2023-12-01, Hall, Monika, Gerber, Vincent, Geissler, Achim

Based on the extensive experience of a building cooperative with interior bathroom gravity (shaft) ventilation in existing apartment buildings, the replacement buildings constructed at the same location are also equipped with gravity ventilation. The aim of the project described here is to demonstrate the possibilities and limitations of gravity ventilation in one of the new replacement buildings by means of monitoring. Detailed monitoring over a complete year recorded the behaviour and effectiveness of the gravity ventilation in all seasons. In winter, gravity ventilation leads to higher air change rates in interior bathrooms than in summer. In general, humidity can be removed with gravity ventilation except in summer, when after a shower the bathroom door stays closed for 24 h. In summer when the indoor and ambient temperature is the same the gravity ventilation does not work. In this case, the interior bathroom should be ventilated by the main apartment ventilation, e.g., while the bathroom door and other room doors and windows are open at the same time. In summer, doors and windows are often open and the gravity ventilation summer problem can be viewed as negligible. Therefore, gravity ventilation is a good alternative to other ventilation systems in interior bathrooms.

2022-09-12, Hall, Monika, Geissler, Achim, Gerber, Vincent, Sattler, Michael, Bichsel, Jürg, Rudel, Roman, Steiger, Olivier, Tillenkamp, Frank

Über ein detailliertes Monitoring wird die Wirksamkeit der Schwerkraftlüftung in acht innenliegenden Bädern in einem Mehrfamilien Neubau bestimmt. Jeweils vier Bäder liegen übereinander. Jedes Bad verfügt über ein eigenes Zu- und Abluftrohr. Frischluft wird auf Kellerhöhe gefasst und die Fortluft auf Firsthöhe abgegeben. Weil bei der Schwerkraftlüftung der Luftaustausch auf Grund von Druckunterschieden am Gebäude erfolgt, ist er nicht bzw. kaum steuerbar und saisonal unterschiedlich. Daher erfolgt das Monitoring über ein komplettes Jahr, um das Verhalten in allen Jahreszeiten zu erfassen. Die Messungen zwischen März und Juli 2022 zeigen, dass sich die rel. Luftfeuchtigkeit der Bäder im Mittel zwischen ca. 45-65 % bewegt. Fallbetrachtungen zeigen, dass kurzzeitige hohe Feuchtebelastungen (bis ~98 % bei einem Duschvorgang) nach ca. 30 min bei offener Badezimmertüre und mindestens einem geöffneten Fenster und entsprechender, geöffneter Zimmertüre wieder auf ca. 60 % reduziert sind (manuelle Fensterlüftung, Juni). Bei einer geschlossenen Badezimmertüre dauert es infolge der Schwerkraftlüftung ca. 2.5 Stunden, um nach zwei Duschvorgängen auf 60 % rel. Luftfeuchtigkeit zu sinken (März). Letztgenannter Fall zeigt, dass durch die Schwerkraftlüftung eine ausreichende Feuchteabfuhr erfolgt.

2021-11-25, Hoffmann, Caroline, Geissler, Achim, Mutti, Miriam, Wicki, Andreas, Schwager, Franziska

Die gewählten Baumaterialien haben Auswirkungen auf das städtische Mikroklima. Zusätzlich beeinflussen die Materialisierung der Fassade und der Bodenbeläge des Gebäudeumfeldes die Umwelt z.B. im Hinblick auf die Versickerungsfähigkeit, die Akustik oder die Blendung. Der Vortrag gibt einen Einblick in den Katalog und Empfehlungen zur Materialienwahl.

2021-08-28, Hoffmann, Caroline, Geissler, Achim, Hauri, Claudia, Huber, Heinrich

The integration of passive window ventilation openings (PWVO, small air inlets integrated in the window frame) with additional exhaust fans in the kitchen and bathroom(s) can ensure a user-independent basic air change rate in dwellings. The project reported on herein is focused on how well buildings with PWVO work in real life.

2023-12-01, Hofmann, Joachim Werner, Amoser, Christian, Geissler, Achim, Hall, Monika

The renovation rate of existing buildings plays a major role in the Swiss Energy Strategy 2050+. To increase this rate, there must be a simple and cost-effective method to determine the heat demand of existing buildings. In this paper, the generation of such a method, based on the Swiss cantonal building energy certificate (GEAK) database with the help of machine learning (ML), is studied. The aim of the project was to develop a ML model which allows the heat demand of existing buildings to be determined quickly with a minimal set of parameters. The comparison of the GEAK building envelope class for single family houses calculated with the new ML model and the original GEAK classes shows that approximately 62 % have the same class, 32 % differ by one class and 6 % by two classes. The ML model is a good starting point for further refinements and developments.

