Design

Thermal storage

Users needs can influence the design process

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During the development of a social housing project we have to face with different users needs, that can influence the design process, but we also have to consider some overall problems: the importance of sustainability, CO2 emissions, low cost in construction and operating and last but not least the summer overheating.

Usually the design criteria are based on environment sustainability and low costs, but latest experiences show problems with overheating in summer, because the temperature in the last 10 years raises.

Sun shading system can improve the comfort temperature, but maintenance must be done regularly. Meanwhile anti sun glazing prevent solar gains during winter period and an active cooling is too expensive for the use in social housing.

The following German case study can explain the complexity of the problem and some ideas about how to solve it.

Case study in Bremen

The example is the development of 70 flats for large families and a children day care facility for 60 children in Germany.

The challenge is conciliate the environmental, comfort and economical problems.

The solution is heat supply by gas absorption heat pump, fed by: ice storage tank (seasonal energy storage);

solar heat absorbers feeding ice storage indirectly or heat pump directly, exhaust air system preheating hot water. There is also an additional gas thermal value heating for supply during peak hours.

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System data summary

  • In the seasonal heat storage there are water and ice, the phase change between fluid and solid state is exploited.
  • Low system temperatures (<50°C) keep the heat pump working efficiently.
  • Floor heating with low system temperature is also able to cool in summer time.
  • Passive cooling in summer avoids use of high reflective anti sun glazing, therefore maximizing solar heat gains in winter.
  • Decentralized electrical heat production for hot water minimizes heat loss.
  • Integration of heat recovery from ventilation for decentralize warm water production.

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