Energy perceptions in South Africa: An analysis of behaviour and understanding of electric water heaters

Abstract

Using data from an online national survey conducted in South Africa, this paper aims to investigate: the awareness of energy savings measures for electric water heaters (EWHs); whether or not consumers are implementing suggested measures; and if consumers understand and effectively control their EWHs' energy usage. Additionally, the data is used to determine the success of educational and rebate programmes aimed at reducing residential energy usage and to determine possible motivations for encouraging users to reduce or alter their EWH energy and warm water consumption. The results of this questionnaire indicate that: convenience is a key factor in consumers' willingness to implement curtailment actions; users don't understand the energy consumption of their EWHs; and they don't know how to control their EWHs efficiently.

How much energy can optimal control of domestic water heating save?

“…Scheduled control with temperature matching (TM): In an attempt to save on bills and reduce loss of energy, financially sensitive and environmentally aware users resort to turning off their heaters for extensive periods between the times when they need hot water (Nel et al, 2016b). The timing applied in this strategy is individually motivated and could vary significantly between users, but the optimal scenario (for a water heater with energy storage) is to switch the heater on just sufficiently in advance of the time the hot water will be needed (Booysen et al, 2013;Nel et al, 2016b). When applying optimisation techniques, as we have done in this study, optimisation constraints can be set to ensure that the same volume of water is drawn at the same temperatures as under thermostat control, but the thermal losses to the environment are minimised.…”

“…The relevant literature and major remaining challenges for energy saving through scheduled control of storage-based water heaters are listed in Table 1 and summarised in the following section. In developing countries, where the user typically pays a time-independent flat fee per kWh, and not a tariff based on time-of-use or congestion, poorer users resort to schedule control simply to reduce their monthly bill, and possibly their environmental footprint (Nel et al, 2016b;Hohne et al, 2019), and not to shift peaks or to avoid congestion charges. In this situation it is the user who bears the burden of the increased energy usage that may result from any demand management schemes (Roux et al, 2018).…”

Optimal schedule and temperature control of stratified water heaters

“…Users in some countries, typically paying a time-dependent flat fee per kWh rather than a tariff based on time-of-use or congestion, resort to schedule control to reduce their monthly costs (Nel et al, 2016b;Hohne et al, 2019). These users thus bear the burden of any increased energy usage resulting from demand management schemes (Roux et al, 2018).…”

Use of smart grid technology to compare regions and days of the week in household water heating

“…Many myths have circulated on how to optimally manage and understand the EWH to provide economic benefits as well as preserve user comfort. Mainly the result is a consumer not knowing when to manually switch on the EWH, or for how long, to ensure lower energy consumption while still ensuring warm water on demand [4].…”