Browsing by Author "Ju, Yuchen"
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Item Analyzing energy flexibility by demand response in a Finnish district heated apartment building(EDP SCIENCES, 2021-03-29) Ju, Yuchen; Jokisalo, Juha; Kosonen, Risto; Kauppi, Ville; Janßen, Philipp; Department of Mechanical Engineering; Energy efficiency and systems; Department of Mechanical Engineering; Hamburg University of Applied SciencesIn order to realize the vision of climate neutrality, the proportion of renewable sources is increasing in the energy system. To accommodate the energy system, demand response (DR) has been established to make the building energy use flexible. This study aims to investigate the effect of DR actions on energy flexibility in a Finnish district heated apartment building. The rule-based control algorithm was applied for the DR control of space heating based on the Finnish dynamic hourly district heat price. This research was implemented with the validated dynamic building simulation tool IDA ICE. The obtained results show that price fluctuation impacts the DR control and further affects the amount of charging and discharging energies. February has the maximum hourly district heat price with the largest variation, which results in the maximum charging energy of 968 kWh during a single charging period being close to the heat storage capacity of a fully mixed 28 m3 water tank with ? T of 30 K. The studied demand response control can significantly shape the heating power demand of the buildings and increase the flexibility of the energy use.Item Analyzing power and energy flexibilities by demand response in district heated buildings in Finland and Germany(TAYLOR & FRANCIS, 2021) Ju, Yuchen; Jokisalo, Juha; Kosonen, Risto; Kauppi, Ville; Janβen, Philipp; Department of Mechanical Engineering; Energy efficiency and systems; Department of Mechanical Engineering; Hamburg University of Applied SciencesThis study aims to investigate the effect of demand response (DR) on power and energy flexibilities with three types of district heated buildings (apartment building, cultural center, and office building) in Finland and Germany. A rule-based control algorithm was applied for the DR control with two country-specific dynamic district heating (DH) prices, the more fluctuating Finnish synthetic DH price and the flatter German synthetic DH price. This research was implemented with the validated dynamic building simulation tool IDA ICE. Set-point smoothing of the indoor air temperature was applied to minimize the rebound effect. Nighttime set-back was adopted in the cultural center and the office building. The results show that the DR control without smoothing creates additional peaks in power demand, while the set-point smoothing significantly decreases the peak power demand. The DR control can significantly shape the heating power demand of the buildings and increase energy flexibility. The range of the resultant seasonal energy flexibility factors is from 3 to 26% for charging and from −6 to −31% for discharging, depending on the building types and countries. Cases with nighttime set-back have higher power and energy flexibilities, while this causes additional peaks, which is detrimental to DH systems.Item Benefits through Space Heating and Thermal Storage with Demand Response Control for a District-Heated Office Building(MDPI AG, 2023-10) Ju, Yuchen; Hiltunen, Pauli; Jokisalo, Juha; Kosonen, Risto; Syri, Sanna; Department of Mechanical Engineering; Energy Conversion and SystemsDemand response techniques can be effective at reducing heating costs for building owners. However, few studies have considered the dynamic marginal costs for district heating production and taken advantage of them for building-level demand response. In this study, a district heating network in the Finnish city of Espoo was modeled to define dynamic district heat prices. The benefits of two demand response control approaches for a Finnish office building, the demand response control of space heating and a thermal energy storage tank, were evaluated by comparing them to each other and utilizing them together. A 5 m3 storage tank was installed in a substation of a conventional high-temperature district heating network. A new demand response control strategy was designed to make the most of the storage tank capacity, considering dynamic district heat prices and the maximum allowed return water temperature. The results indicate that the demand response control of space heating and the storage tank cut district heat energy costs by 9.6% and 3.4%, respectively. When employing the two approaches simultaneously, 12.8% savings of district heat energy costs were attained. Additionally, thermal energy storage provides more potential for peak power limiting. The maximum heating power decreases