Managing and minimising water use in office buildings contributes not only to saving potable water, a very valuable resource, but also to reducing the environmental burden of transporting water from far away and/or treating the water to reach the quality needed for drinking as well as treating waste water (greywater and blackwater) before it is returned to the natural water cycle, all of which is energy- and carbon-intensive. Reductions in hot water use will also save energy in the building (the energy needed to heat it up), again leading to reduced carbon emissions.
There are two key ways of reducing potable water use in offices: becoming more efficient (reducing the amount of water used) and supplementing mains water with harvested rainwater and/or recycled greywater.
These can be accomplished by setting up effective water management that follows the principles of PDCA (plan, do, check, act), facilitates continuous improvement and allows those responsible to be proactive. Within such a system, public administrations typically implement:
- Measurement and monitoring of water use
- Technical solutions (e.g. low-flow taps, rainwater harvesting)
- Measures fostering occupant behaviour change
Effective water management thus involves a cycle of monitoring and measuring consumption, comparing actual with expected consumption, setting targets and implementing measures and solutions.
The first step is implementing meter readings and inventories of water-using devices. This should be based on areas where the maximum impact can be made and return on investment is best.
Automatic meter reading (AMR), ideally linked to the building management system (BMS), is often the best solution because automatic reading can be set at frequent intervals, such as half-hourly. There should be submetering points for major water use areas, e.g. restrooms, kitchens, outdoor areas, etc.
Where AMR is not present, it is recommended that meters be read weekly but also periodically between times when the building is empty or closed (at night or during weekends) to check for leaks.
Public administrations can improve their performance through the implementation of technical solutions to save water, such as water-efficient taps, WCs and showers, pressure-reducing valves, rainwater harvesting systems, greywater recycling systems, the identification of leaks and appropriate design and management of outdoor areas aimed at limiting water use.
Occupants’ behaviour can also have a relevant impact on the building’s water demand; measures fostering change in behaviour impacting water use are thus also very relevant. For instance, awareness campaigns can prove one of the easiest and cheapest ways of reducing water use.