Water softening systems can increase the energy efficiency and longevity of heating and hot water services in commercial buildings. John Bisset explains.
The building services sector is under intense pressure to help deliver more energy efficient buildings and reduced carbon emissions.

Government legislation and incentives are driving through changes in building practices and technologies to ensure that the UK meets its 34 per cent emissions cut on 1990 levels by 2020, which is required under the Kyoto Agreement.

Targets for all new buildings to become carbon neutral represent an important stepping stone on this path.

New schools face a 2016 deadline, public sector non-dwellings are required to become zero carbon by 2018 and other non-dwellings, such as hotels, will need to comply by 2019.

With energy costs rising, it's clear too that financial pressures are playing a part in greening our building stock. Here, it's self-evident that if we as an industry can develop more fuel efficient solutions then this will help reduce running costs for building owners and their occupiers.

However, one of the key challenges facing consultants and contractors is that, while the building services themselves may be designed and installed with impeccable low or zero carbon credentials, what happens over time when the building is occupied?

One of the major enemies in maintaining fuel efficiency is the scale which forms within the water services of a building. Small amounts of scale can form within weeks on heating and hot water equipment and just 1.6mm of scale can lead to a 12% loss in heating efficiency.

As a result, building services equipment which is specified for its energy efficiency at the design stage can be quickly compromised in its performance. This is an especially common problem in the hard water areas of the UK, including London and the South East.

In these parts of the country, minerals, such as magnesium and calcium, can quickly build up as scale and inhibit the heating efficiency of equipment, such as, commercial boilers, DHW cylinders, etc. It accumulates on the heat exchange surfaces and dramatically reduces the heat transfer efficiency of the equipment. Over time, scale will also build up within the pipework itself, reducing its water carrying capacity. These deposits also promotes corrosion within boilers, calorifiers and pipework.

With fuel efficiency and carbon reduction top of the agenda, building services consultants and contractors should consider the positive contribution effective water treatment technology can make.

Without it, problems can quickly escalate resulting not just in poor performance but in component breakdown and needlessly expensive maintenance.

It is not just performance and energy efficiency that can be affected. There are serious environmental risks surrounding scale build-up, including the potential for legionella growth.

Water scaling creates the ideal environment for the bacteria to thrive.

Dripping taps can deposit scale in and around the tap and, with high ambient room temperatures, this provides an ideal growth medium for legionella. In hot systems, scale can trap Legionella which again creates an excellent breeding ground, and one not easily penetrated by disinfectants. And once scale deposits have been colonised by Legionella, they can continuously recontaminate a system, even after disinfection.

Obliged to take precautions

Since the introduction of ACoP L8 (Approved Code of Practice and Guidance L8, 'Legionnaires' Disease - The Control of Legionella Bacteria in Water Systems') organisations are obliged to take sufficient precautions to eliminate the build-up of legionella bacteria.

Descaling of a hot water system is time consuming and expensive. But if low energy, water softening technology is specified at the new build stage or retrofitted where problems have occurred it can help ensure hvac systems perform to their design efficiency and minimise risks associated with legionella.

Non-electric, automatic treatment systems, such as Kinetico's patented systems, are an ideal choice as they suit a wide range of applications and are powered by the kinetic force of moving water, minimising energy consumption still further.

They work by removing the calcium and magnesium ions through an ion exchange process and, due to the twin tank design, this type of technology can continuously provide softened water; while one tank is working the other is being cleaned with a salt solution to remove the calcium and magnesium ions.

Most water softeners have timers so regeneration can take place at a set time when the water is not being used, for example at night. This approach can prove counter-productive, especially if minimal water usage has taken place during the day.

The best option is a fully automatic control valve which measures the soft water used and only regenerates on demand, allowing water usage to vary each day without causing unnecessary waste. A Kinetico water softener system uses the kinetic energy of water so it eliminates the electricity costs needed to run alternative softening technologies. This also brings installation benefits. For example, a non-automatic system requires no power cabling, which speeds up and simplifies the installation process.

As water requirements for buildings vary, water softener systems can be made-to-measure to fit the needs of the project. Being specified for each building's particular needs and services requirements ensures, the final system is more reliable and easier to install, again making it a whole lot easier for the contractor.

Water softening is an important area of building services, but one that demands a higher profile because of the impact it has on the performance of the overall system. It delivers improved energy efficiency, reduced maintenance costs and healthier water services for the building occupants.

• John Bisset is operations director at Kinetico