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A Comparison of Natural Gas and Electricity Consumption in the Residential Sector
Mark A. Rebman, BC Hydro 604-453-6289
Overview
Residential electricity and natural gas customers are each affected by changes in the availability, price and end-use technology of alternative heating fuels.Knowing hownatural gas and electricityusers compare along space, water and supplementary heating dimensions can reveal some of the conditions under which these changesoccur. To model the comparisons, BC Hydro – an electrical utility inBritish Columbia, Canada – drew arepresentative sample of 1,971 customers for whomend-use, electricity and natural gasconsumption informationwas available.
Methods
A general linear model with two dependent variables is used to analyse annual natural gas and electrical energy consumption for space, water and supplemental heating. The model does not estimate unit energy consumption (UEC) by appliance but instead calculates average household values for two simultaneous equations to show the trade-off between electrical and natural gas usage. The technique splits annual consumption between the two dependent variables - Natural Gas and Electricity – and is a simple extension of the usual univariate model but entailing an additional column of dependent readings (Yij), parameter estimates (θij) and error terms (Uij). All natural gas consumption is denominated in Gigajoules (Gj) while electrical units are reported in kilowatt-hours (Kwh). The basic form of the model is:
CElectric= Intercept + Space Heat + Water Heat + Supplemental Heat + Region
CGas= Intercept + Space Heat + Water Heat + Supplemental Heat + Region
Interaction terms arenot included.
Results
SPSS is used to run the specified general linear model with computed estimators showingthe intercepts and coefficients associated with each variable and equation. The intercept term for CGas(101.97 Gj) represents consumption for a typicalsingle family dwellingusingnatural gas for water and space heatwithout supplemental heating while theCElectric(7,777.61 kWh) intercept isthe electric load equivalent for the same household. Parameters for the other variables in CGasestimate the energy required for water, space and supplemental heating when natural gas is replaced by electricity and are thus reported as negative values.This implies that the average household electric space heat valueof -63.4 Gj inCGasis the symmetric equivalent of7,489.5 Kwh in CElectric. Similarly, the CGas value of -30.3 Gj pairs withCElectricvalue of 3,036.1 kWh for water heat and -14.0 Gj with 3,206.0 kWh for supplemental heat.
Conclusions
A costing analysis of space, water and supplemental heat using parameters from the model confirms a price advantage for electricity under current natural gas and electricity tariffs in British Columbia.Results from the model show the competitive advantage of natural gasweakening with the current stock of heating appliances. This could blunt the impact of any demand-side management (DSM) program intended to defer construction of new and expensive power generation facilities. HigherBC Hydro rates could off-set this trend bystimulating growth in residential gas accounts and average gas use per customer while encouraging a coincidental drop in electricity consumption. The extent to which residential electricity rates could be setto meetrelated energy policy outcomes will depend onhow government agencies seekto balance demand for competing fuels.
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