Issue 3/2010


05/02/10

Environmental Impact Evaluation of Elevators in Their Use Phase

José Alberto Roig, Ana Lorente, Agustín Chiminelli and José Luis Núñez

This paper describes a methodological procedure for environmental impact evaluation of elevators during their service life. The method is based on energy consumption measurements and traffic calculations and is presented as an evaluation tool to be applied in life cycle assessments (LCA). The energy consumed by these systems in their use phase has been identified as a key issue, with a significant influence on the complete life cycle environmental load. The method can be used to compare different technologies (type of elevator, drive system, components which affect the energy consumption, etc.) as well as the influence of the installation condition for a fixed traffic pattern. In this sense, the procedure described can be considered also as an energy efficiency evaluation method. As a particular case, the influence that a wrong counterweighting of the elevator can have in the elevator environmental impact has been assessed.
Category: Issue 3/2010
Posted by: Editor

Avoiding the environmental degradation through global warming, stratospheric ozone depletion, destruction of ecosystems and the extinction of wildlife has become one of the highest priorities of all the developed countries to achieve the global sustainability and a high quality of life.

In the case of Energy-using Products (EuP), the environmental impact takes the form of energy use, consumption of materials and natural resources, waste generation and release of hazardous substances.
In Europe, the Directive 2005/35/EC on the eco-design of EuP’s adopted by the European Parliament and the Council in July 2005 and published in the Official Journal of the European Union (L 121 22.7.2005), shows the determination of the Commission to integrate environmental aspects in enterprise policies. The directive defines conditions and criteria for setting requirements regarding environmentally relevant product characteristics and allows them to be improved quickly and efficiently. The introduction of eco-design measures, that include requirements for improved energy efficiency of products, is a long-lasting contribution to combating climate change, securing energy supply and achieving sustainable development.
The first preparatory studies to implement this regulation have been subdivided into 14 families of energy using products, being one of them electric motors of 1 – 150 kW power, and therefore affecting the elevator manufacturers, who, according to this directive, will be required to perform an assessment of the EuP model throughout its lifecycle, based on realistic assumptions about normal conditions and purposes of use. On the basis of this assessment, manufacturers will establish the EuP’s ecological profile according to the environmentally relevant product characteristics and inputs/outputs throughout the product life cycle expressed in physical quantities that can be measured.
In order to give response to this demand, MP Lifts and ITA have been working on an environmental evaluation project, being the scope of the study not only the drive, but also the rest of components of the elevator . The work presented in this paper corresponds to the analysis of the elevators energy consumption during their use phase and the associated environmental load quantified in an internationally acknowledged unit (Ecoindicator 99), which is a commonly used method in Life Cycle Assessment.
Life cycle assessment
A life cycle assessment (‘LCA’, also known as life cycle analysis, eco-balance or cradle- tograve-analysis) is the investigation and valuation of the environmental impacts of a given product or service during its existence, based on the input-output analysis of physical flows (materials, energy , emissions, etc.) at all stages of its life cycle, that is:
  • Extraction of raw materials
  • Production, transport and storage of intermediate materials and components
  • Product manufacture, including transformation processes, assembly and packaging
  • Distribution, including transport and storage
  • Product use and maintenance
  • End of life, valuation, recycling and reuse.
The Life Cycle Analysis identifies and quantifies the use of materials and energyas well as environmental emissions during all these stages, determines the environmental impact that produce these environmental burdens and is considered one of the best Eco-design tools, since it helps to find new strategies for environmental improvement.
The basic structure of the LCA methodology, defined by the International standard ISO 14 040, is the following:
  • Definition of objectives and scope: where the purpose of the study, responsibilities and, functional unit that will relate to the entrances and exits shall be explained. When describing the functional unit, the life cycle stages of the product must be clearly defined.
  • Inventory Analysis: identification and evaluation of the inputs (raw materials and energy) and exits (gaseous emissions, liquid and solid waste) at each stage of a product’s life cycle.
  • Assessment of impacts: classification, characterization, standardization and evaluation of the environmental impacts identified in the analysis of the inventory phase.
  • Interpretation of results: explaining the findings and giving recommendations in accordance with the objectives of the study.
