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Almost one third of the UK's total energy is consumed by the domestic sector. Occupancy measurement could have the potential to save significant amounts of that energy, either instantly via a home automation system or retrospectively via post-occupancy evaluation. However, not many localisation technologies are applicable to a domestic environment. In this paper three unobtrusive occupancy measuring technologies, i.e. Passive Infra-Red (PIR), Carbon Dioxide (CO2) and Device-free Localisation (DfL), are compared. Their operation is explained and possible advantages and disadvantages are outlined. A qualitative experimental study then analyses the abilities of each system to detect overall occupancy, detect room level occupancy, count the number of occupants and localise them. It has been found that CO2 and PIR sensors are very limited. The impacts of other factors, such as windows or occupants' metabolic rates, were significant on the reliability of the measured data.Device-free localisation on the other hand has great potential, but requires further research.

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In March 2020, the United Kingdom (UK) government ruled that householders must stay home as a response to the COVID-19 outbreak to help flatten the curve of the epidemic and reduce the exponential growth of the virus. Commercial activities, workplaces and schools were obliged to temporarily close in compliance with the government rules. This first and most restrictive lockdown took place from late March to early May 2020 when occupants had to stay in their homes except for very restricted essential activities. Two other lockdowns were introduced in November 2020 and January 2021, alongside with a range of restrictive measures during 2020. This offered an unprecedented opportunity to investigate the impact of a prolonged period of occupancy on household electricity consumption. In this work, the authors compared electricity consumption data collected from 21 energy-efficient houses in Nottingham, UK, during these lockdown periods to the same period in previous year. The findings indicated that the monthly electricity consumption in April 2020, during the strictest lockdown, increased approximately 5% in comparison to the same period in 2019. The daily electricity consumption profile during this lockdown showed earlier and longer peaks in the evenings with the emergence of a new midday peak in comparison to typical daily peaks prior to lockdown. The findings supported the idea that electricity consumption is increased as a result of the proportion of time residents spend in their homes and this corresponded to 17% more in 2020-2021, when restrictive measures were in place.

No abstract