The city council of Hannover began an internal energy and water saving programme for its offices in the year 2000. This is an incentive scheme for staff within office buildings. Taking part is on a voluntary basis but there are financial benefits. Saved costs are returned for the benefit of the building – 30% of savings are ringfenced for improvements in the working environment and 40% of savings for energy saving capital equipment. In terms of water costs, it was found that an average of 8.5% were saved (Hannover, n.d.).
Once human resources have agreed a project, an “Oekoteam” (eco team) is formed who are trained by external experts in energy and water saving. In situ, the experts and eco team together develop a series of measures for the building, which are then implemented by the team and other colleagues internally as necessary, as well as suppliers such as cleaning contractors. Any retrofitting e.g. switching to low flow taps is also carried out by contractors as necessary. Once the measures have been implemented, results are presented and publicised and premiums paid.
One building where the project was implemented was Hannover Town Hall. Here water is used for catering, public and staff WCs, wash hand basins in the public toilets, staff tea and coffee-making facilities, wash hand basins in the offices, showers and in the kindergarten. Total average annual consumption is almost 9 million litres costing 30,000 euros.
Initially, an audit was completed at the public and staff toilets and washing facilities. Flow rates were measured at each basin. WC cisterns, their flush volumes and any water saving functions were inventoried.
This was followed with retrofitting of water efficient devices. Hand basins in the offices were fitted with aerators at a cost of 1.50 euros each and flow rate was capped to 6 litres per minute at the angle valve. Washbasins in the toilets were fitted with aerators that cut the flow rate to 1.7 litres / minute (most taps had previously been set to 14 litres / minute). Push button taps that were unsuitable for aerators had their operation time regulated for 10 to 15 seconds instead of 7 to 37 seconds as had been the case previously. For the older toilet cisterns, weights were fitted to counterbalance the lever action, so that the the WC only flushed whilst the handle was being pressed. Stickers explaining this were placed on the cisterns.
Furthermore Ecoteam members were responsible for explaining the new water saving measures at routine staff meetings. Water consumption was monitored weekly at the building’s three water meters.
After the implementation of the measures above in October 2002, water consumption decreased from 25m3 to just over 22m3 a day, and these savings have been sustained. This remained the case despite several major events being held at the Town Hall (Display-Campaign, 2014).