Energy flexible commercial buildings and the electricity grid

New Zealand’s energy and electricity system is likely to undergo serious changes with climate change and the decarbonisation of the grid playing a significant role. Research in New Zealand around flexibly managing the electricity grid using buildings has focused on thermoelectric appliances in the residential sector while there has been limited research and quantification of the energy flexibility offered by commercial buildings. Despite this, managing the grid using energy flexible commercial buildings represents an opportunity to achieve meaningful reductions in electricity demand from buildings that are far less numerous than residential buildings. The aim of this thesis was to establish whether energy flexible commercial buildings in New Zealand can maintain the current quality of indoor thermal comfort and achieve reductions in demand that are sufficiently large that grid operators consider them significant contributors to grid management. By understanding the contribution, we can understand whether energy flexible commercial buildings are worth further investigation. In this thesis, energy flexibility means the ability for a building to manage its demand and generation according to user needs, grid needs, and local climate conditions. Energy flexibility in commercial buildings could then support the integration of more variable renewable energy sources and increase demand response capability which is a cost-effective way to manage network constraints and reduce non-renewable electricity generation. Case studies of New Zealand commercial buildings represented as Building Energy Models (BEMs) were simulated under energy flexible operation in a building performance simulation software (EnergyPlus). The selected case studies were small commercial buildings less than 1,499m² in size and which all contained heat pumps. The buildings were of office, retail, and mixed-use types. Two simple energy flexibility strategies were simulated in the buildings and the results from each building were then aggregated and extrapolated across the New Zealand commercial building stock. The strategies simply shifted and shed heating electricity demand. This was done to test whether implementing basic energy flexibility strategies have the potential to reduce electricity demand by a meaningful magnitude. At best the commercial building stock’s peak demand could reduce by 177MW by energy flexibly operating 45% of the commercial building stock, this was equivalent to around 11,700 buildings. In this scenario heating was shifted to start 150 minutes earlier in the morning. The study concluded that there is energy flexibility potential in New Zealand commercial buildings that results in demand reductions sufficiently large enough for grid operators to consider significant for grid management. This could be achieved without seriously jeopardising the current quality of indoor thermal comfort and warrants further investigation into energy flexible commercial buildings. This thesis also presented a refined methodology and energy modelling practice that could be used by other researchers to model and evaluate energy flexible buildings without the need to recreate the same methodology.