Energy efficiency is right on CUE

With budgets being cut and costs coming under more scrutiny than ever, it seems that the topic of incorporating energy efficiency aspects into the integral framework of commercial buildings may be a hidden victim of the credit crunch and as such is in danger of slipping down the building services agenda.  This is even though it is also becoming increasingly important for M&E designers and engineers to deliver solutions that will be able to prove their sustainable worth for years to come.

Energy focus will continue

One factor that will bring more focus to bear on this aspect, both in new and existing commercial buildings is the introduction of energy performance certificates (EPCs) for non-domestic buildings that were phased in, in England and Wales during 2008 and in Scotland in January 2009.  This now means that whenever a building is constructed, sold or let, an EPC certificate will be required.  This will become an increasingly important factor especially when the existing building stock seeks new buyers/tenants, as owners will need to find new ways to differentiate their premises from others and one way of doing this will be to improve their buildings’ overall energy efficiency rating.    

These changes are only the first part of a wave of changes that will be brought in to help to achieve the Government’s target for all new non-domestic buildings to be zero carbon rated by 2019.  However, to achieve the wider overall target of cutting carbon by a massive 80% by 2050, significant reductions will also have to come from the existing buildings stock – especially from within the commercial sector.

One area that can quickly bring about a significant energy efficiency improvement is by either replacing or upgrading aspects of the existing building services or by ensuring that the most efficient technology is included in a new build.

Payback delivers results

We are all by now well aware that variable speed pumps offer huge savings over their fixed speed counterparts and that the energy consumption accounts for a whopping 90% of their total associated cost during their life cycle. 

What is more interesting is that a recent published report in the UK shows that the payback period for upgrading heating pumps to variable speed options offers an internal rate of return per square metre of 124%, in a standard 1990s office block.  This is actually three times greater  than any other energy efficient upgrade can achieve and means that the payback period for implementing this aspect alone is now as little as one year at the minimal cost per kg CO2/m2 of just £0.14.

Up until recently, there have been instances when it hasn’t always been possible to specify an e-pump solution.  For example when the application required a very large pump (22 kW and above), or where there were space restrictions or in specialist application situations such as sanitary, wastewater, in ATEX areas or where electronics were either undesirable or not allowed.

When control is right on CUE

To meet the demand to plug this gap from the market Grundfos has just launched a range of versatile, wall-mounted frequency converters with e-pump functionality.  These are the latest addition to the e-solutions family and mean that you can now control the speed of virtually any Grundfos pump irrespective of its size, power range and application via the new Grundfos CUE.

Speed control by means of frequency converters is not a new concept and has been part of the Grundfos product portfolio for many years.  But what this new introduction means is that this CUE range of wall mounted external frequency converters can be used in all areas where a centrifugal pump applications solution is needed to support either the new or existing Grundfos fixed speed pump application and will give both the installer and the end-user all the benefits that an integrated solution brings with it.

Application examples

This CUE family of multi-purpose frequency converters are suitable for use in five main situations and the control mode is adapted to meet the required conditions

Water supply and pressure boosting applications such as:

  • water supply
  • pressure boosting
  • washing

The typical control modes are constant pressure, constant flow-rate.  The stop functions are used to protect the pump when the water flow is low.

Heating and air-conditioning applications for liquid transfer in:

  • heating applications
  • cooling and air-conditioning applications

The typical control modes used here are proportional pressure or constant temperature.

Process and sanitary applications such as:

  • breweries and dairies
  • pre-water applications
  • process application
  • purification applications

The CUE is typically controlled by an external controller.  The typical control mode is open loop.

Groundwater applications:

  • groundwater supply to waterworks
  • irrigation in horticulture and agriculture
  • dewatering

The typical control modes here are constant pressure, constant flow rate or constant level control.

Wastewater applications such as:

  • wastewater
  • effluent
  • drainage water
  • process water

The typical control mode here is constant level function i.e. emptying function.

Features and benefits

In addition these systems offer an array of features including plug-and-pump convenience that means that you only need to specify a few application-specific settings and the variants you require and the system is all set-up in just a few minutes.  The CUE family offers extended possibilities to enable the monitoring of the pump motor, frequency converter and surroundings by means of a bus interface.

With a 100 different configurations and a power range of between 0.55 kW to 250 kW the Grundfos CUE family represents one of the most comprehensive and versatile ranges of frequency converters for pump applications currently available to the market.

Besides the intuitive start-up already mentioned, the range offers some additional features including a smart user interface with a very user-friendly operating panel that consists of a graphical display with backlight and self explanatory buttons.

It also offers automatic direction of rotation in that during start-up, the CUE will automatically detect and set the correct direction of rotation to ensure that the pump is running the right way.  If the direction of rotation is wrong the CUE will change the direction electronically.  This means that no manual re-wiring needs to take place.

In addition the CUE has an in-built PI controller that provides closed-loop control to whatever value you require.

All-in-one solution

All-in-one e-pump solutions with their in-built pump, motor and frequency converter still continue to be the best option in many instances as they offer many benefits, from total system integration, to simple installation, optimum interface, space savings, reduced logistics and of course the all-important resultant energy savings.

With the increasing number of options available, it is becoming more difficult for people charged with maximising the energy efficiency within the building services engineering arena to keep pace. However, the introduction of this wall mounted range of frequency converters means that through the CUE range Grundfos can now offer the best choice to fulfil the same control functionality as can be achieved by the e-pump range, especially as a retro-fit option.

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