With the goal to reach net zero carbon emission, countries around the world are expected to switch from fossil fuel to more eco-friendly alternatives. This suggests that heating, transport, and energy sectors will be more dependent on electricity. Heat pump technology is expected to be the most common and clean technology to be used for heating in buildings due to its Coefficient of Performance. Air-source heat pumps are the most common type due to their ease of installation. This paper investigates how different climates around the world would affect the air-source heat pump electricity consumption and its defrost cycles; and hence the potential overall effect on the grid. A novel heat pump simulation model has been developed to understand the behaviour of the heat pump in cold weather scenarios. An experimental validation has been implemented to ensure the accuracy of the simulation model. Global case studies of cities from around the world including Amsterdam, Copenhagen, Helsinki, Stockholm, Vancouver, Ruse, Moscow, Reykjavik, Harbin and Nottingham are selected to assess the defrost cycles of air source heat pumps. The innovation of this research is in the in-depth investigation of heat pump defrost cycles. Electrifying the heating sector is expected to increase electricity consumption significantly, especially in cold weather. A detailed case study of the UK is presented with heat pumps and the examination of the impact this would have on the electricity grid is presented. Heating demands for buildings in cold weather was also simulated to calculate the required heating demand. The results show that the wide implementation of heat pumps in the UK, for example, would increase the total daily demand of electricity by approximately 144% relative to the present level of grid energy demand. In addition, the average daily energy consumption would increase by roughly 106% over the cold season. The findings are critical, and the novel methodology is applicable to many countries on global level in relation to the future effect of heat pumps on the grid and predicting the power demand needed by the additional heat pumps based on geographical location, u-values of building elements, and heating demand. It is crucial for a household to improve the insulation of their dwelling as this could considerably reduce the power demand by the heat pump and therefore the overall electricity consumption. This paper aims to inform future technology developers and policy makers regarding the expected effect of heat pump technology on the grid and the possible sudden peaks in demand.
