Aftercooling concept: system for reduction of district heating return temperatures from buildings

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Products/Technical solution, Technologies and Building systems

DESCRIPTION:

The aftercooling concept is an innovative district heating substation for large multi-apartment buildings where the domestic hot water preparation and reheating of the circulation flows are decoupled and obtained in two separate heat exchangers connected in parallel. The primary return temperature flow from the circulation heat exchanger is further aftercooled by the space heating system before returning to the district heating network. The concept provides a reduced return temperature to the district heating network.

BUSINESS ROUTE

Target Users

Constructors, Landlords, Local authorities, Real-estate developers, Service providers, Social, public and cooperative housing providers

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Sønderborg, Denmark

Oceanic

Sustainable Building (Re)Design

VALUE

A key capability of low-temperature district heating systems is the ability to operate at reduced network temperatures. Aftercooling systems reduce the return temperature from buildings, which is often a prerequisite for lowering the district heating supply temperature. Operating at lower temperatures enables the use of low-temperature surplus energy sources that would otherwise be wasted or require a temperature lift, for example through heat pumps. It also reduces thermal distribution losses in the district heating network. In typical buildings, district heating return temperatures can be reduced by 4–8°C on an annual basis, representing a significant efficiency gain.

APPLICATION

This innovation focuses on the development of the aftercooling concept and the analysis of the district heating return reduction potential. The developed aftercooling system is relevant where a traditional district heating substation is to be installed or to be updated, typical residential and commercial buildings, and where there is domestic hot water circulation service provided. Critical for the deployment of the concept is that the district heating utilities establishes an economic bonus scheme awarding a reduced district heating return temperature. This is the case in Denmark and partly in Sweden, but it’s not widely spread.