Name: Dr. Hanmin Cai

Email: hanmin.cai@empa.ch

Phone: +41 58 765 40 77

Affiliation: Scientist, Cluster leader, Urban Energy Systems Lab, Empa

Address: Überlandstrasse 129, 8600 Dübendorf, Switzerland

Group: www.empa.ch/web/energy-hub/

Cluster: https://www.empa.ch/web/s313/flexibilities

Lab: www.empa.ch/web/s313

Links: Linkedin | Google Scholar | ORCID 

Open-source projects

nestli (Neighborhood Energy System Testing towards Large-scale Integration)

nestli is the virtual sister of the NEST demonstrator at Empa and the open-source code is hosted here: https://github.com/Khayatian/nestli

It is a co-simulation environment for benchmarking the performance of BACS (building automation and control systems). In its core, nestli is a calibrated EnergyPlus model of the UMAR living lab. see: https://www.empa.ch/web/nest/urban-mining

The calibrated EnergyPlus model is wrapped into an FMU (fucntional mock-up unit) using the EnergyPlusToFMU tool. see: https://simulationresearch.lbl.gov/fmu/EnergyPlus/export/

The model is calibrated on measurements that are collected at 1-minute intervals, and thus runs at the same temporal resolution. The HVAC system can be controlled by overriding the setpoint temperature in each room. It is also possible to evaluate the robustness of the controller by manipulating weather conditions and building operation.

Bio

I am a Scientist with the Urban Energy System Lab at Empa. Prior to joining Empa, I worked as a Ph.D. student with the Center for Electric Power and Energy (CEE) at the Technical University of Denmark (DTU). I was mainly involved in developing and demonstrating future energy solutions within the EnergyLab Nordhavn project, using a full-scale smart city energy lab in Copenhagen.

My focus area is the intersection of multiple fields, including building energy flexibility, multi-energy system operation, and machine learning. I am interested in both theoretical research and experimental implementation/validation. Check out our state-of-the-art NEST building. 

Ongoing research projects

PATHFNDR

Will be updated soon.

K3 - Handwerkcity

The overall objective of this project is to show a system-related contribution of the Swiss gas industry to the implementation of the Swiss Energy Strategy 2050. Empa will provide a quantification of energetic flexibilities and free capacities. Additionally, we are conducting an optimization for future adaptions of operation. We evaluate the system stability based on measurement data, and we will evaluate economical factors related to electrical self-sufficiency in the K3 building complex.

K3, a commercially used building complex, will serve as a validation area. Its energy system consists of roof and façade PV systems, air-to-water heat pumps, water-to-water heat pumps, a CHP unit, and several hot- and cold-water storage units.

Funding body: FOGA
Partners: Die Werke Wallisellen, SVGW

CAPITAL - Carbon footprint optimization of electricity in smart buildings

Will be updated soon.

S-DSM

Will be updated soon.

Funding body: Swiss Federal Office of Energy SFOE

Guest lecture

• ICT-Automation & Control for the course "Building systems", at ETHz, Autumn 2022
• Governing Energy Transitions: Urban energy transition management, at Universität St. Gallen, 2021

Past research project(s)

Aliunid

Existing infrastructure in buildings, such as heat pumps or domestic hot water heaters is usually operated to purely satisfy the thermal needs of residents. However, thanks to thermal storage capacities available in buildings' thermal mass or water tanks, there exists energy flexibility in when to charge these storages. These flexibilities can be coordinated to satisfy other interests, e.g. from other players in the electric or thermal distribution grid. In a joint project with the aliunid AG, controllers that optimally utilize these flexibilities are developed and implemented in the NEST demonstrator.

Funding body: Swiss Federal Office of Energy SFOE
Partners: aliunid AG, HSG, BFH

EnergyLab Nordhavn

http://www.energylabnordhavn.com/index.html

From 2015 until 2019 the project EnergyLab Nordhavn – New Urban Energy Infrastructures has developed and demonstrated future energy solutions. The project has utilized and consolidated Copenhagen’s Nordhavn as a full-scale smart city energy lab and demonstrated how electricity and heating, energy-efficient buildings and electric transport can be integrated into an intelligent, flexible, and optimized energy system.

Funding body: EUDP (Energy Technology Development and Demonstration Programme) Denmark
 

Selected journal publications

• Hekmat N., Cai, H., Zufferey, T., Hug, G., and Heer, Philipp. (2021). Data-Driven Demand-Side Flexibility Quantification: Prediction and Approximation of Flexibility Envelopes. arXiv preprint. https://arxiv.org/abs/2110.12796

• Cai, H., and Heer, P. (2021). Experimental implementation of an emission-aware prosumer with online flexibility quantification and provision. arXiv preprint. https://arxiv.org/abs/2110.12831

• Gasser, J., Cai, H., Karagiannopoulos, S., Heer, P., and Hug, G. (2021). Predictive energy management of residential buildings while self-reporting flexibility envelope. Applied Energy, 288, 116653.

• Cai, H., Thingvad, A., You, S. and Marinelli, M., 2020. Experimental evaluation of an integrated demand response program using electric heat boosters to provide multi-system services. Energy, 193, p.116729. 

• Cai, H., You, S. and Wu, J., 2020. Agent-based distributed demand response in district heating systems. Applied Energy, 262, p.114403. 

• Wang, J., You, S., Zong, Y., Cai, H., Træholt, C. and Dong, Z.Y., 2019. Investigation of real-time flexibility of combined heat and power plants in district heating applications. Applied Energy, 237, pp.196-209.

• Klyapovskiy, S., You, S., Cai, H. and Bindner, H.W., 2019. Incorporate flexibility in distribution grid planning through a framework solution. International Journal of Electrical Power & Energy Systems, 111, pp.66-78. 

• Klyapovskiy, S., You, S., Cai, H. and Bindner, H.W., 2018. Integrated planning of a large-scale heat pump in view of heat and power networks. IEEE Transactions on Industry Applications, 55(1), pp.5-15.

• Cai, H., Ziras, C., You, S., Li, R., Honoré, K. and Bindner, H.W., 2018. Demand side management in urban district heating networks. Applied energy, 230, pp.506-518.

• Cai, H., You, S., Wang, J., Bindner, H.W. and Klyapovskiy, S., 2018. Technical assessment of electric heat boosters in low-temperature district heating based on combined heat and power analysis. Energy, 150, pp.938-949.

Student supervision

Open projects:

• Master thesis, Impact of uncertainties on the flexibility quantification of HVAC systems in buildings, Link to project.
• Semester thesis, Impact of uncertain information on the detection of future congestions in distribution networks, Link to project. 
• Master/semester thesis, Use of demand-side flexibility to alleviate congestions in distribution networks, Link to project. 
• Master thesis, Analysis of new flexibility market and pricing models for electrical grid support, Link to project. 

2023, Spring semester

2022, Fall semester

2022, Spring semester

2021, Spring semester

2020, Fall semester

• Semester project student, Timmy Frischknecht, Msc ETH Zurich, project title: Coordinate flexible buildings to support distribution system operation. Co-supervision with Thierry Zufferey and Prof. Gabriella Hug (PSL ETH Zurich)
• Master thesis student, Muriel Beaud, Msc ETH Zurich, project title: Evaluating the impact of dispatch strategy on different energy system configuration. Co-supervision with Dr. Dasun Perera and Prof. Roy Smith (IfA ETH Zurich)

2020, Spring semester