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Rising to challenge of higher energy efficiency

As a result of energy price volatility and government regulation, energy efficiency and cost savings have risen up the corporate agenda. Alister Maclachlan looks at how solar water heating technology through the introduction of renewables can help businesses to become more energy efficient and ensure they meet their legislative commitments
A recent report from the Carbon Trust estimated that a third of a building's energy consumption is attributed to heating and hot water. More interestingly however the report also highlights that UK organisations could be saving £400 million a year by following simple energy saving measures and so it's imperative that buildings, new and old, are energy efficient.

Buildings must already comply with Part L2 of the Building Regulations when constructing or making any alterations. Couple Part L2 with the requirements of the CRC Energy Efficiency Scheme and this should help organisations to reduce their energy usage and thereby lessen the impact of the carbon tax.

The CRC Energy Efficiency Scheme - previously known as the Carbon Reduction Commitment - requires any organisation with a total half-hourly electricity consumption of over 6,000 MegaWatt hours (which equates to around 5,000 organisations in the private and public sector) to assess how much energy they are likely to consume, from all fuel sources, in the forthcoming year.

Incur financial penalty
They purchase a carbon allowance based on this figure, and if they use more energy than their estimate they will incur a financial penalty.

For businesses looking to make savings, reduce carbon emissions and tick corporate social responsibility (CSR) boxes, space and water heating are a good place to start and renewables can add even more value.

In fact, when considering renewable technologies it's important to remember that the RHI (Renewable Heat Incentive) tariffs for the nondomestic sector have already been announced, and commercial installations could be eligible for regular payments at a rate of 8.5p per kW hour for the next 20 years.

It is also worth looking at the Enhanced Capital Allowance Scheme which enables businesses to claim back 100 per cent tax relief on the first year of 'qualifying capital expenditure'. The relevant technologies are detailed in the Energy Technologies List and are there to encourage businesses to invest in low carbon technologies.

The simple way to look at the solar thermal specification process is to first of all consider the hot water requirement for the premises. This will determine the number and size of the panels and hot water cylinder.

Understanding the customer's hot water requirements and usage patterns is therefore essential in order to deliver the best possible energy and carbon savings.

If operating correctly, solar thermal collectors will greatly reduce the amount of energy required from the boiler to heat the hot water up to temperature. If a system is undersized, too little hot water will be produced and greater pressure will be placed on the boiler for heat. On the other end of the scale, if a system is oversized, it will lead to large energy losses as the heat is poured down the drain.

By effectively using energy from the sun, many premises could generate around 60 per cent of their hot water needs. In fact, the Carbon Trust estimates that a well-designed system, can collect more than 450 kW hours of useful energy annually, so it's important to get the specification right.

For many commercial premises, a flat-roof structure is ideal for solar thermal collectors, enabling the erection of an A-frame and the ability to position the panels to gain the greatest benefit from the sunlight.

Once installed the solar thermal collectors can be connected to a cylinder which is fed directly from the cold water mains and can provide a consistent flow of high pressure hot water. Coupled with a high flow rate, an unvented hot water cylinder can provide high performance to a large number of outlets at any one time, perfect for premises with a high demand for hot water like hotels and leisure centres.

Setting the flow rate correctly is incredibly important: If set too fast, the glycol fluid will pass too quickly through the solar panels and therefore not generate enough heat to adequately heat the water. The system will then be reliant on additional heat from the fossil fuel boiler to bring it to temperature and will be less energy efficient for the customer.

If set too slowly the glycol fluid can stagnate in the system and over time will cause damage. Manufacturers will usually provide guidelines for the flow rate settings and it's important to get this right in order for the customer to get the greatest benefit.

Making an educated choice
Crucially, when it comes to water heating it's essential that contractors help businesses to make an educated choice, one that will not only save them energy and money over the longer term, but also help them comply with relevant regulations.

Energy efficiency will continue to rise in the priority stakes and businesses will be looking for advice and guidance on how they can best meet their performance targets.

It's important that contractors take up this challenge and help to shape the energy performance of our commercial building infrastructure.

// The author is technical product director of Vokèra //

19 April 2012


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