Can fan coil refurbishment improve specific fan power (SFP) values to 0.5 W/(l/s) or less?
Yes, fan coil refurbishment can improve specific fan power (SFP) values to 0.5 W/(l/s) or less. It can be achieved where a legacy fan coil unit (FCU) is running a fan with an AC motor. AC motor fans typically have SFP values, expressed in watts per litre per second, in the region of 0.8 W/(l/s). If this AC motor is replaced during a refurbishment with a modern, more energy efficient EC motor, the SFP can be reduced to around 0.25 W/(l/s) or better depending upon the secondary ductwork resistance.
The Specific Fan Power (SFP) is perceived as a measure of how efficiently a fan system moves air at a given operating point. It varies with airflow and pressure difference. Improving the specific fan power during an FCU refurbishment is important, as it indicates the energy efficiency of the fan. It provides a way of expressing the amount of electrical energy required to run a fan relative to the volume of air that the fan can deliver against the external static resistance imposed. Lowering specific fan power can reduce both the energy bills and the operational carbon of the refurbished fan coil units.
How does upgrading an old AC motor with an EC fan motor improve specific fan power in FCU refurbishment?
EC (electronically commutated) motors are around 50-80% more efficient than the AC motors used in many older FCUs requiring refurbishment. AC motors work by generating their own magnetic field. This can use up to 30% of the energy consumed by the motor. EC motors, by contrast, have a design that uses a permanent magnetic field. This gives them an efficiency boost when compared to AC motors. A greater level of control is gained when using fans driven by EC, rather than AC motors. This allows more accurate regulation of airflow volume and reduces excessive energy use when fans run above the required rate. Whilst specific fan power is also influenced by factors such as the type of fan and blade design, the efficiency gains when replacing an AC motor with an EC motor translate to an improved specific fan power for refurbished FCUs.
What are the regulatory requirements relating to the specific fan power of fan coil units?
Approved document L, also known as Part L, of the building regulations, deals with the conservation of fuel and power. In Volume 2: Buildings other than dwellings, it sets out the maximum allowable SFP for air distribution systems. This includes fan coil units in existing buildings, so it covers FCU refurbishment projects. The maximum SFP is 0.4 W/(l/s) based on a rating weighted average.
If you are planning to carry out fan coil unit refurbishments on domestic properties, seek advice from the relevant authorities on the maximum SFP you are required to meet regulatory compliance.
Where can I find more information on how to improve specific fan power when carrying out FCU refurbishments?
Ability has years of experience in carrying out fan coil refurbishments. Our full fan coil refurbishment service can help deliver a considerable reduction in carbon emissions from existing buildings and improve fan coil unit performance.
If you have fan coil units requiring refurbishment and would like to know how we can lower their SFP and improve their performance, please contact us, and we would be happy to help.
