In the future you will likely see mention of the European Ecodesign Directive when looking at stoves. Even though it has not been heavily publicised in the UK this is a directive from the European Union which covers a whole array of products and includes electric and fossil fuelled heating equipment.
At this moment in time the Ecodesign Directive is not firmly in place but is more of a consultation arrangement with the industry. In simple terms it sets out mandatory (eventually) ecological requirements for energy using and energy related products sold across all 28 EU member states. The aim is to reduce energy consumption as well as the impact of various pieces of equipment on the environment. There will come a day when all stoves will need to comply with the Ecodesign Directive assuming this comes in before the UK leaves the European Union.
Impact on the environment
As we have mentioned on numerous occasions, the modern day wood-burning stove is a highly efficient heating machine. Aside from the fact we have primary, secondary and tertiary combustion systems available, in a worst-case scenario burning wood will only release the same amount of CO2 that a tree ingests in its lifetime. So, from a pure burning wood point of view there is little more in the way of improvement required from the combustion system.