Geissler, Achim
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Geissler, Achim
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- PublikationComparison of flexibility factors and introduction of a flexibility classification using advanced heat pump control(MDPI, 13.12.2021) Hall, Monika; Geissler, Achim [in: Energies]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.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationComparison of flexibility factors for a residential building(IOP Publishing, 18.11.2021) Hall, Monika; Geissler, Achim [in: Journal of Physics: Conference Series]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.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationPassive window ventilation openings in every-day use(Elsevier, 28.08.2021) Hoffmann, Caroline; Geissler, Achim; Hauri, Claudia; Huber, Heinrich [in: Building and Environment]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.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationLoad Control by Demand Side Management to Support Grid Stability in Building Clusters(MDPI, 01.10.2020) Hall, Monika; Geissler, Achim [in: Energies]Increasing numbers of photovoltaic systems and heat pumps in existing building clusters can lead to an overload of the associated substations of the electric grid. Based on a multi-agent-based simulation of three building cluster types the impact of building flexibility in regard to the residual substation load is studied. Each building announces its available flexibility, e.g. “heat pump can be switched off/on”. A cluster master coordinator evaluates the incoming offers and decides which offers are accepted in regard to the substation’s capacity utilization. The goal is to honour the substation’s limit by shifting the residual load. This paper presents results from three typical urban building clusters for different penetration scenarios in regard to heat pumps, photovoltaic systems, batteries and electric vehicles. It is shown that in the studied building clusters a high penetration of heat pumps and photovoltaic systems can violate the existing substation’s limits, regardless of the efforts by the master coordinator. Batteries of typical capacities cannot reduce the peak residual load. The load shifting options of the master coordinator are limited.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationMulti-agent based simulation of smart building cluster for electric grid stabilization(IOP Publishing, 21.11.2019) Hall, Monika; Geissler, Achim; Wache, Holger [in: Journal of Physics: Conference Series]With the increasing number of photovoltaic systems and heat pumps in buildings existing substations of the electric grid could be overloaded. A multi-agent based simulation of a building cluster studies the impact of building flexibility in regard to the residual substation load. Each building announces its available flexibility, e.g. "heat pump can be switched off/on". A master coordinator evaluates all incoming offers and decides which offers are accepted. This reduces the residual load at the substation. This paper presents results from a study of the impact at the substation of a smart urban building cluster with different penetration scenarios of heat pumps, photovoltaic systems, batteries and electric vehicles. It is shown that a high penetration of heat pumps and photovoltaic systems violates the substation's limits for the studied building cluster. Batteries cannot reduce the peak utilization. The master coordinator's load shifting options are limited.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationConversion of unheated basements and the conditioning of their indoor climate(IOP Publishing, 2019) Hoffmann, Caroline; Geissler, Achim; Huber, Heinrich; Hauri, Claudia [in: Journal of Physics: Conference Series]This paper deals with unheated basements in existing buildings. Due to soaring housing prices these rooms may be increasingly used for the storage of sensitive goods and temporarily for leisure activities. In order to keep these rooms free of mould various technical solutions are available. However, it is unclear whether they prevent mould growth and how high their energy demand is. This question is explored by simulating an unheated basement in an uninsulated, a renovated and a newly built building. The paper considers and evalueates four different operation modes for the basement.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationThe prebound-effect in detail: real indoor temperatures in basements and measured versus calculated U-values(Elsevier, 12.09.2017) Hoffmann, Caroline; Geissler, Achim [in: Energy Procedia]This paper focuses on the topics U-values and indoor air temperatures of unheated basements with uninsulated cellar ceilings. Measurement values are compared with calculation procedures suggested by building regulations. Concerning the U-values it is shown that they are typically considered to be higher (i.e. worse) in uninsulated existing constructions than they effectively are. Measured temperatures in seven basements are higher (around 8 K) than a calculation according to regulations would yield. The paper derives suggestions for the adjustment of calculations focused on existing residential buildings.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationDem Prebound Effekt auf der Spur – Differenzen zwischen dem Heizwärmeverbrauch und dem rechnerisch ermittelten Heizwärmebedarf bei Bestandsgebäuden (Wohnen)(Wiley, 06/2017) Hoffmann, Caroline; Geissler, Achim [in: Bauphysik]Bei der Energieanalyse von unsanierten Bestandsgebäuden wird typischerweise ein Monatsbilanzverfahren zur energetischen Einordnung des Gebäudes verwendet. Der berechnetet Heizwärmebedarf ist dabei oftmals höher als der tatsächliche Verbrauch des Gebäudes. Der Beitrag zeigt auf, dass diese Abweichungen nicht einem einzigen systematischen Fehler im Berechnungsverfahren gemäß der Schweizer Norm zuzuordnen sind. Vielmehr ist es eine Vielzahl von Gründen, die zu den Abweichungen führt. Die Analyse wird anhand von 33 realen Gebäuden durchgeführt und durch eine Literaturrecherche ergänzt.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationDifferent balancing methods for Net Zero Energy Buildings - Impact of time steps, grid interaction and weighting factors(Elsevier, 2017) Hall, Monika; Geissler, Achim [in: Energy Procedia]Adding large photovoltaic systems to buildings is becoming more and more popular. To date, the self-consumption/grid interaction is not typically part of the energy balance. The choice of symmetric or asymmetric primary energy factors has an impact on the balance. The primary energy factor for import from the grid depends on the chosen type of the power mix in the grid. If this factor is higher/lower than the primary energy factor of the on-site PV-system, a larger/smaller PV system than when using symmetrical factors is required in order to fulfil the NZEB balance.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationMöglichkeiten und Grenzen von grossen Nullenergiegebäuden(Wiley, 02/2016) Hall, Monika; Geissler, Achim [in: Bauphysik]Nullenergiegebäude haben üblicher Weise zwei bis vier Stockwerke. Daher interessiert die Frage, ob auch grosse Gebäude, d.h. Gebäude bis zu 40 Stockwerken, mit langgestrecktem bzw. quadratischem Grundriss genügend Fläche für Photovoltaik zur Verfügung stellen können, so dass eine Nullbilanz für die gesamte Gebäudetechnik (HWLK-Nullbilanz "Nullwärmeenergiegebäude") oder den Gesamtenergiebedarf des Gebäudes (GEB-Nullbilanz "Nullenergiegebäude") im Jahr erreicht werden kann. Auf der Grundlage von Simulationen anhand von vier Basismodellen, je zwei Mehrfamilienhäuser und Verwaltungsbauten, werden die Auswirkungen verschiedener Parameter auf die Nullbilanz analysiert.01A - Beitrag in wissenschaftlicher Zeitschrift