by 43% and the power fee reduces by 41.2%. Therefore, the total cost, including the district heat energy cost and the power fee, can be cut up to 22.4% without compromising thermal comfort and heat supply temperatures to ventilation systems.Item Cost savings and CO2 emissions reduction potential in the German district heating system with demand response(TAYLOR & FRANCIS, 2022-01-25) Ju, Yuchen; Lindholm, Joakim; Verbeck, Moritz; Jokisalo, Juha; Kosonen, Risto; Janßen, Philipp; Li, Yantong; Schäfers, Hans; Nord, Natasa; Energy efficiency and systems; Department of Mechanical Engineering; Hamburg University of Applied Sciences; Norwegian University of Science and TechnologyDemand response (DR) has been an effective technique to maximize the proportion of renewable energies integrated into energy supply systems. This article investigated the benefits of DR on three building types (apartment building, office building and cultural center) and analyzed DR impacts on operation, production costs and CO2 emissions of three district heating (DH) production scenarios. The results indicate that the application of DR cuts 2.8%-4.9% off heating costs for building owners based on different energy production scenarios and building types. From the perspective of DH producers, the large-scale application of DR reduces the total DH demand by 3.6% to 3.9%. It results in higher financial benefits, less CO2 emissions and optimization of energy production in all the analyzed scenarios. The maximum total energy generation cost-saving rate is 12.6%, and the CO2 emissions reduce at most 32.3% because of a more renewable production mix. Moreover, DR control increases the full load operation hours of the heat pump, leading to higher efficiency, and decreases the operation hours of the boilers, leading to less pollution. It indicates that the application of DR effectively decreases fossil fuel usage and improves the energy efficiency of DH systems.Item Demand Response Control of Space Heating in Three Different Building Types in Finland and Germany(MDPI AG, 2020-12) Suhonen, Janne; Jokisalo, Juha; Kosonen, Risto; Kauppi, Ville; Ju, Yuchen; Janßen, Philipp; Department of Mechanical Engineering; Energy efficiency and systems; Hamburg University of Applied SciencesDemand response has been noted as a major element of future smart energy systems. However, there is still a lack of knowledge about the demand response actions in different conditions—including climate, dynamic energy price, and building types. This study examines energy and cost saving potential of the rule-based demand response in district heating network, in three different building types, in Germany and Finland. The studied building types are apartment buildings, cultural centers, and office buildings. The real-time pricing-based demand response is applied to space heating under the climate conditions of Helsinki, Finland and Hamburg, Germany. Moreover, the typical synthetic dynamic price data, which are based on both counties’ district heating production structure, is applied separately for each countries’ cases. Simulations of this study are conducted with validated simulation tool IDA ICE. The results present that the demand response can provide energy and cost savings around 0.5–7.7% and 0.7–8.1% respectively, depending on the building type and country. The results indicate that marginal value of the control signal, climate conditions, and the dynamic price of the district heating have effect on the demand response saving potential. Flatter district heating price profile provides less savings than a more fluctuating profile.Item Demand response in the German district heating system(Institute of Physics Publishing, 2023) Ju, Yuchen; Lindholm, Joakim; Verbeck, Moritz; Jokisalo, Juha; Kosonen, Risto; Janßenc, Philipp; Li, Yantong; Schäfers, Hans; Nord, Natasa; Department of Mechanical Engineering; Energy Conversion and Systems; Hamburg University of Applied Sciences; Norwegian University of Science and TechnologyThe renewable energy share in energy supply systems is increasing for carbon neutrality. The realization of carbon neutrality can be supported by demand response (DR) strategies. This paper analyzed the DR control benefits of a German district heating (DH) system. For the first step, in German conditions, three building types were simulated by IDA-ICE software with and without a rule-based DR control. Secondly, a community was established based on the heat demand of the simulated buildings. This paper selected two different production scenarios. One scenario consisted by a biofuel CHP and gas boilers and the other one included a heat pump, an electric heater, and a solar thermal storage. After that, the production of the two scenarios with and without DR was optimized by the HGSO tool and it calculated the total