Geissler, Achim
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Gravity ventilation for interior bathrooms
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.
Comparison of flexibility factors and introduction of a flexibility classification using advanced heat pump control
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.
Quantifizierung des Umweltnutzens von gebrauchten Batterien aus Elektrofahrzeugen als gebäudeintegrierte 2nd-Life-Stromspeichersysteme
2015-08, Kim, David Pascal, Geissler, Achim, Hengevoss, Dirk, Menn, Claudio
Aufgrund der Energieperspektiven 2050 des schweizerischen Bundesamtes für Energie (BFE) wird das zukünftige Potenzial von gebrauchten Lithium-Ionen-Batterien aus Elektrofahrzeugen als stationäre Stromspeicher in Gebäuden untersucht. In drei Szenarien wird der Umweltnutzen für das Jahr 2035 und 2050 ermittelt. Hierzu wird berechnet wie viel Kapazität an herkömmlichen Speichern durch eine gewisse Kapazität an wiederverwendbaren gebrauchten Batterien substituiert werden kann. Das Substitutionspotenzial wird mit ausgewählten Wirkindikatoren wie dem Treibhauspotenzial (GWP) und dem kumulierten Energieaufwand (CED) analysiert. Im Jahr 2050 können dadurch 760 bis 1170 MWh an herkömmlichen Speichern durch 2nd-Life-Speicher substituiert werden. Dabei kann das Treibhauspotenzial pro Jahr um 11'000 bis 16'000 t CO2 Äq gesenkt und der kumulierte Energieaufwand um 207'000 bis 305'000 GJ verringert werden. Die Resultate zeigen, dass der Einsatz von 2nd-Life-Batterien in stationären Anwendungen einen signifikanten Beitrag zur Reduktion der Umweltbelastung von Batterien beitragen kann.
Determine the heat demand of existing buildings with machine learning
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.
Comparison of flexibility factors for a residential building
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.
Potential-estimation of thermal micro-grids in urban areas based on heat load and building clustering
2023, Hall, Monika, Bereuter, Pia, Geissler, Achim
As a result of climate change, fossil heating systems must be replaced with renewable systems. The question arises whether it makes sense for each building to have its own new heating system or whether a thermal micro-grid is possible. In this paper a model is presented which allows to aggregate buildings into thermal micro-grid clusters. All gas-heated residential buildings of Basel (Switzerland) are marked via geo-data. The heat demand of each building is determined depending on the year of construction and is then converted into the heat load. Each building then is grouped into thermal micro-grids according to a given grid load limit. The thermal micro-grids generated in this way are marked in color, so that the potential of any given city district can be easily and quickly identified. If the grid load limit is increased, the number of possible micro-grids increases, also.
Passive window ventilation openings in every-day use
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.