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This research examines the electricity consumption trends in New Zealand office buildings from 1990 to 2008. The study analyzes data from 418 buildings, including city, location, lettable area, vacancy, office quality grade, and energy expenditure. Key findings include relatively constant electricity expenditure for common area and central services, lower electricity expense for lower quality office buildings, and declining consumption in kWh per m2. The research highlights the need for more comprehensive electricity use data in the office sector.
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17th ERES Conference Milan, Italy, June 2010 Electricity Use Trends in New Zealand Office Buildings 1990-2008 John McDonagh Property Group, Commerce Faculty, Lincoln University New Zealand
Background • Globally, the built environment accounts for 40% of energy consumption (Kolokotsa et. al. 2009) • The built environment is assessed as accounting for 70% of electricity consumption in the USA (Nicolay 2007) • New Zealand generates most of its electricity from renewable hydro electric sources • But there are limited opportunities to expand such generation. • NZ government has been promoting energy efficiency as a means to reduce growth in electricity demand • Focus to date on the residential sector.
Literature • A lot of international energy research • Continuing debate on efficacy of different efficiency strategies • Very little in New Zealand on the office sector • Engineering orientated • Some case studies • International benchmarks not applicable in NZ • Some benchmarking work still underway
Methodology • Property Council office building OPEX survey data • 418 buildings 1990-2008 included - city - location - lettable area - vacancy - office quality grade and energy expenditure (electricity oil and gas) for Common Area and Central Services • Identified national and city electricity expenditure trends (mean $/m2) • Identified electricity expenditure trends for different office grades • Identified electricity price trends ($/kwh) • Converted expenditure to consumption (kwh/m2) using price data • Converted common area and central services consumption to total building consumption using ratios from the data available
Results MeanCommon Area & Central Services Electricity Expenditure - $/m2 National trend 1990-2008
Mean Common Area & Central Services Electricity Expenditure - $/m2 City comparison
Mean Common Area & Central Services Electricity Expenditure - $/m2 Office grade comparison
National Electricity Prices - $ per kw/h Mean of all Suppliers
Electricity Prices – $ per kw/hComparison of Major Suppliers in Large Cities
Electricity Prices – $ /kwhComparison of Commercial Price Indices
Electricity Consumption Common Area and Central Services – kwh/m2 Mean Expenditure Divided by Electricity Price Indices
Conclusions • Electricity expenditure for common area and central services in NZ office buildings has remained relatively constant since1990 • This trend applies to all major cities and office quality categories in NZ • Lower quality office buildings have lower electricity expense • Office buildings in Christchurch have lower electricity expense • Nominal electricity prices for large commercial users have been relatively stable and declined in real terms until recently • Recent electricity price increases have been offset by efficiency gains with consumption in kwh/per m2 declining slightly • Conversion of common area and central services to total building electricity consumption was problematic but indicates an average overall rate of 150kwh/m2 • The research highlighted the need to collect more comprehensive electricity use data.
