With energy expenditure amounting to £750* million per year, the healthcare sector needs to look at how it uses energy and identify ways of improving efficiency. The National Health Service (NHS) alone has a carbon footprint of 25** million tonnes of carbon dioxide (CO2) per year. So to halt and reduce this is going to represent a significant challenge. A hospital is an extremely energy intensive building. Electricity accounts for around 18 percent of a hospital’s delivered energy use and it represents over 50 percent of a hospital’s energy costs. So if energy consumption can be reduced, financial savings can be made as well as substantial reductions in CO2 output. In no other building is indoor air quality as critical as in hospitals. It acts as more than just a facilitator of comfort; it impacts on a patient’s recovery. While temperature and humidity requirements are important in hospitals, it is bacteria concentration and cross-contamination that are of critical importance in heating, ventilation and air conditioning (HVAC) design. Within hospitals the HVAC system is also the greatest drain on electricity. So if HVAC systems can be made to work more efficiently, huge sums of money can be saved.
How variable-speed drives work
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 air is regulated by dampers, valves, vanes or similar throttling mechanisms. Throttling the output in 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. A small reduction in speed can make a big difference in energy use. A centrifugal pump or fan running at 80 percent speed consumes only half as much energy as a unit running at full speed. This is because the power required to run a pump or fan changes with the cube of the speed. Because many pump and fan systems run at less than full capacity for much of the time, VSDs can produce huge savings. If a 100 kW pump is throttled by 20 percent, for example, the investment in a VSD will have a payback of typically six months based on continuous operation.
Benefits of variable speed drives Commercial –
Reduced energy consumption – typically from 20 to 50 percent –
Fast payback – from six months – Reduced CO2 emissions –
Technical – Lower maintenance costs – Starting, stopping and braking can easily be programmed to reduce stress on mechanical equipment – Increases equipment life and reduces maintenance requirements for pumps, motors and pipework. – Easily retrofitted into an installation –
Real time clock – Can easily set up programmes with different running speeds at different times or on different days, making the drive ideal for hospital applications – Low harmonic solutions available as part of installation design
Staff and patients Benefits–
Clean air circulation throughout critical hospital areas – Tighter control over temperature changes – A more comfortable temperate environment
Facilities manager –
Gain control of heating, air condition and ventilation costs –
Easy to retrofit VSD into an installation
Always service your drives to extend the lifetime and maintain the efficiency of your Drives investment. Ask us about ServicePLAN
Coventry Hospital needed to install a new HVAC system to control airflow throughout the site, ABB was chosen to supply the VSDs on a just-in-time basis in order to meet the installation time table of Air Handling Systems, the suppliers
of the ventilation system.
The £210 million Edinburgh Royal Infirmary, needed to install an air handling system to deal with critical and non-criticalareas. This included installation into operating theatres where clean air conditions are critical.
Bradford Teaching Hospitals NHS Foundation Trust wanted to save energy as part of an initiative which includes the ongoing development of a long-term policy to conserve energy and minimise investment costs by optimising the phased
replacement of older motors throughout Bradford Royal Infirmary (BRI) and St Luke’s Hospital.
Medway Maritime Hospital (MMH) is an acute and general hospital primarily serving the needs of people in Medway, Swale and North Kent. The hospital’s main aim is to keep their CO2 contribution low, as well as cutting energy costs. It was
increasingly concerned by the energy consumption of the air handling units (AHUs) in the three plant rooms serving the hospital’s Block A.