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Move to raise heating efficiencies

Amid all the confusion surrounding what some have described as a government’s U-turn on the green levies policy, the global case for energy efficiency has never been stronger.

Indeed, the International Energy Agency names energy efficiency the world’s “first fuel” in efforts to cut carbon and promote energy security in its inaugural Energy Efficiency Market Report.

Improving energy efficiency is particularly relevant for the UK as, according to the building research establishment, 60% of the buildings that will be standing in 2050 are already built and 40% will pre-date the introduction of Part L. So, if we are to achieve our carbon reduction target of 80% by the same year, it is crucial we address the efficiency of our existing building stock.

Space heating and hot water production account for over half of all energy use in commercial and public buildings. The new EU eco-design and energy-labelling regulations for boilers and water heaters are therefore a welcome move to raise energy efficiency standards in heating.

However, many heating manufacturers already quote high efficiency figures of around 98% on their products, meeting the standards set out by the Energy-related Products Directive. Yet around 90% of the condensing boilers in the UK fail to achieve much more than the standard 80%. This is because the maximum efficiency figures quoted are achieved in optimal conditions – typically at low temperatures and half load. A typical existing low temperature hot water system will generally have been sized on high flow and return temperatures, which prevents the boiler from fully condensing and operating at its maximum efficiency. Operating at full load and high temperatures (82/71°C flow and return, for example), even a high-efficiency condensing boiler will waste 10-15% of the energy input up the flue.

One solution to raise efficiency levels for heating on refurbishment projects might be to require heating manufacturers to provide a range of efficiencies on their products rather than just the maximum efficiency figure produced under idealised conditions. This might include the maximum combustion efficiency at different common flow temperatures of the boiler together with the seasonal efficiency, an average of how it performs across the different loads and conditions.

The next step would be to ensure that budgets for boiler plant replacement include an allocation for control upgrades, terminal unit replacement, passive energy saving technologies such as flue gas heat recovery or complementary low and zero carbon technologies to maximise the building’s energy-saving potential wherever possible.

Encouraging innovation

However, by introducing mandatory reporting of a range of efficiencies, we would also encourage the heating industry to question perceived wisdom and challenge existing condensing efficiencies. We would encourage continued innovation towards the creation of a “super condensing” technology that would deliver full-time maximum efficiencies regardless of primary circuit temperatures, which in turn would significantly raise efficiencies on heating refurbishment projects.

Given the UK’s high proportion of inefficient existing buildings, such a development would represent important progress in the move towards a low carbon nation.

Mark Northcott is managing director at Remeha Commercial

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