The full energy and cost savings promised by CHP will not happen if energy use in the building is inefficient.
In order to gain maximum levels of efficiency when looking into Combined Heat and Power (CHP), it’s important to size a unit on the basis of future heat and power demands. One way of ensuring energy costs and are kept down is to implement efficiency measures before the sizing of the unit. Here’s a quick guide to ensuring CHP meets tomorrow’s demands.
Auditing your site
Start with a good look at energy bills and meter readings. Patterns of energy consumption that run counter to what the business should be using could show where energy is being used unnecessarily. Data from bills and meter readings can help to identify unexpectedly high or unusual patterns of energy. An agreed baseline energy usage model can then be established for the site.
A tour of the premises should identify instances of energy wastage that can be stopped and other opportunities for improving energy and therefore CHP efficiency. The tour should be repeated at different times of the day – typically:
- Nights and weekends
- Other times when your energy consumption would be expected to be low
Comparison of the findings from the tour with meter readings should pinpoint areas of excessive energy use. Primary candidates for improvements in energy efficiency will be:
- Office, factory, and warehouse equipment
By identifying these measures, you can overlay their implementation onto the site model in order to establish a new, achievable baseline for energy demand.
Heating typically accounts for about half of the energy used in offices and much of the energy use in other areas of a business. Many businesses are overheated. Heating costs rise by about 8% for every 1°C of overheating.
Overheating is often found in areas such as storage rooms, where people do not spend most of their time. It can also be the result of poor control of heating systems.
Simultaneous heating and air conditioning in a space is commonplace and wastes a lot of money – set a dead band of about 5°C between the temperatures where heating ends and cooling starts.
Consider heating the different zones of a building, so that heating can be adjusted for each area. Zone controls also allow heat to be adjusted to suit the occupants’ needs. This will reduce wasted energy.
A poorly operated or maintained boiler can add 30% to heating costs - consider upgrading your boiler plant.
Lighting in a typical office costs about £3/m2 a year and only £1/m2 in the most efficiently lit offices. Installing high efficiency lighting such as light emitting diode (LED) lamps can reduce lighting energy costs by 30% or more
Office equipment accounts for about 20% of the energy bill in commercial offices. Switching computers off at nights and weekends can reduce their energy tally by 75% a year. Switching off printers, water coolers, and other equipment out of office hours can bring similar energy savings.
Factory equipment is commonly left switched on when it is not being used. Conveyor systems, machine tools, compressors and other equipment should be switched off when not in use.
High efficiency motors now cost no more than normal ones and can save 3-5% of the running cost. Using variable speed motors to reduce the speed of a pump or fan by just 20% can halve its running cost.
Sizing for the future
By highlighting demand side measures as well as energy efficiency and control measures, a new baseline can be modelled, allowing a CHP system to be sized to reflect the site’s future demands. Some CHP suppliers are able to identify and implement these efficiency measures as part of their overall CHP solutions service, often without funding from the client, instead sharing the savings to cover the cost of investment.
Learn more about making savings on CHP operating costs. Download your free eGuide now: Calculating CHP: A guide to savings and operating costs.
Topics: CHP / Cogeneration