Smart Facades. Facade With Function

2023 Author : Hannah Pearcy | [email protected] . Last modified: 2023-11-26 11:39

The facade should protect the interior of the building and give the building a face. But will it really be sufficient in the future that facade surfaces are used solely for weather protection and design? Couldn't the facade take on multifunctional tasks - such as generating electricity or filtering pollutants from the air? A foretaste of the smart facade.

Author: Susanne Sachsenmaier-Wahl

Diesel scandal and related driving bans, the coal phase-out and ever stricter regulations for primary energy consumption. Anyone who has dismissed environmental protection as a minor issue has noticed last year that things are getting serious. Environmental protection no longer only concerns ambitious “greens”, but each of us - more and more by law. For example, in 2009 the federal government put the Renewable Energies Heat Act (EE-WärmeG) into force.

It is intended to drive the expansion of renewable energies in the heating market and to increase their share of heating and cooling provision in Germany to 14 percent by 2020. The law obliges owners of newly constructed buildings to cover their heat supply with renewable energies. In the case of public buildings, this even applies to fundamental renovations. The law gives the home owner various options to fulfill the usage obligation. Solar energy, geothermal energy, biomass and environmental heat are permitted.

Solar panels on the facade

If solar energy is selected, the law stipulates that the solar collector must be at least 0.04 square meters per square meter of usable area. The following example serves to illustrate this: For a house with a living space of 120 square meters, the collector must be at least 4.8 square meters in size. While this requirement can usually be easily implemented in a single-family house, implementation in multi-family or high-rise buildings is rather difficult - at least if only the roof area is to be used for the solar collectors. Because this is small compared to the facade area and is often already occupied elsewhere (e.g. by building elevator shafts). If solar energy is to be used in these cases, switching to the facade surface is almost inevitable.

But do solar collectors make sense on the facade? The total radiation on the facade is significantly lower over the year than on the roof. However, if you look at the irradiation in detail, you will see that the yield on a south facade is even higher in winter than on the roof, which is due to the lower sun. Conveniently, the low-lying sun falls in the heating season - exactly in the time in which solar thermal energy is primarily used as heating support (and of course also for hot water production). Another nice side effect of a solar facade: snow, which sometimes shuts down a roof system in winter, is not a problem on vertical surfaces.

From an economic point of view, the same applies to the solar facade as to roof systems: According to the Energy Saving Ordinance (EnEV), the solar gains can be offset against the primary energy requirement. This means, for example, that the thickness of the insulation material may be smaller, which may result in a gain in living space for the client, especially in cities where space is limited. And this in turn in the form of higher rental income or sold living space represents a direct financial gain. The solar facade - at least if it is integrated into the facade - also saves the facade (insulation) material where the system is located. The solar system also acts as insulation there.

Integration in ETICS as a goal

While photovoltaic facade systems have been successfully installed for several years, the solar thermal facade is still in its infancy. The DAW Group's research, which includes Caparol and VHF specialist Lithodecor (VHF = ventilated rear-ventilated facade), is therefore currently working intensively on the development of solar thermal collectors for the facade. These elements are also to be mounted on a substructure and thus, like VHF facades, initially fall within the area of responsibility of the facade builder. However, DAW is pushing for an easy-to-implement combination with ETICS facades. And with that, the subject of solar facade should also affect the painter and plasterer. Ultimately, a classic combination facade should be sought, e.g. ETICS with integrated glass surface,comparable to the integration of photovoltaic modules in the building envelope (BIPV = Building-integrated Photovoltaic or in German building integrated photovoltaics). The combination of organic photovoltaics with thermal insulation composite systems was also developed as part of a research project. Here, the work can be carried out almost entirely by the craftsman, since the modules can be glued with a mineral plaster (i.e. no substructure is necessary) and the voltage is below the contact voltage. Only the grid connection still has to be carried out by a solar technician or electrician. What currently sounds like a dream for the painter or plasterer could soon be part of his business.

Optics of great importance

Dr. Thomas Loewenstein, project development energetic facade at DAW, knows of course that the aesthetic demands on the smart facade (in contrast to the roof) are very high. When asked about the appearance or the nature of the modules, he replied: “All concepts stand out due to their distinctive design freedom, which is a key parameter for aesthetically demanding facades. The sizes and colors of the elements can be varied in both solar thermal and photovoltaic systems. The gloss level of the surfaces can also be adapted to the customer's wishes.

Due to the possible combination with other products such as natural stone, numerous different optics are available on curtain-type, ventilated facades.”The already available litho-photovoltaic system is based on a curtain-type, ventilated facade (VHF) and thus consists of a substructure that Insulation and the BiPV modules themselves. The situation is similar with the currently researched solar thermal collector, which is also installed in a VHF. Not so with organic photovoltaics on ETICS. "The organic photovoltaics on ETICS, which is also in the research stage, basically has an ordinary ETICS structure, only that the reinforcement layer is thicker so that the electrical connection cables can be laid behind the module level," explains Dr. Thomas Loewenstein."There is no difference to a standard ETICS up to the reinforcement layer."

