Buildings must first and foremost meet the needs of their users. To this end, they can be adapted to suit the exterior climate and the varying user requirements by providing suitable glazing, facades and systems for air and heat management. Clever building concepts and innovative building systems provide the necessary flexibility for this. However, today’s and, in particular, future buildings are not closed systems. In future, buildings will interact more closely via energy systems with other buildings or energy suppliers. As elements in larger networks, buildings have energy interfaces with neighbouring buildings, districts and electricity and heating networks.
Solar-active building envelopes, high thermal insulation and energy- and exergy-optimised building technology enable energy-plus buildings that generate more energy than they consume in the annual balancing. This allows them to take on a more interactive role as grid-supportive buildings in conjunction with the future renewable electricity grid. In future, this will enable excess solar and wind power to be used and stored in a highly efficient manner in the form of heating and cooling energy in buildings.
In many demonstration projects in the new-build and refurbishment sectors, different technological innovations and new systems and concepts are being tested in practice and the resulting building performance and the effects on the energy system scientifically evaluated.
Buildings have a very long life expectancy. A large part of the existing building stock is therefore made up of old buildings that need significantly more energy than the new buildings built today. This means that they have to be refurbished at a suitable time. This usually requires extensive construction work, during which the buildings are often still occupied. This impairs the users and it usually takes many years for the costs of the structural measures to pay for themselves through reduced energy costs. Therefore, refurbishment must become much simpler, more rational and more cost-effective in order to become more attractive for more stakeholders.
Industrial prefabrication based on modular systems and concepts for integrating technical systems are possible strategies for reducing the costs of refurbishment with improved execution quality. Decisive are rational refurbishment processes and the integration of the building energy concepts into local or regional energy systems combined with minimally invasive solutions.
In many refurbishment projects, technological innovations and new refurbishment concepts are being tested in practice and the resulting building performance scientifically evaluated.
The investment cycles for buildings have a duration of roughly 30 years. Buildings currently being constructed today will therefore likely remain largely unchanged in 2050. To achieve the goals of the energy transition, buildings therefore need to be constructed today so that they are largely net-zero. However, to do so, a large number of coordinated measures are required in the field of building envelopes and building technology. The remaining low energy demand can be covered by regional renewable resources or local and regional energy systems. To this end, it is important to not only take into account the construction of buildings but also their entire life cycle. If a building’s energy system is particularly complex and energy-efficient in operation, a lot of energy is often required to produce this system in accordance with the current state of the art, which is then tied up in that building.
Many current building concepts and technological solutions may already significantly exceed statutory standards. They become energy-plus buildings and produce more energy than they consume over the course of a year. These buildings can therefore support the grid, taking on a more interactive role in the renewable power grid of tomorrow. In future, surplus solar and wind power can thus be used in a highly efficient manner in the form of heating and cooling and it can also be stored. In many demonstration projects, various technological innovations and new systems and concepts are tested in a practical setting, with the resulting building performance being scientifically evaluated.
Buildings with an energy-optimised overall concept encompassing the architecture, building physics and building services technology can achieve a small heating and cooling energy demand. Here there are a variety of technology options for the heating, ventilation and cooling. They are linked to form a coherent overall concept in accordance with the specific usage requirements and energy supply options. Often this requires a well insulated and tight building envelope, effective solar shading systems and efficient ventilation adapted to the hygienically required air volume with optional heat recovery. If there is also a sufficiently effective thermal storage capacity in the building, a full air-conditioning system can be dispensed with in many cases.
High indoor comfort is nevertheless achievable, because thermo-active component systems enable these buildings to be heated and cooled with very small temperature differences – mostly in combination with natural, renewable heat sources or heat sinks. Because the temperature differences between the indoor air and the heat sources for heating or cooling are very low, these are known as low-exergy systems.
