Block H: A World Heritage Site as Energy Storage

Where coffee, tea and spices used to be stored, heat will soon be stored too. HHLA Immobilien is working to gradually improve the energy efficiency of the Speicherstadt historical warehouse district. The prototype is Storage Block H. A holistic energy concept is intended to turn Block H into a versatile energy generator and storage.

Energy-efficient solutions for existing buildings

As the construction of a building costs enormous amounts of energy and releases a lot of CO2, existing buildings should be preserved and operated for as long as possible. Therefore, monument protection is always climate protection. As the operator of the Speicherstadt, we at HHLA Real Estate see it as our duty to preserve buildings and conserve resources. However, we do not simply want to preserve history; we also want to shape the future with innovative solutions. Together with the Ministry for the Environment and Energy of the Free and Hanseatic City of Hamburg, we are investigating how renewable energies can be generated and integrated locally while maintaining the aspects of monument compatibility, economic efficiency and usability.

This resulted in the research project ‘CO2-neutral World Heritage Speicherstadt Hamburg’, funded by the Federal Ministry of Economics and Climate Protection (BMWK) and supervised by Project Management Jülich (PtJ). The project aims to answer the question of whether and how we can generate, store and distribute energy. The predicted yields are considerable: around 14 gigawatt hours of thermal energy and around 5 gigawatt hours of electrical energy could be generated via the roof surfaces of the Speicherstadt. This could supply 700 households with heat and 1400 households with electricity for an entire year.

Modern Technology meets Monument Protection

In contrast to a new building, the 140-year-old building stock of the Speicherstadt limits the possibilities for energy upgrades. For example, solar panels must not detract from the appearance of the monument or the Speicherstadt. Nor can we apply thick insulation to the unique brick façades or install heavily insulated windows. Together with the researchers, we are therefore using Speicherblock H as a prototype to investigate how energy efficiency and modern technology can be combined with monument protection and UNESCO World Heritage status.

Creating a Digital Twin with Building Information Modeling

In order for Speicher H to serve as a basis for future simulations and decisions, a large amount of data must be collected and analysed. The BIMLab at HafenCity University Hamburg is therefore creating a digital twin of the storage block, a so-called ‘building information model’ (BIM). By doing so, all of the building's data can be stored and maintained in this model and made accessible to experts from a wide range of fields, such as architects, engineers, energy experts and historians.

The model is also used to record the performance of the energy system. If this monitoring allows successful conclusions to be drawn, this form of local energy generation can be rolled out to the entire Speicherstadt - and, in principle, to any other existing building. Block H is therefore not only a prototype for the Speicherstadt, but can also demonstrate solutions for the energy-efficient refurbishment of buildings where the building fabric is to be preserved.

Prof. Dr.-Ing. Harald Garrecht, University of Stuttgart

"If these prototype developments work, they can be transferred immediately to any normal existing building."

Prof. Dr.-Ing. Harald Garrecht, University of Stuttgart

Sandtorquaihof, Storage Block H, was the first European office building to be built in 1888 using a steel frame construction - and today, pioneering work is once again taking place here.

A varied roofscape, ornamentation, details - everything that makes the storage blocks so attractive - is not to be impaired by the introduction of new technologies.

In order to preserve the special flair of the Speicherstadt and generate renewable energy at the same time, the researchers are developing specific solutions that are both efficient and environmentally friendly.

Two demonstrators have already been installed on the roof of the block, both in slate and copper look. The photovoltaic surfaces are already generating solar power, while the solar thermal system below the roofing collects and stores environmental heat.

The data will now be monitored and analysed over a period of twelve months. If the energy generation is efficient enough, this approach can be rolled out to the entire Speicherstadt neighbourhood.

The path of energy from the roof to the office

The roofs of the Speicherstadt form a sea of turquoise and brown patinated copper panels and slate shingles. 40,000m² of roof surface can be used to ‘harvest’ and utilise solar energy and environmental heat. Click through the slider to learn how the research team has mastered the balancing act between monument protection and innovation and how the energy supply of the heat storage system is structured.

Further technical details can be found here

The building

How is the energy collected, refined and utilised? There is no off-the-shelf system yet. At the same time, however, there are already very good devices, modules and technologies available on the market. What the researchers are creating here is a clever combination of existing components - supplemented by one or two inventions. Click through the slider to find out more.

The solar modules

With the help of a hybrid solar module on the roof that combines photovoltaics and solar thermal energy, we harvest both sunlight and ambient heat. It doesn't have to be particularly warm for this. At outside temperatures of up to 4°C, we can still draw heat from the environment. To do this, a heat transfer medium flows through the pipes of the solar thermal component. This medium is a frost-proof mixture of water and glycol. It absorbs the outside temperature and makes it usable for us in the next step.

The special highlight: the photovoltaic modules were printed in a special process so that they are almost indistinguishable from the historic copper and slate roofs of the other buildings in the Speicherstadt.

