Consumer Assessment Program Research Articles

End-Use Load and Consumer Assessment Program: motivation and overview

The End-Use Load and Consumer Assessment Program (ELCAP) was a major end-use data collection program undertaken by the Bonneville Power Administration from 1983 through 1990 to obtain specific information to support a variety of conservation and forecasting activities. The objectives of the program were to test key assumptions used in current engineering and forecasting models, provide insights regarding how various factors affect energy consumption, provide information to support load management conservation and marketing programs, and identify conservation resource potential from new demand-side technologies or programs. To accomplish this, a well-designed experiment was required that accounted for adequate representation of both existing and new buildings in the residential and commercial sector of the Pacific Northwest. This paper summarizes the motivations for obtaining the data, information regarding the sample, an overview of the analysis agenda, and specifics regarding the data set, both engineering and characteristics.

Metered end-use consumption and load shapes from the ELCAP residential sample of existing homes in the Pacific Northwest

Hourly end-use data have been collected from 454 residences and 140 commercial buildings in the Pacific Northwest. The data presented here provide an overview of electricity consumption patterns for 288 homes in the End-Use Load and Consumer Assessment Program (ELCAP) Residential Base Study. The Base Study is a sample of 454 regional single-family, owner-occupied, electrically space-heated houses. Metered residential electrical end-use loads collected as part of the ELCAP are summarized. The ELCAP was conducted by Pacific Northwest Laboratory for the Bonneville Power Administration. This paper addresses a number of load research questions: • What are the mean annual loads for specific end uses? • How much do end-use loads vary across residences? • Are load shares less variable across residences than end-use loads? • How do end-use loads vary with respect to common demographic variables, such as income level or number of occupants? • To what degree do end-use loads vary by time of year? • What are average hourly end-use load shapes? • What are the estimates of average annual end-use loads and load shares for the residential sector after applying assumed appliance and fuel saturation rates to the metered loads? Descriptions are presented of the metered hourly end-use loads aggregated across time and across time and across the sample of homes. Observations are made regarding common assertions about energy consumption patterns, but models or detailed statistical analyses of these loads are not included because they are the subject of other current and pending analyses.

Heat loss characteristics of the ELCAP residential sample

The fundamental purpose of this study is to analyze heat loss characteristics of the End-Use Load and Consumer Assessment Program (ELCAP) samples of residential buildings and compare these results in a regional context. The two basic objectives of the analysis are to determine the distribution of insulation levels and heat loss potential among the various building components in existing homes as a function of construction vintage and climate zone, and to calculate theoretical residential heat loss potentials for use in subsequent analyses. The vintage and climate zone dimensions explored in this analysis are of particular interest in testing the extent to which the sample supports the general perception that newer houses and houses in colder climates tend to be better insulated than older houses and houses in warmer climates. The distributions of overall heat loss potential and insulation levels, for the houses as a whole and for the houses excluding the foundation, are examined. The effects of house size, shape, and foundation type on these distributions are also examined. Similarly, the distributions of effective insulation levels for each building envelope component are developed. The sample weighted average heat loss potential for each envelope component is also determined by climate zone, to provide information about the relative heat loss through components that are the targets of energy conservation retrofit programs. A principal result of this analysis is the information that home insulation levels are primarily related to vintage rather than climate severity, at both the whole house and component levels. The sole exception to this trend is windows, which exhibit a trend in climate zone but not vitage. The general trend toward vintage as a determinant of thermal integrity of residences may be the consequence of a lack of climatically appropriate energy standards. This illustrates that the lost opportunities for achieving an energy-efficient housing population can be large in the face of a tendency to build to common practices that are not adapted to particular climates. It should also be noted that the historical trend toward larger homes does result in higher thermal conductance, but this is more than compensated by the trend toward increased insulation levels. The homes built to the Model Conservation Standards clearly exceed the historical trends when they are viewed as representative of the next decade of construction.

Analysis of water heater standby energy consumption from ELCAP homes

The Bonneville Power Administration (Bonneville) routinely prepares forecasts of future energy demands in the Pacific Northwest region of the United States. Bonneville also implements conservation programs to reduce load demands. Results from the End-Use Load and Consumer Assessment Program (ELCAP), undertaken by the Pacific Northwest Laboratory for Bonneville, indicated that single-family homes with electric space-heating equipment consume more than 4700 kWh/yr to heat water for domestic uses. This energy use amounts to about 23% of the total electricity consumed. Additionally, the peak consumption for water heating coincides with regional system peak demands. Detailed analyses of the water heating end-use data acquired for residential buildings in ELCAP reveal that the average standby load for existing homes is 1200 kWh/yr, while homes built as part of the Residential Standards Demonstration Program averaged 1100 kWh/yr. These figures are consistent with the current figure of 1300 kWh/yr that is being used in the regional energy forecast. We also determined that standby loads for some of the participants were behaviorally driven. The data indicated the occurrence of vacancy setbacks in which the participant appears to lower the thermostat to save energy while the house is vacant. Anecdotal evidence from interviews revealed that this does occur. Reasons for setting back the thermostat ranged from not thinking about using the breaker, to fear that the tank would freeze in cold weather. These types of activities also appear to create the occurrence of dueling thermostats where the upper and lower thermostats, after the vacancy period, are not returned to the same temperature. This leads to additional energy use in an attempt to maintain a uniform temperature in the tank.

Thermal analysis for the residential base sample

Space-heating electrical load data is used with inside and outside air temperature data, collected as part of the End-Use Load and Consumer Assessment Program (ELCAP), to study the thermal performance of 127 residences. These homes are located in the Pacific Northwest, and are subject to a wide range of climates. The homes were selected to roughly represent the region's owner-occupied homes having permanently installed, electrical space-heating equipment. Several thermal performance parameters are computed from space-heating load data for each residence. These measures include annualized estimates for space-heating consumption under various assumptions, an as-observed heat loss coefficient ( UA), and a building balance temperature difference. The mean as-operated, annualized estimated consumption for 127 Base Sample homes is 12 100 kWh/yr or 82.5 kWh/m 2 yr of conditioned floor area. The mean measured inside air temperature for these homes is 20.6 °C. The mean as-operated, annualized estimated consumption is somewhat lower than other consumption forecasts for single-family housing in the region. The as-observed UAs for the ELCAP Residential Sample indicate most homes are outperforming expectations based on ASHRAE-calculated UAs. This discrepancy points to some differences between as-observed efficiencies for several types of heating system and foundation combinations.

ELCAP operational experience

This paper documents our experience in conducting a major field program to acquire end-use electrical consumption data from a diverse set of commercial and residential buildings throughout the Pacific Northwest. This field program, known as the End-Use Load and Consumer Assessment Program (ELCAP), was initiated in August 1983. As of May 1989, data was being acquired from 390 residential structures and 111 commercial buildings, with 16 million hourly records collected monthly that occupied 2050 megabytes (MB) of electronic storage. This data volume doubled by 1991. A data acquisition program of this size can incur many difficulties. Recruiting sample homes, designing and fabricating data acquisition equipment and sensors, defining protocols, installing and maintaining equipment, acquiring, processing, verifying, and characterizing data all posed challenges, even to those of us with extensive experience in these areas. Because of the ground-breaking character of the study, there was little guidance available, and we made (and overcame) our share of mistakes. We believe that this chronicle of our experience will be useful to others embarking on large-scale end-use load studies.