Flexible Energy Concepts for Decarbonization
The pathway to climate neutrality in the housing sector rests on three key pillars. First, energy-efficient renovation of existing buildings is essential. Second, a shift in heating technology toward low-emission energy sources is required. And finally, the decarbonization of the energy supply itself is crucial to achieving climate targets within the built environment.
When implementing individual corporate strategies, areas of conflict arise between the various goals, such as affordable housing, economic efficiency, and climate goals. Furthermore, there are dependencies on the energy sector and regional development plans as part of municipal heating planning. Anyone who wants to develop the right strategy in this field of tension and ultimately implement it must master a variety of tasks.
Energy-efficient serial renovation can enable some of these challenges to be overcome. With its wide range of configurations of building shells and energy concepts, it offers a high degree of flexibility. In this way, a wide variety of property strategies can be taken up in the portfolio and the greatest possible CO2 reductions can be achieved. This issue of our newsletter will discuss what this can look like in concrete terms.
Insulated Building Shells: The Key to Success
There is a crucial lever for implementing the decarbonization pathway, especially in inefficient housing stock in energy efficiency classes E-H: improving the building shell.
Curbing Losses and Reducing Consumption
Professional insulation and window replacement significantly reduce transmission heat losses and thus the consumption of final energy for heating. On the other hand, the energy costs saved in this way create potential for increasing the basic rent. Lower additional costs and higher rental income are strong arguments. However, reducing final energy consumption brings further advantages. For example, CO2 emissions also fall with a constant emission factor. This is particularly important in view of the increasing CO2 pricing (BEHG and CO2KostAufG) in order to avoid considerable additional financial burdens for owners and tenants. In addition, the lower final energy requirement reduces the impact of external factors, such as energy price fluctuations.
Low-Temperature Capability and Security of Supply
Improving the building shell, therefore, reduces the building's overall energy requirements. It makes it easier to dimension the new generation/supply systems and is a crucial factor in improving a building's low-temperature capability. With a reduced heating load, it is only possible to operate a heating system with flow temperatures in the low-temperature range (≤ 55°C).
The reduced flow temperatures also lead to more efficient operation of heat pumps, which, in combination with PV systems and a green electricity tariff, lay the foundation for the CO2-neutral operation of a building. In addition, when connected to a district heating network, the well-insulated building shell reduces the amount of heat drawn from the grid and, accordingly, also reduces CO2 emissions.
Funding: The Best Conditions
The interaction of building insulation and efficient system technology is the success lever for CO2-neutral building operation. It is, therefore, not surprising that the German government's funding for efficient buildings (BEG) also takes into account the building shell and the system technology with the respective energy source. By combining both areas, final energy consumption can be minimized, the use of renewable energies can be maximized, and a sustainable solution for existing buildings in the portfolio can be implemented.
The requirements necessary for the KfW 55 standard are met by the ecoworks facade system. This means that a high funding rate, including a 15% repayment bonus, is achieved for serial renovation by ecoworks. The prefabricated facade elements are combined with suitable energy concepts. This is achieved by installing the necessary components in the facade elements at the factory: Strands for heating, cold water & hot water, electrics/control and ventilation (with and without heat recovery) are integrated from the outset.
Choose Your Energy Supply
There are many aspects to consider when choosing the right energy supply in order to make it as sustainable and cost-effective as possible. Serial renovation offers various options here.
District Heating
Under certain circumstances, changing the energy source does not make sense. This may be the case, for example, if a building is already connected to an existing district heating network. In this case, improving the energy efficiency class to A/A+ level can be achieved through pure serial shell renovation. Additional measures further reduce heat energy loss. The measure is completed by insulating the basement ceiling and renewing the roof. If necessary, the top floor ceiling can also be insulated while retaining the existing roof.
The initial connection of an existing property to the district heating network in a serial renovation project enables the switch to forward-looking CO2-free heating. But beware: energy suppliers play a central role in creating a sustainable and climate-friendly district heating supply. The grids are not yet CO2-neutral. In addition to this aspect, the connection brings further dependencies with it, for example, with regard to investments and delays in infrastructure expansion. Against this background, early and close coordination with the local energy supplier is necessary. On request, we advise and support our customers in this process.
As already mentioned in the first part, the choice of energy source is also relevant for funding measures. For connection to district heating, this means: If the heating network has a primary energy factor of no more than 0.25 or if a transformation plan is available, the EE bonus (+5% repayment bonus) will be achieved in KfW funding. Compared to the installation costs for new energy generators, the low investment costs for the district heating transfer station are a compelling argument.
