 converter that can power the panel maneuver with minimum 14 hours autonomy. You can use any type of hydraulic elevator, electrical, MRL, escalators and moving walkways. If an elevator consumes energy in standby 1.8 kWh a year would consume 1.8 x 24 x 360 = 15,552 kWh and the building would pay in a year: 15,552 x 0.24 = € .3732,48
DB-Usandosi StByGen saves the cost of energy consumed in standby and reduces CO2 emissions to the atmosphere every year 15,552 kg x 0.57 = 8864.64kg/anno

DB-6REGen Energy Recovery multiplex

Fig.21 DB-6REGen a typical energy recovery system multiplex parallel connections DC Link

DB-6REGen is another way to recover electrical energy can be used with the multi drive systems. The parallel connection of the DC link of several drives can power a PWM converter, the engine of which is used in traction for braking energy / regenerated from another drive. This increases the efficiency of the system since not all the energy recovered is wasted as heat generated by the braking resistors and less energy is drawn from the mains. This can be particularly beneficial if you are using the facilities for Duplex, Triplex, … Sesduplex. Many DC bus systems are used in applications in high performance servo drives where substantial amounts of energy are used in acceleration and braking from the drives.
• The group of varistor for surge protection provides input phase-phase and phase to earth.
• The use of a converter input bulk is preferred if the installation requires that all drives are connected to different power.
• A high voltage capacitor polypropylene should be inserted between the terminals of the rectifier module because this helps to reduce the peak inverse voltage switching and can also provide a way to RFI noise currents in applications where there are long cable runs.
• The inductance of the DC link of standard drives tend to be down when the drive is powered with DC voltage and then you need an external inductance value suitable for all drives connected to the DC link.
• By dividing equally the inductance between the positive and the negative line of the DC link, can provide some impedance to limit fault currents if you see a ground fault in the line in the positive or negative line of the DC link.
• The inductance of the DC link should be chosen with a value such as to maintain constant in a reasonable time constant of the DC link.
• The DC bus is connected to all inverters.
• The limitation of the inrush current is not required if each drive has its own soft start circuit (limiting resistor and relay / contact) as a function until the DC link voltage reaches the correct level.
• Can be still necessary to have a resistor braking requirements for fail-safe.

DB-SM-Gen Energy Recovery for escalators.

Fig.22 DB-SM-Gen a typical energy recovery system for escalators

These types of electric motors AC-1, AC-2 or VVVF are also used for escalators and moving walkways in such a drive system (control panel) moves steps and handrails. Other elements that compose them are steps in addition to the drive, sensors, brakes and chain. The escalators typically traveling at a speed of about 0.5 m / s which is fast enough to provide a rapid shift without neglecting the comfort and safety. Escalators and moving walkways are used especially in malls, airports and metro and its drive system of the engine is running all the time regardless of the loading condition of the stairs or escalators. Thus the electricity is continuously consumed even when there are no passengers on them. Much energy is therefore wasted if the number of passengers is widely fluctuating such as railway stations, shopping malls and places like public transport and meter.
How you can save or recover energy supply if an escalator is in works continuously even when there are no passengers on them?
First of all if the escalator is 1 or 2 AC motor speed must be controlled by a control panel with VVVF. Energy can be saved if the motor speed can be adjusted according to the frequency of transport of passengers. This can be achieved technically through the use of scanning sensors or photocells to barriers for the control of passengers and Intelligent controller that manages the inverter to adjust the speed of the engine. The slow speed is simply to indicate that the escalator is operating. Once the passengers jump a boarding area, the speed of the ladder before it resumes to normal passengers actually board a vessel of the escalator or moving walks. With intelligent controller adjusting the speed of the escalator with the frequency of passengers can achieve energy savings of 30%. If a drive is powered AC1-2 is used a VVVF inverter and you can reach savings of up to 45%.
The recovery of energy from an escalator is via the transformation of electrical energy into potential energy. When passengers are transported from one level lower than the motor acts as a generator and the excess energy can be converted into heat using dynamic braking resistors or can be fed into the public electricity distribution, which of course is more satisfactory if the additional costs of a more sophisticated drive system can be justified by the application.
With DB-SM-Gen recovers energy as a function of the input from the escalator and into a network. The power of the control panel is made directly from the DB-StByGen.
DB-StByGen produces electricity from solar panels and converted from direct current to alternating current is guaranteed at least 14 hours autonomy with intelligent controller that manages to be a function of both an escalator and energy conservation. And with Intelligent Power Controller is totally off the QDM (control panel), as soon as a signal come from a sensor or photocell gives power to the system this way saves 69% of energy from an escalator.

