Life cycle thinking to save water

With Europe facing water scarcity, the European Union (EU) is applying a life cycle thinking framework called Level(s) to save water in buildings.

By Robert C. Brears*

In the EU, water scarcity is becoming more frequent, affecting at least 11% of the population and 17% of its territory. Despite this, 20–40% of Europe’s available water is being wasted through leaks, lack of water saving technologies, and unnecessary irrigation. Under a business-as-usual scenario, water consumption could increase by 16% by 2030.

Thirsty Buildings

In Europe, public water supply accounts for around 21% of total water abstracted, the majority of which is used in buildings. In residential buildings alone, water consumption is about 160 liters/person/day on average across the EU.

Life Cycle Thinking in Buildings: Level(s)

To reduce water consumption in buildings, as well as other resource usage, the EU is testing Level(s), a voluntary reporting framework that provides a common ‘sustainable’ language for the building sector. Level(s) uses a set of simple metrics to measure the sustainability performance of buildings throughout their life cycle. Level(s) encourages life cycle thinking at a whole building level and is a comprehensive toolkit for developing and monitoring operations and encouraging improvement from design to end of life. A key aspect of Level(s) is that it enables building professionals and their clients to identify key areas for better environmental performance. To close the gap between design, as-built, and occupied performance, Level(s) indicators can be applied to different stages of a building project: design, complete, commissioning, and post-occupancy.

Total Water Consumption

One of the key indicators used by Level(s) is Total Water Consumption, with the performance metric being m³ of water per occupant per year. The objective of the metric is to ensure the efficient use of water resources, particularly in areas of continuous or seasonal water stress. The intended actions to be taken at the building level include efficiency measures as well as supply-side measures such as greywater reuse and rainwater harvesting.

Measuring Performance

To measure performance, a dedicated excel spreadsheet tool has been developed for users to conduct three different level assessments. The results generated are on a per occupant basis at both a daily and annual level. The three assessments are:

Level 1 Common performance assessment: With a focus on common sanitary devices/fixtures and water consumption appliances, users of the dedicated spreadsheet tool can generate on a per occupant basis daily and annual water usage with users able to define usage factors (i.e. how many minutes a person showers per day) and occupancy rates (i.e. how many days per year the building is occupied)

Level 2 Comparative performance assessment: This has the same focus as Level 1 except usage factors and the occupancy rates are fixed to allow for comparisons of inherent water efficiency of the sanitary devices/fittings in different buildings

Level 3 Design performance optimization assessment: Users can analyze the effect of different design assumptions on water usage e.g. defining which taps, showers, and toilets in a building are used more frequently based on location and building use patterns as well as include other water consuming features such as HVAC and swimming pools

Implementing Water Efficiency Measures

Overall, the results of Level(s) can inspire the implementation of water efficiency measures in buildings across Europe. For planning authorities, minimum water efficiency requirements for sanitary fittings and devices as well as irrigation requirements can be set at the local, regional or national level. Building design teams can decide how ambitious the design should be in terms of water efficiency. Meanwhile, sub-contractors can ensure the sourcing and quality installation of water-efficient fittings, devices, and appliances to avoid leakage and any sub-optimal performance caused by poor installation. Asset managers can quantify water consumption, estimate its impact on operating costs, and identify cost-effective savings. Actual water consumption can be monitored via meter readings while buildings with greywater and/or rainwater harvesting systems can monitor the total water passing out of storage tanks for irrigation and to consuming water devices and fittings.

Testing Level(s)

Currently, Level(s) is being tested from this autumn onwards for two years, with companies, associations, and public authorities invited to participate in testing with the European Commission providing technical support during this process. Participants can test the complete Level(s) framework or select parts of it. Overall, feedback from the test results will help improve Level(s) ahead of its final release in 2019 to ensure that the indicators and the user guidelines are robust and market-ready.

The take-out

Life cycle thinking is key to identifying water efficiency opportunities in the built environment.

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