Sunday, June 23, 2024

Retrofitting ageing pump systems offers energy savings

For the transition to high-efficiency, low-carbon buildings, retrofitting outdated heating, cooling and water systems can offer significant opportunities, writes Paul Winnett, operations director, Xylem UK

The retrofit of ageing buildings with high-efficiency pumps and drives offers one of the biggest opportunities to achieve smarter, more efficient buildings. This directly aligns with the International Energy Agency’s (IEA) Net Zero Emissions 2050 roadmap, updated in September 2023, which urges the global energy sector to double existing efforts to improve the efficiency of buildings.

Accelerated action will support the UK government’s net zero pathway and, given that the heating of the UK’s 30 million buildings contributes to almost a quarter of all UK emissions. As a result of the Heat and Building Strategy businesses across almost every sector are already taking steps to use less energy in response to rising utility bills, and to achieve environmental goals.

Across the UK are vast numbers of buildings such as office blocks, shopping centres, hospitals and hotels that were built between 20 and 40 years ago, with outdated heating and cooling systems that consume high amounts of energy.

Simply replacing ageing equipment like-for-like is not the solution. This is recognised by the government’s Heat and Building Strategy that says ‘decarbonising heat and buildings will require the adoption of new, smarter technologies and practices’.

Widescale programmes to replace old equipment with high-efficiency technology for heating and cooling, as well as water pressure boosting, would accelerate decarbonisation goals and bring older buildings into a net zero world.

One way to significantly reduce the energy consumption of pumped systems is by switching to variable speed technology. Older pumps typically run at a fixed speed, regardless of demand. Retrofitting with variable-speed drives enables the system to adjust to usage curves.

Upfront capital costs of variable-speed technology may be higher due to their advanced technology, but these costs will be offset over time by expected savings on energy bills. In addition, operational and maintenance costs of variable-speed pumps are generally lower, as they are not running continually and experience less wear and tear.

For large commercial buildings, Xylem’s hydrovar® X is an intelligent variable-speed pump drive, with the highest efficiency IE5 motors, that can cut motor power of pumps by up to 70%. This reduction is achieved by ensuring the pump is only operating at the required speed, depending on demand variations of the system.

The ability to adjust pump speed will have an immediate impact on energy consumption of large buildings, such as hotels, where demand for water and heating fluctuates throughout the day.

Take water pressure in a hotel – in a traditional system, the pumps would be on and the pressure constant. With a variable speed drive, the pumps could run at half their speed during periods of low demand, such as lunchtime when fewer people are in their rooms and increase as guests start checking in and using facilities.   

As the evening goes on and demand rises further, the system will automatically adjust to ensure a constant pressure throughout the building. To achieve this, the system takes pressure or flow readings from sensors to adjust the number of pumps running and their speed, ensuring demand is met while maximum operating efficiency is delivered.

Xylem’s ecocirc XL and XLplus variable speed circulators are designed to manage a similar demand curve for heating and air conditioning systems.

Of course, while retrofitting is essential to decarbonise existing buildings, the use of low carbon technologies in new builds is a must – the government’s Future Homes Standard comes into effect in 2025, bringing a set of rules to ensure new homes produce less carbon.

For contractors who are value engineering a project, using cheaper technology may bring down the capital outlay but if they consider the whole lifecycle of the product, high-end low-carbon technology is likely to be more efficient and deliver the most value because of the significant long-term energy savings. 

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