production costs and CO2 emissions. It indicates that building owners and DH producers all earn benefits from the application of demand response. The maximum heating cost saving by DR is 4.9% for building owners. In the optimized two production scenarios, DH producers gain higher financial benefits and there are less CO2 emissions. The maximum total generation cost and CO2 emission savings are 12.6% and 8.6%, respectively.Item Design of High-Performing Hybrid Ground Source Heat Pump (GSHP) System in an Educational Building(MDPI AG, 2023-07) Xue, Tianchen; Jokisalo, Juha; Kosonen, Risto; Ju, Yuchen; Department of Mechanical Engineering; Energy Conversion and SystemsUnderground thermal imbalance poses a challenge to the sustainability of ground source heat pump systems. Designing hybrid GSHP systems with a back-up energy source offers a potential way to address underground thermal imbalance and maintain system performance. This study aims to investigate different methods, including adjusting indoor heating and cooling setpoints and dimensioning air handling unit (AHU) cooling coils, heat pump and borehole field, for improving the long-term performance of a hybrid GSHP system coupled to district heating and an air-cooled chiller. The system performance, life cycle cost and CO2 emissions were analyzed based on 25-year simulations in IDA ICE 4.8. The results showed studied methods can significantly improve the hybrid GSHP system performance. By increasing the AHU cooling water temperature level and decreasing indoor heating and cooling setpoints, the ground thermal imbalance ratio was reduced by 12 percentage points, and the minimum borehole outlet brine temperature was increased by 3 °C in the last year. However, ensuring long-term operation still required a reduction in GSHP capacity or an increase in the total borehole length. The studied methods had varying effects on the total CO2 emissions, while insignificantly affecting the life cycle cost of the hybrid GSHP system.Item Energy, cost and emission saving potential of demand response and peak power limiting in the German district heating system(Taylor & Francis, 2023) Suhonen, Janne; Lindholm, Joakim; Verbeck, Moritz; Ju, Yuchen; Jokisalo, Juha; Kosonen, Risto; Janßen, Philipp; Schäfers, Hans; Department of Mechanical Engineering; Energy Conversion and Systems; Department of Mechanical Engineering; Hamburg University of Applied Sciences; Hemsö Fastighets ABThe demand response and peak power limiting could potentially reduce the peak power and energy demand. This study examines the effect of rule-based demand response and peak power limiting on the peak power and energy demand of heating. Study was conducted as a co-simulation where buildings and district heating production were simulated separately but both inclusively. Results indicate that demand response provides 2.8–4.7% energy saving and 2.3–3.4% total district heating cost saving potential. Moreover, according to the simulations, demand response provides 32% emission reduction in district heating production in contrast to the reference case. Peak power limiting provides significant reduction in the peak power and district heating base cost. However, its ability to provide additional reduction in the energy demand and emissions is confined compared to the demand response due to the effective time of the limit. Chosen acceptable temperature range can be maintained decently.Item Peak Shaving of a District Heated Office Building with Short-Term Thermal Energy Storage in Finland(MDPI AG, 2023-03) Ju, Yuchen; Jokisalo, Juha; Kosonen, Risto; Department of Mechanical Engineering; Energy Conversion and SystemsShort-term thermal energy storage techniques can be effective to reduce peak power and accommodate more intermittent renewable energies in district heating systems. Centralized storage has been the most widely applied type. However, in conventional high-temperature district heating networks, substations are typically not equipped with short-term thermal energy storage. Therefore, this paper investigated its peak shaving potential. A 5 m3 thermal storage tank directly charged by the district heating supply water was integrated into a substation of a Finnish office building. The substation with the stratified storage tank and the office building were modeled and simulated by IDA ICE. Different storage tank temperature control curves were designed to charge the tank during off-peak hours and discharge to reduce the high-peak-period heating power. Moreover, the peak power was further dimensioned by reducing the mass flow of the primary district heating supply water. The results indicate that the storage tank application significantly decreases the office building daily peak power caused by the ventilation system’s morning start during the heating season. It