Optimizing the efficiency of building air conditioning operation through weather forecasts
Text by DEF 2024/06

When it comes to reducing the energy consumption of air conditioning, the most common method is to replace old equipment. However, with energy efficiency improving year by year, it's not feasible to spend a large amount of money annually to switch to higher-performing air conditioning systems. The challenge, therefore, lies in maintaining a good coefficient of performance (COP) for existing air conditioning equipment.
Weather forecasts play an important role in building decarbonization.

In recent years, the Delta Electronics Foundation has been experimenting with using weather forecasts to manage building air conditioning systems, employing this innovative approach to overcome energy consumption challenges. Under the collaboration with Delta Chungli Plant 5 and the International Climate Development Institute, the daily cooling demand of the buildings in Chungli Plant 5 is calculated by combining the numerical forecast regional model of the Central Weather Administration and the weather parameters such as temperature and humidity measured by the environmental monitoring sensors. This data is used to calculate the daily cooling demand for Chungli Plant 5, determining the number of chiller tons needed each day to avoid low efficiency.
Delta Chungli Plant 5 reduced energy consumption by 18% through adjusting the operation of the chillers  according to weather forecasts​.

For example, after a series of tests, the team found that when the weather forecast predicts a maximum temperature above 33°C and an average temperature above 32.5°C in the morning, two 900-ton chillers need to be activated to meet the cooling demand of Chungli Plant 5. However, if the maximum and average temperatures are each below 33°C and 32.5°C respectively, only one 900-ton and one 400-ton chiller are required to sufficiently handle the cooling demand. After the autumn, when the maximum and average temperatures exceed 19°C, one 900-ton chiller is still needed. However, if the temperatures fall below this value, a single 400-ton chiller is sufficient to meet the cooling demand of the plant.

In addition, the team utilized weather forecasts to calculate the melting efficiency of the ice storage system and determine the optimal start time for the day. This helped reduce the energy consumption of the chillers during daytime operations. After five months of automated scheduling control, the two systems have enabled Chungli Plant 5 to achieve an estimated total energy savings of over 260,000kWh, with a total energy reduction rate of 18%, without the need to replace energy-consuming equipment.

In the past, the team has also used the same method to help the National Museum of Marine Science & Technology reduce its peak electricity usage during the summer. When the weather is hot, the venue will start the chillers at 7 a.m. to pre-cool the museum. By doing this, they avoid the need for the chillers to operate at high speeds during the peak electricity consumption period at noon. As a result, the venue managed to reduce its contracted capacity surcharge by 20% and peak summer electricity consumption by 10%.

In spring and autumn, adjustments to the operation of the chillers were made based on weather forecasts. However, as the weather gradually cools during these seasons, the focus shifted from when to start the air conditioner to how many tons of capacity are needed. Originally, the museum used a more energy-intensive 500-ton chillers. However, after consulting meteorological data, we found that a 200-ton chiller unit would be sufficient for cooling the museum in autumn. Operating in this manner, they were able to reduce electricity consumption and costs by up to 30% each!

From these cases, it can be seen that by making good use of weather forecasts, not only can electricity be saved and carbon emissions reduced, but also electricity expenses can be lowered. And once the air conditioning usage is reduced, the energy-saving effect is immediately reflected on the electricity bill. Isn't it worth considering such a quick and optimized method for improving the efficiency of building air conditioning?