Preparing for change

Published:  11 December, 2015

Forthcoming European regulations will have an impact on the choice of space heating equipment in the future. Melanie Sadler, Engineering Manager with Powrmatic, provides an overview of the changes to come

Anyone involved in the management of building services and other energy consuming systems will be no stranger to changing regulations, with many such changes relating to environmental impact in one form or another.

This is certainly the case with space heating products, where forthcoming European regulations – through the Ecodesign of Energy Related Products (ErP) Directive - are designed to achieve improved energy efficiency and reduced NOx emissions. The changes are still a couple of years off, but it’s important to be aware that they are on their way.

While some are inclined to see such changes as a bureaucratic inconvenience, it is worth noting they also bring benefits. Improved energy efficiency, for example, clearly reduces energy bills and the cost of any associated carbon tax. Similarly, lowering NOx emissions should be a key element of any company’s sustainability policy.

A ‘glass half full’ approach would therefore see these changes as an opportunity to improve the performance of buildings, contribute to a healthier bottom line and improve the company’s ‘green’ image.

The ErP Directive

The ErP Directive comprises both the Ecodesign and Ecolabelling requirements for energy-related products, however the Ecolabelling aspects do not apply to the higher capacity heating products that are typically used in industrial and logistics premises.

To set the scene, Ecodesign has a number of sections, known as ‘Lots’, each of which covers certain types of product.

Lot 21 covers air heating products (warm air heaters) with a rated heat output up to 1MW, as well as cooling products up to 2MW, fan coil units and high temperature process chillers.

With regard to warm air heaters, from 1st January 2018 these will be required to have a seasonal space heating energy efficiency of not less than 72%, rising to 78% from 1st January 2021.

There will also be stricter requirements relating to NOx levels from 26th September 2018, as follows:

• Warm air heaters using gaseous fuels: maximum NOx 100 mg/kWh fuel input GCV (gross calorific value).

• Warm air heaters using liquid fuels: maximum NOx 180 mg/kWh fuel input GCV.

From 1st January 2021, maximum permissible NOx levels will fall to:

• Warm air heaters using gaseous fuels: maximum NOx 70 mg/kWh fuel input GCV.

• Warm air heaters using liquid fuels: maximum NOx 150 mg/kWh fuel input GCV.

Similarly, the requirements for radiant tube heaters, covered under Lot 20, will change from 1st January 2018 (this applies to commercial local space heaters with a nominal heat output of the product or of a single segment of 120 kW or less). These will be expected to deliver a seasonal space heating energy efficiency of not less than 74%, with NOx levels not exceeding 200 mg/kWh input based on GCV.

Seasonal performance

One of the key points in these regulations is that the efficiency figures refer to seasonal space heating efficiency. This is why the new figures at first appear to require lower efficiencies that the 91% minimum net efficiency currently required by the Building Regulations – as the latter relates only to the maximum power condition.

As a result, compliant heaters will need to perform efficiently at all heating loads. This is achieved partly by using modulating burners, rather than on/off or two-stage burners, so that the heaters can respond to changing demands for heat. Efficient heating controls should also be used to optimise part-load performance.

Maintaining efficiency with variable heat loads also becomes increasingly important as the thermal performance of buildings improves. Lower heat losses means set-point temperatures are reached more quickly, after which the heating system performs at part-load.

In addition, it is important to ensure that the products have an inherently efficient design. In the case of direct-fired warm air space heaters, it will be necessary to use condensing models to meet the new performance requirements. These will perform particularly efficiently at lower heat loads, as the lower return water temperatures will enable more condensing.

In fact, condensing warm air space heaters have been available for several years and tested in a wide range of applications using either natural gas or liquefied propane gas (LPG). As with condensing boilers, the use of a secondary heat exchanger results in slightly higher cost compared to non-condensing units.

It will also be necessary to incorporate a condensate removal system – typical condensate production rates are 0.06 litres/kWh for natural gas and 0.03 litres/kWh for LPG. In new installations this can be designed in from the start and will have a low impact on installation costs. In a retrofit situation the need for additional condensate pipework will make the project a little more complex - reflected in a slightly higher cost.

Nevertheless, upgrading to more efficient heating plant will save money over the lifetime of the units.

For instance, an efficient non-condensing 140kW heater will have an average seasonal energy cost of around £5171 per annum (based on typical commercial gas tariffs and heaters running 10 hours per day, 5.5 days per week during a typical heating season). A more efficient condensing heater running for the same hours and capable of meeting the new ErP requirements will have an average seasonal energy cost of about £4700 per annum.

If we consider a modern well insulated building with a floor area of 2,500m² and a volume of 13,500m3, the typical installed cost for a non-condensing warm air space heater would be £6500. A typical installed cost for a condensing heater would be around £7900. Therefore there is a cost difference of £1400.

When the energy savings are taken into account, an installation based on these figures would deliver a return on investment within five years. It is not unreasonable to expect at least a 10 year life for a warm air space heater, so over the life of the unit the savings will be considerable.

Additional energy savings can be achieved through measures such as using some recirculated air, rather than full fresh air (~15% saving), and installing destratification fans ~10% saving).

BREEAM (Building Research Establishment Environmental Assessment Methodology)

While the ERP Directive sets the minimum standard for efficiency and emissions levels, there are advantages in voluntarily pushing the boundaries. BREEAM (www.breeam.com) is a widely used scheme for quantifying the ‘green’ credentials of a building. Credits are awarded for various categories and the total corresponds to a BREEAM rating from Unclassified (<30) to Outstanding (>85). A high score can make the difference in being awarded planning permission or not.

For warm air heaters, BREEAM encourages the use of automatic temperature control and zone temperature sensors where units supply heat to multiple areas. Reducing NOx emission levels to ≤40 mg/kWh generates three credits and ≤70 mg/kWh generates two credits for building types other than industrial. For industrial buildings, up to two credits are awarded for achieving ≤70 mg/kWh in the office and in operational areas.

Clearly there is still some time before the new regulations come into force, but when budgeting for future planned plant replacement it’s useful to know what’s on the horizon. Taking advantage of the most efficient heating and control technologies is clearly the best way to achieve maximum financial and environmental benefits.

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