If you have recently submitted a planning application to North Somerset Council—or received a validation checklist or pre-application letter—you may have been told that you need to provide an “Existing Habitat Appraisal.”

If you’ve tried searching for that exact phrase online and come up empty-handed, don’t worry. You aren’t missing a brand-new piece of legislation.

At Southwest Environmental Limited, we regularly help homeowners, architects, and developers across North Somerset navigate local planning requirements. Here is a plain-English breakdown of what an Existing Habitat Appraisal actually is, why the council is asking for it, and the most cost-effective way to tick this box for your planning application.

What is an “Existing Habitat Appraisal”?

In short, an Existing Habitat Appraisal is North Somerset Council’s specific wording for a Biodiversity Net Gain (BNG) Baseline Survey (often carried out alongside or as part of a UKHab survey or Preliminary Ecological Appraisal).

Under the mandatory Biodiversity Net Gain rules in England, most planning applications must demonstrate a minimum 10% net gain in biodiversity. However, before you or the council can calculate a 10% improvement, you have to prove what is currently on the site before any ground is broken.

That starting point is your “baseline”—and the assessment of that baseline is what North Somerset Council refers to as an Existing Habitat Appraisal.

What Does the Appraisal Involve?

To satisfy the council’s ecology officer, an ecologist visits your site to map and assess the current land prior to development. During an Existing Habitat Appraisal, we record:

• • Habitat Types: Classifying every part of your site using the UK Habitat Classification (UKHab) system (e.g., modified grassland, native hedgerows, mixed scrub, or developed land).

• • Surface Areas and Lengths: Accurately measuring each parcel of land or linear feature (like hedgerows and watercourses) in hectares or kilometres using GIS mapping software.

• • Habitat Condition: Assessing the ecological quality of each habitat (from “Poor” to “Good”) against strict statutory criteria set by Defra.

• • Protected Species Potential: Flagging any features (such as veteran trees, ponds, or buildings) that might require further protected species consideration.

Can I Complete the BNG Metric Myself if I Have an Existing Habitat Appraisal?

One of the most common questions we get from planning agents, architects, and hands-on developers is: “Can I just pay an ecologist for the Existing Habitat Appraisal, and then fill in the Biodiversity Metric spreadsheet myself?”

The short answer is: Sometimes, yes—especially on small sites—but there are traps to watch out for.

1. 1. The Small Sites Metric (SSM): If your development qualifies as a “small site” and no priority habitats or protected species are present, you do not strictly need an ecologist to fill out the final Small Sites Metric calculation. However, getting the baseline habitat identification wrong is the number one reason BNG submissions get rejected by North Somerset Council. Having a qualified ecologist conduct your Existing Habitat Appraisal gives you rock-solid baseline data to plug into the metric.

1. 1. The Statutory (Main) Biodiversity Metric: For larger sites, or sites containing complex/priority habitats, the Defra Statutory Metric must be completed by a qualified ecologist. Furthermore, every habitat requires a technical Condition Assessment sheet, which only an ecologist can reliably produce and defend to a council planning officer.

Our Flexible Approach at Southwest Environmental Limited

We know that every project budget is different. That’s why we offer two straightforward options for North Somerset planning applicants:

• • Option 1: Standalone Existing Habitat Appraisal (Baseline Only) Ideal if you or your planning architect are confident managing the Small Sites Metric yourselves, or if you just need to establish the baseline value of a site before finalising your architectural layouts. We visit the site, classify and map your habitats, complete the condition assessments, and hand over the exact baseline data you need.

• • Option 2: Full Biodiversity Net Gain (BNG) Assessment & Report If you open the Defra metric spreadsheet and decide life is too short for complex ecological trading rules, we can handle the entire process from start to finish. We’ll take our Existing Habitat Appraisal data, overlay your proposed landscaping plans, calculate your post-development biodiversity units, and produce a council-ready BNG Report and Statutory Metric file. (And if you start with Option 1 and change your mind, you can upgrade to the full report at any time!)

Why Use a Local Ecologist for North Somerset Applications?

Every Local Planning Authority (LPA) has its own nuances, validation checklists, and local ecological priorities—from the North Somerset and Mendip Bats Special Area of Conservation (SAC) consultation zones to local Nature Recovery Networks.

Because Southwest Environmental Limited works directly with North Somerset’s planning requirements, we ensure our reports use the exact terminology, mapping standards, and condition evidence that the council’s ecology team expects to see—preventing costly validation delays.