Project Description

We cool Vienna down in an environmentally-friendly way when temperatures soar

Iver-longer periods of high temperatures are causing the demand for environmentally-friendly, space-saving air conditioning in buildings to rise sharply, which is why Wien Energie is focusing squarely on expanding the use of environmentally-friendly district cooling. By 2024, we will invest EUR 65 million in the generation of district cooling, which involves converting waste heat (generated during combustion processes) into environmentally-friendly cooling energy. We currently operate a twelve-kilometre-long district cooling network with 16 district cooling plants. The total output is 130 MW, corresponding to over 2,500,000 m² of air-conditioned office space.

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Project details

Wien Energie has been offering district cooling (green cooling) on hot days since 2007. This smart technology uses waste heat to power the cooling machines and reduces CO2 emissions by around 50 percent compared with conventional air-conditioning systems.

District heating is produced both in summer and in winter to supply heating and hot water and, at the same time, is used to make environmentally-friendly district cooling. The same energy sources that are used for district heating can also be used to power cooling machines. Equipment known as absorption refrigeration units make use of waste heat from industrial facilities, cogeneration plants or waste incineration plants, which operate all year round. As in the case of district heating, buildings are supplied centrally (or decentrally, in which case a refrigeration centre is installed at the consumer’s premises). Insulated pipes transport the water, cooled to 6°C, to the customers. It flows back at a temperature of around 16°C to be cooled again.

Four to ten times less primary energy is required compared to conventional air-conditioning systems, making district cooling a smart cooling solution. Other benefits of district cooling include the fact that, in contrast to air-conditioning systems, district cooling units are space-saving, quiet and visually unobtrusive. And, thanks to Wien Energie’s central production facility, the cooling process does not take place individually for each building, which means that the users’ surroundings also remain cool and do not heat up.

A total of 16 district cooling centres at present in Vienna work to keep indoor temperatures down when it is hot outside. Wien Energie supplies customers throughout the city via its district cooling network with a total district cooling capacity of around 130 MW and covering a distance of over twelve kilometres. This is equivalent to 250 football pitches.

So far, the Spittelau pipeline network primarily covers the area around Heiligenstädter Lände and along the Währinger Gürtel. Important public buildings such as the Vienna General Hospital (AKH), the University of Natural Resources and Life Sciences (BOKU) or the Ö3 building on Muthgasse are supplied with environmentally-friendly cooling from here.

A new, additional supply line towards the Franz-Josef railway station was connected in July 2019, enabling 80 privately owned apartments at Althangrund to obtain district cooling for the first time.

Work will soon start on constructing an additional line towards Döbling, but demand for district cooling is especially high in the city centre of Vienna. Conventional air-conditioning systems require significantly more space than is the case for district cooling. Moreover, the heat exchangers on the roof required for air-conditioning systems often fall foul of regulations in place to protect listed buildings and have a negative impact on the surrounding micro-climate.

This is why Wien Energie plans to supply district cooling for the whole of the first district. The step here involves building a new, additional district cooling centre at Stubenring, near the Alte Post, in autumn 2019, with 10 MW of cooling capacity being installed to begin with. It is set to enter service in spring 2021.

Further reading

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Power-to-heat plant

The power-to-heat plant resembles an oversized kettle that converts excess electricity into environmentally-friendly heat. The plant has a total capacity of 20 MW and supplies 20,000 households with district heating, thereby playing a key role in maintaining stability in the power grid.


Large-scale heat pump

Utilising existing waste heat is an essential part of being able to supply heating in an even cleaner way. Simmering is where we run the most powerful large-scale heat pump in Central Europe, supplying around 25,000 households in Vienna with environmentally-friendly district heating, thereby saving 40,000 tonnes of CO2 every year.