We are often asked by Clients to achieve Net Zero Carbon when designing a building. Our first question is often what do you mean by Net Zero Carbon? The first, most obvious definition is that from the UK Green Buildings Council (UKGBC), they stipulate the energy consumption should be reduced as far as possible through energy efficiency measures, gas combustion should be replaced, generation should be installed, and then any remaining emissions are offset to zero carbon either through a true green electricity tariff or an approved offsetting scheme. This definition appears to be the most robust and the true path to Net Zero Carbon.
What are the alternatives? Net Zero Carbon is described within the London Plan after completion of the Energy Hierarchy process. In London, all proposals should reduce emissions as far as possible and then offset into the Local Boroughs carbon offset scheme the remaining emissions for 30 years, typically at £95 per tonne. This however should not be confused with the Net Zero Carbon definition above as the requirement to offset only relates to regulated emissions i.e. those that the Design Team have control over such as heating, cooling, lighting, pumps/fans and domestic hot water. The Net Zero Carbon stipulation in London should really be seen as a tax on construction and not a badge to establish sustainability credentials.
There does appear to be an element of greenwashing by schemes claiming to be Net Zero Carbon and the industry is keen on addressing this through industry initiatives such as LETI that aims to toughen up the definition of what can be considered Net Zero Carbon and what cannot.