  • Critical review: Checking the methodology, assumptions and data used by adding an assessment of improvements. This step is optional.
At the end of the inventory phase, the product environmental impact can be quantified in a dimensionless figure called Eco-indicator 99 (usually expressed in milipoints mpt), what makes it possible for the designers to compare their product design with other alternatives.
Although according to the ISO 14 042 standard these figures should not be used in comparative assertions disclosed to the public, they are very useful for internal assessments.
The eco-indicator 99 is a damage oriented method for life cycle impact assessment that weights the following types of environmental damages:
  • Damage to the human health (expressed in years of loss of health, DALY, for lifeshortening or disability)
  • Damage to the ecosystem quality (reduction in the number of species per unit area in a given time)
  • Damage on resources (extra energy that will be required for future extraction of mineral or fossil fuels)
Independently of these damages, the categories of environmental impact considered for the “Eco-indicator’99” are the following : Acidification / Eutrophication, Climate Change, Ecotoxicity, Use of Land, Consumption of Resources (fossil fuels and minerals), Stratospheric Ozone Depletion, Radiation, Effects on the Respiratory System (divided into those caused by organic and inorganic substances) and Carcinogenicity.
Regarding the Information and its uncertainty, there are three different perspectives:
  • Hierarchist, that include effects based on consensus with the perspective that there is a balanced distinction between short and long term effects, that a proper policy based on control measures can avoid many problems (more control).
  • Individualist, that include only proven effects with a short term perspective and the conviction that technology can avoid many problems.
  • Egalitarian, that includes all possible effects with a longterm approach and the perspective that the environmental problems can lead to a catastrophe.
In our specific study, the assessment has been made form an egalitarian perspective.
Procedure for the measurement of energy consumption of Lifts and the prediction of their consumption during the use phase for their Evaluation in a LCA
In order to assess the environmental impact of the elevator in its use phase, it is necessary to define a procedure for the measurement of the energy consumption, which shall describe how to carry out the measurements, in what specific conditions and what parameters shall be taken into account. The procedure shall ensure that the measurements can be carried out both on a test tower and on the field, using portable measurement equipment.
Under these considerations, the following procedure was defined:
  • Energy consumption in a representative cycle. First, the procedure describes a methodology based on the draft standard ISO/DIS 25 745-1 for measurement of the energy consumed in a representative cycle:
  • Rise to the highest landing
  • Door Operation (Open and Close
  • Descent to the lowest landing
  • Door Operation (Open and Close)
The facility shall have as many stops as defined in the functional unit.
  • Calculation of the energy consumed in other trips. The energy consumed in other trips is calculated from the graphs and data obtained above.
  • Integration in a traffic pattern to calculate the total consumption. The application of this model on a specific traffic profile (posed as a set of paths/ trips) and the integration of each of these outcomes at the time of assessment will give the total energy consumption of a lift in the period considered.
  • Inclusion of wear and tear effects. Finally, and based on graphics and data obtained in intensity measurements, it can be estimated what will be the influence of wear and tear in the installation in the life of the elevator (these data may be updated in the model of consumption, although this case is not presented in this paper).
The measurement of the energy consumption of an elevator on the above described representative trip is performed in accordance with the Draft ISO/ DIS 25 745-1 Standard.
Following this standard, the energy consumed is measured in at least ten cycles and then an average consumption for a single trip of reference is calculated. When carrying out these measurements, it must be ensured that all the energy consumed by the lift is being considered, since sometimes the power generation and power complementary (lights, fans, alarms, CTV, battery chargers, displays, etc.), are connected to different supply sources. Once the values of the reference trip have been recorded, the standby consumption shall be measured by leaving the lift rest for 5 minutes on the lower ground floor (in some cases the lift reduces consumption by turning off lights and high consuming controls during this period).
These measurements define two energy reference values: energy consumed during a reference trip and energy consumed in “standby” condition. These values are only valid for an installation where the measurements have been made, since two elevators, even though they have the same load, the same speed and are installed in the same building, may differ in the distance between two stops, doors opening and closing times, counterbalanced weight of the car, kind of guideshoes, wiring, number of entries in the cabin, drive system, etc.
