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North Yorkshire - United Kingdom

Saving energy through voltage power optimisation


In September 2005 North Yorkshire County Council installed a ‘voltage power optimisation’ (VPO) device at its County Hall headquarters, located in Northallerton, England. Analysis of its performance in January 2006 confirmed electrical energy savings of over 14% were being achieved. In February 2007 the savings were calculated based on the whole of 2006. This showed savings of €27,000 (£18,500) from the annual baseline electricity bill and CO2 emissions reductions of 114 tonnes – this is equivalent to the emissions of around 20 households - a fantastic result. This Shining Example shows that it is possible to significantly reduce greenhouse gas emissions in a simple, cost-effective manner.

County Hall

Building details

Type of building County Hall
Year built / Floor area / Operating hours Original block built 1906, major extensions added, mostly in 1970s/80s.

Floor area: 17,870m²

Operating hours: Mon-Thurs 8:30am-5:00pm, Fri 8:30am-4:30pm

Heating and cooling installed Heating – 11 boilers totalling 5,800kW

Cooling – 1 unit: 37kW served by the VPO

Energy / Water / CO2 label

Note: During 2006
a lot of additional electrical equipment was installed on the County
Hall Campus, which is why the Display energy and CO2 ratings did not
improve, despite the reductions in electricity consumption due to the

Project details

Aim The aim of this project was to reduce electrical energy consumption (and associated CO2 emissions) of County Hall by installing a VPO.
Key points

How Voltage Power Optimisation works

Energy consumption is proportional to the supply voltage. Using equipment at higher than optimum voltages results in higher energy consumption. In particular, things like lighting and motors consume more power at higher voltages. The higher voltage puts extra stress on components, reducing their operating life and increasing maintenance costs. By optimising the voltage to a particular site, energy consumption can be reduced.

Electrical equipment carrying the CE mark (which is a declaration by the manufacturer that the product meets all the appropriate provisions of the relevant legislation implementing certain European Directives) still works at a lower voltage because throughout the European Union (since 2003) the law is that all equipment carrying the mark must work with voltages in the range 207V – 253V. In the UK, the nominal voltage was 240V for many years, whilst in the majority of other European countries it was 220V. The ‘new’ nominal voltage in the UK is 230V with a tolerance of +6%/-10% until 2008, after which time the tolerance will be +/-10%. The current CE marking means any new equipment already meets this new ‘voltage harmonisation’.

It is important to note that the actual voltages have NOT been changed – harmonisation is being achieved by altering tolerances and modifications to equipment. This means that much of the electrical equipment presently installed can work reliably at a much lower voltage.

Installing VPO at County Hall

Prior to the installation of the VPO a voltage logger was plugged in to a 13A socket at County Hall to record the supply voltage variation over the course of a week. From this data the optimised voltage was calculated, together with an indication of potential savings. In September 2005 an approved contractor installed a 560kVA powerPerfector VPO device. The supplier of the VPO managed the whole process, liaising with the contractor and electricity company as necessary. The VPO installed at County Hall stabilises the voltage for the whole site.

Display® certificate and powerPerfector VPO device at County Hall

Reason for inclusion as Shining Example This Shining Example demonstrates how voltage power optimisation technology can reduce energy consumption and associated in CO2 emissions. In this case, energy consumption was reduced by over 14% against a like for like pre-VPO baseline.

The installation of the VPO has counteracted the increased energy usage that would have occurred as a result of installing additional electrical equipment and has helped to counteract the increase in CO2 emissions.

Costs and benefits</h2

Costs and funding The savings from installing the VPO device will repay the capital investment of €55,000 (£37,000) in less than three years.

The County Council funded the cost of the VPO device from prudential borrowing (where the revenue savings that will be achieved are equal to or more than the expenditure that will be incurred in borrowing the money) and an internal Energy Efficiency Fund it had established with an interest-free loan from the Carbon Trust, through the Local Authority Energy Financing Scheme (LAEF). The Carbon Trust is an independent company funded by the UK Government, which works with UK businesses and the public sector to cut CO2 emissions and develop commercial low carbon technologies. The LAEF scheme aims to reduce CO2 emissions through investment in energy efficiency measures and technologies.

Benefits The VPO device has resulted in an electrical energy saving of over 14% on a like for like basis. In 2006, this equated to a saving of €27,000 (£18,500) and reduction of CO2 emissions of 114 tonnes.

The success of the project has enabled the County Council to positively raise the profile of energy conservation and climate change throughout its organisation and to partner organisations, local businesses and the public.

Partnership details

Partners & role In June 2006 the County Council hosted a ‘Knowledge Sharing Day’ at County Hall in order to share its success in applying VPO technology with the North Yorkshire district councils, the East Riding of Yorkshire Council and the Office of Government Commerce (OGC, responsible for central government procurement).

In partnership with the Carbon Trust, County Council officers have delivered presentations on the Council’s experience of installing and using a VPO to other local authorities and organisations in the UK.



VPO options

The powerPerfector device at County Hall uses a ‘whole site’ approach. There are several other VPO products that are easy to install and that offer similar benefits on a more local level. For example, SAVAWatt (UK) Ltd specialise in products to optimise the voltage in compressors (typically used in refrigeration and air-conditioning plant). North Yorkshire County Council recently instigated a separate programme to address these issues.

Lighting circuits can be tackled using devices such as the fluoresave.

Funding for VPO technologies

Most VPO technologies qualify for interest free energy efficiency loans in the UK from the Carbon Trust, see:


Uncertainty about the effectiveness of the VPO device, and in particular concerns over the effect on IT equipment, were overcome by arranging joint meetings with engineering staff from the Council and the equipment supplier. Previous customers were contacted and their experiences researched.


The device is ideally suited to sites with a large electricity demand (100kW and above). These sites have mandatory half-hourly metering. This enables easy monitoring of consumption ‘before and after’.


The significant CO2 and financial savings confirm the success of the project.

Lessons learned The project lends itself very easily to replication, and the County Council is engaged in a rolling programme of evaluating all of its 100kW + sites to see if they are suitable for this technology. More VPOs are currently being installed and further installations are likely.

To know more

Organisation name North Yorkshire County Council
Contact Neil Dodson
Phone +44 (0)1609 532133

Useful info


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