2022-06-16, Hoffmann, Caroline, Geissler, Achim

Städte erwärmen sich stärker als ländliche Gegenden. Dieser Materialkatalog zeigt auf, mit welchen Baumaterialien sich die Umwelt weniger erwärmt. Das Nachschlagewerk richtet sich an Planerinnen und Planer sowie Bauträgerschaften, die Gebäude im urbanen Raum erstellen oder sanieren.

2021-11-18, Hall, Monika, Geissler, Achim

Buildings that are able to shift their loads without comfort restraints are important for the ongoing transformation of the power supply. This flexibility potential can be expressed in flexibility factors. The usefulness of four factors is investigated based on load control for the heat pump of a small apartment building according to electricity prices (high/low tariffs, spot market prices), CO2eq emissions share in the grid and a restricted operation period during daytime. The calculation methodology of the presented flexibility factors GSC, RIP, FF and FI is very different. RIP and FF are preferable because they have defined valid ranges which makes them easier to understand. Current electricity prices force the heat pump operation mainly into the night. The optimization of CO2eq emissions encourages operation mainly during the day. The optimization goals costs or CO2eq emissions thus lead to opposing heat pump operation times and can currently therefore not both be met simultaneously.

2022-12-22, Dürr, Jonas, Geissler, Achim, Hoffmann, Caroline

An enormous range of building materials that is almost impossible to keep track of is available. The trend toward building densification in cities continues apace. Coupled with climate change, a situation is emerging that poses ecological as well as economic risks in terms of living comfort in public, urban spaces. Building designers need help (tools) to be able to address a wide range of requirements within their planning. The development of the Multi-Criteria Decision-Making (MCDM) model BASK (engl. “Construction Materials for Cities in Climate Change”) is presented. The goal of the model is to assist building designers in determining surface materials for wall, ground and roof construction and help determine the best compromise between environmental, economic, and building practice criteria. Currently available criteria are heat stress, visual reflectance, CO equivalents, electricity production, retrofitability, sound absorption, construction costs, and life span. The criteria can be weighted by the designer, resulting in a customized ranking of construction systems that best meets the designer’s prioritized criteria. The design of BASK basically allows for an extension of the criteria. The version of BASK described in this paper includes 10 construction systems covering a wide range of construction types focused on walls. The tool requires technical data for materials considered in construction systems included, which are made available via a data base. The scope of construction systems can also be extended in the future. Based on the restricted set of construction systems the results of a sensitivity analysis and initial validation are given.

2021-12-13, Hall, Monika, Geissler, Achim

With the increasing use of renewable energy, the energy flexibility of buildings becomes increasingly important regarding grid support. Therefore, there is a need to describe this flexibility in a concise manner. For the characterization of building energy flexibility, flexibility factors can be used. The comparison of a selection of existing flexibility factors shows that they are not easy to use or understand for designers and users. A simplification is necessary. The aim of this study is to introduce a flexibility classification that is easy to understand and shows in an easy way if a building already uses the lowest energy cost level or if further improvement is possible. The classification expresses the annual energy costs in colored classes: green (class A) for lowest up to red (class D) for highest level. Basically, the flexibility classes can be derived for any metric of interest, in this paper examples are shown for energy costs and CO2eq emissions. The results given are based on the simulation of load management scenarios with different penalty signals applied for the heat pump operation of a residential building.

2021-10-01, Hoffmann, Caroline, Geissler, Achim

U-Wert Messungen vor Ort eigenen sich für Gebäude, bei denen die Konstruktion unbekannt ist und eine zerstörungsfreie, sichere Aussage zu den thermischen Eigenschaften getroffen werden soll. Die entsprechenden Messgeräte sind am Markt erhältlich und zielen auf eine breite Anwendung. Ziel des Projektes ist es, eine praxisorientierte Anwendungshilfe für die U-Wert Messung vor Ort zu erstellen. Als Basis dienen in-situ U-Wert Messungen und vergleichende Messungen im Labor, die mit drei unterschiedlichen Messgeräten durchgeführt werden. Ergänzend dazu werden Simulationen erstellt und Kontakt- und Haftmittel zur Befestigung der Sensoren an den zu messenden Bauteilen getestet. Untersucht werden schwere, homogene Bauteile, damit beziehen sich die Hinweise hauptsächlich auf diesen Bauteiltyp.