Science-based targets for achieving the goals of the 2015 Paris Agreement

The Paris Agreement was adopted at the 21st Conference of the Parties to the United Nations Framework Convention on Climate Change (COP21) in 2015. It can be said that the agreement is the successor to the Kyoto Protocol.

The Paris Agreement’s goal is to keep global temperature rise this century well be low 2℃ above pre-industrial levels, and to strive to limit the temperature increase even further to 1.5℃. These are evidence-based action goals derived from reports issued by the United Nations Intergovernmental Panel on Climate Change (IPCC), etc.

Science-based targets are GHG emission reduction targets for the next 5-15 years set by companies in order to achieve the Paris Agreement’s goals for limiting temperature rise. Each company submits its GHG emission reduction targets to the joint initiative, SBTi,^※1 and if the target meets the guidelines, it is certified as a science-based target.

Initially, the SBTi’s certification guideline was to keep the rise below 2℃. But in 2019, it was revised to “well below 2℃” with the further goal of limiting increase to 1.5℃, in accordance with a special report issued by the IPCC in 2018. Companies are supposed to review their targets at least every five years in light of new guidelines.

Science-based targets greatly affect corporate financing

Thermal storage mechanisms are also used on a large scale. A typical example is an HVAC system with thermal storage.

In large buildings, the thermal energy for cooling in summer and heating in winter is generated by the central plant equipment. For HVAC systems with thermal storage, there is central plant equipment that generates thermal energy, HVAC equipment that uses the thermal energy, and a thermal storage tank for storing the thermal energy. This storage tank stores thermal energy in the same way that a chest freezer or insulated coffee pot does, contributing to the efficient use of energy.

A storage tank filled with water is a common example of a thermal storage tank. The water in the thermal storage tank is cooled using electricity at night, and the next day it is used by the central plant equipment, and it can be used by the air conditioning so that a large amount of cooling can be produced with a small amount of equipment. The water in the tank can also be used in case of fire or for other daily living needs. This is one of the benefits of storing water in a tank.

This same mechanism can be used for heating, but it is not as efficient as for cooling because recent buildings have good thermal insulation that prevents the room temperature from dropping easily.

Working to reduce GHG emissions across the entire supply chain

In addition to thermal storage tanks, the building’s skeleton can provide thermal storage. Here is an example when air conditioning is used in the summer. The walls and floors of a building are cooled by the air conditioning, so you may feel cool for a while even after the HVAC system is turned off. This is an effect of thermal storage by the frame of the building. As in the case of a thermal storage tank, the frame of the building can be cooled at night when the demand for electricity is low, in order to reduce the amount of energy consumption during the day.

The reasons for doing so are the following: there are plans with less expensive electricity rates at night,; energy consumption during the day, when society needs energy the most, can be reduced (helping to even out the usage of energy); and the equipment can operate more efficiently at night.

During the day, according to how the air conditioning is used, the central plant equipment adjusts its performance, so its efficiency may drop correspondingly. In contrast, at night, the air conditioning load is low, and the equipment can operate in the most efficient way in order to cool the thermal storage tank. In addition, since the outside temperature is lower at night, less energy is required to lower the temperature to the same level, resulting in high overall energy efficiency.

As we have seen, in order to use thermal storage for HVAC purposes, preparation on the previous day is important. If the next day will be hot, it is not possible to suddenly increase the amount of thermal storage. Also, if the amount of storage for cooling is more than what is needed, the energy used to cool the storage medium will have been wasted.

For this reason, research is underway to develop simulations for thermal storage demand forecasting. By combining data on the weather, building usage, and air conditioning usage in the past, the relationship between weather and the demand for stored thermal energy can be modeled, and the required amount of thermal energy can be calculated by using the model with the weather forecast for the next day. Various efforts like this are being made for the efficient use of energy and facilities.