Model-based co-design of LowEx heat supply and active thermal insulation systems

The acceptance of and response to advancing global warming has a significant impact on the con-struction sector. It must respond to existing and future challenges with a significant increase in energy efficiency and thermal comfort. This often requires the integration of existing building and settlement structures to create sustainable solutions. This restricts the available scope for solutions and requires very individual and complex designs. However, the consideration of individual solutions alone will not lead to the necessary savings. The use of synergy effects and sector coupling (e.g. waste heat utiliza-tion – combined heat, power and cooling) is already necessary today in order to achieve the medium-term planning targets.

Heating and cooling requirements represent the majority of energy demand in the building sector. Depending on the settlement structure, the location and land use, it is not unusual for cooling and heat-ing requirements to be close to each other. Short-term or even seasonal storage of surpluses is also possible with today’s technologies (e.g. ice storage, aquifers). However, this requires suitable grids that enable such a synergetic exchange. The smaller the temperature differences between heat and cold sources, storage facilities as well as heat and cold sinks, the higher the efficiency that can be achieved by reducing the required auxiliary energy. Such grids with a low exergy level are usually called LowEx grids.

However, such complex planning tasks require suitable, domain-specific, dynamic simulation tools. This paper describes how physical building models as well as system and grid models including system controls images become fundamentals of a holistic design process. Particular attention is paid to the implementation of a large number of iterative sensitivity analyses from all decision-relevant areas of influence (e.g. approvability, cost-effectiveness, energy efficiency, resource utilization, etc.). Another focus is on the interactive linking of these models using existing exchange standards (e.g. Functional Mockup Interface).

A local heating grid for various existing and new residential buildings demonstrates the use of these various modeling tools (e.g. Nandrad for building performance simulation and Modelica for networks, control and systems engineering). Special emphasis is put on innovative construction techniques to cre-ate new heating and cooling surfaces on the exterior of the building envelope as part of the refurbish-ment without interfering with the actual living space. On the one hand, this simplifies refurbishment measures during ongoing operation. On the other, it creates the technical prerequisites for setting up a LowEx grid that also includes refurbished existing buildings.