Organic solar modules and organic photovoltaics are currently still in the research stage. DAW is currently preparing processing instructions together with craftsmen who are involved in test objects. After the end of the research phase, the painting tradesmen would have to be trained to install the organic photovoltaics so that the modules can be properly installed and connected.

The greener the better

More and more people are moving to the cities. The buildings are getting denser, as is the traffic. In contrast, urban green spaces are increasingly decreasing. So while more and more exhaust gases are generated in cities, plants are missing to filter the pollutants out of the air again.

To increase the proportion of air-purifying plants in the city, attempts have therefore been made for some time to use the vertical as a green space. A moss wall installed in Stuttgart in spring 2017 may still be remembered by many. When it was dismantled after about a year, not only was the sight unsatisfactory (the mosses had turned brown), but also the sobering result. There was hardly any air-improving effect. Nevertheless, this damper did not result in the research for moss walls being discontinued. Rather, you have learned from the mistakes and optimized the systems.

In a joint project with the Berlin start-up Green City Solutions, Alsecco has developed a modular system with which moss surfaces can be integrated into facades. Max Gimpel-Henning, Product Manager at Green City Solutions, presented the facade system to the specialist audience at the Caparol Materials Day in November 2018. He is certain that mosses can clearly improve the air quality - provided the conditions are optimal. In laboratory tests, the natural product was able to filter 97 percent of the harmful fine dust crystals from the air and the “City Trees” (see www.greencitysolutions.de) of the Berlin company are already successful not only in major German cities, but also in Amsterdam, Oslo, Paris and London in use - as a combination of moss wall and park bench. The pollutants are bound on the leaf surface of the moss and permanently integrated into their biomass. Thanks to their large leaf surface, mosses are clearly superior to normal trees as fine dust killers. However, mosses not only need moisture to thrive, they also need cool temperatures. These were clearly too high for the moss wall in Stuttgart, which was fatally facing south in the summer, which eventually led to the moss drying up. This could not stop well-meaning, but also not optimally designed irrigation. These were clearly too high for the moss wall in Stuttgart, which was fatally facing south in the summer, which eventually led to the moss drying up. This could not stop well-meaning, but also not optimally designed irrigation. These were clearly too high for the moss wall in Stuttgart, which was fatally facing south in the summer, which eventually led to the moss drying up. This could not stop well-meaning, but also not optimally designed irrigation.

The smart facade

So that the innovative “AeroCare” system from Alsecco does not face the same fate, it has been equipped with modern IoT technology. This technology is used to collect, analyze and visualize all data relating to the status and performance of the system. The system uses sensors to provide information about the condition of the plants and provides data on, for example, moisture, temperature and fine dust concentration, and ensures that the mosses are always sufficiently humidified. By activating an additional ventilation system in the construction, it is possible to increase the air flow and to increase the efficiency of the system again. Alina Schneider, project manager for AeroCare at Alsecco, explains the individual components:“AeroCare consists of a module with an area of one square meter. This is a stainless steel frame in which two fans are integrated. Two trays are then inserted into the module, in which the pre-cultivated moss mats, the sensors with IoT technology and a filtration body for irrigation are located. The module is attached to the wall with a VHF substructure. The resulting rear ventilation of the facade is then used to suck in air polluted by fine dust with the help of the fan and to guide it through the moss. The plant technology for the supply and operation is in the building.”the sensors with IoT technology and a filtration body for irrigation are located. The module is attached to the wall with a VHF substructure. The resulting rear ventilation of the facade is then used to suck in air polluted by fine dust with the help of the fan and to guide it through the moss. The plant technology for the supply and operation is in the building.”the sensors with IoT technology and a filtration body for irrigation are located. The module is attached to the wall with a VHF substructure. The resulting rear ventilation of the facade is then used to suck in air polluted by fine dust with the help of the fan and to guide it through the moss. The plant technology for the supply and operation is in the building.”

At first glance, you might get the impression that the system is not only complicated, but also expensive to maintain due to the constant water and power supply. Alina Schneider has a solution here too: “When connecting a cistern, rainwater can be used. And the system can also be self-sufficient through photovoltaic systems.”And it also dispels the concerns about assembly:“The trays are simply hung in. The cables are connected using plug connections.”AeroCare can either be integrated into a classic ETICS or into a VHF facade. In general, processing is also an option for the painter or plasterer. However, the craftsmen should have appropriate training. Alina Schneider:"The tradesman must have knowledge of the installation of a VHF facade." Those who have not yet had this can do so. alsecco will offer special training for AeroCare as soon as the system is ready for the market. The first pilot objects are currently being realized. Series production of the modules is scheduled to start in autumn 2019.

