Blog #5: Final Results

Hi everyone! Thanks for keeping up with my blog post progress from the beginning up until now! This is going to be my last post with the Cal Energy Corps since I have finished my summer internship program.


The past two weeks were the busiest for me, yet those weeks were the highlight of my experience during the past 3 months. For the final week, I was invited by Dr. Tianzhen to present my work during the weekly team meeting on Monday, and I was also invited by Kaiyu to present during the California Energy Commission meeting on Thursday. Thus, I spent my 9th week (even during the weekend) finishing all my simulations and data analysis, so I could compile and organize my results into a coherent presentation.

The following are several results from my 10 weeks of internship.

As it can be seen in figure below, I outlined 4 specific targets as the guiding principles of my work: maximize energy-saving, maximize carbon emission reduction, complete electrification, and maximize cost reduction.

For the energy-saving and carbon emission reduction results as seen in the two figures above, the most effective package is the combination of these 7 ECMs: LED upgrade, heat pump water heater, mini-split heat pump, roof insulation, wall insulation, interior window storm, and window film. With this package, it can save up to 60% of energy-saving as well as a 60% carbon emission reduction. This is because when building reduces energy consumption, it decreases its carbon footprint.

For electrification in the figures below, there are two possible packages to eliminate the use of natural gas for heating: package 1 consists of heat pump water heater and single-zone air source heat pump while package 2 consists of heat pump water heater and mini-split heat pump. Both of these packages eliminate the use of natural gas for heating, but the second package is more effective in reducing electricity consumption during its conversion. The remaining 10% of natural gas came from the use of appliances and currently, it cannot be eliminated.

This the zero-net potential analysis which shows the minimum percentage of rooftop required for electricity generation to fully satisfy each building’s electricity consumption. This chart identifies which percentage of rooftop coverage can satisfy each building’s electricity consumption under different simulated cases. With this chart, the energy-saving package requires a less minimum percentage of the rooftop with only 15% for nearly 70% of the buildings compared to its baseline at 15-20% of total roof coverage. Whereas for the electrification, both packages increase their minimum percentage of roof area, but only the package with a single zone heat pump has its peak at 40% of the total rooftop. However, with this zero-net potential analysis result, the electrification of the Winchell district is feasible because it still only requires less than 50% of the total rooftop for enough PV generation.

In terms of cost reduction target, which is to evaluate the measures from the monetary perspectives for residents. The package containing LED upgrade, portable fan, water tank insulation improvement, and mini-split heat pump can save up to 50% of energy and require approximately only 6 years of payback with up to $10 of energy cost saving per m². This package, however, fails to achieve the investment cost target because the cost of the initial implementation of the mini-split heat pump is too expensive. There are a lot of incentives by PG&E, Pacific Power, and Energy Upgrade California Program to help reduce the investment cost problem, but currently, they are still being reviewed to see which are applicable for the measures and the buildings. Thus, the next step is applying incentives for the package to reduce the cost.

Hence, those are the results of my summer internship work of modeling and simulating over 1300 existing residential houses at Winchell district using CityBES as part of the California Energy Commission project. In conclusion, my results show that it is feasible to achieve a 100% clean energy (electrification) neighborhood and Zero-Net Energy (ZNE) district using different active and passive measures.

In my opinion, it was a really meaningful experience to be able to work beyond my comfort zone and learn from many professional and experienced researchers who are passionate about working in this field of building technology. I am grateful for my seniors who helped and guided me to do my work because without them, I wouldn’t be able to achieve those results within the span of merely 10 weeks. Therefore, as I reflected on my whole internship experience, including the challenges and difficulties I encountered, I would continue to seek more similar opportunities and experiences like this in the future.