DB-Hydro-Gen Energy Recovery for hydraulic elevators.

Fig.23 DB-Hydro-Gen a typical energy recovery system for hydraulic lifts

Hydraulic elevators typically do not have a counterweight, are the most inefficient, sometimes consume three times more energy for electric lifts. The energy is dissipated as heat when it goes downhill. Hydraulic lifts travel at low speeds, typically less than 1 m / s. The maximum stroke for this type of plant is about 20 m. This is due to the fact that with increasing height of travel, of larger diameter pistons must be used to withstand the greater forces of instability. This increases the cost of equipment and facilities makes hydraulic use a less attractive choice. In addition to the low initial cost, the hydraulic elevators have some advantages compared to cable systems, namely:
• The installation is very simple and fast.
• The space occupied by the equipment, as controls (control panel), motor (pump) is small and, therefore, the engine room becomes useless. These parts are usually located in low cost areas of the building, such as basements or under the stairs.
• The unit does not have conventional hydraulic counterweights, allows a closer race in vain. The absence of counterweights also decreases the load on the building structure.
• The load is transferred to the ground and not to the building structure that results in lower manufacturing requirements and costs.
• Emergency procedures in hydraulic systems are relatively simple. The machine can be lowered by means of a manually operated valve of an emergency. Similarly, a hand pump can be used to lift the machine in case of power failure or breakdown of control.
Some of the disadvantages of conventional hydraulic elevators are:
• High consumption of energy as the entire weight of the car must be raised.
• Request high electrical power and power when moving uphill
• the number of starts times are limited and the operation speed is slow.
• Since the changes of viscosity of the oil are changed with the temperature increase or decrease with its sometimes necessary to maintain quality and performance of the oil deveno be heated or cooled.

With DB-Hydro-Gen you can save the total energy consumed in standby and the power of the panel in operation of the maneuver.
Example: 11 kW engine power, speed del’impianto 1m / s, running daily 150, TP (departure gate closure + + + Expected + stroke length door opening) is 9 seconds, for 360 days
E = 1.7 x 11 x 150 x 9/3600 = 7.05 kWh / day
Eanno = 7.05 x 360 = 2524.5 kWh / year
Estand-by = 1.6 x 24 x 360 = 13,824 kWh / year CO2 emission = 7879.68kg/anno
Etot = 16348 kWh / year
Annual cost Standby: 0.24 x 13824 = € .3317,70
A total annual energy savings with DB-Hydro-Gen is 85% and saving money of € annal .3317,70

Conclusions and recommendations
There  are  currently  over  4,8  million  lifts  installed  in  the  EU‐27  and,  each  year,  another  115 thousand units are placed into service. Lifts are responsible for the consumption of 18 TWh of electricity which corresponds to 0,7% of the total European electricity consumption. In addition, there are approximately 75 thousand escalator and moving walks units installed in the EU27 with about 3.500 new

units installed each year.

The monitoring campaign carried out during the project covered 81 installations throughout Europe: 74 lifts and 7 escalators. The main goal of this monitoring campaign was to create a data basis to make valid estimations of the energy consumed by lifts and escalators. For this purpose  a  monitoring  methodology  was  developed  based  on  previous  work  carried  out  by international standardisation bodies and other relevant institutions.

The monitoring results highlighted the relative importance of standby consumption, which in some  installations can  be  as  high  as  90%  of  the  overall  lift  electricity  consumption.  The proportion of standby to overall consumption is greatly influenced by the usage pattern. This explains the fact that the estimated proportion of standby to overall electricity consumption of lifts  in  the  residential  sector  is  dominant  (68%),  whereas  in  the  tertiary  sector  it  represents 41%.

This usage patterns also helps to explain the following effects: Lifts in the residential sector, although  being  the majority  of  lifts  installed  (64%  of  units),  are  responsible  for  only  35%  or 7 TWh of the electricity consumed. Lifts installed in the tertiary sector with a more intensive use, consume about 11 TWh of electricity annually, which corresponds to about 1.5 % of the electricity consumed in that sector.

