Energy monitoring and targeting
Encyclopedia
Energy monitoring and targeting (M & T) is an energy efficiency technique based on the standard management
axiom stating that “you cannot manage what you cannot measure”. M&T techniques provide Energy Managers with feedback on operating practices, results of energy management projects, and guidance on the level of energy use that is expected in a certain period.
The goal of using M&T to determine the relationship of energy use to key performance indicators
(production
, weather, etc.) is to help business managers:
The ultimate goal is to reduce energy costs through improved energy efficiency
and energy management control. Other benefits generally include increased resource efficiency, improved production
budgeting and reduction of greenhouse gas
(GHG) emissions.
cycle, therefore improving control of energy use.
on energy use, in order to establish a basis for energy management and explain deviations
from an established pattern. Its primary goal is to maintain said pattern, by providing all the necessary data on energy consumption, as well as certain key variables, as identified during preliminary investigation (production
, weather, etc.). More recently, smartphones and tablets are becoming mainstream platforms for monitoring.
and the equipment to estimate their energy consumption level.
It is also necessary to assess what other measurements will be required to analyze
the consumption appropriately. This data will be used to chart
against the energy consumption: these are underlying factors which influence the consumption, often production
(for industry processes) or exterior temperature
(for heating processes), but may include many other variables.
Once all variables to be measured have been established, and the necessary meters installed, it is possible to initiate the M&T procedures.
Driving factors such as production or degree day
s also constitute streams and must be collected at intervals to match.
in order to define the general consumption base-line. Consumption rates are plotted in a scatter plot against production
or any other variable previously identified, and the best fit line is identified. This graph is the image of the business’ average energy performance, and conveys a lot of information:
The slope
is not used quite as often for M&T purposes. However, a high y-intercept
can mean that there is a fault in the process, causing it to use too much energy with no performance, unless there are specific distinctive features which lead to high base loads. Very scattered points, on the other hand, may reflect other significant factors playing in the variation of the energy consumption, other than the one plotted in the first place, but it can also be the illustration of a lack of control over the process.
consumption and the actual measured consumption. One of the tools most commonly used for this is the CUSUM
, which is the CUmulative SUM of differences. This consists in first calculating the difference between the expected
and actual performances (the best fit line previously identified and the points themselves).
The CUSUM
can then be plotted against time on a new graph
, which then yields more information for the energy efficiency specialist. Variance
s scattered around zero usually mean that the process is operating normally. Marked variations, increasing or decreasing steadily usually reflect a modification in the conditions of the process.
In the case of the CUSUM
graph, the slope
becomes very important, as it is the main indicator of the savings achieved. A slope
going steadily down indicates steady savings. Any variation in the slope
indicates a change in the process. For example, in the graph on the right, the first section indicated no savings. However, in September (beginning of the yellow line), an energy efficiency measure must have been implemented, as savings start to occur. The green line indicates an increase in the savings (as the slope
is becoming steeper), whereas the red line must reflect a modification in the process having occurred in November, as savings have decreased slightly.
graph and identify the causes leading to variations in the consumption. This can be a change in behaviour, a modification to the process, different exterior conditions, etc. These changes must be monitored and the causes identified in order to promote and enhance good behaviour, and discourage bad ones.
Targeting consists in two main parts: the measure to which the consumption can be reduced, and the timeframe during which the compression will be achieved.
A good initial target is the best fit line identified during step 2. This line represents the average
historical performance. Therefore, keeping all consumption below or equal to the historical average is an achievable target, yet remains a challenge as it involves eliminating high consumption peaks.
Some companies, as they improve their energy consumption, might even decide to bring their average
performance down to their historical best. This is considered a much more challenging target.
in order to consistently improve performance. Once the targets are set and the desired measures are implemented, repeating the procedure from the start ensures that the managers are aware of the success or failure of the measures, and can then decide on further action.
, which provides real-time and historic energy use and generation data for facilities of Arizona State University
on a public web site.
