The importance of not over-sizing CHP
Following research revealing that commercial buildings in the UK may be producing 3.8 times more carbon than estimated at their design stage, Gary Stoddart of SenerTec, explains how to avoid CHP contributing to the problem.
With research from the Government-appointed body Innovate revealing that commercial buildings in the UK may be producing as much as 3.8 times more carbon than estimated at their design stage, it’s clear that technology in many properties is falling short of predicted performance.
The recent research by Innovate shows that only one of the 50 leading-edge buildings studied produced the amount of carbon specified by its design, with some buildings yielding emissions rates up to 10 times higher than the Building Emission Rate (BER), which is calculated by designers and developers for every new building.
Part of the problem lies with the integration of new technologies, with many teams having difficulties with maintenance, controls and metering. Without consideration of these factors when new technology such as CHP is installed, it is difficult for buildings to achieve predicted energy performance.
In addition, it is important that new technologies are correctly installed and specified in the first instance. For example, although CHP can help to achieve carbon reduction, we still see cases where CHP is being oversized, with the ‘10% for luck’ rule being applied.
This means that many buildings have larger plant than required, and as oversized CHP units will not run if the heat/hot water demand is not present, the system will not be efficient, leading to higher operational costs and higher carbon emissions than predicted.
For this reason, specifiers should ensure that CHP units are kept as small as possible, resulting in the continuous generation of low-cost, low carbon electricity which is produced as a by-product of meeting base-load heating/hot water requirements.
However on top of ensuring CHP systems are correctly sized to begin with, we would also encourage specifiers to ensure that CHP units are commissioned and maintained correctly and are continually monitored to ensure the system continues to perform to its optimum level — allowing predicted carbon savings to be realised.
Gary Stoddart is general manager of SenerTec, part of Baxi Commercial.