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Case Study No.10

Installation of LPG heating in Mobile Classrooms for the Southern Education Library Board

Many schools use temporary buildings or mobile classrooms, either as full time classrooms or for specialised activities.  These classrooms are generally poor energy performers and could incur very high energy costs if used on a long term basis.  The Southern Education and Library Board replaced electric storage heaters with individual LPG systems in 96 temporary classrooms across 10 schools, the benefits resulting from the upgrade include:

  • Increased occupant Comfort

  • Annual Cost Savings of £45,900 or 71%

  • Carbon dioxide savings of over 326 tonnes/annum

  • A payback period of about 3.6 years

The Southern Education and Library Board

The Southern Education and Library Board serves the district council areas of Armagh, Banbridge, Cookstown, Craigavon, Dungannon and South Tyrone, and Newry and Mourne.  These areas span 1,450 square miles, with a total population of approximately 332,000 people, including 75,000 pupils and over 137,900 registered library users.  The mission of the board is to ensure that high quality education, youth and library support services exist throughout the area in order to promote learning, provide opportunities for personal development, encourage individuals to acquire core skills, and promote spiritual and moral values in individuals and in the community.  

The Project

The project involved the replacement of direct electric convector heaters with LPG fired boilers and low pressure hot water (LPHW) heating systems in 96 mobile classrooms (5,290m2) in 10 separate schools in the Southern Education and Library Board (SELB) area.  This project received 100% funding from the public sector Central Energy Efficiency Fund in Northern Ireland in April 2001 and was installed and commissioned in March 2002.  

Replacement of Direct Electric Heaters

Electric heaters have relatively low capital and installation costs but have very high running costs.   Electricity is currently the most expensive form of energy on a £/MWh basis.  The high price of electricity is largely due to the low efficiency of central power stations, where approximately two thirds of the energy is wasted as low grade heat to the environment.  Off-peak electric heating is less expensive than on-peak electric heating; however, storage heater installation costs are much higher than convector heaters.  If another form of energy is available (Natural Gas, LPG, or Biomass) electric convector heaters should be replaced.  Cost savings of up to 70% could be possible, depending on the cost of the new energy source.  

When replacing any heating system it is imperative that controls are also upgraded to ensure energy efficient operation.  

Energy and Cost Savings

Before the LPG systems were installed, the annual electricity energy consumption for the 96 mobile classrooms was metered at 719MWh, with a total annual cost of £64,800.  Table 1 summarises the project benefits.  

Table 1 – Project Benefits

  Predicted Post Project Evaluation
Electricity Consumption 72 MWh 23 MWh
LPG Consumption 648 MWh 742 MWh
CO2 Savings 313 tonnes/yr 326 tonnes/yr
Capital Cost £149,000 £166,000
Savings £40,100 £45,900
Payback Period 3.7 yrs 3.6 yrs

Considerations for Other Sites

  • Close control is necessary to ensure energy efficient operation.  In an environment such as a school, where pupils and students may have access to heating controls it is important to install tamper-proof covers to avoid problems due to  interference with settings.  During this project the delay in installing sensor covers resulted in an energy usage increase that was higher than expected under normal conditions.  In addition the retrofit of sensor covers resulted in an increase in capital cost for the project.  

  • Proper commissioning of the new systems is paramount.  For this project, commissioning was a major problem with ongoing problems in some mobile classrooms for up to 8 months after installation.  Commissioning should be carried out under the supervision of the Consultant or Engineer, and only after a period of satisfactory operation should installations be signed off.

  • Staff training in the new maintenance regimes and in operation of controls is imperative in order to ensure efficient system operation and increased occupant comfort.  In this project problems occurred on one site as the pressurization vessels were not being checked regularly.  Elsewhere, caretakers have changed during recent years, and handovers did not fully cover the control procedures resulting in unnecessary call outs.

  • The Consultant appointed met with the Principals at each site and explained the proposed project.  During the works, meetings with relevant staff were ongoing to ensure a smooth operation.  

Project Conclusions

Following proper commissioning and the retrofit of the classroom controller/ sensor covers, the project was very successful. Many teachers are happy with the improved thermal comfort conditions.  

More information and help

Supporting Information

For Further information on the Central Energy Efficiency Fund see website: www.psecni.gov.uk

Publications from the Carbon Trust

GIL 13: Energy Savings in Schools – energy conservation measures in temporary classrooms

For details of the Carbon Trust’s services and free publications, call the helpline on 0800 85 20 05 or visit the website www.thecarbontrust.co.uk

Other Publications

Energy Efficiency Best Practice Programme:

GPG 312 - Invest to Save?

Further Project Information

Robert McCreery

SELB

3 Charlemont Place

The Mall

Armagh

BT61 9AX

Tel 02837512454

Fax 02837512555

robert.mccreery@selb.org