Management
Management in all business and organizational activities is the act of getting people together to accomplish desired goals and objectives using available resources efficiently and effectively...
axiom stating that “you cannot manage what you cannot measure”. M&T techniques provide Energy Managers with feedback on operating practices, results of energy management projects, and guidance on the level of energy use that is expected in a certain period.
The goal of using M&T to determine the relationship of energy use to key performance indicators
Key performance indicators
A performance indicator or key performance indicator is an industry jargon for a type of performance measurement.. KPIs are commonly used by an organization to evaluate its success or the success of a particular activity in which it is engaged...
(production
Production, costs, and pricing
The following outline is provided as an overview of and topical guide to industrial organization:Industrial organization – describes the behavior of firms in the marketplace with regard to production, pricing, employment and other decisions...
, weather, etc.) is to help business managers:
- Identify and explain increase or decrease in energy use
- Draw energy consumption trends (weekly, seasonal, operational…)
- Determine future energy use when planning changes in the business
- Diagnose specific areas of wasted energy
- Observe how the business reacted to changes in the past
- Develop performance targets for energy management programs
- Manage their energy consumption, rather than accept it as a fixed cost that they have no control over.
The ultimate goal is to reduce energy costs through improved energy efficiency
Efficient energy use
Efficient energy use, sometimes simply called energy efficiency, is the goal of efforts to reduce the amount of energy required to provide products and services. For example, insulating a home allows a building to use less heating and cooling energy to achieve and maintain a comfortable temperature...
and energy management control. Other benefits generally include increased resource efficiency, improved production
Production, costs, and pricing
The following outline is provided as an overview of and topical guide to industrial organization:Industrial organization – describes the behavior of firms in the marketplace with regard to production, pricing, employment and other decisions...
budgeting and reduction of greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
(GHG) emissions.
History
M&T is an established technique that has proved its worth. First launched as a national program in the UK in 1980, it then spread throughout Europe and its reputation is now slowly growing in America.Goals and benefits
Throughout the numerous M&T projects implemented since the 1980s, a certain number of benefits have proved to be recurrent:- Energy cost savings: generally 5% of the original energy expenses, according to The Carbon TrustThe Carbon TrustThe Carbon Trust is a not for dividend company limited by guarantee created by the UK government to help businesses and public organisations to reduce their emissions of carbon dioxide into the atmosphere, through improved energy efficiency and developing commercial low carbon technology...
. Carbon Trust has conducted a study over 1000 small businessesSmall businessA small business is a business that is privately owned and operated, with a small number of employees and relatively low volume of sales. Small businesses are normally privately owned corporations, partnerships, or sole proprietorships...
and has concluded that on average an organisation could save 5%. - Reduction in GHGGreenhouse gasA greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
emissions: lower energy consumption helps reduce emissions - Financing: measured energy reductions help obtain grantsGrant (money)Grants are funds disbursed by one party , often a Government Department, Corporation, Foundation or Trust, to a recipient, often a nonprofit entity, educational institution, business or an individual. In order to receive a grant, some form of "Grant Writing" often referred to as either a proposal...
for energy efficiency projects - Improved product and service costing: sub-meteringUtility submeterUtility Submetering is the implementation of a system that allows a landlord, property management firm, condominium association, homeowners association, or other multi-tenant property to bill tenants for individual measured utility usage...
allows the division of the energy bill between the different processes of an industryIndustryIndustry refers to the production of an economic good or service within an economy.-Industrial sectors:There are four key industrial economic sectors: the primary sector, largely raw material extraction industries such as mining and farming; the secondary sector, involving refining, construction,...
, and can be calculated as a production cost - Improved budgeting: M&T techniques can help forecast energy expenses in the case of changes in the business, for example
- Waste avoidance: helps diagnose energy waste in any process.
Key principles
Monitoring and Targeting techniques rely on three main principles, which form a constant feedbackFeedback
Feedback describes the situation when output from an event or phenomenon in the past will influence an occurrence or occurrences of the same Feedback describes the situation when output from (or information about the result of) an event or phenomenon in the past will influence an occurrence or...
cycle, therefore improving control of energy use.