Smart facade: regular maintenance

Alina Schneider recommends not planning the moss modules on the south facade, as mosses cannot tolerate direct sunlight. In the case of high sun exposure, there is also the possibility of shading the moss with a transparent, air-permeable and UV-protective fabric. After assembly, you should also keep an eye on the moss wall. "As it is an organic material, we recommend changing the Moostrays within 2 to 3 years based on current knowledge," explains Alina Schneider. “But this is not due to a reduced cleaning performance, but to the growth of the plant. Moss has an extremely slow growth rate, so the trays should be replaced after 2 to 3 years for visual reasons."In addition, the project manager points out the need for regular maintenance:" In addition to the replacement of the Moostrays, regular maintenance of the electrical components such as sensors, data cables and fans is required. "This is the only way to ensure the full functionality of the moss facade with all its advantages. Because the moss surfaces not only have a sound-absorbing effect and are an extremely effective humidifier and fine dust filter, they also support winter thermal insulation and offer significant cooling in summer. This is due to the high moisture retention of the mosses. An enlarged evaporation surface creates a noticeable cooling effect. And finally, the system offers a variety of new design options. With AeroCare, for example, parts of the facade can be accentuated extremely effectively. At the same time, the system solution can be combined with all other Alsecco facade insulation systems and curtain-type, rear-ventilated facades as well as different surface materials such as plaster, clinker, natural stone and glass.

One man's meat is another man's suffering

But moss on the facade does not always trigger positive reactions. In most cases, green facades cause trouble for the painter or plasterer, because the once flawless plaster or paint loses aesthetics due to undesirable growth and is often the cause of customer complaints. "The algae and fungus infestation on the facade is still an unsolved problem," says Dr. Helge Kramberger, managing director of the Robert Murjahn Institute (RMI) in Ober-Ramstadt. In the past few years, numerous solutions have been tried to get the problem under control - unfortunately only with moderate success. Thanks to the development of a surface moisture sensor at the RMI, Dr. Kramberger prove that the exposure to condensation has a much greater impact on the “undesired green facade” than driving rain:"Very small amounts of water can keep the facade moist for a very long time." Kramberger therefore sees the solution in removing the defrost water from the facade surface as quickly as possible: "The decisive factor is not how much condensate is on the surface, but how long it is there remains.”For Kramberger the solution was clear: the condensation had to be reduced by higher surface temperatures.

The heated facade

Together with his research assistant Dr. Ayman Bishara, who is now responsible for developing and implementing the system, came up with the idea for Kramberger to develop facade heating. "The facade heating is still a dream of the future," said Dr. Kramberger at the Caparol Material Day in November 2018, on which he presented the project, "but actually all the necessary components are available." Kramberger explains which they are: "The overall system consists of sensors, which, depending on the system, measure the surface temperature directly or indirectly and moisture, a central control module, a heating layer between the top coating and the insulating material as well as the electrical connections and connections. The heating layer itself can be embedded in the reinforcement in the form of a fabric or applied in the form of a coating between the reinforcement and the top coating.”Such heating coatings are already on the market for indoor use. They contain carbon fibers that are electrically conductive. It is crucial for the functioning of the heating paint that it is applied in a certain layer thickness. An expert would be required here for correct execution. Kramberger also confirms this: "Basically, the system will work in the low-voltage range, so that the work can also be carried out by trained painters and stucco companies and not just by electricians." But he adds: "However, it will be a complex system,that can only be implemented for customer advice and for implementation in close cooperation between the manufacturer and the specialist company. To do this, the craftsmen will have to be qualified through special certification training courses.”Anyone wanting to install the facade heating must therefore be trained accordingly. “As soon as the system is marketed, certification training is required for the entire system structure. These training courses will be a prerequisite for processing and installing the facade heating system,”emphasizes Dr. Helge Kramberger.“As soon as the system is marketed, certification training is required for the entire system structure. These training courses will be a prerequisite for processing and installing the facade heating system,”emphasizes Dr. Helge Kramberger.“As soon as the system is marketed, certification training is required for the entire system structure. These training courses will be a prerequisite for processing and installing the facade heating system,”emphasizes Dr. Helge Kramberger.

When asked by the Malerblatt whether the facade heating would be on the market in the foreseeable future, he replied: "The first prototypes could probably be exposed to the weather within a year and the first test objects could be realized within 2 to 3 years." So it remains for the time being with the music of the future - but the sounds are gradually louder..:

More about the Caparol Material Day:

bit.ly/2InCnB5

Dr. Helge Kramberger, Managing Director RMI

Very small

amounts of water can keep the facade moist for a long time.

Dr. Thomas Loewenstein, project development facade at DAW

The sizes

and colors of the

elements can be varied in both solar thermal and photovoltaic systems

Alina Schneider, project manager for Aero Care at alsecco

The processor must have knowledge of the installation of

a VHF facade