Elsevier

Energy and Buildings

Volume 128, 15 September 2016, Pages 530-539
Energy and Buildings

Analysis of real-time electricity consumption in Canadian school buildings

https://doi.org/10.1016/j.enbuild.2016.07.022Get rights and content

Highlights

  • Electricity use increase in newer schools was statistically significant.

  • However, spaces in new schools were using less electricity.

  • Other factors (e.g. increased automation and advanced HVAC) may explain the increase.

  • Occupancy patterns also significantly affected electricity use in school spaces.

  • Therefore, efforts to decrease buildings’ electricity use should focus on occupancy.

Abstract

Previous studies indicate electricity consumption is increasing in new and green buildings highlighting the importance of investigating parameters affecting that increase. The majority of previous studies also focused on studying commercial or residential buildings emphasizing the need to study energy consumption in other building types. This study analyzed historical energy consumption data in a representative sample of thirty schools in Manitoba, Canada. It showed that the decrease in gas consumption for heating in new schools was counteracted by a statistically significant increase in their electricity consumption. Three cases study schools were selected for further analysis of their electricity consumption. Within each school, one classroom, the gymnasium, as well as spaces with significant community use, were sub-metered to collect real-time electricity consumption data. Results indicated total electricity consumption increased in the newest school, although sub-metered spaces in older schools consumed more electricity. Variations in electricity consumption between sub-metered spaces were attributed to occupant behaviour. The study is the first to provide an in-depth investigation of electricity consumption in Canadian school buildings and consider the potential effect of typically overlooked parameters such as occupant behaviour on their overall energy consumption.

Introduction

Buildings accounts for 20–40% of energy use worldwide [1], representing an excellent opportunity to achieve large scale energy reductions. Advances in new and green buildings can help decrease their energy use by improving building envelopes; and heating, ventilation and air conditioning (HVAC) systems which can make them 25–30% more energy efficient on average than conventional ones [2]. However, some studies (e.g. [3], [4]) indicate these buildings used more electricity than conventional ones which can be attributed to occupant behaviour [5]. Therefore, closing the gap between actual and expected buildings’ energy performance is essential by considering all parameters influencing buildings’ energy consumption, such as those related to occupancy and usage [6]. Previous studies also focused on analyzing energy consumption in commercial buildings, highlighting the need to analyze energy consumption in other building types [7]. School buildings contribute considerably to overall energy consumption due to their large number within the building stock [8]. They represent an excellent opportunity towards improving energy efficiency as they “can be used as communication means towards pupils and their families, and can thus reach many different society groups” [8].

This study aimed to evaluate the energy performance of school buildings in Manitoba, Canada. It entailed analyzing historical energy consumption in a randomly selected sample of thirty schools over nine years. The analysis revealed newer schools used more electricity than older ones while using less gas annually, reinforcing the need to investigate their electricity consumption in more detail. Therefore, three case-study schools were selected for further analysis of their real-time electricity consumption from the end of January 2015 till the end of May 2015. These schools included a new Leadership in Energy and Environmental Design (LEED) certified school built in 2009, a middle-aged school built in 1968 and an old school building, built in 1951. The study entailed analyzing real-time electricity consumption in classrooms, gymnasiums and spaces believed to be heavily used by the community in those three schools. Specific objectives of this study involved evaluating: (1) differences in electricity consumption between the three schools at the building and space levels, (2) differences in electricity consumption between work and non-work hours, and (3) changes in electricity consumption patterns during the analysis period.

Section snippets

Background

A review of the literature on buildings’ energy consumption in relation to occupancy showed mixed results. In some studies, (e.g. [9], [10]) energy consumption varied significantly between similar buildings, highlighting the potential effect of building occupants. The performance gap between expected and actual energy consumption was also more significant in “green buildings” built to specific standards such as LEED and the Building Research Establishment Environmental Assessment Method

Methods

This study evaluated energy consumption in a sample of Manitoba schools. The research entailed collecting general information about the population of 126 schools in four school divisions. This information helped determine these schools’ floor areas, their dates of construction, number of occupants, grade levels as well as information regarding major renovations, retrofits and additions. The information was used to select, using stratified random sampling and Neyman proportional allocation

Results

This section reports on the results of analyzing historical energy data for the thirty schools, followed by the results of analyzing real-time electricity consumption data for the three case study schools.

Discussion and conclusions

The analysis of historical energy consumption revealed a decrease in gas consumption for heating in newer schools but a statistically significant increase in their electricity consumption. The decrease in gas consumption in newer schools could be due to advancements in building insulation that emanate from the introduction of the Model National Energy Code for Buildings in Canada in the 1990s. However, the use of more complex HVAC systems including programmable thermostats in newer buildings

Acknowledgments

This research was supported by a Discovery grant (RGPIN 418532-2012) from the Natural Sciences and Engineering Research Council of Canada. The authors would also like to thank Manitoba Public Schools Finance Board for their help with providing access to school records and Manitoba Hydro’s Customer engineering department for providing and installing sub-metering equipment. The authors would also like to thank undergraduate students Mr. Panos Polyzois and Mr. Nishant Nain for their help with the

References (38)

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