Companies that have facilities which use refrigeration and air-conditioning systems or heating, ventilation and air conditioning systems have to measure changes which are imposed upon them due to greenhouse gas emissions. Additionality is a measure which compares the level of emissions prior to implementation with the levels after a greenhouse gas reduction project has been introduced.

Additionality metrics are part of a monitoring and verification plan, which is set up when a greenhouse gas reduction project is underway. The metrics explain when and how the plan would be implemented as well as who is responsible for conducting the process. As this is a complicated area, software has been developed by specialists to simplify the procedure.

Project specific assessments are implemented by facilities that use refrigerant. Projected greenhouse gas reduction levels are calculated on an individual basis, by creating a baseline of levels to commence. Once a project is in place, a emission levels are compared to the baseline and the actual greenhouse gas emission reduction is calculated.

Additionality can be determined using a performance standard assessment. This is common for a specific industry, like manufacturers of refrigeration and air-conditioning (RAC) systems or heating, ventilation and air conditioning (HVAC) systems. It measures performance improvements to the existing industry standard for a particular appliance or process as they relate to greenhouse gas reduction.

Additionality plays an important role in determining the effectiveness of any reduction project. Global climate change is severely impacted by greenhouse gas emissions. Numerous industries are affected by greenhouse gas offsets projects in all sectors, just a few examples including renewable energy efforts, reforestation and methane capture and recovery in landfills.

Businesses are held accountable and must show the benefits of a greenhouse gas reduction program. Additionality criteria must be established and met. For reporting purposes, ongoing monitoring and verification must ensure that actual reductions are in place, with long-term sustainability. Those facilities developing methods to reduce their overall use of refrigerant gas, can take advantage of monitoring and tracking processes through software and web-based applications.

Part of any additionality equation is an examination of how permanent the project will be and a determination of any risk factors involved. The issue of leakage should be addressed and properly accounted for through monitoring and verification.

Currently there is a lot of discussion around the world concerning the availability of funding for companies who are engaged in greenhouse gas reduction projects. Determination of any funding would rely on additionality to determine if the project is more than just a business as usual improvement. Funding will not be made available if the project would have occurred anyway.