BNG FAQs

On this page we are compiling commonly asked questions about Biodiversity Net Gain (BNG) that we are receiving here in East Cambridgeshire and our local response to them.

However, you may also find it helpful to review national resources such as the following:

Please note that the following FAQs have been answered to the best of our knowledge, but should only be used as a starting point. The council can not be held liable if any of the advice below is inaccurate, misleading, incomplete or does not comply fully with national legislation. BNG is new to all of us, and understanding and best practice is evolving rapidly. Please always check the national rules and guidance rather than relying on the advice below, and always seek your own specialist assistance.

Who completes the BNG metric?

First and foremost, it is not the council that will complete or help you complete your metric.

The applicant has the responsibility to make sure the metric is completed comprehensively and accurately. This means it must be done by a competent, and most likely qualified, person such as an ecologist.

When should I start to consider BNG?

BNG is mandatory, and therefore it is a crucial aspect of your entire development proposal. It should not be an after-thought. To achieve mandatory minimum 10% BNG could mean your entire development scheme layout and design has to be adjusted significantly. In some cases, it is entirely possible that achieving BNG might make a development scheme difficult to achieve from a viability perspective, and a complete re-think of what development is right for the site might be necessary.

Please remember that you cannot be excused from meeting BNG requirements, so the earlier you factor it into your designs, the better.

Does BNG replace other ecology requirements?

No. BNG has not replaced any requirements previously in place.

BNG is in addition to other ecological surveys such as (but not limited to) Preliminary Ecological Surveys, Protected Species Surveys, Tree Preservation Order checks, Arboreal Impact Assessments, Conservation or Species impact zones assessments and more.

How long does my ecological report last?

Typically 12 to 18 months, but this could be extended to three years if it can be demonstrated by a competent person that there has been no change to the area. The simple message is that the longer you leave a site or habitat, there is likelihood it will change and you will have to start your survey work again.

What is the baseline starting point for the metric? Can I clear the site first, then do my baseline assessment?

Your baseline metric will need to be assessed at some point in the time scale of 1 January 2020 to now, and at the point it was in its best condition. This is to stop developers clearing a site first and then doing their habitat surveys.

So, if your site has been cleared of habitat recently or has in any other way degraded since 1 January 2020, your baseline metric should be completed at the point the land was in its best state for biodiversity since 1 January 2020. On the other hand, if the site has the greatest degree of biodiversity now (compared with any other time since 1 January 2020), then the baseline should be assessed as of the site's condition now.

The simple rule is that you cannot pick and choose the date when to do the baseline metric in order to reduce the subsequent net gain you will need to provide. The baseline must be done when the site was in its best condition any time since 1 January 2020.

The council will robustly check and challenge any baseline metric assessments, if it is considered the wrong baseline period has been chosen or the information is inaccurate.

The council takes a very dim view of any landowner or developer clearing their site of habitats, such as trees, wetlands or grasslands, in the hope that it will be easier to get planing permission. Where appropriate, we will take whatever enforcement or other action as is appropriate under such scenarios, and we will ensure any 10% BNG requirement is achieved from the baseline position before the site was cleared. This could make achieving BNG very expensive, and put at risk your entire development proposal. Site clearance before submitting your proposals is therefore never likely to be a sensible option.

How do I know if my land is designated for something related to nature, or near a designated site?

The competent person who completes your metric should be able to find this information out for you. They are likely to start by viewing the comprehensive data on the DEFRA website (external link).

My development is tiny - surely I do not need to do BNG?

Some small developments are exempt from complying with BNG - please see advice at BNG and Minor Development.

Where is best to deliver my BNG obligations?

This is not always straight forward to answer, and we are unsure in practice which option most developers will choose. You will need to seek your own advice on what is the best solution for you. Your basic options are:

On-site: Generally speaking, try to achieve as much biodiversity gains on-site. Biodiversity gains (or units) on-site are worth a higher value in the metric.
Off-site: If it proves difficult to fit BNG on-site or is ecologically not the best solution, then the next best option is likely to be choosing an off-site solution. There are different options involved in this, but a golden rule is that 'local is best'. Due to the way the metric works, providing off-site gains a long way from your development site means you will need to provide more gains (or units) overall.
Statutory Credits: This is likely to be the option of last resort, and only when no other reasonable options are available. It is highly likely the most expensive option.

East Cambridgeshire District Council