The reason behind the introduction of the Microgeneration Certification Scheme (MCS) was to establish a standard requirement for domestic low and zero carbon (LZC) systems. But, despite these good intentions, the scheme as it stands neglects the testing criteria and heat loss measurement of LZC cylinders sold in the UK, so are we selling our customers and the environment short? Spencer Clark, sales and marketing director of Heatrae Sadia, discusses the limitations of the MCS scheme and how improvements could boost its effectiveness.
MCS was brought in to replace the ClearSkies Scheme for renewable technologies. Since its introduction, the initiative has become a familiar accreditation for heating and water heating manufacturers looking to improve their products and develop greener equipment for the sake of their customers and the planet.

There is no doubt that solar thermal has become the LZC technology of choice for many, because it is relatively easy to understand and install, and it openly highlights the green credentials of the customer.

Under the previous ClearSkies scheme, the solar collectors were required to meet minimum design and construction standards to enable them to be listed, and the cylinder, which is an integral part of any solar thermal water heating system, was also subject to stringent testing procedures and rules.

It therefore seems strange that, under MCS, the solar collectors only need to be listed, and even to those with limited technical knowledge, it is clear that the efficiency of a solar thermal water heating system should be the sum of all its parts.
Simply having efficient collectors does not guarantee an overall efficient system and there is much to consider when specifying and installing a solar water heating arrangement.

For example, if the cylinder is incorrectly sized, has a poorly designed heating coil or inadequate controls, this can have an extremely detrimental effect on the overall performance. In addition, the controls for the system also need to be carefully selected to ensure they will provide maximum operational performance for the customer.

Again, controls do not require accreditation or any listing under the MCS as it currently stands and this seems almost like a retrograde step.

However, the current scheme allows for existing cylinders to be used, whatever their age, type or design. This could lead to solar thermal systems utilising cylinders where the insulation levels fall well below the requirements of the new Building Regulations Part L.

In many situations, it is likely the cylinder would not have been designed with solar in mind and will probably have inadequate heat transfer and controls provision.
While enjoying the benefits of harvesting free energy from the sun to heat water, it seems strange to even attempt to use it with cylinders that have poor heat loss performance and in turn have to use more conventional energy to supplement the solar heat.

The subject of heat loss is critical to an effective solar system and at Heatrae Sadia we've undertaken in-depth, highly accurate thermal imagery testing as part of the development of our new Megaflo eco unvented cylinder. This testing has resulted in nearly 30% less heat loss when compared with the previous model.
To enable accurate specification, a level playing field is required for all heat loss measurement and this is something that the Hot Water Association should be encouraged to make a primary objective for 2011.

The reason for legislation and instigating accreditation schemes is to promote best practice in terms of the equipment being selected and installed, particularly where government funds are being used to provide the most efficient products and operation. However, if only part of a system is subject to the requirements, how can best practice possibly be the end result?

Our industry needs to take steps to make sure all areas are tested and measured accurately to provide credibility for our products and maintain customer confidence.