Also interesting are component- or facade-integrated systems, especially as part of rational, minimally invasive refurbishment concepts. And with a view to the largely renewable electricity grids of the future, electrical heat pumps can potentially play a key role in the grid-supportive operation of buildings.
Renewable electricity is used efficiently for heating applications and the electricity and heating sectors are coupled for smart load management via heat pumps and thermal energy storage systems in buildings. In addition, there are sophisticated, predictive and adaptive building automation systems that communicate with the energy system.
Today’s buildings are increasingly complex “systems”. This applies in particular to non-residential buildings, which are often individually planned and crafted prototypes in order to also support individual user profiles with a high level of comfort. The commissioning of such buildings requires a phase of intensive adjustment and optimisation. Even during ongoing operation, suitable skills and tools are required to constantly guarantee user comfort in an energy-and cost-efficient manner.
However, there is often a lack of understanding about how to “correctly” use modern heating and ventilation technology as well as about the functions and concepts of building operational management using appropriate systems. Normally, users can intervene individually, because this increases the acceptance and personal comfort. Their behaviour can be contrary, however, to the energy and comfort concept, for example when windows are opened in winter or high summer. That is why well-designed human-technology interfaces are just as important as information campaigns about how the building functions.
In many new-build and refurbishment projects, the systems for the building operational management are examined in particular detail and scientifically evaluated in terms of the building’s energy efficiency performance, user behaviour and user satisfaction.
Innovations from research and development significantly expand the design scope for architects and specialist designers. New materials and components provide new properties for the building envelope and building technology.
Current developments include high-performance insulation materials with foam pores on the nanometer scale, as well as insulation materials based on renewable raw materials. Coated films with selective, adaptive or switchable properties can expand the properties of the building envelope as a thin, taut membrane. Innovative coating technologies provide component surfaces with new or improved properties.
There is also potential for innovation in the glazing field. Optically adaptive or selective layers and glazing support the solar and glare protection in buildings and can be integrated into the operational management strategies for buildings.
Switchable modules are even being developed for opaque elements in the building envelope so that, for example, heat can be dissipated from buildings in accordance with needs. Multifunctional facade modules assume several functions simultaneously, for example as daylight systems integrated into the glazing with solar-active modules and solar shading, or as prefabricated facade modules for minimally invasive refurbishments with integrated ventilation technology.
Daylight is important for the well-being of people. In buildings it conveys the relation to the outside space and is, in contrast to static artificial light lighting, much more dynamic and thus more stimulating. The new focus on energy efficiency and amenity value is creating greater demands on buildings. Well-planned lighting and daylight systems ensure a harmonious balance between the lighting level and solar shading while simultaneously contributing to a lower energy requirement. Innovative daylight and control systems help to maintain an adequate daylight supply during changing sky conditions, during heat periods or with overcast conditions.
The daylight-dependent control of electrical lighting and presence-dependent light switching are already becoming standard. The linking of facade control systems and electrical lighting brings further energy saving effects. Self-learning, adaptive or switchable systems can leverage additional comfort gains and energy efficiency effects, and offer each user the individually required lighting environment.
The installation of solar panels and solar thermal collectors means that more and more building rooftops and facades are becoming electricity generators and heat generators. Both these technologies are important when it comes to covering energy consumption in buildings and districts with renewable energy sources. The area-specific energy yield is higher for the solar thermal solution than the photovoltaic one. However, solar panels are currently finding more widespread application in buildings (building-integrated photovoltaics, BIPV) than solar thermal solutions. In contrast to rooftop solar panels, approval is required on an individual basis for the integration of solar panels in building facades, since a general construction permit is required. Various trades have to work hand in hand with one another. In this respect, experiences from publicly funded demonstration projects can serve as a precursor for more widespread application. Building facades are of great interest for the generation of solar heat, complementing the use of rooftop photovoltaics.
In addition to yield and efficiency, architectural aspects such as the overall design, the integration of solar technology into the building envelope and systems technology, and the design quality and functionality of buildings and solar installations also play an important role.