reflected a higher peak shaving potential for colder days with 31.5% of maximum peak power decrease. Cutting the mass flow by up to 30% provides an additional peak power reduction without sacrificing thermal comfort.Item Simulation of demand response on buildings and district heating production(EDP Sciences, 2022-12-01) Ju, Yuchen; Lindholm, Joakim; Verbeck, Moritz; Jokisalo, Juha; Kosonen, Risto; Janßenc, Philipp; Li, Yantong; Schäfers, Hans; Nord, Natasa; Department of Mechanical Engineering; Energy efficiency and systems; Department of Mechanical Engineering; Hamburg University of Applied Sciences; Norwegian University of Science and TechnologyDemand response (DR) has effectively maximized renewable energies integrated into energy supply systems. This paper investigated DR benefits on three building types and the district heating (DH) production of a community consisted by these buildings in German conditions. Firstly, the buildings and the DH production were simulated without DR by tools IDA-ICE and HGSO, separately. Secondly, the three buildings were simulated by a rule-based DR control. After that, the tool HGSO calculated the total production costs and CO2 emissions based on the power demand with DR. The results show 2.8%-4.8% heating cost savings by DR for different building types. For DH producers, DR application reduces the total DH demand and CO2 emissions by 3.8% and 32.3 %, respectively.Item Utilization of short-term thermal energy storage for demand response and peak power reduction in district-heated buildings(Aalto University, 2024) Ju, Yuchen; Jokisalo, Juha, Senior Scientist, Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; HVAC Technology; Insinööritieteiden korkeakoulu; School of Engineering; Kosonen, Risto, Prof., Aalto University, Department of Mechanical Engineering, FinlandThe European Commission has set ambitious targets to cut at least 55% of greenhouse gas emissions from 1990 levels by 2030 and to realize carbon neutrality by 2050. In 2020, space heating consumed 28% of the total energy consumption in Germany while only 18% was produced by renewable sources. In Finland, district heating is the most common source of space heating. In 2020, it covered 45% of the market share of space heating for residential, commercial, and public buildings. Therefore, decarbonization strategies should be developed for district heating systems and the connected buildings. When renewable energies are utilized more in production, there is the demand to enhance the smart readiness of buildings. Demand side management is an approach to adjusting consumer energy use and power demand according to the production pattern. By utilizing short-term thermal energy storage, such as building thermal mass and thermal energy storage tanks, energy flexible strategies could be applied to buildings and their energy systems for peak power cutting and load shifting. This thesis investigated energy flexibility and the benefits of demand response based on dynamic district heat prices of space heating and a thermal storage tank for district-heated buildings. The meaning of building-level rule-based demand response control strategies on district heating production was also analyzed in the thesis. There were three different production scenarios. The first scenario utilized a biofuel CHP as the basic source and three gas boilers for backup. The second one had a biofuel CHP and a green-electricity heat pump as the basic source and two gas boilers as backup. The last one included a heat pump as the basic unit and an electric heater as backup used grid electricity. In addition, strategies were also developed for peak shaving and peak power limiting with a 5 m3 short-term thermal storage tank. Demand response of space heating cuts up to 9.6% of heating costs for building owners. The demand response control of the storage tank decreases the district heat energy cost by 3.4%. When employing the demand response control of space heating and the storage tank, it gains 12.8% of district heat energy cost savings. In addition, thermal energy storage provides the potential for peak shaving and peak power limiting. It reflects a higher peak shaving potential for colder days with a 31.5% maximum peak power decrease of a Finnish office building. The maximum heating power is limited by 43% and the power fee reduces by 41.2% without compromising room air and ventilation supply air temperatures. The large-scale demand response application decreases the total district heating demand from 3.6% to 3.9% with higher financial benefits and less CO2 emissions. Moreover, it increases the full load operation hours of renewable energy generation units, reducing emissions. Therefore, demand response effectively decreases fossil fuel usage and improves the energy resiliency of district heating systems.