Monitoring
Monitoring is the regular collection of informationInformation
Information in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...
on energy use, in order to establish a basis for energy management and explain deviations
Deviation (statistics)
In mathematics and statistics, deviation is a measure of difference for interval and ratio variables between the observed value and the mean. The sign of deviation , reports the direction of that difference...
from an established pattern. Its primary goal is to maintain said pattern, by providing all the necessary data on energy consumption, as well as certain key variables, as identified during preliminary investigation (production
Production, costs, and pricing
The following outline is provided as an overview of and topical guide to industrial organization:Industrial organization – describes the behavior of firms in the marketplace with regard to production, pricing, employment and other decisions...
, weather, etc.). More recently, smartphones and tablets are becoming mainstream platforms for monitoring.
Reporting
The final principle is the one which enables ongoing control of energy use, achievement of targets and verification of savings: reports must be issued to the appropriate managers. This in turn allows decision-making and actions to be taken in order to achieve the targets, as well as confirmation or denial that the targets have been reached.Procedures
Before the M&T measures themselves are implemented, a few preparatory steps are necessary. First of all, key energy consumers on the site must be identified. Generally, most of the energy consumption is concentrated in a small number of processes, like heating, or certain machinery. This normally requires a certain survey of the buildingBuilding
In architecture, construction, engineering, real estate development and technology the word building may refer to one of the following:...
and the equipment to estimate their energy consumption level.
It is also necessary to assess what other measurements will be required to analyze
Analysis
Analysis is the process of breaking a complex topic or substance into smaller parts to gain a better understanding of it. The technique has been applied in the study of mathematics and logic since before Aristotle , though analysis as a formal concept is a relatively recent development.The word is...
the consumption appropriately. This data will be used to chart
Chart
A chart is a graphical representation of data, in which "the data is represented by symbols, such as bars in a bar chart, lines in a line chart, or slices in a pie chart"...
against the energy consumption: these are underlying factors which influence the consumption, often production
Production, costs, and pricing
The following outline is provided as an overview of and topical guide to industrial organization:Industrial organization – describes the behavior of firms in the marketplace with regard to production, pricing, employment and other decisions...
(for industry processes) or exterior temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
(for heating processes), but may include many other variables.
Once all variables to be measured have been established, and the necessary meters installed, it is possible to initiate the M&T procedures.
Measure
The first step is to compile the data from the different meters. Low-cost energy feedback displays have become available. The frequency at which the data is compiled varies according to the desired reporting interval, but can go once every 30 seconds to once every 15 minutes. Some measurements can be taken directly from the meters, others must be calculated. These different measurements are often called streams or channels.Driving factors such as production or degree day
Degree day
A degree day is a measure of heating or cooling. Totalized degree days from an appropriate starting date are used to plan the planting of crops and management of pests and pest control timing...
s also constitute streams and must be collected at intervals to match.
Define the base-line
The data compiled must then be plotted on a graphChart
A chart is a graphical representation of data, in which "the data is represented by symbols, such as bars in a bar chart, lines in a line chart, or slices in a pie chart"...
in order to define the general consumption base-line. Consumption rates are plotted in a scatter plot against production
Production, costs, and pricing
The following outline is provided as an overview of and topical guide to industrial organization:Industrial organization – describes the behavior of firms in the marketplace with regard to production, pricing, employment and other decisions...
or any other variable previously identified, and the best fit line is identified. This graph is the image of the business’ average energy performance, and conveys a lot of information:
- The y-interceptY-interceptIn coordinate geometry, using the common convention that the horizontal axis represents a variable x and the vertical axis represents a variable y, a y-intercept is a point where the graph of a function or relation intersects with the y-axis of the coordinate system...
gives the minimal consumption in the absence of the variable (no productionProduction, costs, and pricingThe following outline is provided as an overview of and topical guide to industrial organization:Industrial organization – describes the behavior of firms in the marketplace with regard to production, pricing, employment and other decisions...
