Smart controls can enable household heating and EVs to interact flexibly with increasingly decentralised electricity generation. As renewables continue to be added to the energy mix, it will increase efficiency, reduce load, and save money. Marco Reiser and Karoline Steinbacher at Guidehouse summarise the challenges and opportunities, before looking at the SINTEG pilot in Germany. The main hurdles are technological (standardisation, interfaces, every household is different), economic (up front costs) and social (households relinquish some control of their time of use). SINTEG enabled 100-plus demonstration projects and 5 showcase regions over more than 4 years to assess how flexibility can be integrated and used in the power system. One lesson learned is the aim should not be to control single appliances (e.g. individual heat pumps) but to treat whole buildings as flexibility resources. Issues covered include district heating, rooftop solar, monitoring, comfort, and anticipating future innovations.

Scaling up sector coupling options, such as EVs and heat pumps, is necessary to decarbonise the building and transport sector. At the same time, the electrification of heating and cars will result in higher electricity demand and local peaks, potentially creating grid bottlenecks.

As shown in Figure 1, the conventional way to provide flexibility in the power system through fossil-based power plants on higher voltage levels cannot address these local challenges. By using smart controls and the flexibility that households, buildings and cars can provide, challenges can be turned into opportunities for the energy transition.

Smart controls

To make sure that new distributed energy resources contribute to the stable operation of the grid, smart controls are necessary. By combining local renewable energy generation (e.g. through a solar PV rooftop) with a smart charging EV and a smartly controlled heat pump, households can be enabled to consume higher shares of renewable energy produced onsite. It also allows for a better match between consumption and times of high renewables infeed to the grid and for considering the status of the grid in decisions on when to charge an EV or run a heat pump.

This article, drawing from insights from one of Germany’s flagship programs on flexibility and sector coupling, SINTEG, outlines main points to consider and challenges on the way when using household and building flexibility.

Flexible buildings: EVs, heating, rooftop solar

Flexibility, the ability of a resource to react to price or activation signals and adjust demand or generation, will need to be used for systems with high shares of renewables on all voltage levels. Industrial processes, commercial facilities and cross-cutting technologies, such as ventilation, can all provide valuable flexibility to the system as the share of dispatchable generation declines in the energy transition. In buildings, the main sources of demand side flexibility are EVs and electric heating systems; on the supply side, the main source of flexibility is rooftop solar PV.

Local household flexibility can be used to address local grid congestion through direct signals from the grid operator or can be aggregated and also offered in, for example, balancing markets. New mechanisms to use the flexibility that households can offer are being discussed across Europe. Local flexibility markets, as experimented with in the UK, Germany or the Netherlands, and time-variable tariffs are receiving increasing attention. However, substantial challenges remain when it comes to using households’ flexibility potential — from slow digitalisation to infrastructure-related obstacles.

Barriers hindering the use of household flexibility

There are technological, economic and social hurdles to overcome when using the flexibility that EVs or domestic heat pumps can provide.

First, players from various backgrounds — grid operators, manufacturers, providers of energy management systems and aggregators — need to collaborate and require standardised access to hardware and software interfaces.

Additionally, household flexibilities are, by definition, heterogenous, and the individual flexibility potential that each appliance can offer is limited. Hence, time and investment costs for the necessary digitalisation and digital infrastructure need to be kept low for installation to enable flexibility-based business models in the first place. Furthermore, the acceptance of and willingness of residents to participate and agree to their EV or heat pump being controlled externally under certain circumstances are important aspects. Naturally, reservations to external players intervening in a household’s heat supply or mobility behaviour are strong.

SINTEG: Germany’s large scale pilot

Germany, with its ambitious renewable energy targets (80% of consumption by 2030), has a strong interest in flexibility. The large-scale SINTEG research and implementation project enabled 100-plus demonstration projects and 5 showcase regions over more than 4 years to assess how flexibility can be integrated and used in the power system.

Several important success factors regarding the use of household flexibility emerged from the program. To reduce complexity and increase the overall flexibility potential, flexibility users — mostly grid operators — should not aim to control single appliances, such as an individual heat pump, but rather regard whole buildings as flexibility resources.

The installation of an energy management system (EMS) is a precondition to using the potential available from installations in a building, from battery storage to PV rooftops to smart charging EVs. The EMS locally controls the installations and can align with user preferences, such as an EV needing to be charged to a certain percentage by a certain time. External load signals to activate flexibility are then sent to the EMS, which executes them. The exact installation that then supplies the requested flexibility is scaled locally. The readiness of users to offer flexibility is increased by the possibility for the EMS to consider residents’ individual needs. The aggregation of multiple appliances by the EMS offers a more constant and higher flexibility potential, another advantage of EMSs.

The idea of regarding buildings as flexibility sources by aggregating the potential of all appliances behind the meter has been coined the digital grid connection, or Digitaler Netzanschluss (DiNA) in the SINTEG showcase region C/sells by a team from Munich’s municipal utility. The approach is illustrated in Figure 2.

Monitoring, comfort, intelligent hardware

Apart from aggregation approaches, such as DiNA, combining flexibility with other use cases for digitalisation in buildings makes it easier to overcome economic barriers. By using the EMS not only to offer flexibility but to also monitor energy flows and capture energy efficiency potentials in the building, the investment in the EMS and other digital infrastructure can be amortised more quickly. In other combined use cases, the living comfort of occupants could be enhanced by enabling smart control of the heating system. The infrastructure required for future flexibility can therefore already be installed but be used for other purposes in the meantime. It is important, though, to consider the later provision of flexibility in the development of intelligent hardware (heaters, wall boxes and battery storage) in the form of open interfaces and the ability to be controlled.

Neighbourhoods

Looking at neighbourhoods rather than individual households is another effective way to increase the cost effectiveness of making loads flexible. Several buildings and households can be equipped with systems, controls and sensors by only one player, such as the building owner or developer of the neighbourhood. The scale of this solution makes it more cost-effective and at the same time, easier to implement from a technological perspective than at the individual household level. Additionally, infrastructure, such as district heating networks, can be used as flexibility without any interaction with the residents. Building loads are thereby aggregated at the neighbourhood level.

The improvement of social acceptance and participation will be one of the key elements to activate flexibilities in the wider population. The SINTEG demonstration projects showed that it is useful to approach residents or building owners on a local level given the high level of trust in local installers and known energy providers. Advertising the programs in local press proved to be successful. Furthermore, it is important to facilitate that flexibility provision is, at least, not connected to additional cost and ideally brings net revenue for the residents. Besides the monetary arguments to participate, many consumers were convinced with local and green energy supply and active participation in the energy transition.

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Marco Reiser is a Senior Consultant for Energy, Sustainability, & Infrastructure at Guidehouse Germany GmbH, Cologne

Karoline Steinbacher is Associate Director for Energy, Sustainability, & Infrastructure at Guidehouse Germany GmbH, Berlin