Credits cost between £30,000 to £130,000 per hectare - a steal compared to the loss of a hectare of developable land, which has an average value of £400,000 to £700,000.
"Offsetting gives developers certainty and financial clarity, as well as the opportunities to do what they do best - develop. It lets them provide funds, through us, to create more successful mitigation, restoration and creation of habitats."
Strict valuation methods protect areas from inappropriate development. "We want habitats like ancient woodlands to be screened out at the beginning of the process. You can't do anything else - you just can't recreate ancient woodland," states Hill.
Rare ecosystems or endangered species are protected at both a national and European level. The more distinct and better the condition of the proposed development site, the bigger the bill.
Developers must adhere to the principle of 'like for like', ensuring the same type of habitat is created in an offset as the type destroyed (otherwise a more expensive offset will be needed) and create 'no net loss', or a net gain, as a result of the offset.
So, say a wind farm was going to kill 20 birds each year, developers could invest in a breeding programme ensuring 40 more of those same birds hatched every year, creating a 'net gain' of 20 birds. ?Offsetting schemes tend to attract cynical opponents, fuming about the 'license to trash' - letting fat cat developers destroy at will.
According to Hill, that's exactly what won't happen. "You can say to developers 'you could develop there, but the cost would be so massive to offset, so why would you?' It provides incentives to develop somewhere else."
The Royal Society of New Zealand is currently funding a cross-departmental research programme into biological offsetting in New Zealand. Biodiversity offsets programme manager for the Department of Conservation, Gerri Ward, explains:
"There is a need for the government to clarify our view on offsetting, whilst not indicating that we are advocates of offsetting in any way." Ward is clear that soon-to-be released recommendations will set the bar for what is an appropriate offset, as many developers are now presenting their own version to the Environment Court as part of their mitigation strategies.
Ward says they want to phrase offsetting in terms of conservation actions rather than monetary value - ensuring developers, for example, increase the populations of kiwis in an affected area rather than pass the money, and responsibility, over to DoC.
"We see it as a commitment to ongoing conservation and enhancement when there wasn't one, preferably for perpetuity."
A lack of science means valuing biodiversity can be problematic, often resulting in a poor reflection of the true 'value' of a site. But as long as the language of money rules in decision-making, a 'valued' environment will be an important consideration in any kind of development.