, zero degree-day...). This is the base load of the system, the minimal consumption when it is not operating. - The slopeSlopeIn mathematics, the slope or gradient of a line describes its steepness, incline, or grade. A higher slope value indicates a steeper incline....
represents the relationship between the consumption and the previously identified variableVariable (mathematics)In mathematics, a variable is a value that may change within the scope of a given problem or set of operations. In contrast, a constant is a value that remains unchanged, though often unknown or undetermined. The concepts of constants and variables are fundamental to many areas of mathematics and...
. This represents the efficiency of the process. - The scatterScatterIn ordinary English, to scatter is to distribute randomly. Scatter also has the following meanings:*In physics, scattering is the study of collisions, especially of waves and particles...
is the degree of variability of the consumption with operational factors.
The slope
Slope
In mathematics, the slope or gradient of a line describes its steepness, incline, or grade. A higher slope value indicates a steeper incline....
is not used quite as often for M&T purposes. However, a high y-intercept
Y-intercept
In coordinate geometry, using the common convention that the horizontal axis represents a variable x and the vertical axis represents a variable y, a y-intercept is a point where the graph of a function or relation intersects with the y-axis of the coordinate system...
can mean that there is a fault in the process, causing it to use too much energy with no performance, unless there are specific distinctive features which lead to high base loads. Very scattered points, on the other hand, may reflect other significant factors playing in the variation of the energy consumption, other than the one plotted in the first place, but it can also be the illustration of a lack of control over the process.
Monitor variations
The next step is to monitor the difference between the expectedExpected
Expected may refer to:*Expectation*Expected value*Expected shortfall*Expected utility hypothesis*Expected return*Expected gainSee also*Unexpected...
consumption and the actual measured consumption. One of the tools most commonly used for this is the CUSUM
Control chart
Control charts, also known as Shewhart charts or process-behaviour charts, in statistical process control are tools used to determine whether or not a manufacturing or business process is in a state of statistical control.- Overview :...
, which is the CUmulative SUM of differences. This consists in first calculating the difference between the expected
Expected
Expected may refer to:*Expectation*Expected value*Expected shortfall*Expected utility hypothesis*Expected return*Expected gainSee also*Unexpected...
and actual performances (the best fit line previously identified and the points themselves).
The CUSUM
CUSUM
In statistical quality control, the CUSUM is a sequential analysis technique due to E. S. Page of the University of Cambridge. It is typically used for monitoring change detection...
can then be plotted against time on a new graph
Chart
A chart is a graphical representation of data, in which "the data is represented by symbols, such as bars in a bar chart, lines in a line chart, or slices in a pie chart"...
, which then yields more information for the energy efficiency specialist. Variance
Variance
In probability theory and statistics, the variance is a measure of how far a set of numbers is spread out. It is one of several descriptors of a probability distribution, describing how far the numbers lie from the mean . In particular, the variance is one of the moments of a distribution...
s scattered around zero usually mean that the process is operating normally. Marked variations, increasing or decreasing steadily usually reflect a modification in the conditions of the process.
In the case of the CUSUM
Control chart
Control charts, also known as Shewhart charts or process-behaviour charts, in statistical process control are tools used to determine whether or not a manufacturing or business process is in a state of statistical control.- Overview :...
graph, the slope
Slope
In mathematics, the slope or gradient of a line describes its steepness, incline, or grade. A higher slope value indicates a steeper incline....
becomes very important, as it is the main indicator of the savings achieved. A slope
Slope
In mathematics, the slope or gradient of a line describes its steepness, incline, or grade. A higher slope value indicates a steeper incline....
going steadily down indicates steady savings. Any variation in the slope
Slope
In mathematics, the slope or gradient of a line describes its steepness, incline, or grade. A higher slope value indicates a steeper incline....
indicates a change in the process. For example, in the graph on the right, the first section indicated no savings. However, in September (beginning of the yellow line), an energy efficiency measure must have been implemented, as savings start to occur. The green line indicates an increase in the savings (as the slope
Slope
In mathematics, the slope or gradient of a line describes its steepness, incline, or grade. A higher slope value indicates a steeper incline....
is becoming steeper), whereas the red line must reflect a modification in the process having occurred in November, as savings have decreased slightly.