Below, the graph of an ISO reference cycle of an empty car driven by a permanent magnets gearless machine travelling up and down between the lower and upper floor is shown. The purple line shows the elevator displacement whereas the blue one shows the power consumption. As it can be seen, in the most favourable case, which is the upwards movement, the power consumption is virtually nil. This is because the motor acts as a generator, converting the potential energy into electrical energy, which is dissipated through a resistance brake. The only power consumption is hence due to energy losses and the electronic devices.
In the case of an asynchronous geared machine, the graph of power consumption in both directions would look like the same.
As mentioned before, the reference trip cycle consists of four parts: Power consumption travelling upwards (this in turn has a peak power at the start up, which decreases when the rated speed is achieved) (1), doors operation at the highest landing (2), Power consumption for travelling downwards and doors operation at the lowest landing (4). At the end of the running time, the power falls to idle power.
The energy consumed is the area under the chart. Of course, the energy consumed depends on the length of the reference trip, so in the event that the trip has a different duration, the results vary.
For the calculation of the energy consumption in other routes, there are three possibilities:
1. Undertake energy consumption measurements for each possible trip,
2. Calculate what is the energy consumption inferring it from the graphs of reference cycle.
3. Calculate the energy consumption on the basis of a simplified model.
In the first case, the consumption data are collected directly, so there is no need to make any extrapolation. In the second case, the graph of the journey is obtained by subtracting from the reference cycle graph, the not travelled routes. For example, if in a 5 landings building the elevator travels just from the first to the 4th landing, the energy consumption graph will correspond to the reference cycle measurements, subtracting from it the interval that corresponds to the displacement between two intermediate stops at rated speed. This process can be made automated with data analysis tools such as Matlab.
In the particular case that the trip takes place between two consecutives landings, it may happen that the rated speed is not reached (depending on the distance between plants and acceleration), and the graphics can not be extrapolated. In that case, it will be necessary to carry out the measures directly or estimate what will be energy consumption according to the data available.
To insert an energy model in a traffic simulation program, it is necessary to know the power required for the start-up and operation for a range of charges between 0 % and 100 % in both directions (up and down), so that the energy consumption can be calculated for different number of passengers travelling.
Due to the fact that the electrical elevators are counterweighted, it is necessary to at least make measurements with 0, medium of full load. The rest can be either be measured or calculated assuming that there is a linear relationship. This is not exact, but the error can be neglected.
Nobody can predict the traffic pattern of a lift, so it is necessary to use simulators that give us the information of the load carried, travelling direction, number of passengers entering and exiting the cabin, distance travelled, time of doors operation, etc. These profiles may vary to analyze the impact on consumption.
In case a simulator is not available, the traffic can be estimated in a way that is representative of the type of installation and its use.
Case of study
As a particular case, the environmental impact of a 600 kg lift installed in a Spanish residential building, travelling at 1 m/s speed with a traffic pattern equivalent to 150,000 starts/year has been calculated.
If the traffic pattern of the building is available, it can be used to estimate the energy consumption during the whole life of the product, however, since the inputs needed for model are related to the number of times that each possible standard trip occurs, independently of the time sequence, an estimation of the daily traffic can be made taking into account what are the characteristics of the building: number of floors, number of people living (residential use) or working (offices) in each floor, number of people in transit etc. and the possible differences in the traffic between a working day or a day in the weekend.
The standard trip is defined by:
  • Distance travelled (expressed in nº of floors)
  • Direction of movement (down- or upwards)
  • Number of passengers (expressed as number of passengers or as weight)
The energy consumption of each standard trip has been previously calculated according to the procedure described above and saved in a data base, that apart from that information, contains the following data:
  • Energy consumption during the doors operation
  • Energy consumption in Standby
  • Trip duration
  • Time to open and close the doors
  • The time in Standby is calculated as the difference between the full day duration and the time the elevator is on use.
