Using Water Resources Efficiently

Using Water Resources Efficiently in Buildings

The effects of climate change brought about by global warming have led to a greater risk of water shortages worldwide. In Japan, there are doubts about the continued stable supply of water from dams due to changing rainfall patterns in recent years. To mitigate the effect of water shortages on socio-economic activities and ensure the stable use of water, it is important to systematically promote the efficient use of water resources and enact strategies based on supply and demand considerations.
In recognition of this pressing issue, the Mitsubishi Estate Group is working on improvement measures such as adjusting the amount of water used by toilets and bathrooms in order to streamline water use in buildings. It is also reducing the use of water resources in buildings that use recycled water* by, for example, purifying cooling tower blow water and kitchen wastewater and reusing it as toilet water.

* Recycled water: Processed water derived from rainwater, tenant kitchen wastewater and other sources. Recycled water is also used for watering outdoor plants and as toilet water in the Marunouchi Building.

Water consumption and water consumption per unit of floor space in Mitsubishi Estate's ISO14001-certified buildings

Graph:Water consumption and water consumption per unit of floor space in Mitsubishi Estate's ISO14001-certified buildings

(Note) Number of buildings included in scope of data may differ by fiscal year due to renovations and sales/purchases.

Mitsubishi Estate Group's Waste Generation and Water Consumption Rates

Waste generated/water used

44,967 t/About 5,648,000 m³ a year

The Public and Private Sector Team Up to Mitigate the Heat Island Phenomenon
- Sprinkling Recycled Water from the Marunouchi Building on Gyoko Street -

Mitsubishi Estate has been working with the Tokyo Metropolitan Government Bureau of Construction since 2010 to sprinkle recycled water from the Marunouchi Building on Gyoko Street, which extends from the Tokyo Station Marunouchi Exit to Hibiya Street. Sprinkling water suppresses the road surface temperature and helps mitigate the heat island phenomenon. The initiative continued through fiscal 2017 as well. When the sprinkled recycled water evaporates due to a rise in atmospheric temperature, it absorbs heat from the surrounding area, reducing the road surface temperature by up to 10℃ (based on measurements from summer 2010).
To make this project possible, the Tokyo Metropolitan Government Bureau of Construction constructed a "water-retaining road surface" containing water-absorbing materials capable of saving up water within the road surface in Gyoko Street. Mitsubishi Estate installed the equipment needed to sprinkle the recycled water from Marunouchi Building onto the street.

Image:Sprinkling Recycled Water from the Marunouchi Building on Gyoko Street

Sprinkling Recycled Water from the Marunouchi Building on Gyoko Street

Photo:Development status of Gyoko Street (near Marunouchi Building)

Development status of Gyoko Street (near Marunouchi Building)

Using Recycled Water Continuously

In fiscal 2017, SunshineCity was able to recover 343,608 m³ of its precious water resources out of the 582,781 m³ of tap water that was used in the building that year. The recycled water was used to flush toilets.
The treatment system for this wastewater is called the "recycled wastewater system" and is in the middle of the water and sewage works. It was installed 40 years ago when Sunshine City was first built. It was the first recycled wastewater system installed in Japan for a single building. The treatment plant is located in the 3rd floor basement of the Sunshine 60 building. In a single day it purifies up to 1,200 tons of wastewater from toilet sinks, kitchen wastewater from the building and drain water from the Hotel bathrooms. The treated recycled water is used to flush toilets inside the building.

Image:How recycled water(reclaimed water) is made

How recycled water (reclaimed water) is made

A Paint Wash Water Purification System Using Ecosinks

To keep from polluting the water in rivers and in the areas near its construction sites, Mitsubishi Estate Home, in collaboration with Hokuyo, developed an on-site system that purifies the water used for washing water-soluble paints.
In November 2009, the Ecosink System went into operation after clearing all the wastewater regulation standards for the shared water bodies of each local government in the Tokyo city area. Furthermore, it was also able to recycle paint wash residue into raw materials for cement in August 2010.

Photo:Processed water generated at the site

Processed water generated at the site

Overview of the Ecosink System

Image:Overview of the Ecosink System