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Energy Consumption of Major Household Appliances Shipped in Canada – Trends for 1990–2005


APPENDIX A – METHODOLOGY

A.1  Data Preparation

A.1.1  Introduction

To improve the monitoring of trends in Canadian energy use, Natural Resources Canada's (NRCan's) Office of Energy Efficiency proposed an annual data collection arrangement with the Canadian Appliance Manufacturers Association (CAMA) in 1996, as part of the National Energy Use Database initiative.

Under this agreement, CAMA members contributed for analysis their annual shipment data for six appliance categories – refrigerators, freezers, dishwashers, electric ranges, clothes washers and electric clothes dryers. To keep their data confidential, these appliance manufacturers suggested that a third party receive and prepare the database in a format in which no one (other than the third party) could determine the shipment data for an individual model or manufacturer. NRCan retained the services of Electro-Federation Canada (EFC), chosen by CAMA, as the third party to receive the data.

For 2005 (and for the previous year), the manufacturers agreed to provide data on their shipments by province/region and by distribution channel (builder versus retailer), where possible. These additional shipment data have allowed a more detailed analysis of the distribution and energy efficiency of the appliances.

A.1.2  Database Preparation Process

The data presented in this report combine shipment figures from the major appliance manufacturers in Canada with the energy use information in NRCan's annual EnerGuide Appliance Directory. Analysts from EFC matched the model number from the manufacturer with the corresponding model in the EnerGuide Appliance Directory. Thus they arrived at the energy consumption represented by all shipments of that model within each year. The analysts then aggregated these figures by province/region, by channel and for Canada to provide the data presented in this report. They produced separate aggregated data for ENERGY STAR® models, where appropriate.

The analysts assembled the data using standard database and spreadsheet software and submitted it to NRCan for analysis and report generation. For the reporting stages, any information that could identify the manufacturer or model number was removed.

A.1.3  Manufacturers' Data

NRCan sent a letter to each appliance manufacturer, requesting annual shipment data for each model of refrigerator, freezer, dishwasher, electric range, clothes washer and electric clothes dryer on the Canadian market from 1990 to 2005. When the project began in 1996, only three manufacturers provided shipment data. The number of data contributors has since increased to eight, covering the majority of appliance models sold in Canada. NRCan is approaching additional manufacturers to improve the coverage for future data collection.

Manufacturers submitted the data in various electronic and printed formats. EFC converted the electronic data to a common database format. The analysts entered the data into the database from the printed reports.

The data included the appliance type, model number and number of shipments (by province/region and channel, where possible, for 2004 data onwards) for each year. Because each manufacturer provided data in a different format, the analysts amalgamated the files to produce a single file for all models subdivided by appliance type, province/region, channel and model year.

The nature of the freezer market prevented EFC from obtaining a model-by-model breakdown of shipments. Instead, the analysts received total shipments and average energy use by freezer type. NRCan used this information to generate the freezer reports.

A.1.4  EnerGuide Data

The analysts used the size, type and unit energy information from NRCan's EnerGuide ratings for each appliance to calculate the shipment-weighted energy use of each appliance type. Also, the EnerGuide Appliance Directory was used to identify which models were listed as ENERGY STAR.

A.1.5  Data Matching

Analysts from EFC matched the manufacturer's data for each model with the corresponding energy consumption data from the EnerGuide Appliance Directory for that model. They then multiplied the manufacturer's shipments for each model by the corresponding EnerGuide model's energy rating. This result is the shipment-weighted total energy consumption for that model. Each appliance category (such as refrigerator, dishwasher) and type and size category (as defined in the EnerGuide directories, such as Type 7 refrigerators, self-cleaning ranges, front-loading clothes washers) was then subtotalled so that the average unit energy consumption could be calculated.

The EnerGuide Appliance Directory shows the basic model numbers for appliances available on the Canadian market. Many slight model variants have the same energy rating; therefore, the listings use symbols (such as * and #) to indicate model families. Because some model numbers have additional prefixes or suffixes to indicate features that do not affect energy use (such as colour and door-swing), there were relatively few one-to-one matches.

Analysts needed to manipulate the data to perform pattern matching. They wrote programs to compare the model numbers supplied by the manufacturers with those in the EnerGuide Appliance Directory. When a match was found, the corresponding energy consumption figure and the information about the type from the EnerGuide Appliance Directory were added to the record for the annual shipments of the model.

Because there were many combinations of character substitution, the analysts adopted a method to work from the closest matches to the least likely matches. Matches in which only one character differed were flagged and removed. Attempts were then made with a difference of two characters, and so on.

The analysts developed reasonability tests to ensure the integrity of the data-matching process. For example, if the manufacturer's model number contained many characters but was matched by a model in the EnerGuide Appliance Directory that had considerably fewer characters, the model was flagged for manual checking. They also realized that manufacturers might re-use the same numbers for different models after several years.

For example, 128 models of refrigerators in the file containing 1980 to 1993 data from the EnerGuide Appliance Directory have the same model number as those in the 1997 file, but with different energy ratings. They flagged these models for special treatment. During the matching process, analysts applied "reasonability" criteria. For example, a model would be checked manually if its shipments were reported more than three years after the last time the corresponding model appeared in the EnerGuide list or if the EnerGuide model number contained considerably fewer characters than that of the manufacturer.

Some difficulties occurred when the model number in NRCan's EnerGuide Appliance Directory differed from the actual model numbers used by the manufacturers in their internal shipment recording systems. In some cases, for example, manufacturers used special codes to denote models that were branded for other companies, such as department stores. The manufacturers helped resolve most of these cases.

