Energy flexibility potential of domestic hot water systems in apartment buildings

Abstract

Domestic Hot Water (DHW) storage tanks are identified as a main source of flexible energy use in buildings. As a basis for energy management in apartment buildings, this paper describes the aggregated DHW use in a case building, and analyses the potential for DHW energy flexibility by simulating different control options. The case study for the work is an apartment building in Oslo with 56 apartments and a shared DHW system. Energy measurements are available for consumed hot water, hot water circulation, and energy supplied to the DHW tanks. The measurements are presented with minute, hourly and daily values. Aggregated daily energy use for the consumed hot water is in average 362 kWh, while the energy supplied is 555 kWh. The potential for energy flexibility is analysed for a base case and for four different rule-based control options: Power limitation, Spot price savings, Flexibility sale and Solar energy. Economic consequences of the control options are compared. With the Norwegian tariff structure, maximum hourly power use has the main impact on the cost. Control systems that aim to reduce the maximum power use may be combined with spot price savings or to offer end-user flexibility services to the grid.

Analysing the Economic Viability of Implicit Demand Response Control of Thermal Energy Storage in Hot Water Tanks

“…Alternatively, energy companies can pay a flexibility bonus per kWh of shifted demand. It has been shown that such incentives can greatly improve the return on investment [37,69]. However, too many incentives without regulation can lead to the use of less efficient technologies which offer greater flexibility.…”

“…The study used measured DHW profiles recorded for 50 days. Sørensen et al [37] further developed this research by applying four rule-based control strategies to the measured data using a simplified tank model based on energy capacity. The four control strategies were peak power limitation; spot price saving where each day was divided into low, medium and high price periods; flexibility sale with no heating in peak periods; and maximising self-consumption of a photovoltaic system.…”