Novel TI wall system and application demonstration

The optimized small-celled TI structure was tested on a demonstration object. The demonstration object was an ultra-low energy solar single family house with office unit in Graz, Austria (planning and implementation: Planungs — und Bauges. m.b. H. HEGEDYS — HAAS). The objective of the building owner was to explore in practice the technological possibilities and potentials of a full-fledged solar energy supply relying on the innovative use of plastics and polymer materials based on renewable raw materials. Ecological and biological criteria were taken into account during the building design and construction and the material selection process. The building for the application demonstration consists of two main wings: a main wing in a countryhouse style and a south oriented “solar” wing (s. Fig. 2). The “solar” wing features the TI facade with summer shading through the roof, a thermal collector with a steep tilt angle for high winter yields as well as roof-mounted
photovoltaic modules with ventilation at the back. While the concept of the building does not follow the usual compact design of a passive house, energy efficiency criteria set forth for the passive house standard (space heating demand < 15 kWh/(m2a)) were nevertheless achieved.

Concerning the TI facade of the building (Fig. 2) an optimized frame and facade structure based on timber profiles with minimized material fraction and shading of the absorber was developed and realized. A sketch through the TI facade is shown in Fig. 3. A 3.5 cm thick timber profile is mounted onto the 25 cm thick concrete filled brick wall and integrated into the plaster. The plaster is painted with a black solar collector absorber. The Fig. 2. Solar wing of the demonstration object featuring 13.5 cm thick TI structure the TI facade with summer shading through the roof is in close contact with the

absorber. At the outside an

6.5 cm thick air gap was realized between TI structure and a 6 mm thick structured low iron glass pane. The outer timber profile carrying the glass panes was connected to the inner profile by plywood. However, only about 30% of the area between inner and outer timber profile are covered by plywood.

The TI facade elements have a width of 0.72 m at the edge and 1.05 m in-between. The heights of the elements varies between 0.51 and 5.04 m depending on the windows of the TI facade. Due to the fact that a transparent insulation material with a relatively high moisture uptake is used, a diffusion open TI facade system was realized. Fig. 4 reveals the openings (air-holes) of the TI facade. The openings with a thickness of 3 cm are positioned at the bottom and at the top of the air gap between the glass pane and the TI structure of each element. The air-holes span the whole element width. To prevent insects and infiltration of polluted air into the TI facade the openings are covered by a perforated metal plate and a fleece.

To evaluate the TI facade system, a measuring concept for solar irradiation, other climate data and the yields to be expected in the demonstration object was developed and realized in cooperation with the Arbeitsgemeinschaft ERNEUERBARE ENERGIE. A testing field of about 1 m2 was implemented, made of 25 cm thick concrete and insulated against the surrounding wall with 5 cm thick foam glass. The testing field was positioned in the middle of the TI fagade near the window at the bottom. Whereas for the testing field a stapled TI structure was used, in the other elements of the TI facade rolled structures were installed. The testing field was equipped with various temperature, solar irradiation, heat flux and humidity sensors. Temperature and heat flux sensors were positioned at the inside, the middle and the outside of the concrete wall. To record temperature and humidity within the TI facade element temperature and humidity sensors were installed in the TI structure, in the air gap and at the glass pane. The sensors were positioned in the middle of the testing element. Solar irradition was measured at the top of the testing field using various sensors (to detect shading effects).

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