Energy Management in Plastics Processing - Part 12
A series of energy efficiency worksheets by Dr. Robin Kent
for the Carbon Trust to
help the plastics industry reduce costs through efficient
use of energy.
UK Government Environment and Energy Helpline 0800 585 794
Previous Worksheets have concentrated on process related energy use. The buildings related energy use is often seen as secondary but it actually represents an average of 17% of the total energy costs. The buildings related energy is an easy area to make energy savings because any changes do not impact on production. In most cases a simple site survey can reduce costs considerably.
Building energy costs are a significant percentage of the total energy costs.
For the plastics processing industry, recent years have seen vast improvements in factory buildings and working conditions. This upgrading of conditions has produced significant improvements in all-round site efficiency, and this has resulted in a general reduction in the usage of energy. However, large opportunities still remain for energy savings in areas such as lighting, space heating and general hot water supplies.
Many processes generate excess heat (which should be reduced if you have followed the tips in this series) and it is worth investigating if this can be used for other purposes, such as space heating on colder days.
Tip - Processes that involve vaporising solvents will require ‘Local Exhaust Ventilation’. Processes that only generate heat have options for general or local ventilation or preferably energy recycling through a heat exchanger.
The starting point to reduce building energy use is an audit of the buildings and systems. The following tips can serve as a basis for the initial audit:
Tip - Reducing heating load is the top priority, so prevent unnecessary heat loss by making buildings as air tight as possible. Draught proofing doors and windows is cheap but effective.
Tip - Automatic fast-acting roller shutters save energy on external access doors used with forklifts and other mechanised access.
Tip - High ceilings increase your heating costs. Investigate the use of false ceilings, or destratification fans to blow hot air from the roof space down to the working area.
Tip - Restrict the areas to be heated by using partitions or local systems to control the key areas. Don’t ventilate or heat the whole building space for a few small areas.
Tip - Do not heat areas where you have windows or outside doors open.
Tip - Do not heat lightly occupied stores or warehouses when you are only trying to prevent excessive dampness.
Tip - Insulate supply pipes to radiators.
Tip - Install tamperproof thermostats and controllers to prevent s tampering with them. For larger sites, Building Energy Management Systems control energy costs without relying on staff.
Improving building energy efficiency also improves staff comfort and work output
Tip - Request 'GPG304 - The Purchaser’s Guide to Energy-Efficient Buildings for Industry' from the Helpline and look for energy efficient designs with passive solar heating, passive ventilation, added thermal mass, and natural lighting systems.
Tip - Review building insulation and fabric meet the current best practice.
Tip - Double glazing can both reduce heat loss and improve comfort. Modern low-e glass and systems are even more effective than standard double glazing.
Tip - Condensing boilers are the best option for new or replacement small hot water systems.
Although it is only a relatively small part of the overall energy usage, lighting systems offer easily demonstrable opportunities to save energy. Pay attention to areas with:
- High or continuous lighting levels and no or low occupancy. Use occupancy sensors or time switches.
- Fluorescent tubes at high levels without reflectors. The use of reflectors increases light levels which may mean that the number of fittings can be reduced.
In lighting, simple measures can save money easily and a well designed lighting system can be a permanent energy saving feature. Examples and information on improved lighting methods is available in Best Practice Reports from the Helpline.
Tip - Many major lamp manufacturers also offer advice and contract consultancy on lighting. Use the help that is available for free to save energy.
Tip - Replacing normal tungsten bulbs with compact fluorescent (CF) lighting saves money in the long-term. Although they cost more, CF bulbs use only 25% of the energy of tungsten bulbs and last about ten times longer. The reduced maintenance costs, especially for lights in high fitments, can easily fund the extra purchase costs.
Tip - High frequency tri-phosphor T8 tubes should always be installed when replacing or refurbishing existing older systems where good colour is needed. For areas where colour is not critical, high pressure sodium lighting is an option Research shows that lighting switched on in the morning will rarely be switched off until the evening - whatever the changes in light levels in the intervening period.
Tip - Use natural daylight where possible and keep skylights clean to reduce the amount of artificial lighting needed.
ECG018 ‘Energy Efficiency in Industrial Buildings and Sites’ presents the results of a survey conducted across all UK industry. The figures below give the average annual delivered energy use and cost. The main figures represent an average working day of 2.3 eight hour shifts and the figures in brackets give the values per eight hour shift worked.
% total kWh
% total cost
Of the buildings energy use, the space heating element was over 50%:
The buildings energy use values from the sample ranged from 300 (130) to 550 (239) kWh/m2. Calculate your annual buildings energy use per m2 per shift, and compare it to the sample range above.
The "Energy Management" series is designed to give plastics processors an insight into how to manage a valuable resource.
Download the complete series as an Adobe Acrobat file.
Last edited: 11/03/10
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