Are there any good ways to save energy by hot water abroad? What are the leading green building technologies?

Europe has always been the leader of hot water energy saving, and the key to domestic hot water is the scale. 3 mm scale on the heat exchanger will increase energy consumption by 30%, and the waste is amazing. Traditionally, calcium and magnesium ions in water are removed by chemical salt exchange and replaced by salt. However, it is also troublesome. It is necessary to change the salt every month. Once the salt is forgotten, the scale will not be easily removed. The latest one in Europe is "EMI vortex electromagnetic technology" from Zhuosheng, Spain, which converts calcium and magnesium ions in water into microcrystals and small molecules through vortex magnetic field to inhibit scaling, just like turbocharging of aircraft engines. There are only three aircraft engines in the world, which shows that this technology is very advanced. It has been used in the world for more than 20 years, including many high-end hotels, famous parks and hospitals. It also won a series of awards such as the Spanish National Science and Technology Award. China is the general agent of Glen China.