This report uses the GREEN Grid project research data to analyse a variety of residential household appliances and their contribution to peak demand under several scenarios. Although the data does not derive from a representative sample of households, we demonstrate that identifiable heating contributes ~ 21% to residential peak (17:00-21:00) demand in winter with Hot Water at ~ 17%, Lighting at 14% and Ovens at 7% while non-identified appliances contribute ~ 40%. These percentage contributions are generally similar at both regional network and sample co-incident peaks and across seasons although total power demand varies by season according to the appliance. Thus ‘Others’, heating and lighting are substantially lower in summer and whilst further research is clearly needed to unpack ‘Other’ demand, this suggests heating may be a major component.

Our results also show that simple mean (or median) values or single indicators such as average load factors mask considerable variation both within and between households. Overall we conclude that future work should focus on collecting data from a larger and representative sample of New Zealand households, ensuring that appliances are identified on circuits (especially electric heaters) and that both inter and intra-household heterogeneity should be adequately represented in analytic results.

1 About

1.1 Citation

If you wish to use any of the material from this report please cite as:

  • Dortans, C., Anderson, B. and Jack, M. (2019) NZ GREEN Grid Household Electricity Demand Data: EECA Data Analysis (Part B) Report v2.1_Final, Centre for Sustainability, University of Otago: Dunedin.

This work is (c) 2019 the authors. Usage rights are specified in the License section (1.3).

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  • Public – this report is intended for publication following EECA approval.

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1.4 History

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1.5 Support

This work was supported by:

  • The New Zealand Energy Efficiency and Conservation Authority (EECA)

2 Introduction

This report uses the GREEN Grid project (Stephenson et al. 2017) research data to analyse a variety of residential household appliances and their contribution to peak demand under several scenarios.

3 Data

The NZ GREEN Grid household electricity demand study recruited a sample of c 40 households in each of two regions of New Zealand (Stephenson et al. 2017). The first sample was recruited in early 2014 and the second in early 2015. Research data includes:

  • 1 minute electricity power (W) data was collected for each dwelling circuit using GridSpy monitors on each power circuit (and the incoming power). The power values represent mean(W) over the minute preceding the observation timestamp;
  • Dwelling & appliance surveys;
  • Occupant time-use diaries (focused on energy use).

The data collection was supported by the New Zealand Ministry of Business, Innovation and Employment (MBIE) through the Renewable Energy and the Smart Grid (GREEN Grid) grant (Contract ID: UOCX1203).

As background, Table 3.1 shows the mean half-hourly and mean total kW and kWh by season for the sample households in 2015. For this purpose the periods are defined as:

  • 21:00 - 07:00 Off peak (night)
  • 07:00 - 09:00 Peak (morning)
  • 09:00 - 17:00 Off peak (day)
  • 17:00 - 21:00 Peak (evening)
Table 3.1: Descriptive statistics for power data
Season Peak Mean total kWh Mean kW s.d. (kW) N households
Autumn Off peak (day) 11.05 0.39 0.67 39
Autumn Off peak (night) 11.04 0.30 0.54 39
Autumn Peak (evening) 9.95 0.68 0.93 39
Autumn Peak (morning) 4.34 0.60 0.94 39
Spring Off peak (day) 12.08 0.36 0.65 32
Spring Off peak (night) 13.18 0.31 0.57 32
Spring Peak (evening) 10.79 0.64 0.93 32
Spring Peak (morning) 4.82 0.58 0.92 32
Summer Off peak (day) 6.74 0.33 0.56 35
Summer Off peak (night) 6.52 0.24 0.41 35
Summer Peak (evening) 4.66 0.44 0.65 35
Summer Peak (morning) 2.16 0.41 0.69 35
Winter Off peak (day) 15.20 0.48 0.80 36
Winter Off peak (night) 16.66 0.41 0.71 36
Winter Peak (evening) 15.21 0.94 1.18 36
Winter Peak (morning) 6.16 0.76 1.13 36

Figure 3.1 shows the mean total kWh consumed per household by period and season. Note that this total reflects not only the power demand level but the number of hours in each period.

Mean total kWh per period by season (2015)

Figure 3.1: Mean total kWh per period by season (2015)

Figure 3.2 on the other hand shows the mean half-hourly kW demand per household by period and season and reflects the greater power demand in the evening and morning peak periods.