A  technological  assessment  was  carried  out  aiming  at  the  characterisation  of  the  existing technologies,  as  well  as  the  identification  of  emerging  energy  efficient  solutions  which  can provide  electricity  savingsboth  in  standby  and  in  running  of  lifts  and  escalators.  The  most important key technologies identified include the following:

  • Premium efficiency induction motors or Super Premium efficiency permanent magnet synchronous motors;
  • Efficient pumps in hydraulic elevators
  • Efficient drives with regeneration capability in   buildings  with intensive lift use;
  • Efficient transmission and roping;
  • Traffic  management  directed  not  only  at  efficacy  when  transporting  passengers,  but also at energy efficiency
  • Low  standby  power  components  such  as  door  operators,  lamps,  ventilators  and displays

The technology assessment performance indicators, combined with the results from a market survey  determining  the  main  characteristics  of  the  installed  stock  and  of  the  monitoring campaign,  were  used  toprovide  a  credible  baseline  for  the  evaluation  of  potential  energy savings.

Using  the  best  available  technologies  would  produce  savings  in  the  standby  consumption  of over 70%. In particular, energy efficient lighting options and the use of electronic components with low standby power (e.g. controllers and inverter) were found to play a major role in this reduction.  Turning  off  non‐essential  equipment  or  putting  it  into  a  very  low  power  “sleep” mode, whenever possible, would produce even larger electricity savings.

The  potential  overall  (running  plus  standby)  savings  are  estimated  to  be  of  11  TWh,considering that the Best Available Technologies are used, or up to 13 TWh if technologies that are  being  developed  but  not  yet  widely  used  in  the  lift  industry  are  applied.  These  savings  translate into a reduction of carbon emissions of around 4,9 Mtons of CO2eq and 5,8 Mtons of CO2eq , respectively, considering  the current electricity production mix in Europe.

Concerning  escalators  our  analyses  came  to  the  following  results:  The  ability  to  adjust automatically  the  speed  of  the  escalator  to  the  passenger  demand  is  a  solution  that  can produce  energy  savings.  The  results  of  the  monitored  installations  showed  that  escalators operating in “reduced speed” mode consume approximately half of the electricity consumed in normal operation mode.  The estimated electricity consumption of escalators in Europe is relatively modest (900 GWh), and  a  potential  reduction  of  around  250 GWh  (30%)  could  be  feasible  if  all  the  escalators installed  would  be  equipped  with  automatic  speed  controls  and  with  low  power  standby

modes. However,  before  these  potentials  can  be  realized  some  barriers  in  the  market  need  to  be overcome that are present in the market today. In a further step, the most significant barriers were identified, as well as possible strategies and measures to overcome those barriers. The main barriers identified are:

  • lack  of  information  and  awareness  of  the  actual  electricity  consumption  of  lift  and escalator systems;
  • lack of information and awareness of the energy efficient technologies in the market;
  • low state of knowledge on the economic efficiency of the technological measures;
  • split incentives between general contractors, owners of installations as well as those paying for the energy consumption of installations .

These main barriers may be addressed by a combination of the following strategies:

  • Raising  awareness  through  campaigns  and  the  provision  of  information  material  for relevant  stakeholder  groups,  such  as  the  main  dissemination  materials  (available online at www.e4project.eu) developed in this project:

a) “Options to improve lift energy efficiency”

b) “Energy Efficient Elevators and Escalators – Technology Assessment”

c) “Barriers  to  and  strategies  for  promoting  energy‐efficient  lift  and  escalator technologies”

d) “Guidelines for new lift installations and retrofitting”

e) “Public Buildings Procurement Guidelines for Lifts and Escalators”

National  energy  agencies  can  play  a  major  role  to  improve  awareness  towards  the selection and proper operation of energy‐efficient lift and escalator systems.

‐Implementation of a harmonized standard for measuring and predicting the electricity consumption for lifts and escalators, based on the previous international work and on the methodology developed in this project.

‐Inclusion  of  lifts  and  escalators  into  a  future  revised  version  of  the  EPBD  Directive, providing an incentive to use energy efficient technologies both in new buildings and in retrofits.

‐Implementation  of  energy  labels  similar  to  those  already  in  use  in  some  European countries, providing easily accessible and understandable information, for buyers and specifiers of lifts and escalators systems to support decision making processes

‐Minimum energy performance indicators to be defined in close cooperation with lift and escalator manufacturers (e.g. maximum standby consumption for all systems, and maximum specific consumption for non‐residential high traffic installations).

MSEE Ibrahim GULESIN

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