Measuring the regulations

Understanding energy and building regulations is becoming essential for energy managers in order for them to deliver added value to their business through good energy management. Mike Lawrence of Havells outlines how to keep your installations compliant – and future-proof.

There can be no doubt that the drive to save energy is having an effect on the electrical trade, especially in the lighting sector. But the drive to save energy is also having an impact in other areas, amongst them, switch gear and the trend toward sub-metering at the distribution board.

For the electrical contractor out on site, it can be a challenge to stay on top of which building and energy regulations are relevant, and their latest editions. Important pieces of legislation and guidance with implications for switch gear design and installation are Part L2 of the UK Building Regulations, and the requirement for an Energy Performance Certificate (EPC) to be issued, and displayed, for new buildings (or parts of) that are built, sold or rented.

Electrical contractors are in a good position to help owners and managers get to grips with this new landscape as sub-metering has emerged as a popular strategy to achieve better building performance and ultimately, lower energy bills.


The UK Building Regulations Part L2 has a requirement that energy meters should be installed in order that 90% of energy consumption can be monitored, analysed and then assigned to categories such as lighting, power, building services (such as lifts), ventilation, IT equipment etc. This requirement applies to any building greater than 500sqm and to do this effectively, installation of sub meters is recommended. For buildings with a total floor area greater than 1000sqm, provision should be made for automatic meter reading and data collection.

The ultimate objective is to achieve energy savings of 5-10% by identifying wastage and replacing any under-performing equipment. The requirement for accurate EPCs, issued by trained assessors, can be effectively met by a well-planned sub-metering strategy that lets building owners or occupiers monitor their energy use and identify any significant trends that arise. For this to work and for the target energy savings to be achieved, property owners and tenants need detailed information about their energy consumption.

Installation issues

There has been an enthusiastic uptake of sub-metering in the UK since legislation was introduced to encourage it. This is to be applauded and it is satisfying to see how many are now recognising the benefits that a well executed sub-metering installation offers. While this is good news and there are many examples of successful sub metering installations, there is now a large enough body of experience and data to ask whether these perceived benefits are actually being achieved and if not, why not, and what kind of equipment can help us do things better?

A common problem is the incorrect installation of energy meters through complicated wiring and confusing programming settings. This can directly impact on the overall final cost of a project with site revisits required to re-validate the installation and operation of energy meters. Meters that are incorrectly wired can still collect a reading and therefore can cause confusion for the contractor and end user. A solution to this problem is pre-configured meters such as Havells QuikWire which features fool-proof plug connectors and pre-set CT ratios to eliminate programming errors and simplify installation, making it virtually impossible to commission the meter installation incorrectly.

There are various approaches to installing sub-metering. In some cases all metering is provided at the in-coming main switchboard. This has the advantage of installation simplicity and makes data collection easy. It also gives a good overall picture of energy consumption which is useful on one level but does have its drawbacks if more detail is required. Because this type of approach will typically be monitoring a mixed bag of lighting, power, motors etc indiscriminately, you will have your overall energy consumption figures, but rarely will this type of approach generate the level of detail that allows meaningful conclusions to be drawn from the collected data. An effective sub-metering installation will deliver information that the building owner/operator can act on.

There are a number of distribution boards on the market with integral metering to offer a neat, easy to install and cost effective solution. There are options available for a single meter that monitors the entire board – whether Type A (single-phase) and Type B (three-phase) – or for split-metering which provide separate monitoring data for grouped circuits. Dual load boards with separate metering of lighting and power loads are popular but the most effective method is to separately monitor consumption of lighting, power and HVAC/building services equipment – typically the largest consumers of power.

A Type ‘B’ distribution board with integral metering is the ideal solution for this type of installation. There are many boards on the market that allow separate measurement of just two types of load (lighting and power, for example), however there is clearly a need for a board that can monitor three types of load simultaneously, so consumption figures for other categories, such as building services equipment, can be separated out. In this way, the data collected for your client is more accurate and relevant to their actual application.

The power of three

Havells has developed Tri-Load, a UK specific distribution board which squarely addresses the new sub metering requirements to the mutual benefit of installers and end users.

Tri-Load is a unique distribution board design offering integral metering with the facility to monitor three independents loads from one digital multi-function meter. The boards can be configured to operate as tri-load, or dual-load, using a simple menu interface. This allows users to identify various different load combinations depending on the project metering requirements. This separate energy monitoring for power, lighting and mechanical services, is the ideal solution for compliance with Part L2 of the Building Regulations.

In addition to this there are also features designed with the installer in mind which contribute to improved electrical safety. Current Transformers (CTs) are integrated within a single-piece busbar design to reduce the number of electrical connections which are commonly required by other manufacturer’s solutions. This reduces potential hot spot failures. Furthermore, all meters and CTs are fully pre-wired and a trunking interface kit is supplied as standard.

The Tri-Load board has been designed to minimise the amount of on-site work for the contractor, whilst at the same time, providing the end-user with improved data collection and reporting functionality. The future for electrical contractors working in the commercial environment has to be to consider this type of client-focused solution.

The Tri-Load product family has now be developed further to address the increasing integration of micro generation e.g. PV and wind, within building designs. The new Tri-load Green range, provides a convenient connection point for these generated sources. The board monitors power and lighting loads, but also provides measurement of the export energy from renewables within a single distribution board i.e. power lighting and renewable. Accessing data from the feed-in tariff meter is often not straight forward and not all PV or small wind turbine installations employ a feed-in tariff meter. Tri-load and Triload Green provide a ready to install convenient solution to monitoring e
nergy within commercial, retail and industrial buildings.

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