Innovative co-simulation tool for assessment and optimisation of energy consumption in deep retrofitted buildings

The building sector has a strong impact in terms of energy consumption and greenhouse gasses emissions, for this reason the scientific community is dedicating an increasing attention to this sector. In this context, the REMOURBAN H2020 project has carried out a pilot deep refurbishing work on a small cluster of 10 homes. The interventions included the implementation of passive energy saving measures to the buildings envelope and the replacement of the old heating system, based on individual gas boilers, with an all new hybrid energy-supply system capable of satisfy both the space heating and the domestic hot water demand. This retrofitting scheme aims to achieve near-zero-energy homes level of performance at reasonable cost by offsetting part of the energy demand renewable energy produced in loco. The new layout is designed as a local low temperature district heating system and includes ground source heat pumps, photovoltaic panels, electric, and thermal energy storage devices. The management of the complex hybrid system requires a suitable control strategy to optimise the energy consumption and consequently running cost. With this purpose a co-simulation tool has been developed, coupling a model of the energy system built using Dymola/Modelica and the EnergyPlus model of the buildings. A subsequent expansion of the case study to a total of 27 dwellings highlighted the modularity of the co-simulation tool, as well as its ease of scalability. The co-simulation tool allows a precise assessment of the building energy performance before and after the refurbishment. It has also been used to develop different control strategies aiming to reduce the energy consumption from the grid, maximize the self-consumption of photovoltaic energy and ultimately move away from fossil fuel to sustainable energy resources

Tariff-based load shifting for domestic cascade heat pump with enhanced system energy efficiency and reduced wind power curtailment

Cascade air-to-water heat pumps may have good potential for retrofitting UK domestic buildings because they can directly replace existing fossil-fuel boilers without the requirement of considerable modifications to heat distribution systems. A widespread uptake of these heat pumps, however, would pose challenges to the grid. Furthermore, wind power generation has increased in the UK to achieve the target of decreasing CO2 emissions by 2050, but there are high levels of wind curtailment due to the mismatch between electricity supply and demand. In this paper, a load shifting study for cascade heat pumps coupled with thermal energy storage addressing these issues is presented. The main objective is to find the best tariff-based schedule load shifting for cascade heat pumps, which can help to avoid peak demand periods while obtaining enhanced system energy efficiency with minimised running costs and reduced wind energy curtailment. How the retrofit performance of the cascade heat pumps with load shifting is further investigated. TRNSYS was used to simulate the system performance validated against experimental results. Northern Ireland (UK) was selected as the evaluated scenario. Simulation results showed that the tank temperature set point of 75 °C and the storage size of 1.2 m3 could wholly shift the cascade heat pumps’ operation to off-peak periods. The best times to start the cascade heat pumps to charge the storage were at 3 am and 2 pm for the morning and afternoon heating demands, respectively. Compared to oil boilers, the cascade heat pumps with load shifting could obtain lower running costs (16–34%) and carbon emissions (20–37%)