by Steve Ruddell — Hospitals are extremely energy intensive buildings with a constant demand for lighting, heating and electricity. As a result energy expenditure amounts to £400m per year across the UK, so improving energy efficiency could help hospitals meet some of the savings that will be necessary.
The NHS alone has a carbon footprint of 18 million tonnes of carbon dioxide (CO2) per year. Since 1990 the NHS’s CO2 output has grown by 40 percent. To reduce this is going to be a mammoth task. However, even a one per cent change in electricity consumption can have a significant impact on running costs and these savings could help make cutbacks less drastic.
By far the biggest consumers of electricity within buildings are pumps and fans, especially those used within HVAC systems. Fans and pumps are controlled by motors, so motors need to be made to run in a more efficient manner.
Since the introduction of the Carbon Reduction Commitment (CRC) Energy Efficiency Scheme in April, hospitals are actively looking at ways of reducing their carbon footprint.
Hospitals that consume more than 6 GWh/year and use a half-hourly meter, must register for the CRC Energy Efficiency Scheme. Although neutral to the Exchequer, the scheme will have cash flow implications for qualifying organisations. An energy saving of five percent will be needed to cover the average cost of administration within an organisation.
Hospitals that qualify for the scheme will be allocated an agreed number of carbon allowances which decreases over time. Organisations that can successfully reduce their emissions will be able to sell their allowances to other organisations who have not met their targets. The cost of carbon allowance will be paid back to participating organisations. However, payment will be based upon a league table of energy performance. With HVAC being the biggest drain on hospitals running cost, any saving here can have a massive impact.
Hospitals can implement other smart technology such as lighting control or temperature control, but addressing electricity consumption in pump and fan applications offers by far the biggest potential for lowering costs. By installing variable speed drives (VSD) and high efficiency motors into HVAC systems it is possible to reduce running costs by up to 50 percent. This is because a VSD delivers the precise amount of power needed by the motor at any given time to meet the demand of the application. Within hospitals it is very rare that the motor needs to run at full speed to cope with the demand placed upon it, so it makes sense to reduce the speed of the motor and ramp up only when necessary to cope with peaks in demand.
Many existing pump and fan systems are based on throttling arrangements: the motor is driven at full speed and then the flow of liquid or gas is regulated by valves, vanes or similar throttling mechanisms. Throttling the output this way wastes energy. A VSD can increase the system’s efficiency by adjusting the motor speed to the correct operation point and eliminating the need for throttling. With many pump and fan systems running at less than full capacity for much of the time, VSDs can produce huge savings in hospital buildings. If a 100 kW pump is throttled by 50 percent, for example, the investment in VSD will have a payback of approximately six months when in continuous operation.
In most buildings there is a significant difference between peak demand and the normal requirements of the building. It makes sense for a motor to use less energy during quieter times of the day and to ramp up when necessary. Matching the motor speed to demand creates less stress on the motors which means they will last longer and require less maintenance as well as being much cheaper to run.
Coventry Hospital
Coventry’s new £400m hospital is benefitting from the introduction of ABB drives and motors, installed in the new HVAC system to control airflow throughout the site. ABB was chosen to supply the drives on a just-in-time basis in order to meet the installation timetable of Air Handling Systems, the suppliers of the ventilation system. ABB was brought in to supply a range of drives and motor packages ranging in size from 0.55 kW to 45 kW. Because the 230 drives and motors packages are matched to each other, the site benefits from extremely efficient power consumption. ABB is also providing a 24-hour support service to keep the installation up and running should anything go wrong.
Matched pairs of ABB high efficiency motors and drives will reduce energy consumption at the new Coventry Hospital by over 1,400 MWh per year for the ventilation system in block A. Similar savings are expected for the planned blocks B and C. The £150,000 contract is one of a number of large projects ABB has become involved in. In addition, ABB is also delivering low voltage switchgear to the hospital to further enhance energy usage on site.
Finance
Investing in energy efficient equipment is viewed by the government as an essential act in meeting its climate change agreements and with funding cuts likely to be a prominent feature of the Coalition Government’s agenda, it may also offer organisations a way of safeguarding their existence. Help is available through Salix Finance, a company set up specifically to help public sector companies such as hospitals to improve energy efficiency, reduce energy bills and meet emission targets. They offer interest-free loans to those willing to invest in energy saving equipment. The cost savings achieved through reduced energy consumption can then be used to pay back the Salix Finance loan.
The Hospital guide (right) is one in a series of CRC Energy Efficiency Scheme guides designed by ABB to help organisations meet their legal requirements. The series includes: The 6-step CRC Energy Efficiency Scheme guide, a swimming pool guide, a data centres guide and a car park guide with a number of other guides dedicated to other areas currently in production.
Help is also available in the shape of ABB’s swappage scheme, offering any organisation willing to trade in old drives or motors at least 17.5 percent discount off a new ABB equivalent. The discount can be used to offset the cost of government loans, making investment in energy reduction technology more affordable.
Steve Ruddell is Division Manager, Discrete Automation & Motion, ABB Limited. For more information energy@gb.abb.com and www.abb.co.uk/energy. ABB has put together a hospital guide outlining everything you need to know about VSDs and electric motors in order to reduce energy bills and meet your CRC Energy Efficiency Scheme requirements. To order a copy freephone Brochureline 0800 783 7491 or email: energy@gb.abb.com quoting reference “CRC hospital guide”.