New TEWI guide published

BRA has revised its established guide to Total Equivalent Warming Impact or TEWI.

In designing refrigeration systems, there is a need to evaluate their environmental impacts, and the overall climate change impact in use is best evaluated using Total Equivalent Warming Impact (TEWI). This helps to ensure that these impacts are no more than necessary, and that the vital services provided do not have a disproportionate environmental cost.

TEWI is a measure of the global warming impact of equipment based on the total related emissions of greenhouse gases during the operation of the equipment and the disposal of the operating fluids at the end of life. It takes into account both direct fugitive emissions, and indirect emissions produced through the energy consumed in operating the equipment. TEWI is measured in units of mass of carbon dioxide (CO2) equivalent.

The first edition of this guideline was issued in 1996, and has been well received as providing a standardised method of calculation when designing new systems. Since then, there have been changes in electricity generation efficiency, and changes in the accepted GWP values of refrigerants. In updating the guideline to allow for these, the opportunity has been taken to revise the whole document to add greater clarity.

The guideline is recommended to all those involved in refrigeration and air conditioning, in the hope that its use will enable the climate change impact of all types of these systems to be evaluated fairly and consistently in the UK.