Retrofit – the sustainable approach to huge energy savings

Renewable technologies may grab all the headlines, but today’s retrofit technologies head up the energy saving technologies in terms of effectiveness. Remeha Commercial looks at how councils can massively cut fuel bills and emissions with minimum disruption and without huge capital expenditure. This article was originally published in PSBJ May 2014.

With tighter budgets in place, councils are looking to make efficiency savings wherever possible. Reducing energy consumption should be a priority for all local authority estate managers: not only will it lower operating costs but it will help councils meet their environmental commitments, which will in turn help the UK towards its steep carbon reduction target of 80 per cent by 2050.

With heating accounting for around 60 per cent of the energy use in a building and 40 per cent of the carbon emissions, it should be top of the list of any energy reduction strategy.

A lesson in retrofit

Renewable technologies may grab all the headlines, but it would be unwise to overlook relatively simple and affordable energy efficiency improvements on refurbishment projects. While they may not have the visible ‘Wow’ factor of renewable equipment, they do offer a high return on energy efficiency investment. In its survey ‘The Business of Energy Efficiency’, the Carbon Trust found that financial officers were underestimating the returns for energy efficiency investments by around half their actual value. In reality, retrofit technologies have advanced considerably over the last decade, heading up the energy saving technologies in terms of effectiveness. What’s more, the nature of the UK’s notoriously inefficient old building stock and the heating system in place may preclude installing any renewable energy equipment. So, for many properties, retrofit technologies will be the only option available for greater energy efficiency in heating.

Halve energy bills and cut emissions by 90 per cent

To achieve the greatest reduction in energy bills and emissions and the fastest payback, the accepted advice is to replace old existing boilers with a modern condensing gas boiler. As a general rule, building managers should look to replace any boiler over 10 to 15 years old with a high efficiency, fully-modulating condensing boiler. A 5 to 10 year old system operates at around 70 per cent efficiency whilst one that is over 15 years old drops down to 50 per cent. Replacing them with a high efficiency system can therefore deliver very real benefits. Advances in technology mean that the latest boiler models already exceed the required efficiencies standards outlined in the Energy-related Products (ErP) Directive that is expected to come into force in 2015. In real terms, when replacing old atmospheric boilers, they have proven to more than halve energy bills and reduce the levels of harmful greenhouse gases such as CO2 and NOx by as much as 90 per cent.

Time and cost savings

Technological progress has not only resulted in improved efficiencies but improved design. Today’s boilers are smaller and lighter, making them easier to install and maintain. In buildings where access to the plant room is awkward, look for models that are supplied on wheels or able to be disassembled into sections. This will facilitate installation, thereby reducing time and labour costs as well as minimising disruption. Prefabricated heating systems also reduce installation time and costs as well as improving quality control. Condensing boilers on cascade and rig systems, for example, are delivered on site as a whole system in a pre-configured and tested wheeled unit, rather than individual components from a number of suppliers. The cascade operation also allows the heat output demand to be matched more accurately and more reliably in a fraction of the space.

Maximising efficiencies with controls

In order to maximise the effectiveness of the heating system, it is important look at how the system works as a whole rather than the individual components. Cars are a good analogy: technological advances have made them capable of operating far more efficiently, but even so, if you drive around in first gear you won’t reap the energy saving benefits. In the same way, controls are central to effective performance as they ensure that the boiler operates at its highest efficiency level. If the controls are not used, the benefits will not be realised. The Carbon Trust says that controls achieve payback in just one to two years and suggests that lowering set points by one degree could bring a reduction in an annual heating bill of up to eight per cent. We recommend that the minimum control strategy should encompass valved zone control, thermostats and timers. Further improvements can be achieved by two-zoned temperature and time control, weather compensation, and sequential control of boilers.

From condensing to ‘super condensing’

Perhaps the optimum solution for retrofit solutions is the very latest development in condensing technology known as passive flue gas heat recovery technology. These ‘super condensing’ heating systems are proven to slash energy use and emissions by as much as two thirds. On old heating systems which take more energy to heat, even the most efficient boiler could struggle to achieve its maximum efficiencies, as they are sized on high flow and return temperatures which prevent the boiler from fully condensing. ‘Super condensing’ systems use the energy input more effectively, recovering the otherwise wasted energy and passing it back into the system to preheat a cold water feed, heat return water or simply circulating it to a thermal. This means that they can deliver around 10 to 15 per cent higher efficiency levels than standard condensing boilers, delivering the highest possible efficiency of 107 per cent NCV at all times and all flow and return temperatures.

As technologies have advanced, so our energy saving options for heating have increased, offering huge reductions in fuel bills and emissions that will help stretch budgets further and make environmental targets achievable. At Remeha Commercial, we look forward to sharing our knowledge with councils and assisting with best system design for maximum efficiency savings that will help the nation move forward to a low carbon future.

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