The heat pump

The heated heat transfer medium is now fed to the heat pump. This extracts the heat from the water-glycol mixture. As the mixture is frost-free, even down to 5°C below freezing point. The heat pump should be operated as efficiently as possible using electricity from the photovoltaic modules. We are also researching suitable electrical storage systems so that we can use the electricity regardless of the position of the sun.

After the heat pump, the cycle starts all over again: the ice-cold water-glycol mixture flows back onto the roof, where it absorbs the heat again. Heat recovery is therefore a continuous cycle. But how is the heat stored?

The concrete hybrid storage unit

The first storage medium is a new type of hybrid concrete storage tank. A concrete block with such coarse pores that its cavities are filled with water. Concrete and water are an ideal combination for storing sensitive heat and making it available for the heating systems.

Sensible heat in this context means that the heat can be felt, because both water and concrete heat up noticeably. In contrast to our second storage medium for particularly cold days - here the heat remains hidden, i.e. latent...

The ice storage unit

The second storage component is a cascade of ice storage tanks. This is where we store our ‘heat reserves’ in the form of water. We draw on these reserves when no environmental heat can be absorbed on the roof at sub-zero temperatures. The innovative feature of the ice storage tanks is the heat exchanger system, which conducts the heat transfer medium so that the heat pump can extract any heat from the water. When the water freezes, ‘latent heat’ is released. In contrast to sensible heat, latent heat cannot be measured or felt. The energy is completely invested in the phase change (liquid to solid).

In this way, one ice store after another is frozen solid. Whenever the outside temperature climbs above freezing, the ice stores can be regenerated, i.e. melted.

The heaters

The heating system is operated at a low temperature level. This enables us to achieve a good ratio between the energy gained and the energy released. Every joule of energy from the roof should be converted into room temperature in the best possible way. The water-bearing heating systems are supported by electric wall heating systems, such as heating paint or textile heating mats. These two electrical systems work in a similar way to the sun with radiant heat. This type of heat is not only efficient, but also pleasant.

We are testing various highly efficient interior insulating plasters for insulation that takes both climate and monument protection into account. In this way, we want to determine which of the purely mineral interior insulation systems currently in use is the most ecological and economical for widespread use in the Speicherstadt.

The roof

The building encloses a beautiful inner courtyard. The research project is also investigating how the inner courtyard could be roofed over. This would mean that the façades, which are still on the outside, would suffer less temperature loss. In addition, the inner courtyard could be made available for the building's tenants.

Heritage conservation meets climate action

Keeping grey energy in the building

As the owner of the Speicherstadt, we at HHLA Real Estate follow the principle: ‘The best new building is the one that doesn't have to be built’. The Speicherstadt buildings have been in operation for almost 140 years and are a prime example of how buildings can be preserved for centuries through continuous care and maintenance. The materials originally used and the resources they contain continue to be utilised as a result of decades of use.

These five arguments are decisive for the sustainable building substance of the Speicherstadt:

Durable building materials: The Speicherstadt was built mainly from bricks, wood and steel. Thanks to the durability of these materials, resources are conserved.
Preservation and utilisation of existing structures: Instead of constructing new buildings, the existing structure is preserved and used. This avoids CO2 emissions that would be associated with demolition and new construction.
Reduced energy consumption: The continuous use and maintenance of the Speicherstadt requires less energy than the construction of new buildings, which further reduces CO2 emissions.
Energy-efficient renovations: Energy-efficient techniques and materials are used in renovations to optimise energy and resource use.
Low land sealing: The Speicherstadt consists of compact, multi-storey warehouses that enable efficient use of space and thus reduce the need for additional land sealing, which in turn minimises CO2 emissions.

Hamburg's Speicherstadt acts as a storage facility for the CO2 bound in the buildings, as it optimises the use of existing resources and reduces the need for new, energy-intensive construction projects.

Combined with local energy generation from renewable energy sources

Preserving the building fabric is therefore an elementary component of our sustainability strategy. With this research project, we want to prove that conservation and innovation are not mutually exclusive, but complement each other perfectly. “If we succeed in meeting the environmental, economic, regulatory and heritage protection requirements that this unique project demands, our vision of a significantly lower-emission energy supply for the Speicherstadt historical warehouse district will be within reach.

Franz-Josef Höing, Chief Building Director Hamburg

It would be a milestone if, at the end of the research project, there was a ‘kit of measures’ for the energy-efficient modernisation of listed buildings in line with conservation requirements.

Franz-Josef Höing, Chief Building Director Hamburg

The project partners: a strong research team

HHLA Real Estate is responsible for the overall coordination of the project. The project sponsor is the Jülich Research Centre (FZJ), while the Institute for Materials in Civil Engineering (IWB) at the University of Stuttgart is responsible for research coordination. HafenCity University Hamburg (BIMLab) and RWTH Aachen University (EONERC) are also project partners. The Ministry for the Environment and Energy and the Monument Protection Office of the Free and Hanseatic City of Hamburg are supporting the project in an advisory capacity as associated partners. The project is funded by the Federal Ministry of Economics and Climate Protection (BMWK).

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