Some models remained unmatched even after the automated processes were performed. Whenever one of these models represented a substantial number of shipments for that appliance type, analysts handled it on an exceptional basis. Manufacturers were again helpful in identifying these models and verifying energy ratings and types.

The process continued until all but a few minor models were matched.

A.1.6  Data Summary and Transfer

After the matching process, analysts summarized the data. To calculate the total annual energy consumption for each model, they multiplied the model's energy rating by the number of shipments for the year. This yielded the shipment-weighted total energy use of that model for that year. For example, model XYZ has annual shipments of 5238 and an annual energy consumption of 683 kilowatt hours (kWh); its shipment-weighted total energy use for the year is 5238 x 683 kWh = 3 577 554 kWh. This aggregate figure and the shipment figures were added as necessary to provide totals for each appliance type and size category as appropriate. Separate aggregated data were provided for ENERGY STAR models. All these aggregate figures were given for province/region, channel and country.

For refrigerators, the actual volume of each model was available from the EnerGuide Appliance Directory. Therefore, it was possible to monitor the trend of changes in the size of refrigerators over the years. Furthermore, it was possible to determine the amount of energy used by each size category. Analysts summarized this information and added it to the database for NRCan.

The final database prepared by EFC consisted of such information as the appliance type, model year, total energy consumption and average unit consumption. Refrigerators were further categorized by type and size. The aggregated data were broken down by ENERGY STAR versus non-ENERGY STAR (as of 1999) and province/region and channel (as of 2004). All the information was transferred to spreadsheets and sent to NRCan for analysis and reporting.

A.2  Analysis

The shipment-weighted average annual unit energy consumption (UEC) by category was calculated as total energy consumption of all the refrigerators sold in Canada in that category divided by total number of shipments in that category. The following gives an example of the shipment-weighted average UEC for the refrigerators:

Example of the shipment-weighted average energy consumption for the refrigerators.

As mentioned in section A.1, "Data Preparation," data were obtained for some appliances by size category. Therefore, the UEC per cubic foot was calculated by dividing the UEC of a given size category by the midpoint of the category.

A.2.1 Incremental Energy Savings

Calculating the incremental energy savings for each appliance type was a three-step process, as follows:

  1. Baseline levels of energy consumption were estimated for each appliance type for each year between 1990 and 2005. For all appliances, baseline levels of energy consumption reflected NRCan's assumptions about how much energy each appliance type would have consumed without the energy efficiency improvements made by manufacturers and the minimum energy performance standards (MEPS). To estimate baseline levels of energy consumption, the following was assumed:

    • Without the implementation of Canada's Energy Efficiency Regulations and general energy efficiency improvements made by manufacturers, the UEC for all appliance types would have remained constant at the 1992 levels.

    • The number of units shipped would have remained the same between 1990 and 2005 even in the absence of the general efficiency improvements made by manufacturers and the implementation of the Energy Efficiency Regulations.
Even though the MEPS were not introduced until 1995, the baseline year used for all estimates of energy savings was 1992. This is because energy efficiency began to improve almost immediately after the Energy Efficiency Act came into force in 1992, thanks to market forces, such as the regulations expected from the Act and United States regulations.
  1. "Actual" or current levels of consumption for all appliances were calculated in an identical fashion. The average annual UEC for each appliance type for each model year was used, instead of holding it constant at 1992 levels, to determine the actual levels of energy consumption.

  2. Incremental energy savings for all appliances were then calculated as the difference between baseline and actual levels of energy consumption.

Because 1992 was the baseline year used in the calculations, a retirement function was included to take into account the aging of appliances, based on the life expectancies set out in the 2005 EnerGuide Appliance Directory.37 Applying this retirement function was done to avoid overestimating the actual energy savings from appliance stock that has been retired (or is no longer in use). The calculation involved using the average life expectancy, annual shipment data and annual incremental energy savings for each appliance type. Average life expectancy and annual shipment data for each appliance type were used to estimate the annual stock of each appliance type in use. This estimate was then applied to the annual incremental unit energy savings for each appliance type (shipment-weighted UEC for 1992 less the shipment-weighted UEC for each year) to calculate the cumulative energy savings.

A.2.2 Cumulative Energy Savings

This calculation was a four-step process, as follows:

  1. The average life expectancy of each appliance type was assumed to be the industry average reported in the 2005 EnerGuide Appliance Directory:

    1. refrigerators – 17 years
    2. freezers – 21 years
    3. electric ranges – 18 years
    4. dishwashers – 13 years
    5. clothes washers – 14 years
    6. clothes dryers – 18 years
  1. A retirement function was used to estimate the retirement rate of each appliance type. In this linear function, no appliances retire in the first two thirds (0.67) of their average life expectancy, and all units are retired by four thirds (1.33) of their average life expectancy. The ranges for the retirement function are as follows:

    1. if age < (2/3 * [average life expectancy]), 100 percent survive
    2. if age > (4/3 * [average life expectancy]), 0 percent survive
    3. otherwise, (2 – age * 1.5/[average life expectancy]) survive

  1. The rate of retirement was applied to the annual shipments of each appliance type to estimate the total stock of appliances in use for each year since the baseline year of 1992.

  2. The total stock of appliances for each year since 1992 was separated into categories based on the year the appliances were shipped. Cumulative energy savings were then calculated by multiplying the annual shipments that made up the stock by the incremental unit energy savings for each corresponding year.

This retirement function is demonstrated in Figures A.1 and A.2.

Retirement Function for Aging Appliances.

Cumulative Energy Savings for All Appliances With and Without Retirement Factor, 1992-2005.

Click here to view larger image


37 Natural Resources Canada EnerGuide Appliance Directory 2005 (Ottawa: February 2005), p. 13.