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Pressing targets need a systematic approach

These are challenging times in building services. In January the EU announced a carbon reduction target of 40 per cent by 2030 against 1990 levels, an increase in energy generated by renewable sources by 27 per cent and an 'indicative' target of improving energy efficiency by 25 per cent by the same year. This April the amendments to Part L of the Building Regulations come into force, requiring a reduction of carbon emissions for non-domestic buildings by nine per cent compared with 2010 standards, ahead of the zero carbon target for new non-domestic buildings by 2019. The Government has also set the UK a carbon reduction target of 80 per cent by 2050. Mark Northcott tackles the challenges we face
Our buildings are responsible for over half of the UK's total carbon emissions, so addressing the design of new buildings and improving the energy efficiency of our existing stock is key to achieving these goals. Yet despite the arrival of new low-carbon and energy-efficient technologies, there are increasing concerns about 'performance gaps' between how buildings are predicted to perform and the actual results. One way to address this is through smarter, more effective system design.

Take heating, for example. With space and water heating responsible for around 60 per cent of a building's total energy usage and 40 per cent of the UK's carbon emissions, it is crucial that the heating system operates at its optimum efficiency. On new build developments, the carbon reduction requirements are often met with renewable energy equipment.

However, it is essential to factor in at the design stage how the chosen renewable technology will work for a particular building and how it will operate with additional components in the heating system. Renewable equipment such as biomass, solar and heat pumps often require the backup of a boiler to guarantee reliable heat delivery. For this reason, it is advisable to specify where possible the various components from the same supplier who can provide in-depth knowledge of the product range to help ensure that all the components working in tandem will maximise the efficiency of the system as a whole.

The UK's high proportion of old, existing building stock arguably represents a greater challenge than new development in terms of carbon reduction.

According to the Building Research Establishment (BRE), of the buildings that will be standing in 2050, 60 per cent are already built while 40 per cent of these will pre-date 1985, the year when Part L regulations were first introduced. So what is the most effective route to achieving significant savings on our older buildings? For the majority of existing buildings, replacing the existing boiler with a modern condensing boiler is often the only possible solution to cutting energy use and emissions, given the nature of the heating system in place. Certainly, condensing technology is a cost-effective, tried-and-tested, reliable solution that delivers rapid financial payback. Replacing a 10-15 year old atmospheric boiler with a modern condensing boiler and the appropriate control is proven to reduce fuel bills by more than half and achieve carbon reductions by as much as 90 per cent. However, here again smarter system design could reap greater efficiency savings: while manufacturers quote impressively high efficiencies of up to 98 per cent for their products, some 90 per cent of the UK's condensing boilers fail to achieve their maximum combustion efficiencies, dropping to the standard 80 per cent, due to the way in which they are installed.

Including an allocation in the boiler plant renewal budget for control upgrades, terminal plant replacement, passive energy saving technologies such as flue gas heat recovery and complementary low to zero carbon technologies (where relevant) would address this performance gap and significantly raise efficiencies.

Controls are crucial to a more effective heating system. Adding the appropriate control - such as weather compensation and optimisation - allows the boiler to operate at its optimum efficiency, while sequence control is essential where multiple boilers are operated in cascade.

Heating systems that incorporate passive flue gas heat recovery (PFGHR) technology - like Remeha's own 'super condensing' solutions - are particularly successful on commercial refurbishment projects. By recovering the maximum useable waste heat from the boiler and passing it back into the system, they achieve the highest possible efficiency of 107 per cent NCV at all times and at all flow and return temperatures. To put it another way, PFGHR systems raise efficiencies by 10-15 per cent above the standard condensing boiler under conditions where you cannot optimise the flow and return temperatures to gain the highest efficiencies from a standard condensing boiler.

Fortunately, given the importance of smart system design, advances have been made to improve information sharing between all members of a project team, making optimum carbon and energy savings more achievable.

Building Information Modelling (BIM) is a new collaborative approach that will bring outstanding benefits: improved efficiencies, reduced carbon emissions of an estimated 20 per cent and greater accuracies that deliver time and cost savings both at the design stage and throughout the life cycle of the building. So for heating, digital 3D BIM files of the various products inserted into the design will provide detailed, regularly updated, accurate data that will not only help designers and specifiers produce smarter, more effective designs, but will also provide useful information to assist building operators with maintenance and refurbishment.

As heating manufacturers, our aim is to improve quality of life with clean, green products that achieve the highest level of 'Blue Efficiency' not just in laboratory tests but in real life conditions. With our specialist knowledge of our products, our BIM Library and over 70 years' experience, we look forward to supporting building services professionals and commercial buildings owners in the design of smarter heating systems that will take us one step further along the path to a more sustainable future.

// The author is the managing director of Remeha Commercial //
10 March 2014


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