Confusion with Seasonal Efficiency Ratings

Confusion with seasonal efficiency ratings
There is often confusion around Seasonal Efficiency Ratings relating to ErP

Compliance regulations under the Energy-related Products (ErP) Directive covering local space heaters came into force as from 1st January 2018. These rulings have been incorporated into UK law and supersede previous legislation covering these and other products listed by this EU Directive.

In theory this should mean that suppliers in countries which have signed up to these regulatory standards would all be singing off the same hymn sheet when it comes to presenting the energy efficiency of their products. In practice this is just not happening in the UK, at least not universally.

Using the wrong CV measurements

The problem has come about in the case of the seasonal efficiency Calorific Value (CV) calculations in relation to gas-fired heaters, such as the infrared radiant plaque and tube heating systems manufactured by Schwank. The CV represents the amount of heat or energy in a given volume of gas. So, the higher the CV score is, the more energy efficient the heater appears to be.

However, there are two types of CV and this is where the confusion arises.

  1. Gross Calorific Value (GCV):  also known as the Higher Calorific Value, which is the amount of heat released by the complete combustion of a unit of natural gas.
  2. Net Calorific Value (NCV):   or Lower Calorific Value, which is determined by subtracting the heat used to vaporise water under test conditions from the total heat generation as used for calculating the Gross Calorific Value.
deltaSchwank is ErP compliant
Schwank deltaSchwank gas-fired infrared tube heater exceeds ErP directive GCV seasonal efficiency bennchmark compliance level

The ErP Directive uses the higher GCV value for calculating the all-important seasonal energy efficiency rating of a heating product, which relates to its performance over a 12-month period. This has now replaced the formula used by UK Building Regulations Part L2A, which stated that that “heat generator seasonal efficiency is equivalent to the appliance’s measured steady state thermal efficiency (net calorific value).”

The IEA (International Energy Agency) calculates that a unit of NCV for natural gas is equivalent to 90% of GCV. So if a heating product supplier continues to use the previous Part L2A calorific value calculations based on the NCV as opposed to the GCV unit stipulated by the ErP Directive, then the product will appear to have a higher seasonal efficiency score (by 10% using the IEA’s measure).

Make sure your business is correctly informed

Our research has shown that there are some suppliers still using the old NCV measurement when describing the seasonal efficiency ratings of their heating products.

Whether this is by accident or design, it means that competitive products that are marketed employing the correct GCV measure can be put at a disadvantage.  It also means that end users of industrial and commercial heating systems could make purchasing decisions based on misleading information.

It is therefore important for businesses to confirm with suppliers that the seasonal efficiency ratings of their products are based on Gross Calorific Value in compliance with the new regulations. By doing so, they will acquire heating solutions that are based on higher standards of energy efficiency and that offer reduced environmental impact.