Identify causes
Energy efficiency specialists, in collaboration with building managers, will decipher the CUSUMControl chart
Control charts, also known as Shewhart charts or process-behaviour charts, in statistical process control are tools used to determine whether or not a manufacturing or business process is in a state of statistical control.- Overview :...
graph and identify the causes leading to variations in the consumption. This can be a change in behaviour, a modification to the process, different exterior conditions, etc. These changes must be monitored and the causes identified in order to promote and enhance good behaviour, and discourage bad ones.
Set targets
Once the base line has been established, and causes for variations in energy consumption have been identified, it is time to set targets for the future. Now with all this information in hand, the targets are more realistic, as they are based on the building’s actual consumption.Targeting consists in two main parts: the measure to which the consumption can be reduced, and the timeframe during which the compression will be achieved.
A good initial target is the best fit line identified during step 2. This line represents the average
Average
In mathematics, an average, or central tendency of a data set is a measure of the "middle" value of the data set. Average is one form of central tendency. Not all central tendencies should be considered definitions of average....
historical performance. Therefore, keeping all consumption below or equal to the historical average is an achievable target, yet remains a challenge as it involves eliminating high consumption peaks.
Some companies, as they improve their energy consumption, might even decide to bring their average
Average
In mathematics, an average, or central tendency of a data set is a measure of the "middle" value of the data set. Average is one form of central tendency. Not all central tendencies should be considered definitions of average....
performance down to their historical best. This is considered a much more challenging target.
Monitor results
This brings us back to step 1: measure consumption. One of the specificities of M&T is that it is an ongoing process, requiring constant feedbackFeedback
Feedback describes the situation when output from an event or phenomenon in the past will influence an occurrence or occurrences of the same Feedback describes the situation when output from (or information about the result of) an event or phenomenon in the past will influence an occurrence or...
in order to consistently improve performance. Once the targets are set and the desired measures are implemented, repeating the procedure from the start ensures that the managers are aware of the success or failure of the measures, and can then decide on further action.
Examples
An example with some features of an M&T application is the ASU Campus MetabolismASU Campus Metabolism
ASU Campus Metabolism is a website managed by Arizona State University, demonstrating Energy monitoring and targeting through use of real-time and historic energy use data of buildings on the campus in Tempe, Arizona...
, which provides real-time and historic energy use and generation data for facilities of Arizona State University
Arizona State University
Arizona State University is a public research university located in the Phoenix Metropolitan Area of the State of Arizona...
on a public web site.
See also
- Building automationBuilding automationBuilding automation describes the functionality provided by the control system of a building. A building automation system is an example of a distributed control system...
- Demand responseDemand responseIn electricity grids, demand response is similar to dynamic demand mechanisms to manage customer consumption of electricity in response to supply conditions, for example, having electricity customers reduce their consumption at critical times or in response to market prices...
- Energy management softwareEnergy Management SoftwareEnergy Management Software is a general term and category referring to a variety of energy-related software applications which may provide utility bill tracking, real-time metering, building HVAC and lighting control systems, building simulation and modeling, carbon and sustainability reporting,...
- Energy saving
- Nonintrusive load monitoringNonintrusive load monitoringNonintrusive Load Monitoring , or Nonintrusive Appliance Load Monitoring, is a process for analyzing changes in the voltage and current going into a house and deducing what appliances are used in the house as well as their individual energy consumption...
- ChellowChellowChellow is open source Energy accounting software for checking the correctness of UK electricity bills.Energy accounting software is a class of software products used for tracking, managing, processing, reporting and analyzing for accuracy of utility bills and energy information...