A connection as part of a serial renovation by ecoworks allows customers to continue using existing pipe networks in the building (for heating and cold/hot water) and connect them to the transfer station. If necessary, a riser renovation can be carried out via the facade. If there is no centralized supply in the building, the ecoworks pipe elements in the facade offer a minimally invasive installation option. It is, therefore, possible to switch to district heating with comparatively little effort and thus ensure a more sustainable supply to the residential units.
Central Heating Supply
The centralization of the heat supply is also a suitable interface for existing buildings that are supplied with decentralized gas central heating systems. Switching from gas-fired heaters to an air-to-water heat pump or a district heating connection enables the use of renewable energies and reduces operating costs. The number of fossil-fueled energy generators in the building is thus significantly reduced! The centralized control ensures optimized system operation, which benefits owners and tenants. We have developed an innovative product for this: Here, too, we can retrofit the risers minimally invasively using our external ecoworks pipe elements. Core drilling is only required to connect the new risers to the existing pipes in the apartments.
Depending on the building type and technical requirements, hot water can be heated centrally or decentrally. A central solution in the basement means that no additional devices are required in the apartments, which reduces maintenance and repair costs. The prerequisite is the installation or existence of the corresponding hot water distribution network in the building - always in compliance with the Drinking Water Ordinance and hygiene in drinking water installations. Regular checks are also mandatory.
An existing supply via electric instantaneous water heaters can be maintained, although a higher level of energy efficiency may be required with a view to the primary energy demand and the targeted KfW funding standard. In decentralized supply situations, apartment or fresh water stations, which heat the water as required by means of a heat exchanger from the central heating system, are, therefore, a sensible alternative. Here, the central heating (e.g. district heating or central heat pump) is used for hot water preparation at the apartment level. As the water is only heated in the apartment, there are fewer losses from pipelines. In addition, apartment stations can be easily integrated into existing heating systems. As this hot water preparation probably falls under the 3-liter rule (according to §3 TrinkwV ["Definitions"] Para. 12), the landlord is not obliged to take samples.
Heat Recovery
In accordance with current requirements and the KfW efficiency house standards, we equip the buildings we renovate with suitable ventilation concepts. They guarantee the necessary ventilation to ensure hygienic and health requirements as well as structural protection when the users are present during normal operation and remove excess moisture.
Ventilation concepts can be divided into systems with and without heat recovery. Systems with heat recovery use the heat from the exhaust air to heat the supply air. This reduces the heating requirement and saves energy. According to the BEG-WG Directive, the use of a ventilation system with heat recovery is mandatory in the EE class. Central, decentralized, and mixed forms of central and decentralized ventilation systems can be used. Systems without heat recovery can also be used up to the KfW 55 standard. However, the lower investment in these cases also means lower funding. As part of the project consultation, we, therefore, show our customers the optimal variant in each case, taking into account the customer's goals.
Photovoltaic (PV) Systems
The strategic goal of PV expansion can also be driven forward during serial renovation projects. As part of roof renovations with modular trapezoidal sheets, we can install full-surface PV systems. The three most important concepts for operation are tenant electricity models, full feed-in, and partial feed-in.
Tenant electricity models make it possible to supply the solar energy generated on the roof of a residential building directly to the tenants. Here, the generated electricity is not fully fed into the public grid but is consumed on site. However, they require careful legal and technical implementation, including the billing and management of the electricity supply, as well as compliance with the regulatory framework. We advise our customers on the implementation of the appropriate model.
In the case of full feed-in, all of the solar power generated is fed into the public power grid. The operator of the PV system receives a feed-in tariff in accordance with the Renewable Energy Sources Act (EEG). This method is less administratively complex, as no separate billing with the tenants is required and the entire electricity is fed into the grid operator.
With partial feed-in, part of the solar power generated is consumed directly in the building, while the surplus power is fed into the public grid. A specific application example is the supply of an air-to-water heat pump. The heat pump uses the PV electricity to generate heat and hot water, which reduces dependence on external energy sources and lowers operating costs. This solution requires intelligent control and an energy management system in order to optimally coordinate the PV yield and the energy requirements of the heat pump.
Are you interested in a serial renovation?
We would be happy to provide you with transparent advice on the options for serial restructuring of your portfolio. Arrange a non-binding Consultation appointment and learn more about our flexible energy concepts for decarbonization.
