Bachelor's thesis Patrick Zühlke

 

A literature based review of the dynamic thermal comfort sensation in residential buildings

Due to national and international climate policy decisions , the power system is subject to a structural change in the coming decades. The conversion of the energy production of predominantly non-renewable towards renewable energy sources represents major challenges for the fluctuating electrical distribution network. In addition to the technical requirements of the expansion of renewable energies, especially intelligent solutions for energy storage will have to be found. The need for storage technology lies in the fact that a large proportion of renewable energies are not subject to any control . A large proportion of primary energy in industrialized countries is used for heating of non-industrial buildings. Therefore, among other things, the investigation of the thermal storage options for residential buildings is subject of current research. To use the thermal storage capacity of residential buildings efficiently, it is necessary to be able to customize the interior temperatures at the present energy supply dynamically. In particular, the supply of electrical energy from renewable sources is volatile, therefore electric heating systems are suitable for dynamic adjustment of the indoor room temperatures. Thus, the power grid can be relieved in high-load times by targeted heating of the living space in times of high renewable electricity generation. This work will be based on a literature review, and study the dynamic thermal sensation of comfort in residential buildings. Other non-industrial buildings, due to the comparable situations and the wide range of available data, are also mentioned. It is shown that static comfort models are a good prediction tools for buildings with a mechanical ventilation systems and low user influence. Buildings with a high user influence lead to an increased adaptation of the interior temperatures to the outside air and to an increase in comfort areas. The thermal comfort sensation is also subject to natural fluctuations during the day, so that the hot and cold threshold in the early morning hours is 0.5 to 1.0 K lower than in the afternoon. In the course of temperature transitions "down- steps" lead to a spontaneous disproportionate assessment of thermal sensation which can be quantified by the factor „2“. The overestimation oft the thermal sensation dissipates after about 30 minutes., The thermal sensation in "steps-ups" corresponds to the rating under steady environmental conditions, the adaption speed here is 1 to 2 minutes. Furthermore temperature fluctuations of about 2 K/h within the range of comfort temperatures show no additional effect on the thermal comfort.
Excessive temperature gradients lead to an overestimation oft the thermal sensation, while excessive temperature drifts lead to a delayed perception of temperature. Generally the comfort zone of the operative room temperature can be extended by individual user influence.

 

The Economic and Technical Feasibilty of Various Storage Technologies to Compensate the Volatile Electricity Generation Produced from Renewable Energy Sources

With the growing share of renewable energies in our power grids characterized by a strong fluctuation,
the challenge of matching electricity generation and consumption arises. Many solutions
have been proposed in the past including expanding the storage capacity in the power system and
deploying conventional power plants that can supply additional electricity during peak times. The
bachelor thesis at hand discusses both approaches by creating multiple scenarios in which the storage
costs of several technologies are benchmarked against each other and against the power generation
costs of a typical gas turbine. The observed technologies in this analysis are at least in an early
stage of commercialization and include centralized as well as decentralized storages with installation
costs for today and the year 2020. As of to date, pumped hydroelectric storages are one of the
few storage plant types installed in our power system. Nevertheless, there are many other technologies
being developed aiming to solve the mismatch of renewable energy generation and electricity
demand. Therefore, different large-scale batteries, compressed air energy storage and Power-to-
Gas technology are considered in this thesis to compare to local storages such as lithium-ion and
lead acid batteries as well as the conventional sensible heat storage in regard to their suitability to
cover the heating demand of a single-family house. Market environments are set by the scenarios
and feature electricity pricing schemes that include dynamically adjusted energy procurement
costs and different sets of levies, fees and taxes. Within these boundary conditions and the given
use case, the sole technical storage costs, storage costs incorporating energy losses and costs to be
paid by the end-consumer are calculated using the annuity method. Thereby, the profitability of
the observed systems is evaluated revealing the potential of emerging technologies to economically
compete with existing and well-established storages, such as hot water buffer tanks.