The results in energy consumption are extrapolated to the whole year and then to the time that the lift will be operating (30 years), obtaining the Quantity of energy consumed expressed in kWh. This value is then introduced in the LCA tool to calculate the associated environmental impact, which depends not only on to the amount of energy, but also on the characteristics of the energy production technologies employed to produce it. Usually these technologies are hydropower, nuclear, hard coal, natural gas, wind, photo voltaic, cogeneration and others.
Depending on the weight that each technology has in the energy production mix of the country where the elevator will be installed, the environmental impact can differ substantially for a same value of energy consumption.
For example, the environmental impact associated to the use phase of identical lifts installed in 2000 in five different European countries varies from 0.45 KPt in France, 1.2 in Finland, 1.55 in Germany and 1.87 in Great Britain to 2.1 KPt in Spain (see figure 3).
Being the percentage of technologies present in the energy mix of the two countries with the lowest and highest impact the following:
In the same sense, the incorporation of new environmentally friendly technologies can have beneficial effects on the elevator impact. As shown in the graph below, the environmental burden of an elevator installed in Spain in 2000 would have in 2007 a reduction of approximately 28 % due to the introduction of these technological improvements. If further environmental policies are applied, this reduction could continue until the end of its lifetime.
Applying the procedure described in this paper to the elevator of our case study, the energy consumption results in about
1855 kWh/year, that causes an environmental impact of 1.5 KPt (Eco 99). The main damages are associated to the use or natural resources (fossil fuels) and to the human health (respiratory inorganics).
Then, the same calculations are made for an elevator, which is wrong counterweighted (charged with 75 kg more than necessary). With this traffic pattern, this fact leads to an increase of energy consumption, whose environmental impact increases in approximately 5 % the above given value (see Fig. 1). Other studies show that the elevator conditions or misalignments , cause an increase in the energy consumption compared to the ideal case.
5. Conclusions
The methodology described in this article has demonstrated to be a very effective tool to evaluate the environmental impact of the energy consumption of an elevator in its service life. In this sense, it can be very useful for the companies working in the sector to better assess the impact of their products.
Usually, the energy consumption is used as an argument to defend that an elevator technology or a given configuration is better than other from an environmental point of view. However, this study shows that there are more factors that influence this environmental impact than the elevator technology itself, for example the energy mix of the country considered. Since this energy mix varies considerably between countries and for the same country in the course of time, this argument depends on the specific circumstances of the location where the product will be operating.
Another factor that cannot be considered in the development phase is the effect of the installation conditions. For example an unbalanced counterweighted elevator (lighter or heavier than necessary) can have a different average of energy consumption that varies depending on the traffic pattern. Therefore it is important that the instructions provided by the manufacturers for the product installation are very precise and that when commissioning the product, a check is made to ensure that this undesired effect appears. In the same way, a proper traffic control would give very useful information to the company in charge of the maintenance to optimize the energy consumption of the lift.
References
Barney, G. Elevator Traffi c Handbook: Theory and practice.
Barney, G. Energy performance models for lifts. Elevatori 2007, July/August.
International Organization for Standardization, ISO 14 040:2006. Environmental management – Life cycle assessment – Principles and framework.
Goedkoop, M. and Spriensma R. The Eco-indicator 99. A damage oriented method for Life Cycle Impact Assessment. PRé Consultants B.V.
PRé Consultants B.V. Introduction to LCA with SimaPro.
PRé Consultants B.V. SimaPro 7 tutorial. Ecoinvent center 2004. Ecoinvent Reports.
Biographica Details
José Alberto Roig is Mechanical Engineer with 14 years of professional experience in the elevator industry, mainly in Quality and Research and Development . Currently, he works in MP Lifts as Technology Research Manager. Since 2000, he has been continuously collaborating with the Instituto Tecnológico de Aragón in local and European innovation projects.
Ana Lorente is Mechanical Engineer by the University of Zaragoza with professional experience in international companies in R&D, quality and environmental departments. Since February 2006, she is working in the Instituto Tecnológico de Aragón in European Projects and activities related to Ecodesign.
Agustín Chiminelli is Materials Engineer and Ph.D in Mechanical Engineer by the University of Zaragoza. He is working in the Instituto Tecnológico de Aragón in different projects related to new materials and Ecodesign.
José Luis Núñez is Ph.D in Mechanical Engineer by the University of Zaragoza, working since 1998 as researcher in the Instituto Tecnológico de Aragón. Currently, he works as Technical Coordinator of the Research, Development and Technical Services Area of this centre.
3/2010

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